JP6051437B2 - Electronic device manufacturing method by laser heating method - Google Patents

Description

  The present invention relates to a method of manufacturing an electronic device by a laser heating method. More specifically, the present invention relates to a method of manufacturing an electronic device having a joint formed by melting, cooling, and curing a solder joint material with laser light. The present invention relates to a method for manufacturing an electronic device characterized by using a solder bonding material that is reflected on the surface and does not cause scorching on a substrate outside the irradiated region, an electronic component disposed in the vicinity, or the like.

  2. Description of the Related Art In recent years, high-density mounting substrates on which various electronic components are mounted at high density have been actively produced. Electronic components are usually mounted on a substrate by an automatic mounting process including an automatic printing machine, a component mounting mounter, a reflow furnace, and the like. However, since the electronic parts with special shapes, electronic parts with low heat resistance that cannot withstand the temperature of the automatic mounting process, and electronic parts that require repair cannot be mounted in the automatic mounting process, the local soldering method It is mounted in a later process.

  As one of the local soldering methods, there is a laser heating method using a laser beam, and there are a case where heating is performed only by heat treatment using a laser beam and a case where heating is performed using hot air or the like in combination. As a laser beam to be used, a YAG laser, a pulse laser, or the like that can obtain a large energy density and is easy to control is used. Since these laser lights are single-wavelength and coherent light, the light flux can be narrowed down to about φ0.2 mm at the present and is suitable for local heating. There is also a laser heating method that does not use flux by making the soldering atmosphere an inert gas atmosphere or a reducing gas atmosphere.

  By using these laser heating methods, it is now possible to minimize the effect of heat on the component mounting of fine pitches and the periphery of the mounting part. Although it depends on the shape of the workpiece, the use of the laser heating method is expected to increase production and improve quality compared to manual methods and conventional methods.

  As an electronic component that requires a laser heating method, there is a low heat resistant electronic component that needs to be mounted in a subsequent process after an automatic mounting process. Among them, in particular, insertion mounting parts on printed circuit boards, various sensors, surface mounting parts (SMD), chip parts, COMS sensor ICs, narrow pitch surface mounting connectors, urethane wires, optical pickups, probe cards, small speakers, The laser heating method described above is employed for mounting substrate bonding and the like. In order to reliably mount these electronic components in a short time, it is necessary to set the output of the laser beam high and irradiate the laser beam with a high energy density.

However, setting the laser output high has the following problems.
FIG. 3 is a conceptual diagram of the vicinity of a soldering location for explaining the problems of the laser soldering method according to the prior art, and FIG. 4 is an enlarged view of the main part of FIG. Referring to these figures, normally, when a soldering part is irradiated with laser light, the soldering part that is the laser irradiation part absorbs the laser light and the temperature rises, and the solder paste or thread solder supplied thereto And the like melt and spread on the substrate land electrode, the through hole, and the lead portion of the electronic component. In the process where the solder melts and spreads, the solder surface becomes mirror-like and reflects the irradiated laser beam. 3 and 4, the electronic component to be soldered is the insertion mounting component 2, and the supplied solder paste or thread solder is melted by the irradiation of the laser beam 5, and the lead pin 21 of the insertion mounting substrate 2. And the laser beam 5 is reflected on the surface of the molten solder 41 that has spread and wetted on the land electrode 11 of the substrate 1, and a part of the reflected light 52 is irradiated on the side surface of the surface-mounted component 3 that is already mounted. Yes. 3 and 4 show only the reflected light 52 applied to the surface-mounted component 3, the reflected light is applied in other directions.
When the energy density of the laser beam 5 is high, when the reflected light is irradiated to the surface mount component 3 or the like already mounted on the periphery of the laser beam, the surface mount component 3 or the like is burned out by the energy of the reflected light. May end up. In addition, if the human body is irradiated with reflected light, the human body may be damaged.

  In order to prevent burnout of other electronic components and the like due to the reflected light of the irradiated laser light, the following Patent Document 1 discloses that the laser light irradiated from the laser light irradiation portion is reflected in the irradiated region of the electronic component. A laser heating device is disclosed in which a shielding portion that blocks an optical path of reflected light is provided to prevent burning.

  Patent Document 2 below discloses a temperature sensor used for temperature measurement in order to prevent burning, a laser oscillator used for heating, and an emission head for condensing the laser light output from the laser oscillator onto a soldering object. A laser heating device is disclosed that includes a control device that controls the output of a laser oscillator so that electronic components are not burned out based on the measurement result of the infrared sensor.

JP 2012-655 A JP 2010-260093 A

  However, although Patent Document 1 clearly shows the effect of suppressing burning against laser light soldering of probe card pins or the like, a space for providing a shielding portion that blocks the irradiation angle of laser light and the optical path of reflected light is required. For some reasons, electronic components that can be used are limited, and it is difficult to apply to high-density mounting made of surface-mounted components.

  Moreover, in patent document 2, although the laser output is controlled by detecting the temperature of the laser beam heating part in real time so as to obtain an optimum temperature condition, the burnout suppression effect is achieved. There is a problem that the control device needs to be incorporated into an old device, and the device becomes complicated.

  The present invention has been made in view of the above problems, and the problem to be solved by the present invention is that an electronic component or a substrate by reflected light without any special measures on the apparatus during heat treatment by laser light. It is an object of the present invention to provide a method for manufacturing an electronic device that can prevent burning and the like.

  As a result of intensive studies and repeated experiments to solve the above problems, the present inventors have found that the average regular reflectance at 500 to 1000 nm of light incident on the joint surface of the solder material used in the laser heating method is 5 degrees. When it was in the specific range, it was unexpectedly found that the above-mentioned problems could be solved, and the present invention was completed.

That is, the present invention is as follows.
[1] A method of manufacturing an electronic device including a step of bonding at least two members to each other with a bonding material heated and melted with a laser beam, the temperature of the bonding material being raised to 250 ° C. until the temperature reaches room temperature The said method whose average regular reflectance in 500 nm-1000 nm of the light which injected 5 degree | times with respect to the surface of the junction part formed by cooling is 40% or less.

  [2] The method according to [1], wherein the bonding material is a solder bonding material including a solder component and high melting point particles having a higher melting point than the solder component.

  [3] The method according to [2], wherein the solder component is solder particles.

  [4] The method according to [2] or [3], wherein a melting point of the high melting point particles is higher than a heating temperature by the laser beam.

  [5] The solder particles are Sn particles or Sn alloy particles containing at least one metal selected from the metal group consisting of Ag, Bi, Cu, Ge, In, Sb, Ni, Zn, Pb, and Au. The method according to [3] or [4] above.

  [6] The method according to [5], wherein the solder particles are Sn alloy particles having a melting point of 200 ° C. or lower, including any of Bi, In, or Zn.

  [7] The high melting point particles include at least one metal selected from the group consisting of Ag, Bi, Cu, Ge, In, Sn, Sb, Ni, Zn, Pb, and Au, and have a melting point of 300 ° C. or higher. The method according to any one of [2] to [6] above, which is a refractory metal particle.

  [8] The method according to [7], wherein the refractory metal particles are Cu particles, Cu alloy particles, Ni particles, or Ni alloy particles.

  [9] The method according to [8], wherein the Cu alloy particles include 50 to 99% by mass of Cu.

  [10] In the above [9], the Cu alloy particles include 50 to 99% by mass of Cu and 1 to 50% by mass of at least one element selected from the group consisting of Sn, Ag, Bi, In, and Ge. The method described.

  [11] The Cu alloy particles contain Sn 13.5 to 16.5% by mass, Ag 0.1 to 11% by mass, Bi 4.5 to 5.5% by mass, In 0.1 to 5% by mass, and the balance containing Cu. The method according to [10], wherein the Cu alloy particles are Ag 0.11 to 25% by mass, Cu alloy particles containing Cu in the balance, or Sn 1 to 10% by mass and Cu alloy particles containing Cu in the balance.

  [12] The method according to any one of [2] to [6], wherein the high-melting-point particles are high-melting-point ceramic particles made of a ceramic of a compound composed of a metal element or a metalloid element and a nonmetal element.

  [13] The refractory ceramic particles are oxide particles of at least one element selected from the group consisting of Si, Al, Ca, Ti, B, Ba, Bi, P, Sr, Mg, Y, and Zr, The method according to [12] above, which is any one of nitride particles, carbide particles, boride particles, or silicide particles.

  [14] The method for manufacturing an electronic device according to any one of [1] to [13], which is performed on a substrate on which electronic components are already mounted.

  [15] The method of [2] to [14], wherein the method of supplying the solder bonding material between at least two members is any one of a screen printing method, a dispense printing method, a jet dispense printing method, or a transfer method. The method according to any one.

  [16] The electronic device is any one of a surface mounting board, an insertion type electronic component mounting board, a narrow pitch surface mounting connector, an optical pickup component, a probe card, a small speaker, a camera module, or a PoP (package on package). The method according to any one of [1] to [15].

  According to the manufacturing method of the present invention, it is possible to avoid burning of electronic parts, substrates and the like generated by reflected light of a laser beam. Therefore, according to the manufacturing method of the present invention, a laser heating method can be used for mounting various electronic components, and the degree of freedom in manufacturing electronic devices can be increased.

It is a conceptual diagram for demonstrating the laser beam soldering construction method which concerns on this Embodiment. It is a principal part enlarged view of FIG. It is a conceptual diagram for demonstrating the problem of the laser beam soldering method by a prior art. It is a principal part enlarged view of FIG. It is a graph which shows the relationship between the 5-degree regular reflectance of Examples 1-5 shown in Table 1, and Comparative Examples 1-6, and a wavelength. 4 is a photograph replacing a drawing of a component bonding portion after laser light heat treatment in Example 1. FIG. 4 is a photograph replacing a drawing of a burned-out component joint portion after laser heat treatment in Comparative Example 1;

  Hereinafter, modes for carrying out the present invention (hereinafter abbreviated as “embodiments”) will be described in detail. In addition, this invention is not limited to the following embodiment, It can implement by changing variously within the range of the summary.

  The present embodiment is a method for manufacturing an electronic device including a step of bonding at least two members to each other with a bonding material heated and melted with a laser beam, and the bonding material is heated to 250 ° C. In the above method, the average regular reflectance at 500 nm to 1000 nm of the light beam incident on the surface of the bonded portion formed by cooling to room temperature is 40% or less. The at least two members may be, for example, a substrate electrode and an electronic component electrode, or an electronic component electrode and an electronic component electrode, or a substrate electrode and a substrate electrode. The bonding material may be a solder bonding material including a solder component and high melting point particles having a higher melting point than the solder component, and the solder component may be a solder particle. Further, the melting point of the high melting point particles may be higher than the heating temperature by the laser beam.

Hereinafter, the preferable aspect of each component of the solder joint material which forms a junction part is demonstrated.
<Solder joint material>
In the solder bonding material of the present embodiment, the average regular reflectance at 500 to 1000 nm of light incident on the surface of the bonded portion formed by heating to 250 ° C. and cooling to room temperature is 40% or less. It will be. An average regular reflectance of 40% or less indicates that the irradiated laser light is irregularly reflected. By irradiating the irradiated laser light irregularly, it is possible to avoid burning an electronic component, a substrate, or the like disposed in the vicinity of the heated electronic component in the irradiated region.

  As described below, in a method of manufacturing an electronic device having a joint formed by melting, cooling, and curing a solder bonding material with a laser beam, the irradiated laser beam is a mirror-like solder surface generated when the solder melts In order to avoid scorching scorching on the substrate in the irradiated area and electronic components that are placed in close proximity to the irradiated area, the reflectivity on the mirror-like solder surface that occurs during solder melting should be specified However, it is difficult to measure the reflectance when the solder is melted. Therefore, in this embodiment, as an index of the reflectance at the time of melting the solder, for convenience, the average regular reflectance at 500 to 1000 nm of the light incident on the surface of the bonded portion after heat curing at 5 degrees. Is used. However, as will be described in the following examples, the reflectivity after heat curing and the occurrence of burnout have a clear relationship.

  Here, the regular reflectance is complete light reflection, and is that light from one direction is reflected in one other direction and goes out. According to the law of reflection, the incident angle of light and the reflection angle are the same with respect to the reflecting surface. On the other hand, the diffuse reflectance is obtained based on the amount of diffused light from a standard reflector with a known diffuse reflectance, with respect to the amount of reflected light obtained by removing specularly reflected light from the total reflected light by an optical trap. These reflectances can be measured by, for example, a commercially available ultraviolet-visible near-infrared spectrophotometer equipped with an integrating sphere unit.

  In this embodiment, in order to suppress burning of electronic components and the like by reflection of laser irradiation light, an average regular reflectance of 500 to 1000 nm, including wavelengths 808 nm and 980 nm of a laser light source normally used by a laser heating apparatus. Is preferably 40% or less, more preferably 20% or less, and still more preferably 10% or less. The reason why the laser reflected light can prevent the electronic parts from being burned out is that the specular reflectance decreases, the diffuse reflected light in the total reflected light increases, and the light energy of the specular reflected light decreases, so that It is considered that even when the reflected light is irradiated to the electronic component, the light energy is not enough to cause burning. On the other hand, if the average regular reflectance is more than 40%, the light energy of the regular reflection light cannot be sufficiently reduced, and the reflected light burns out the surrounding electronic components, substrates, and the like.

  As a means for suppressing the average specular reflectance at 500 to 1000 nm of light incident on the surface of the joint at 5 degrees in the joint after the heat curing of the solder joint material to 40% or less, the melting point is higher than that of the solder particles and the solder particles. Use of a solder bonding material containing at least one kind of high melting point particles having a high melting point. As a form of the solder bonding material of the present embodiment, a plate-like, linear, solder paste, paste-like conductive adhesive is fried, but regardless of the shape / height of the electronic component and the interval between the electronic components, the substrate A solder paste is preferable from the viewpoint of providing mounting of an electronic component in which additional supply of a solder bonding material to the electrode can be easily performed.

<Solder paste>
(Solder particles)
The solder particles used in the solder paste, which is a bonding material used in the present embodiment, mean metal particles containing Sn and having a melting point of 300 ° C. or less, and heat treatment is performed at a heat treatment peak temperature equivalent to that of a general lead-free solder paste. From this viewpoint, the melting point of the solder particles is preferably 240 ° C. or lower. From the viewpoint of forming an intermetallic compound containing Sn between the metal particles contained in the bonding material when the bonding material is heat-treated, the solder particles are Sn particles, or Sn and Ag, Au, Bi, Sn alloy particles containing at least one metal selected from the group consisting of Cu, Ge, In, Sb, Ni, Zn and Pb are preferable.

Specifically, Sn-Bi system, Sn-In system, Sn-Cu system, Sn-Zn system, Sn-Ag system, Sn-Au system, Sn-Pb system, Sn-Sb system, Sn-Bi-Ag Type, Sn-Ag-Cu type, Sn-Bi-Cu type, Sn-Zn-Bi type, Sn-Bi-In type, Sn-Ag-In type, Sn-Ag-In-Bi type, Sn-Cu- Examples thereof include Ni-based, Sn-Cu-Ni-Ge-based, and Sn-Ag-Cu-Ni-Ge-based solder particles. As a solder having a recommended heat treatment peak temperature of a solder paste as a bonding material of 230 ° C. or higher, Sn—Ag—Cu (for example, Sn-3.0Ag-0.5Cu) series or Sn—Ag (for example, Sn-3) is used. .5Ag) and Sn are preferred. Moreover, as the lead-free solder whose reflow peak temperature is 200 ° C. or lower, Sn alloy particles containing Sn and containing either Bi, In, or Zn and having a melting point of 200 ° C. or lower are preferable. Among these, Sn-58Bi and Sn-57Bi-1Ag are preferable. Here, it is possible that a specific element is mixed at an inevitable impurity concentration.
In the present specification, the melting point means the temperature of the endothermic peak top in the measurement with a differential scanning calorimeter (DSC).

  The solder particles used are not limited to one type. For example, Sn particles or Sn alloy particles containing Sn and at least one metal selected from the group consisting of Ag, Au, Bi, Cu, Ge, In, Sb, Ni, Zn, and Pb are separated. It can be used in combination with solder particles having the following composition. For example, by combining Sn particles or Sn alloy particles as the second solder particles with the first solder particles of 42Sn / 58Bi, the Bi composition of the joint after reflow can be reduced. In general, Bi exhibits mechanically fragile characteristics, so that the Bi composition after reflow can be reduced by further using the Sn particles or Sn alloy particles, which leads to improvement in brittleness.

(High melting point metal particles)
The refractory metal particles used as the refractory particles having a melting point higher than that of the solder particles preferably include at least one metal particle having a melting point of 300 ° C. or higher. Thereby, a metal bond can be appropriately formed between the solder particles and the refractory metal particles, and good conductivity can be obtained. The melting point of the refractory metal particles is more preferably 350 ° C. or higher, and further preferably 400 ° C. or higher. The melting point is preferably 2000 ° C. or less, more preferably 1500 ° C. or less, from the viewpoint of lowering the necessary heat treatment temperature in the process of producing high melting point metal particles by atomization or the like.

  The refractory metal particles contain at least one metal selected from the group consisting of Ag, Bi, Cu, Ge, In, Sn, Sb, Ni, Zn, Pb, and Au, and have a melting point of 300 ° C. or higher. Preferably there is. From the viewpoint of metal diffusibility between molten solder particles and refractory metal particles, the refractory metal particles include Cu particles, Ni particles, or alloy particles containing Cu or Ni (both Cu alloy particles and Ni alloy particles, respectively). Is preferred).

  The Cu alloy particles are preferably Cu alloy particles containing Cu and at least one metal selected from the group consisting of In, Ni, Sn, Bi, Ag and Ge. In and Ni have the effect of refining the crystal grains of the Cu-Sn intermetallic compound formed at the interface between the melted solder and the Cu alloy particles, so that the Cu alloy particles contain In or Ni. Is preferred. From the viewpoint of forming a stable alloy phase, the total content of In and Ni in the Cu alloy particles is preferably 0.10 to 10% by mass, more preferably 0.50 to 8.0% by mass, and still more preferably. It is 1.0-6.0 mass%. Since Sn and Bi have good wettability with molten solder, it is preferable to contain Sn and / or Bi in an amount of 50% by mass or less in total in the Cu alloy particles. From the viewpoint of obtaining good wettability, the total content of Sn and Bi is preferably 10% by mass or more, more preferably 15% by mass or more. Moreover, Ag is preferable from the viewpoint of forming a joint having heat resistance because it easily forms an Sn component of molten solder and an intermetallic compound having a high melting point.

  From the viewpoint of reducing the resistance of the solder joint and improving the electrical characteristics, the Cu alloy particles preferably contain 95% by mass or less and contain Ag. In this case, the content of Ag in the Cu alloy particles is preferably 50% by mass or less from the viewpoint of cost. The content of Ag is preferably 2% by mass or more, more preferably 5% by mass or more, from the viewpoint of obtaining a favorable effect of improving electrical characteristics. Since Ge is preferentially oxidized when the solder is melted and has an effect of suppressing oxidation of other solder components such as Sn, it is preferably contained in Cu alloy particles by 0.10% by mass or more. From the viewpoint of preventing the oxide from inhibiting the solder flow and adversely affecting the bondability, the Ge content is preferably 5.0% by mass or less. In a more preferred embodiment, the Cu alloy particles are composed of Ag 0.1 to 11% by mass, Bi 4.5 to 5.5% by mass, In 0.1 to 5% by mass, Sn 13.5 to 16.5% by mass, and the balance Cu. Can be included.

  Moreover, it is preferable that Ni alloy particle contains Sn from a viewpoint of improving the wettability with the molten solder. Furthermore, the Ni alloy particles are preferably alloy particles containing Ni and In or Bi from the viewpoint of improving the bondability at a low temperature. It is possible that a specific element is mixed in at an inevitable impurity concentration.

  In the mixed powder of solder particles and refractory metal particles, the mixing ratio of the solder particles with respect to 100 parts by mass of the refractory metal particles is the viewpoint of the average regular reflectance at 500 to 1000 nm of the light beam incident on the joint surface 5 degrees. From the viewpoint of the initial joining state, the lower limit is preferably 55 parts by mass or more.

  The shape and size of the solder particles and refractory metal particles can be determined according to the application. In solder paste applications, it is preferable to use particles having a relatively high sphericity with an average particle diameter of 2 to 40 μm in consideration of printability. For conductive adhesive applications, it is preferable to use irregularly shaped particles in order to increase the contact area of the particles. In addition, the “average particle diameter” in the present specification means a value measured by a laser diffraction particle size distribution measuring device.

  The particle size distribution of the solder particles and the refractory metal particles can be determined according to the paste application. For example, in screen printing applications, emphasis is placed on plate loss and the particle size distribution is preferably broad. In dispensing applications, it is preferable to emphasize discharge fluidity and sharpen the particle size distribution.

(High melting point ceramic particles)
The high-melting-point ceramic particles used as the high-melting-point particles having a melting point higher than that of the solder particles are composed of a compound of a metal element or a semimetal element and a nonmetal element. The metal element is not particularly limited as long as it can form ceramics. For example, Al, Ti, Zr, Cr, Ta, Nb, and the like can be used. These metal elements can be used alone or in combination of two or more. The metalloid element is not particularly limited as long as it can form ceramics. For example, Si, B, or the like can be used. On the other hand, examples of nonmetallic elements that form compounds with these metal elements or metalloid elements include C, N, and O. Specific examples of compounds of these metal elements or metalloid elements and nonmetal elements include alumina (aluminum oxide), titania (titanium oxide), zirconia (zirconium oxide), chromium oxide, tantalum oxide, niobium oxide, and silica (oxidation). Silicon), oxides such as boron oxide; nitrides such as titanium nitride, zirconium nitride, boron nitride, silicon nitride; carbides such as titanium carbide, zirconium carbide, chromium carbide, tantalum carbide, niobium carbide, silicon carbide, boron carbide, etc. Is mentioned.

  Although each of the above compounds has a different crystal system depending on the type (for example, alumina, titania, etc.), any crystal system can be used in the present embodiment. For example, alumina includes α-alumina, β-alumina, γ-alumina, etc., any of which can be used. Moreover, the ceramic which consists of said each compound may contain the other compound for the purpose of improving the stability. For example, when silicon nitride ceramics is used as the ceramic, alumina or yttria may be added as an auxiliary agent. The surface of the ceramic particles made of each of the above compounds may be coated in advance with a dispersant to prevent aggregation. As the types of dispersants, there are polymer type dispersants, surfactant type dispersants (low molecular type dispersants), inorganic type dispersants, etc., but these may be used alone or in combination with a plurality of components. Good. Specific examples of the polymeric dispersant include polycarboxylic acid, naphthalene sulfonic acid formalin condensation, polyethylene glycol, polycarboxylic acid partial alkyl ester, polyether, polyalkylene polyamine, and the like. Specific examples of the surfactant type dispersant (low molecular weight type dispersant) include alkyl sulfonic acid type, quaternary ammonium type, higher alcohol alkylene oxide type, polyhydric alcohol ester type, alkyl polyamine type and the like. Specific examples of the inorganic dispersant include polyphosphate sodium tripolyphosphate.

  In the mixed powder of solder particles and high melting point ceramic particles, the mixing ratio of solder particles with respect to 100 parts by weight of high melting point semi-lux particles is the average regular reflectance at 500 to 1000 nm of light incident on the joint surface 5 degrees. From the viewpoint, the solder particles are 400 parts by mass or less, while the lower limit can be 55 parts by mass or more from the viewpoint of the initial bonded state.

  The shape and size of the solder particles and the high melting point ceramic particles can be determined according to the application. In solder paste applications, it is preferable to use particles having a relatively high sphericity with an average particle diameter of 2 to 40 μm in consideration of printability. In addition, the “average particle diameter” in the present specification means a value measured by a laser diffraction particle size distribution measuring device.

  The particle size distribution of the solder particles and the high melting point ceramic particles can be determined according to the paste application. For example, in screen printing applications, emphasis is placed on plate loss and the particle size distribution is preferably broad. In dispensing applications, it is preferable to emphasize discharge fluidity and sharpen the particle size distribution.

(Other ingredients)
The solder bonding material may further include various optional components for improving paste characteristics in addition to the solder particles, the high melting point particles, and the flux. Examples of such components include thixotropic agents, antifoaming agents, antioxidants, solvents, halogen compound activators, inorganic fillers, and the like.

(Thixotropic agent)
As the thixotropic agent, any thixotropic agent conventionally used as a flux of Pb-free solder can be used, and examples thereof include castor oil, hydrogenated castor oil, and sorbitol-based thixotropic agents.

(Inorganic filler)
The solder bonding material may further contain an inorganic filler separately from the high melting point ceramic particles used for the high melting point particles. Examples of the inorganic filler include ceramic particles such as silica particles. By adding the inorganic filler, for example, when the electronic component and the substrate are bonded with a solder bonding material, the difference in linear expansion coefficient between the electronic component and the bonding portion can be reduced.

<Electronic Device Using Manufacturing Method of the Present Embodiment>
The electronic device that can be manufactured by the manufacturing method of the present embodiment includes a component mounting substrate in which a substrate electrode and an electronic component electrode are bonded, a stacked electronic component in which an electronic component electrode and an electronic component electrode are bonded, or a substrate electrode and a substrate It includes a laminated substrate to which electrodes are joined.

The electronic device manufacturing method according to the present embodiment can avoid burning of a substrate, an electronic component, or the like due to laser reflected light during manufacturing. Such electronic devices include sensor modules, photoelectric modules, unipolar transistors, MOS, FET, CMOS, memory cells, FC (Field Complementary) chips, their integrated circuit components (IC), LSIs of various scales, etc. Most of them include electronic circuits as functional elements.
More specific electronic devices include a surface mount substrate, an insertion type electronic component mounting substrate, a narrow pitch surface mount connector, an optical pickup component, a probe card, a small speaker, a camera module, and PoP (package on package).

  In addition, the manufacturing method according to the present embodiment is an electronic device in which a normal electronic component is primarily mounted by reflow heat treatment at a normal 250 ° C. peak, and then an optical component having low heat resistance is secondarily mounted by laser heat treatment. The effect of preventing burning of components and boards can be achieved.

  As a coating method in the case of using a solder paste as a bonding material in the manufacturing method of the present embodiment, general known techniques such as a screen printing method, a dispensing method, a jet dispensing method, and a transfer method can be used. Dispensing method and jet dispensing method are suitable as methods for applying solder paste to secondary mounting of optical components with low heat resistance on an already mounted substrate that has already been mounted by laser heat treatment. By combining with the bonding material used in the manufacturing method of this form, it is possible to manufacture an optical component having low heat resistance with a high yield with secondary mounting while preventing burning of electronic components, substrates and the like generated by laser heating.

EXAMPLES Hereinafter, although an Example demonstrates this invention concretely, this invention is not limited to this.
The average particle diameter of each metal particle was determined as an average particle diameter value by measuring a volume integrated average value with a laser diffraction particle size distribution measuring device “HELOS & RODOS” manufactured by Sympatec (Germany).
The melting point of the solder particles was measured using “DSC-60” manufactured by Shimadzu Corporation under a nitrogen atmosphere at a temperature increase of 10 ° C./min, and the melting point obtained according to JIS Z3198-1 for the lowest endothermic peak. did. When the endothermic amount was quantified, those with 1.5 J / g or more were regarded as peaks derived from the measurement object, and peaks less than that were excluded from the viewpoint of analysis accuracy.
The specular reflectance of the solder surface after heat-curing is measured using a 5-degree reflection measurement unit made by Asahi Spectrometer Co., Ltd. The measurement was performed by using a high-speed spectroscopic unit HSU-100S manufactured by Asahi Spectroscopic Co., Ltd. A halogen light source was used as the light source. In actual measurement, prior to measurement of the sample, the reference light is measured using a specular reflection standard plate, and then the specular reflectance is measured in the range of 500 to 1000 nm by exchanging with the sample. The average regular reflectance at 1000 nm was calculated.

[Example 1]
(1) Solder particles As the solder particles, solder powder Sn having a particle size of 15 to 25 μm (element composition: Sn: 100% by mass) manufactured by Yamaishi Metal Co., Ltd. was used. When the average particle size of the solder particles was measured with a laser diffraction particle size distribution analyzer (HELOS & RODOS), the average particle size was 21 μm. The solder particles were measured with a differential scanning calorimeter (Shimadzu Corporation: DSC-50) in a nitrogen atmosphere at a temperature rising rate of 10 ° C./min. An endothermic peak (melting point) was detected. In addition, the melting point of the solder in this specification is based on the measurement result of the endothermic peak by the DSC.

(2) High melting point metal particles The production method of the high melting point metal particles was as follows: Cu 6.5 kg (purity 99% by mass or more), Sn 1.5 kg (purity 99% by mass or more), Ag 1.0 kg (purity) 99 mass% or more), Bi 0.5 kg (purity 99 mass% or more), and In 0.5 kg (purity 99 mass% or more) (that is, the target element composition is Cu: 65 mass%, Sn: 15 mass%, Ag: 10 Mass%, Bi: 5 mass%, and In: 5 mass%) were placed in a graphite crucible and heated and melted to 1400 ° C. with a high-frequency induction heating apparatus in a helium atmosphere of 99 volume% or more. Next, this molten metal is introduced into the spray tank in the helium gas atmosphere from the tip of the crucible, and then helium gas (purity 99 volume% or more, oxygen concentration 0.1 volume) from a gas nozzle provided in the vicinity of the crucible tip. A high-melting-point metal particle was produced by ejecting a pressure of less than% and a pressure of 2.5 MPa). The cooling rate at this time was 2600 ° C./second. The first metal particles were classified using an airflow classifier (Nisshin Engineering: TC-15N) at a setting of 5 μm, and after collecting the large particles, they were classified again at a setting of 30 μm, and the small particles were collected. The recovered alloy particles were measured with a laser diffraction particle size distribution analyzer (HELOS & RODOS), and the average particle size was 11.2 μm.

(3) Preparation of solder paste The Cu alloy particles and Sn particles were mixed at a weight ratio of 100: 186 to obtain a metal filler. Next, 90.7% by mass of a metal filler and 9.3% by mass of a rosin-based flux are mixed, and a solder softener “SPS-1” manufactured by Malcolm Co., Ltd., a defoaming kneader “SNB-350” manufactured by Matsuo Sangyo Co., Ltd. A solder paste was prepared in sequence.

(4) Regular reflectance measurement of the bonding material surface after heat-curing The solder paste is 30 mm × 30 mm × 0.1 mmt on the entire Cu-clad substrate made of a high heat-resistant epoxy resin glass cloth having a size of 50 mm × 50 mm and a thickness of 1.0 mm. After printing by size, a sample was prepared by reflow heat treatment at a peak temperature of 250 ° C. in a nitrogen atmosphere.
The heat treatment apparatus used was a reflow simulator “SRS-1C” manufactured by Malcolm Corporation. The temperature profile was raised from the start of heat treatment (room temperature) to 140 ° C. at 1.5 ° C./second, gradually increased from 140 ° C. to 170 ° C. over 110 seconds, and then from 170 ° C. to 250 ° C. The temperature was raised at a rate of 0.0 ° C./second, and the conditions were maintained at a peak temperature of 250 ° C. for 15 seconds.
When this sample was measured using a 5-degree reflection measurement unit manufactured by Asahi Spectrometer Co., Ltd., and the regular reflectance incident at 5 degrees on the solder surface was measured in the range of 500 to 1000 nm, the measurement results shown in FIG. 5 were obtained. . At this time, the average value of the regular reflectance in the range of 500 to 1000 nm (average regular reflectance) was 6.4%. In addition, it was also found that a plurality of regular reflectance peaks observed in the region of 800 to 1000 nm in the regular reflectance measurement results were bright lines derived from a halogen light source used as a light source at the time of measurement.

(5) Component mounting by laser heat treatment and confirmation of burnout 1005 size 0Ω resistance component (1005R) was mounted using the above solder paste, and then subjected to laser heat treatment to produce 1005R, 45 daisy chains. . For the printing of the solder paste, a screen printing machine manufactured by Micro Tech Co., Ltd. (MT-320TV) was used. The printing mask is made of metal, and the squeegee is made of urethane. The mask has a printing opening size of 400 μm × 500 μm and a thickness of 0.08 mm in accordance with the 1005R electrode portion. The printing conditions were a speed of 50 mm / second, a printing pressure of 0.1 MPa, a squeegee pressure of 0.2 MPa, a back pressure of 0.1 MPa, an attack angle of 20 °, a clearance of 0 mm, and a printing frequency of once. For mounting 1005 parts, YV100 manufactured by Yamaha Motor Co., Ltd. was used.

For laser heat treatment, a fine laser soldering apparatus MLS-808CS manufactured by Subaru Optoelectronics Co., Ltd. was used. The laser beam shape was a square shape, and the irradiation area was 400 μm × 300 μm in consideration of the electrode size. Further, the laser was a 808 nm semiconductor CW laser, and was irradiated for 1.5 seconds while increasing the amount of current from 8A to 19A. The laser output at 19 A was 2.7 W.
After irradiating the component electrode part of the 1005R mounting part with laser and performing heat treatment, there are no burnout parts around the mounting part, or a total of 90 parts of 45 1005R electrode parts are manufactured by KEYENCE CORPORATION. It was confirmed by magnifying 200 times with Scope VHX-500. As a result, as shown in FIG. 6, no burnout was observed in the 1005R electrode portion after the laser heating, and all the joint portions of 1005R parts were confirmed, but the number of burnouts was zero. The evaluation results are shown in Table 1 below.

[Comparative Example 1]
The composition of the solder particles and the high melting point particles was fixed to the metal species shown in Table 1, and the mixing ratio of the solder particles and the high melting point particles was changed to a solder paste containing only the solder particles as shown in Table 1. Each evaluation was performed under the same conditions as in 1. As a result of measuring the regular reflectance by the same method as in Example 1, the average value of the regular reflectance (average regular reflectance) in the range of 500 to 1000 nm was 84.2%. Next, laser heat treatment was performed in the same manner as in Example 1, and the presence or absence of burnout was confirmed by enlarging the 1005R electrode portion. As shown in FIG. 7, burnout was found on the substrate close to the component mounting portion. It was. When all the joints of 1005R parts were confirmed, the number of burnouts was 78, and the burnout rate was 86.7%.

[Examples 2 to 5, Comparative Examples 2 to 6]
Each evaluation was performed under the same conditions as in Example 1 except that the composition of the solder particles and the high melting point particles was fixed to the metal species shown in Table 1 and the mixing ratio of the solder particles and the high melting point particles was changed as shown in Table 1. Carried out. FIG. 5 and Table 1 show the evaluation results.

<Relationship between average regular reflectance of solder surface and burnout caused by laser heat treatment>
From the results of Examples 1 to 5 and Comparative Examples 1 to 6 in Table 1, by changing the mixing ratio of the solder particles with respect to 100 parts by mass of the refractory metal particles, 500 to 1000 nm of the solder surface after heat curing. It can be seen that the average regular reflectance is lower, and the lower the mixing ratio of the solder particles to the refractory metal particles, the lower the average regular reflectance. On the other hand, when the burnout portion around the component electrode after the laser heat treatment was examined, it was found that the more solder particles with respect to the high melting point particles, the more burnout occurred. That is, it can be seen that the smaller the mixing ratio of the solder particles with respect to the high melting point particles, the less the burning damage occurs. If the solder particles are 500 parts by mass or less with respect to 100 parts by mass of the high melting point particles, no burning occurs. I understand. From these results, it was found that if the average regular reflectance is 40% or less, burning by laser heat treatment can be prevented. The reason why burnout can be prevented is that the average specular reflectance decreases, so that the light energy output from the laser diffuses, and the light energy of each diffusely reflected light is reduced to a level that does not cause burnout. It is thought that it is because it is doing.

[Examples 6 to 10, Comparative Examples 7 to 11]
(1) Solder Particles As in the case of Example 1, solder powder Sn having a particle size of 15 μm to 25 μ (element composition is Sn: 100% by mass) manufactured by Yamaishi Metal Co., Ltd. was used.

(2) High melting point metal particles The high melting point metal particles were produced in the same manner as in Example 1. The high melting point metal particles are classified using an airflow classifier (Nisshin Engineering Co., Ltd .: TC-15N) at a setting of 1.6 μm, and after collecting the large particle side, it is classified again at a setting of 10 μm to obtain small particles. The target refractory metal particles were obtained by collecting the side. The collected alloy particles were measured with a laser diffraction particle size distribution analyzer (HELOS & RODOS), and the average particle size was 2.3 μm.

(3) Preparation of solder paste The Cu alloy particles and Sn particles were mixed at a weight ratio shown in Table 2 to obtain a metal filler. Next, a solder paste was prepared in the same procedure as in Example 1.

(4) Regular reflectance measurement of bonding material surface after heat curing The regular reflectance was measured by the same method as in Example 1 using the prepared solder paste.

(5) Component mounting by laser heat treatment and confirmation of burnout Laser heat treatment and confirmation of burnout were performed in the same manner as in Example 1 using the prepared solder paste. The results are shown in Table 2 below.

<Relationship between average regular reflectance of solder surface and burnout caused by laser heat treatment>
From the results of Examples 6 to 10 and Comparative Examples 7 to 11 in Table 2, by changing the mixing ratio of the solder particles with respect to 100 parts by mass of the refractory metal particles, 500 to 1000 nm of the solder surface after heat curing. It can be seen that the average regular reflectance is lower, and the lower the mixing ratio of the solder particles to the refractory metal particles, the lower the average regular reflectance. On the other hand, when the burnout portion around the component electrode after the laser heat treatment was examined, it was found that the more solder particles with respect to the high melting point particles, the more burnout occurred. That is, it can be seen that the smaller the mixing ratio of the solder particles with respect to the high melting point particles, the less the burning damage occurs. If the solder particles are 500 parts by mass or less with respect to 100 parts by mass of the high melting point particles, no burning occurs. I understand. From these results, it was found that if the average regular reflectance is 40% or less without depending on the average particle diameter of the high melting point particles, it is possible to prevent burning by laser heat treatment.

[Examples 11 to 17, Comparative Examples 12 to 13]
(1) Solder particles As the solder particles, solder powder Sn having a particle size of 15 μm to 25 μm (element composition: Sn: 100% by mass) manufactured by Yamaishi Metal Co., Ltd. was used in the same manner as in Example 1.

(2) High melting point metal particles The high melting point metal particles were produced in the same manner as in Example 1. The high melting point metal particles are classified using an airflow classifier (Nisshin Engineering Co., Ltd .: TC-15N) at a setting of 30 μm. After collecting the large particles, they are classified again at a setting of 50 μm. The intended refractory metal particles were obtained by collection. When the collected alloy particles were measured with a laser diffraction particle size distribution analyzer (HELOS & RODOS), the average particle size was 26.9 μm.

(3) Preparation of solder paste The Cu alloy particles and Sn particles were mixed at a weight ratio shown in Table 3 to obtain a metal filler. Next, a solder paste was prepared in the same procedure as in Example 1.

(4) Regular reflectance measurement of bonding material surface after heat curing The regular reflectance was measured by the same method as in Example 1 using the prepared solder paste.

(5) Component mounting by laser heat treatment and confirmation of burnout Laser heat treatment and confirmation of burnout were performed in the same manner as in Example 1 using the prepared solder paste. The results are shown in Table 3 below.

<Relationship between average regular reflectance of solder surface and burnout caused by laser heat treatment>
From the results of Examples 11 to 17 and Comparative Examples 12 to 13 in Table 3, by changing the mixing ratio of the solder particles with respect to 100 parts by mass of the refractory metal particles, 500 to 1000 nm of the solder surface after heat curing. It can be seen that the average regular reflectance is lower, and the lower the mixing ratio of the solder particles to the refractory metal particles, the lower the average regular reflectance. On the other hand, when the burnout portion around the component electrode after the laser heat treatment was examined, it was found that the more solder particles with respect to the high melting point particles, the more burnout occurred. That is, it can be seen that the smaller the mixing ratio of the solder particles with respect to the high melting point particles, the less the burning damage occurs. If the solder particles are 1900 parts by mass or less with respect to 100 parts by mass of the high melting point particles, no burning occurs. I understand. From these results, it was found that if the average regular reflectance is 40% or less without depending on the average particle diameter of the high melting point particles, it is possible to prevent burning by laser heat treatment.

[Examples 18 to 21, Comparative Examples 14 to 18]
(1) Solder particles As the solder particles, solder powder Sn having a particle size of 15 μm to 25 μm (element composition: Sn: 100% by mass) manufactured by Yamaishi Metal Co., Ltd. was used in the same manner as in Example 1.

(2) High melting point metal particles As the high melting point metal particles, Cu powder Cu-HWQ 15 μm manufactured by Fukuda Metal Foil Powder Co., Ltd. was used. When this Cu particle was measured with a laser diffraction particle size distribution analyzer (HELOS & RODOS), the average particle size was 15.0 μm.

(3) Preparation of solder paste The Cu particles and Sn particles were mixed at a weight ratio shown in Table 4 below to obtain a metal filler. Next, a solder paste was prepared in the same procedure as in Example 1.

(4) Regular reflectance measurement on the surface of the bonding material after heat curing The regular reflectance was measured by the same method as in Example 1 using the prepared solder paste.

(5) Component mounting by laser heat treatment and confirmation of burnout Laser heat treatment and confirmation of burnout were performed in the same manner as in Example 1 using the prepared solder paste. The results are shown in Table 4 below.

<Relationship between average regular reflectance of solder surface and burnout caused by laser heat treatment>
From the results of Examples 18 to 21 and Comparative Examples 14 to 18 in Table 4, by changing the mixing ratio of the solder particles with respect to 100 parts by mass of the refractory metal particles, 500 to 1000 nm of the solder surface after heat curing. It can be seen that the average regular reflectance is lower, and the lower the mixing ratio of the solder particles to the refractory metal particles, the lower the average regular reflectance. On the other hand, when the burnout portion around the component electrode after the laser heat treatment was examined, it was found that the more solder particles with respect to the high melting point particles, the more burnout occurred. That is, it can be seen that the smaller the mixing ratio of the solder particles with respect to the high melting point particles, the less the burning damage occurs. If the solder particles are 400 parts by mass or less with respect to 100 parts by mass of the high melting point particles, no burning occurs. I understand. From these results, it has been found that if the average regular reflectance is 40% or less without depending on the composition of the high melting point particles and the average particle diameter, burning by laser heat treatment can be prevented.

[Examples 22 to 27, Comparative Examples 19 to 21]
(1) Solder particles As the solder particles, solder powder Sn having a particle size of 15 μm to 25 μm (element composition: Sn: 100% by mass) manufactured by Yamaishi Metal Co., Ltd. was used in the same manner as in Example 1.

(2) Refractory Metal Particles Ni powder SFR-Ni 10 μm manufactured by Nippon Atomizing Co., Ltd. was used as the refractory metal particles. When this Ni particle was measured with a laser diffraction particle size distribution analyzer (HELOS & RODOS), the average particle size was 10.1 μm.

(3) Preparation of solder paste The Ni particles and Sn particles were mixed at a weight ratio shown in Table 5 below to obtain a metal filler. Next, a solder paste was prepared in the same procedure as in Example 1.

(4) Regular reflectance measurement on the surface of the bonding material after heat curing The regular reflectance was measured by the same method as in Example 1 using the prepared solder paste.

(5) Component mounting by laser heat treatment and confirmation of burnout Laser heat treatment and confirmation of burnout were performed in the same manner as in Example 1 using the prepared solder paste. The results are shown in Table 5 below.

<Relationship between average regular reflectance of solder surface and burnout caused by laser heat treatment>
From the results of Examples 22 to 27 and Comparative Examples 19 to 21 in Table 5, by changing the mixing ratio of the solder particles with respect to 100 parts by mass of the refractory metal particles, 500 to 1000 nm of the solder surface after heat curing. It can be seen that the average regular reflectance is lower, and the lower the mixing ratio of the solder particles to the refractory metal particles, the lower the average regular reflectance. On the other hand, when the burnout portion around the component electrode after the laser heat treatment was examined, it was found that the more solder particles with respect to the high melting point particles, the more burnout occurred. That is, it can be seen that the smaller the mixing ratio of the solder particles with respect to the high melting point particles, the less the burning damage occurs. If the solder particles are 900 parts by mass or less with respect to 100 parts by mass of the high melting point particles, no burning occurs. I understand. From these results, it has been found that if the average regular reflectance is 40% or less without depending on the composition of the high melting point particles and the average particle diameter, burning by laser heat treatment can be prevented.

[Examples 28 to 31, Comparative Examples 22 to 26]
(1) Solder particles As the solder particles, solder powder Sn having a particle size of 15 μm to 25 μm (element composition: Sn: 100% by mass) manufactured by Yamaishi Metal Co., Ltd. was used in the same manner as in Example 1.

(2) High-melting-point ceramic particles As high-melting-point ceramic particles, Al ₂ O ₃ powder Admafine AC9500-SI manufactured by Admatechs Co., Ltd. was used. When the Al ₂ O ₃ particles were measured with a laser diffraction particle size distribution analyzer (HELOS & RODOS), the average particle size was 8.4 μm.

(3) Preparation of solder paste The Al ₂ O ₃ particles and Sn particles were mixed at a weight ratio shown in Table 6 below to obtain a metal filler. Next, a solder paste was prepared in the same procedure as in Example 1.

(4) Regular reflectance measurement on the surface of the bonding material after heat curing The regular reflectance was measured by the same method as in Example 1 using the prepared solder paste.

(5) Component mounting by laser heat treatment and confirmation of burnout Laser heat treatment and confirmation of burnout were performed in the same manner as in Example 1 using the prepared solder paste. The results are shown in Table 6 below.

<Relationship between average regular reflectance of solder surface and burnout caused by laser heat treatment>
From the results of Examples 28 to 31 and Comparative Examples 22 to 26 in Table 6, by changing the mixing ratio of the solder particles with respect to 100 parts by mass of the refractory metal particles, 500 to 1000 nm of the solder surface after heat curing. It can be seen that the average regular reflectance is lower, and the lower the mixing ratio of the solder particles to the refractory metal particles, the lower the average regular reflectance. On the other hand, when the burnout portion around the component electrode after the laser heat treatment was examined, it was found that the more solder particles with respect to the high melting point particles, the more burnout occurred. That is, it can be seen that the smaller the mixing ratio of the solder particles with respect to the high melting point particles, the less the burning damage occurs. If the solder particles are 400 parts by mass or less with respect to 100 parts by mass of the high melting point particles, no burning occurs. I understand. From these results, it has been found that if the average regular reflectance is 40% or less without depending on the composition of the high melting point particles and the average particle diameter, burning by laser heat treatment can be prevented.

[Examples 32-39]
(1) Solder Particles For the Sn0.7Cu of Example 32, solder particles having a particle size of 10 to 25 μm and an average particle size of 21.2 μm were used. Sn0.3Ag0.7Cu of Example 33 having a particle size of 20 to 38 μm and an average particle size of 29.8 μm was used. For Sn3.0Ag0.5Cu of Example 34, one having a particle size of 10 to 25 μm and an average particle size of 22.0 μm was used. Sn3.5Ag of Example 35 having a particle size of 10 to 25 μm and an average particle size of 22.0 μm was used. For Sn4.0Ag0.5Cu of Example 36, one having a particle size of 10 to 25 μm and an average particle size of 21.8 μm was used. Sn58Bi of Example 37 having a particle size of 25 to 38 μm and an average particle size of 25.6 μm was used. Pb5Sn of Example 38 having a particle size of 25 to 38 μm and an average particle size of 28.9 μm was used. In Pb63Sn of Example 39, one having a particle size of 25 to 38 μm and an average particle size of 32.5 μm was used.

(2) High melting point metal particles The high melting point metal particles were produced in the same manner as in Example 1. The refractory metal particles are classified using an airflow classifier (Nisshin Engineering: TC-15N) at a setting of 5 μm, and after collecting the large particles, they are classified again at a setting of 30 μm, and the small particles are collected. The intended refractory metal particles were obtained by collection. When the collected alloy particles were measured with a laser diffraction particle size distribution analyzer (HELOS & RODOS), the average particle size was 11.2 μm.

(3) Preparation of Solder Paste The refractory metal particles and Sn particles were mixed at the weight ratios shown in Table 7 below to obtain metal fillers. Next, a solder paste was prepared in the same procedure as in Example 1.

(4) Regular reflectance measurement on the surface of the bonding material after heat curing The regular reflectance was measured by the same method as in Example 1 using the prepared solder paste.

(5) Component mounting by laser heat treatment and confirmation of burnout Laser heat treatment and confirmation of burnout were performed in the same manner as in Example 1 using the prepared solder paste. The results are shown in Table 7 below.

<Relationship between average regular reflectance of solder surface and burnout caused by laser heat treatment>
From the results of Examples 32 to 39 in Table 7, when the mixing ratio of the solder particles is fixed to 186 parts by mass with respect to 100 parts by mass of the refractory metal particles, the average regular reflection of 500 to 1000 nm on the solder surface after heat curing. The rate was 5% or less, and it was found that there was almost no change regardless of the composition of the solder particles. On the other hand, when the burnout portion around the component electrode after the laser heat treatment was examined, it was found that no burnout occurred in the vicinity of any component. From these results, it has been found that if the average regular reflectance is 40% or less without depending on the composition of the solder particles and the average particle diameter, burning due to laser heat treatment can be prevented.

[Examples 40 to 62]
(1) Solder particles As the solder particles, solder powder Sn having a particle size of 15 μm to 25 μm (element composition: Sn: 100% by mass) manufactured by Yamaishi Metal Co., Ltd. was used in the same manner as in Example 1.

(2) Refractory metal particles The refractory metal particles were produced under the same atomizing conditions as in Example 1. In addition, atomization was performed with the composition of refractory metal particles as shown in Table 8 below. High melting point metal particles are classified using an airflow classifier (Nisshin Engineering Co., Ltd .: TC-15N) at a setting of 5 μm. After collecting the large particles, they are classified again at a setting of 30 μm, and the small particles are collected. As a result, target high melting point metal particles were obtained. The collected alloy particles were measured with a laser diffraction particle size distribution analyzer (HELOS & RODOS), and the average particle diameters were as shown in Table 8 below.

(3) Production of Solder Paste The refractory metal particles and Sn particles were mixed at a weight ratio shown in Table 8 below to obtain a metal filler. Next, a solder paste was prepared in the same procedure as in Example 1.

(4) Regular reflectance measurement on the surface of the bonding material after heat curing The regular reflectance was measured by the same method as in Example 1 using the prepared solder paste.

(5) Component mounting by laser heat treatment and confirmation of burnout Laser heat treatment and confirmation of burnout were performed in the same manner as in Example 1 using the prepared solder paste. The results are shown in Table 8 below.

<Relationship between average regular reflectance of solder surface and burnout caused by laser heat treatment>
From the results of Examples 40 to 62 in Table 8, when the mixing ratio of the solder particles is fixed to 186 parts by mass with respect to 100 parts by mass of the refractory metal particles, the average regular reflection of 500 to 1000 nm on the solder surface after heat curing. The rate was 6% or less, and it was found that there was almost no change regardless of the composition of the refractory metal particles. On the other hand, when the burnout portion around the component electrode after the laser heat treatment was examined, it was found that no burnout occurred in the vicinity of any component. From these results, it was found that if the average regular reflectance is 40% or less without depending on the composition and average particle diameter of the refractory metal particles, burning by laser heat treatment can be prevented.

  According to the manufacturing method of the present invention, it is possible to avoid burning of electronic parts, substrates and the like due to reflection of a laser beam. Therefore, the manufacturing method of the present invention can be suitably used for mounting various electronic components using the laser heating method, and the degree of freedom of electronic device manufacturing can be increased.

DESCRIPTION OF SYMBOLS 1 Board | substrate 2 Insertion mounting component 3 Surface mounting component 4 Solder material which concerns on this Embodiment 5 Irradiation laser beam 11 Land electrode 21 Lead pin 41 Conventional solder material 51 Scattered light 52 Reflected light

Claims (16)

  A method of manufacturing an electronic device comprising a step of bonding at least two members to each other with a bonding material heated and melted with a laser beam, wherein the bonding material is heated to 250 ° C. and cooled to room temperature. The said method that the average regular reflectance in 500 nm-1000 nm of the light ray which injected 5 degree | times with respect to the surface of the formed junction part is 40% or less.   The method according to claim 1, wherein the bonding material is a solder bonding material including a solder component and high melting point particles having a melting point higher than that of the solder component.   The method of claim 2, wherein the solder component is solder particles.   The method according to claim 2 or 3, wherein a melting point of the high melting point particles is higher than a heating temperature by the laser beam.   The solder particles are Sn particles or Sn alloy particles containing at least one metal selected from a metal group consisting of Ag, Bi, Cu, Ge, In, Sb, Ni, Zn, Pb, and Au. Item 5. The method according to Item 3 or 4.   The method according to claim 5, wherein the solder particles are Sn alloy particles having a melting point of 200 ° C. or less, including any of Bi, In, and Zn.   The high melting point particles include at least one metal selected from the group consisting of Ag, Bi, Cu, Ge, In, Sn, Sb, Ni, Zn, Pb, and Au, and have a melting point of 300 ° C. or higher. The method according to claim 2, wherein the method is a particle.   The method according to claim 7, wherein the refractory metal particles are Cu particles, Cu alloy particles, Ni particles, or Ni alloy particles.   The method according to claim 8, wherein the Cu alloy particles contain 50 to 99 mass% of Cu.   The method according to claim 9, wherein the Cu alloy particles include 50 to 99% by mass of Cu and 1 to 50% by mass of at least one element selected from the group consisting of Sn, Ag, Bi, In, and Ge.   The Cu alloy particles are Sn 13.5 to 16.5% by mass, Ag 0.1 to 11% by mass, Bi 4.5 to 5.5% by mass, In 0.1 to 5% by mass, Cu alloy particles containing Cu in the balance. Or Ag 0.11 to 25 mass%, Cu alloy particles containing Cu in the balance, or Sn 1 to 10 mass%, Cu alloy particles containing Cu in the balance.   The method according to any one of claims 2 to 6, wherein the high-melting-point particles are high-melting-point ceramic particles made of a ceramic of a compound composed of a metal element or a metalloid element and a non-metal element.   The high melting point ceramic particles include oxide particles and nitride particles of at least one element selected from the group consisting of Si, Al, Ca, Ti, B, Ba, Bi, P, Sr, Mg, Y, and Zr. The method of claim 12, wherein the method is any of carbide particles, boride particles, or silicide particles.   The manufacturing method of the electronic device of any one of Claims 1-13 performed with respect to the board | substrate with which the electronic component is already mounted.   The method for supplying the solder bonding material between at least two members is any one of a screen printing method, a dispense printing method, a jet dispense printing method, or a transfer method. the method of. The electronic device is any one of a surface mounting board, an insertion type electronic component mounting board, a narrow pitch surface mounting connector, an optical pickup component, a probe card, a small speaker, a camera module, or PoP (package on package). The method according to any one of 1 to 15.