JP2011176111A - Wiring board - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a wiring board responding to a request for improving electric reliability. <P>SOLUTION: The wiring board 3 has: a first resin layer 7a containing a first resin material and a first inorganic insulation filler 10a with a smaller coefficient of thermal expansion than that of the first resin material; and a second resin layer 7b formed on an upper surface of the first resin layer 7a, containing a second resin material and a second inorganic insulation filler 10b with a smaller coefficient of thermal expansion than that of the second resin material, and having a larger coefficient of thermal expansion in a planar direction than that of the first resin layer 7a. The first resin layer 7a has a plurality of first protrusions 7a1 on its upper surface and has the first inorganic insulation filler 10a disposed only in an area other then the first protrusions 7a1. The second resin layer 7b has a second protrusion 7b1 sandwiched between the adjacent first protrusions 7a1, and also has the second inorganic insulation filler 10b disposed in the second protrusion 7b1. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a wiring board used for electronic equipment (for example, various audiovisual equipment, home appliances, communication equipment, computer equipment and peripheral equipment).

  2. Description of the Related Art Conventionally, as a mounting structure in an electronic device, an electronic component mounted on a wiring board is used.

  Patent Document 1 describes a wiring board that includes a core substrate and an insulating resin layer formed on the core substrate, and the resin material included in the core substrate is different from the resin material included in the insulating resin layer. ing.

  In such a wiring board in which a core board and an insulating resin layer made of different resin materials are laminated, heat is applied to the wiring board by heating when mounting the electronic part on the wiring board or generating heat when operating the electronic part. In this case, thermal stress is applied to the boundary between the core substrate and the insulating resin layer due to the difference in the thermal expansion coefficient of the resin material, and the core substrate and the insulating resin layer easily peel off at the boundary.

  On the other hand, when a plurality of conductive layers separated from each other along the planar direction are partially formed between the core substrate and the insulating resin layer, they are separated from each other along the planar direction when the wiring board is used. When an electric field is applied between the conductive layers, the conductive material contained in the conductive layer is ionized due to moisture contained in the core substrate and the insulating resin layer, and a part of the conductive layer is separated along the planar direction. May extend toward (ion migration).

  Here, as described above, when the core substrate and the insulating resin layer peel at the boundary, moisture easily accumulates in the voids generated by the peeling, so that a part of the conductive layer extends along the peeled boundary. It's easy to do. Therefore, the conductive layers are easily short-circuited, and the electrical reliability of the wiring board is likely to be reduced.

JP-A-10-65340

The present invention provides a wiring board that meets the demand for improving electrical reliability.

  A wiring board according to an aspect of the present invention is formed on a top surface of a first resin layer including a first resin material and a first inorganic insulating filler having a smaller coefficient of thermal expansion than the first resin material. A second resin material and a second inorganic insulating filler having a smaller coefficient of thermal expansion than the second resin material, a second resin layer having a larger coefficient of thermal expansion in the plane direction than the first resin layer, The first resin layer has a plurality of first protrusions on an upper surface, the first inorganic insulating filler is disposed only in a region other than the first protrusions, and the second resin layer is And a second convex portion interposed between the adjacent first convex portions, and the second inorganic insulating filler is disposed in the second convex portion.

According to the wiring board according to an aspect of the present invention, the wiring board is relaxed by reducing the difference in thermal expansion coefficient between the first resin layer and the second resin layer at the boundary between the first resin layer and the second resin layer. When heat is applied to the first and second resin layers, it is possible to reduce the thermal stress applied to the boundary between the first resin layer and the second resin layer, and to reduce the separation between the first resin layer and the second resin layer. Therefore, ion migration between conductive layers spaced apart from each other along the planar direction can be reduced, and a short circuit between the conductive layers can be reduced. As a result, a wiring board excellent in electrical reliability can be obtained.

FIG. 1A is a cross-sectional view of a mounting structure according to an embodiment of the present invention, and FIG. 1B is an enlarged view of a portion R1 shown in FIG. FIG. 2A is a cross-sectional view for explaining a manufacturing process of the mounting structure shown in FIG. 1, and FIG. 2B is an enlarged view of a portion R2 shown in FIG. 3A is a cross-sectional view illustrating a manufacturing process of the mounting structure shown in FIG. 1, and FIG. 3B is an enlarged view of a portion R3 shown in FIG. FIG. 4A is a cross-sectional view illustrating a manufacturing process of the mounting structure shown in FIG. 1, and FIG. 4B is an enlarged view of the R4 portion shown in FIG. It is sectional drawing explaining the manufacturing process of the mounting structure shown in FIG.

  Hereinafter, a mounting structure including a wiring board according to an embodiment of the present invention will be described in detail based on the drawings.

  A mounting structure 1 shown in FIG. 1 is used for electronic devices such as various audiovisual devices, home appliances, communication devices, computer devices or peripheral devices thereof. The mounting structure 1 includes an electronic component 2 and a wiring board 3 on which the electronic component 2 is mounted.

  The electronic component 2 is a semiconductor element such as an IC or LSI, and is flip-chip mounted on the wiring substrate 3 via conductive bumps 4 such as solder. The base material of the electronic component 2 is formed of a semiconductor material such as silicon, germanium, gallium arsenide, gallium arsenide phosphorus, gallium nitride, or silicon carbide. As the electronic component 2, for example, one having a thickness of 0.1 mm or more and 1 mm or less can be used. The thickness of the electronic component 2 is calculated by observing the polished surface or fractured surface of the electronic component 2 with a scanning electron microscope, measuring the length along the thickness direction (Z direction) at 10 or more points, and calculating the average value. Is measured.

  The wiring substrate 3 includes a core substrate 5 and a pair of buildup portions 6 formed above and below the core substrate 5.

  The core substrate 5 is intended to increase the rigidity of the wiring substrate 3 while achieving conduction between the pair of build-up portions 6 and has a thickness of, for example, 0.05 mm or more and 0.8 mm or less. The core substrate 5 includes a first resin layer 7a, a cylindrical through hole penetrating the first resin layer 7a in the thickness direction, and a cylindrical through hole conductor 8 formed along the inner wall of the through hole. And an insulator 9 formed inside the through-hole conductor 8. The thickness of the core substrate 5 is measured in the same manner as the thickness of the electronic component 2.

  The first resin layer 7a is a main part of the core substrate 5, and includes, for example, a first resin material, a base material coated with the first resin material, and a first inorganic insulating filler contained in the resin material. 8a. The first resin layer 7a has a thermal expansion coefficient in the plane direction set to, for example, 5 ppm / ° C. or more and 50 ppm / ° C. or less, and a thermal expansion coefficient in the thickness direction set to, for example, 10 ppm / ° C. or more and 50 ppm / ° C. or less, The Young's modulus is set to, for example, 0.1 GPa or more and 15 GPa or less.

  The Young's modulus is measured using Nano Indentor XP / DCM manufactured by MTS Systems. The thermal expansion coefficient is measured by a measuring method according to JISK7197-1991 using a commercially available TMA apparatus.

  The first resin material contained in the first resin layer 7a is a main part of the first resin layer 7a, and for example, a thermoplastic resin such as a polyamide resin or an aromatic liquid crystal polyester resin can be used. By using such a thermoplastic resin, it is possible to increase the rigidity of the first resin layer 7a while reducing cracks in the first resin layer 7a.

  The first resin material has a thermal expansion coefficient in the plane direction set to, for example, 5 ppm / ° C. or more and 50 ppm / ° C. or less, and a thermal expansion coefficient in the thickness direction set to, for example, 10 ppm / ° C. or more and 100 ppm / ° C. or less. The Young's modulus is set to, for example, 0.1 GPa or more and 20 GPa or less.

  The base material coated with the resin material increases the rigidity of the first resin layer 7a and has a smaller coefficient of thermal expansion in the plane direction (XY plane direction) than in the thickness direction (Z direction). 2 to reduce the difference in thermal expansion coefficient in the plane direction, and a woven fabric or a non-woven fabric composed of fibers, or fibers arranged in one direction can be used.

  This base material has a coefficient of thermal expansion in the plane direction set to, for example, -10 ppm / ° C. or more and 7 ppm / ° C. or less, and a coefficient of thermal expansion in the plane direction is set to be, for example, 0.05 times to 1 time that of the first resin material. Set, the coefficient of thermal expansion in the thickness direction is set to, for example, 2 ppm / ° C. or more and 80 ppm / ° C. or less, and the coefficient of thermal expansion in the thickness direction is set to, for example, 0.2 to 2 times that of the first resin material, The Young's modulus is set to, for example, 30 GPa to 300 GPa, and the Young's modulus is set to, for example, 30 times to 300 times that of the first resin material.

  Moreover, as a fiber contained in this base material, glass fiber, a resin fiber, carbon fiber, a metal fiber, etc. can be used, for example.

  The first inorganic insulating filler 8a contained in the resin material has a smaller coefficient of thermal expansion in the planar direction and thickness direction than the first resin material, and reduces the coefficient of thermal expansion of the first resin layer 7a. In addition, the first resin layer 7a is increased in rigidity. For example, a material including particles formed of an inorganic insulating material such as silicon oxide, aluminum oxide, aluminum nitride, aluminum hydroxide, or calcium carbonate can be used.

  The first inorganic insulating filler 8a has a coefficient of thermal expansion in the plane direction and thickness direction of, for example, 0.5 ppm / ° C. or more and 7 ppm / ° C. or less, and the coefficient of thermal expansion in the plane direction and thickness direction is the first resin material. For example, the Young's modulus is set to, for example, 70 GPa or more and 800 GPa or less, and the Young's modulus is set to, for example, 7 times or more and 80 times or less that of the first resin material. The diameter is set to, for example, 0.1 μm to 10 μm, and the content in the first resin material is set to, for example, 5% by volume to 60% by volume.

  In addition, the particle size of the particles contained in the first inorganic insulating filler 8a includes particles of 20 particles or more and 50 particles or less when the polished surface or fracture surface of the first resin layer 7a is observed with a field emission electron microscope. It measures by imaging the cross section expanded in this way and measuring the maximum diameter of each particle | grain in this expanded cross section. In addition, the content (volume%) of the first inorganic insulating filler 8a in the resin portion of the first resin layer 7a is obtained by photographing the polished surface of the first resin layer 7a with a field emission electron microscope and using an image analyzer or the like. Then, the area ratio (area%) of the first inorganic insulating filler 8a occupying the resin portion of the first resin layer 7a is measured at 10 cross-sections, and the average value of the measured values is calculated to obtain the content (volume% ).

  The through-hole conductor 8 formed in a cylindrical shape along the inner wall of the through-hole penetrating the first resin layer 7a in the thickness direction electrically connects the upper and lower build-up portions 6 of the core substrate 5; For example, those formed of a conductive material such as copper, silver, gold, aluminum, nickel, or chromium can be used.

  The insulator 9 formed in a columnar shape inside the through-hole conductor 8 forms a support surface for a via conductor 15 to be described later with its end face and the end face of the through-hole conductor 8. For example, polyimide resin, acrylic resin, What was formed with resin materials, such as an epoxy resin, cyanate resin, a fluororesin, a silicon resin, a polyphenylene ether resin, or a bismaleimide triazine resin, can be used.

  On the other hand, the build-up portions 6 provided on both sides of the core substrate 5 include the second resin layer 7b, the first resin layer 7a or the conductive layer 11 formed on the second resin layer 7b, and the second resin layer 7b. And via conductors 12 formed inside via holes penetrating in the thickness direction. The conductive layer 11 and the via conductor 12 are electrically connected to each other to form a wiring portion, and this wiring portion includes a grounding wiring, a power supply wiring, or a signal wiring.

  The 2nd resin layer 7b is for ensuring the insulation of parts other than a wiring part in the buildup part 6, and the 2nd resin material and the 2nd inorganic insulating filler contained in this 2nd resin material 10b.

  The second resin layer 7b has a coefficient of thermal expansion in the plane direction set to, for example, 15 ppm / ° C. or more and 100 ppm / ° C. or less, and the coefficient of thermal expansion in the plane direction is, for example, 1.2 times that of the first resin layer 7a. The thermal expansion coefficient in the thickness direction is set to, for example, 10 ppm / ° C. or more and 150 ppm / ° C. or less, and the thermal expansion coefficient in the thickness direction is set to, for example, 0. It is set to 1 to 15 times, the Young's modulus is set to 0.1 GPa to 15 GPa, for example, and the Young's modulus is set to, for example, 0.006 to 150 times that of the first resin layer 7a. For example, the thickness is set to 5 μm or more and 40 μm or less. The second resin layer 7b is set to have a higher coefficient of thermal expansion in the planar direction than the first resin layer 7a.

  The second resin material contained in the second resin layer 7b is a main part of the second resin layer 7b, and for example, a thermosetting resin such as an epoxy resin or a cyanate resin can be used. By using such a thermosetting resin, the workability of the conductive layer 11 and the via conductor 12 can be improved, and the conductive layer 11 and the via conductor 12 can be formed more finely.

  This second resin material has a Young's modulus set to, for example, 0.1 GPa or more and 15 GPa or less, and a thermal expansion coefficient in the plane direction set to, for example, 15 ppm / ° C. or more and 100 ppm / ° C. or less. For example, the thermal expansion coefficient in the thickness direction is set to, for example, 10 ppm / ° C. or more and 150 ppm / ° C. or less, and the thermal expansion coefficient in the thickness direction is the first resin material. For example, it is set to 1 to 15 times that of one resin material. Note that the second resin material is set to have a higher coefficient of thermal expansion in the plane direction than the first resin material.

  Further, as a combination of the first resin material and the second resin material, for example, an aromatic liquid crystal polyester resin as the first resin material, an epoxy resin as the second resin material, or a polyamide resin as the first resin material, A combination using a cyanate resin as the two-resin material can be used.

  The second inorganic insulating filler 10b contained in the second resin material is set to have a smaller coefficient of thermal expansion than the second resin material, and reduces the coefficient of thermal expansion of the second resin layer 7b and the second resin layer 7b. This increases the rigidity. The second inorganic insulating filler 8b can be the same as the first inorganic insulating filler 10a described above, and the coefficient of thermal expansion in the plane direction and the thickness direction is, for example, 0.005 times or more that of the second resin material. .5 times or less, Young's modulus is set to, for example, 4 times or more and 8000 times or less of the second resin material, and the content in the second resin material is set to, for example, 10% by volume or more and 70% by volume or less. .

  The second inorganic insulating filler 10b contained in the second resin material is made of the same material as the first inorganic insulating filler 10a contained in the first resin material. As a result, since the difference in Young's modulus between the first resin layer 7a and the second resin layer 7b can be reduced, such stress is applied when stress is applied to the first resin layer 7a and the second resin layer 7b. It is possible to disperse stress concentrated on the interface between the first resin layer 7a and the second resin layer 7b due to the difference in rate, and thus reduce the separation of the first resin layer 7a and the second resin layer 7b at the interface. can do.

  The conductive layer 11 constitutes a wiring portion together with a via conductor 12 to be described later, and is separated from each other along the thickness direction or the planar direction via the second resin layer 7b. For example, copper, silver, gold, aluminum , Nickel or chromium can be used, and the Young's modulus is set to, for example, 50 GPa or more and 200 GPa or less, and the thermal expansion coefficient in the thickness direction and the planar direction is, for example, 10 pmm / ° C. or more. It is set to 25 ppm / ° C. or less.

  The via conductor 12 connects the conductive layers 11 separated in the thickness direction to each other, and is formed in a tapered shape whose area in plan view becomes smaller toward the core substrate 5, for example, copper, silver, gold , Aluminum, nickel or chromium formed of a conductive material can be used, Young's modulus is set to 50 GPa or more and 200 GPa or less, for example, and the thermal expansion coefficient in the thickness direction and plane direction is 10 pmm / ° C., for example. It is set to 25 ppm / ° C. or less.

  By the way, in the wiring board 3 of this embodiment, the first resin layer 7a is set to have a smaller coefficient of thermal expansion in the plane direction than the second resin layer 7b. As described above, when the first resin layer 7a and the second resin layer 7b have different coefficients of thermal expansion in the plane direction, when heat is applied to the wiring board 3, the first resin layer 7a and the second resin layer 7b. Due to the difference in thermal expansion coefficient between the first resin layer 7a and the second resin layer 7b, thermal stress is applied to the boundary between the first resin layer 7a and the second resin layer 7b. May peel.

  On the other hand, in the wiring board 3 of the present embodiment, as shown in FIG. 1B, the first resin layer 7a has a plurality of first convex portions 7a1 on the upper surface, and other than the first convex portions 7a1. The first inorganic insulating filler 10a is disposed only in the region, and the second resin layer 7b has a second convex portion 7b1 interposed between the adjacent first convex portions 7a1, and the second convex portion 7b1. A second inorganic insulating filler 10b is disposed inside.

  As a result, while maintaining the coefficient of thermal expansion along the planar direction of the second convex portion 7b1 of the second resin layer 7b located at the boundary with the first resin layer 7a, it is located at the boundary with the second resin layer 7b. The difference in thermal expansion coefficient between the first resin layer 7a and the second resin layer 7b can be reduced by increasing the thermal expansion coefficient along the planar direction of the first convex portion 7a1 of the first resin layer 7a. The thermal stress applied to the boundary between the first resin layer 7a and the second resin layer 7b when heat is applied to the wiring board 3 is reduced, and the first resin layer 7a and the second resin are reduced at the boundary. Separation from the layer 7b can be reduced.

As a result, it is possible to reduce the occurrence of voids in which moisture is likely to accumulate due to such peeling, so that when the wiring board 3 is used, an electric field is applied between the conductive layers 11 that are separated from each other along the planar direction. In addition, ionization of the conductive material contained in the conductive layer 11 due to the moisture can be reduced, and elongation of the conductive layer 11 due to the ionization can be reduced. Therefore, a short circuit between the conductive layers 11 separated along the planar direction can be reduced, and as a result, the wiring substrate 3 excellent in electrical reliability can be obtained.

  Further, by reducing the occurrence of voids in which moisture is likely to be accumulated due to such peeling, voids due to evaporation of accumulated moisture are generated when heat is applied to the wiring board 3 due to heat generated during operation of the electronic component 2. Expansion, the stress applied to the conductive layer 11 and the via conductor 12 can be reduced by the expansion, and the disconnection of the conductive layer 11 and the via conductor 12 can be reduced.

  Further, since the first convex portion 7a1 and the second convex portion 7b1 form irregularities at the boundary between the first resin layer 7a and the second resin layer 7b, the first resin layer 7a and the second resin layer are formed by the anchor effect. Adhesive strength with 7b can be increased and peeling between the first resin layer 7a and the second resin layer 7b can be reduced.

  The first protrusion 7a1 has a height (length in the protruding direction) and width (length in the direction perpendicular to the protruding direction) set to be larger than the particle size of the particles contained in the first inorganic insulating filler 10a. It is desirable that As a result, by forming the first convex portion 7a1 larger, the anchor effect at the boundary between the first resin layer 7a and the second resin layer 7b is enhanced, and the adhesive strength between the first resin layer 7a and the second resin layer 7b. Can be increased.

  Moreover, as for the 2nd convex part 7b1, it is desirable for height and width to be set larger than the particle size of the particle | grains contained in the 2nd inorganic insulating filler 10b. As a result, the second inorganic insulating filler 10b can be easily arranged between the first convex portions 7a1 adjacent to each other, and the anchor effect at the boundary between the first resin layer 7a and the second resin layer 7b can be enhanced. it can.

  The first convex portion 7a1 has a height set to, for example, 1 μm to 4 μm, and a width set to, for example, 0.5 μm to 3 μm. Further, the height of the second convex portion 7b1 is set to, for example, 1 μm to 4 μm, and the width is set to 0.5 μm to 3 μm.

  The second inorganic insulating filler 10b in the second convex portion 7b1 is preferably separated from the first resin layer 7a, and the surface is preferably covered with the second resin material. As a result, by reducing the contact of the second inorganic insulating filler 10b with the first resin layer 7a, it is possible to reduce the contact region with low adhesive strength from peeling off. It can reduce extending | stretching along the boundary with the 2nd resin layer 7b.

  Further, it is desirable that the first inorganic insulating filler 10a in the region other than the first convex portion 7a1 is separated from the second resin layer 7b and the surface is covered with the first resin material. As a result, it can reduce that the contact area | region with low adhesive strength peels by reducing that the 1st inorganic insulating filler 10a contact | abuts to the 2nd resin layer 7b.

  Thus, the mounting structure 1 described above exhibits a desired function by driving or controlling the electronic component 2 based on the power and signals supplied via the wiring board 3.

  Next, the manufacturing method of the mounting structure 1 mentioned above is demonstrated based on FIGS.

(1) First resin layer precursor 7ax including first resin layer precursor filler non-containing portion 7ax1 and first resin layer precursor filler containing portion 7ax2 shown in FIG. 2 is prepared. Specifically, for example, the following is performed.

  First, a plurality of resin sheets containing the first inorganic insulating filler 10a and having the base material impregnated with the first resin material, which is a thermoplastic resin, are stacked to form the first resin layer precursor filler containing portion 7ax2. Next, the first resin material that does not contain the first inorganic insulating filler 10a is applied to the upper and lower surfaces of the first resin layer precursor filler-containing portion 7ax2, thereby forming the first resin layer precursor filler-free portion 7ax1. To do. Thereby, the 1st resin layer precursor filler containing part 7ax2 and the 1st resin layer precursor 7ax containing the 1st resin layer precursor filler non-containing part 7ax1 formed in the upper and lower surfaces can be formed.

  In addition, the thickness of the first resin layer precursor filler non-containing portion 7ax1 is set larger than the particle diameter of the first inorganic insulating filler 10a. The first resin layer precursor filler non-containing part 7ax1 is set to a thickness of, for example, 0.5 μm to 4 μm, and the first resin layer precursor filler-containing part 7ax2 is set to a thickness of, for example, 20 μm to 100 μm. ing.

  As described above, the first resin layer precursor 7ax can be manufactured.

  (2) As shown in FIG.2 and FIG.3, the 1st resin layer 7a is formed by laminating | stacking the copper foil 11x on the upper and lower sides of the 1st resin layer precursor 7ax, and heat-pressing. Specifically, for example, the following is performed.

  First, a copper foil 11x having irregularities formed on one main surface is prepared by roughening using an etching solution mainly composed of an organic acid such as formic acid. Next, the copper foil 11x is laminated on the upper and lower sides of the first resin layer precursor 7ax while bringing one principal surface of the copper foil 11x on which the irregularities are formed into contact with the first resin layer precursor filler non-containing portion 7ax1. Next, the first resin layer 7a is formed by heating the laminated body of the first resin layer precursor 7ax and the copper foil 11x in the thickness direction while heating at a temperature equal to or higher than the melting point of the first resin material and lower than the thermal decomposition temperature. .

  Here, the 1st convex part 7a1 is formed in the 1st resin layer precursor filler non-containing part 7ax1 by embedding the unevenness | corrugation of the copper foil 11x in the 1st resin layer precursor filler non-containing part 7ax1. Furthermore, since the first resin layer precursor filler non-containing portion 7ax1 does not include the first inorganic insulating filler 10a, the first convex portion 7a1 that does not include the first inorganic insulating filler 10a can be formed. That is, the first resin layer 7a including the first inorganic insulating filler 10a can be formed only in the region other than the first convex portion 7a1.

  The melting point is a temperature measured by differential scanning calorimetry according to ISO11357-3: 1999. The thermal decomposition temperature is a temperature at which the mass of the resin is reduced by 5% in thermogravimetry according to ISO11358: 1997.

  As described above, the first resin layer 7a having the first convex portion 7a1 can be formed.

  (3) As shown in FIG. 4, the through-hole conductor 8 and the conductive layer 11 are formed in the first resin layer 7a, and the core substrate 5 is manufactured. Specifically, for example, the following is performed.

First, a plurality of through holes penetrating the core substrate 5 in the vertical direction are formed by, for example, drilling or laser processing, and the inner wall surface of the through hole is electrically conductive by, for example, electroless plating, vapor deposition, CVD, or sputtering. A material is deposited to form a cylindrical through-hole conductor 8. Next, the insulator 9 is formed by filling the cylindrical through-hole conductor 8 with a resin material or the like, and the conductive material is made of the insulator 9 by, for example, electroless plating, vapor deposition, CVD, or sputtering. Then, the conductive layer 11 is formed by patterning the copper foil 11x by a well-known photolithography technique, etching, or the like.

  Here, the surface of the 1st resin layer 7a in which the 1st convex part 7a1 was formed is exposed by patterning of the copper foil 11x.

  The core substrate 5 can be manufactured as described above.

  (4) As shown in FIG. 5, build-up portions 6 are formed on both surfaces of the core substrate 5 to produce the wiring substrate 3. Specifically, for example, the following is performed.

  First, a second resin layer precursor including a second resin material that is an uncured thermosetting resin and a second inorganic insulating filler 10b contained in the second resin material is disposed on the conductive layer 11, and the second resin By heating the second resin layer precursor at a temperature equal to or higher than the curing start temperature of the material and lower than the thermal decomposition temperature, the second resin layer 7b is formed on the conductive layer 11 by being cured while being fluidly adhered. Next, a via hole is formed in the second resin layer 7b by, for example, a YAG laser device or a carbon dioxide gas laser device, and at least a part of the conductive layer 11 is exposed in the via hole. Next, for example, by forming the via conductor 13 in the via hole and forming the conductive layer 11 on the upper surface of the second resin layer 7b by a semi-additive method, a subtractive method, or a full additive method, the build-up portion 6 is Can be formed.

  Here, when the second resin layer precursor is heated and fluidly adhered, a part of the second resin layer precursor including the second inorganic insulating filler 10b is formed on the exposed surface of the first resin layer 7a. In addition, the second protrusion 7b1 can be formed and the second inorganic insulating filler 10b can be disposed in the second protrusion 7b1 by being disposed between the first protrusions 7a1. In addition, since the second resin layer precursor flows while the second resin material covers the second inorganic insulating filler 10b, the second inorganic insulating filler 10b is disposed in the second convex portion 7b1 in this way, While being separated from the first resin layer 7a, the surface can be covered with the second resin material.

  The uncured state is an A-stage or B-stage according to ISO 472: 1999. The curing start temperature is a temperature at which the resin becomes a C-stage according to ISO 472: 1999.

  The wiring board 3 can be produced as described above. By repeating this process, a multilayer wiring substrate 3 can also be produced.

  (5) The mounting structure 1 shown in FIG. 1 can be produced by flip-chip mounting the electronic component 2 on the wiring board 3 via the bumps 4.

  The present invention is not limited to the above-described embodiments, and various changes and improvements can be made without departing from the scope of the present invention.

  For example, although the above-described embodiment of the present invention has been described by taking as an example a configuration in which a thermoplastic resin is used as the first resin layer and a thermosetting resin is used as the second resin layer, in the planar direction of the first resin layer. It is sufficient that the coefficient of thermal expansion of the second resin layer is smaller than that of the second resin layer. For example, a thermosetting resin may be used as the first resin layer and a thermoplastic resin may be used as the second resin layer. A thermosetting resin may be used as the layer, and a thermoplastic resin may be used as the first and second resin layers.

Moreover, although embodiment of this invention mentioned above demonstrated to the example the structure in which a 1st resin layer contains a base material,
The 1st resin layer should just contain the 1st resin material and the 1st inorganic insulating filler, for example, may use the 1st resin layer which does not contain a substrate.

  Moreover, although embodiment of this invention mentioned above demonstrated to the example the structure where the 2nd resin layer contained in a buildup part is one layer, the 2nd resin layer may have any number of layers.

  In the embodiment of the present invention described above, the first resin layer precursor-free portion not containing the first inorganic insulating filler is formed in the step (1), and the first resin layer is formed in the step (2). Although the structure which forms the 1st resin layer by which the 1st inorganic insulating filler was distribute | arranged only to area | regions other than a 1st convex part by forming a 1st convex part in a precursor non-containing part was demonstrated to the following, Thus, the first resin layer may be formed.

  First, a plurality of resin sheets obtained by impregnating a base material with a first resin material containing a first inorganic insulating filler are stacked to form a first resin layer precursor. Here, as the first resin material, a reaction terminator is not added, an active group remains in the terminal group of the resin molecule, and a thermoplastic resin having a low degree of polymerization can be used. An aromatic liquid crystal polyester resin can be used as such a thermoplastic resin. The degree of polymerization of the first resin material can be measured by molecular weight measurement by a chromatography method (GPC method).

  Next, the first resin layer precursor is heated to incompletely polymerize the first resin material. The first resin material obtained by such heating contains polymerized resin molecules and unpolymerized resin molecules, and the degree of polymerization is set to, for example, 80% or more and 96% or less when complete polymerization is performed. Has been.

  Here, it is desirable that the temperature of the first resin layer precursor is set to, for example, a polymerization start temperature or more and a polymerization start temperature + 20 ° C. or less, and a time is set to, for example, 1 hour or more and 12 hours or less. Thus, the polymerization degree of the first resin material can be appropriately adjusted by slowly advancing the polymerization reaction of the first resin material. When an aromatic liquid crystal polyester resin is used as the first resin material, the temperature of the first resin layer precursor is set to, for example, 180 ° C. or more and 290 ° C. or less, and the time is set to, for example, 1 hour or more and 12 hours or less. It does not matter. The polymerization start temperature is a temperature at which the viscosity starts to increase by measuring a change in viscosity while heating the sample by a viscosity measuring method according to ISO3219: 1993.

  The heating of the first resin layer precursor is desirably performed in a reducing atmosphere. As a result, even if the polymerization proceeds slowly, the oxidation of the first resin material can be reduced and the deterioration of the first resin material can be reduced.

  Next, a copper foil having irregularities formed on one main surface is prepared, and the upper and lower sides of the first resin layer precursor are brought into contact with the first main surface having the copper foil irregularities formed on the first resin layer precursor. After laminating the copper foil on the first resin layer, the first resin layer precursor and the copper foil laminate are heated in the thickness direction while being heated at a temperature higher than the polymerization start temperature of the first resin material and lower than the thermal decomposition temperature. The material is polymerized to form the first resin layer.

  Here, when pressurizing the laminate of the first resin layer precursor and the copper foil in the thickness direction, the first resin material of the first resin layer precursor is polymerized and unpolymerized resin molecules, Since polymer molecules that are polymerized have low molecular weight due to their large molecular weight, unpolymerized resin molecules have low molecular weight and high fluidity. It oozes out to the surface of the first resin layer precursor by pressurization and fills the concave portion of the copper foil. Thereby, the 1st convex part is formed in the upper surface of the 1st resin layer.

On the other hand, the fluidity of the first inorganic insulating filler is reduced by polymerized resin molecules. Therefore, since only the unpolymerized resin molecules are filled in the concave portions of the copper foil, the first inorganic insulating filler is not disposed on the first convex portions of the first resin layer, and the first inorganic regions are only in the regions other than the first convex portions. A first resin layer having an inorganic insulating filler can be formed.

DESCRIPTION OF SYMBOLS 1 Mounting structure 2 Electronic component 3 Wiring board 4 Bump 5 Core board 6 Build-up part 7a 1st resin layer 7a1 1st convex part 7b 2nd resin layer 7b1 2nd convex part 8 Through-hole conductor 9 Insulator 10a 1st inorganic Insulating filler 10b Second inorganic insulating filler 11 Conductive layer 12 Via conductor

Claims (6)

A first resin layer including a first resin material and a first inorganic insulating filler having a smaller coefficient of thermal expansion than the first resin material; and a second resin material and the second resin formed on an upper surface of the first resin layer. A second inorganic insulating filler having a smaller coefficient of thermal expansion than the material, and a second resin layer having a larger coefficient of thermal expansion in the plane direction than the first resin layer,
The first resin layer has a plurality of first convex portions on the upper surface, and the first inorganic insulating filler is disposed only in a region other than the first convex portions,
The second resin layer has a second convex portion interposed between the adjacent first convex portions, and the second inorganic insulating filler is disposed in the second convex portion. Wiring board. The wiring board according to claim 1,
The wiring board, wherein the second inorganic insulating filler in the second convex portion is separated from the first resin layer. The wiring board according to claim 2,
The width of the 1st convex part is larger than the particle size of the particle contained in the 1st inorganic insulating filler, The wiring board characterized by things. The wiring board according to claim 3,
The wiring board, wherein the second resin material has a larger coefficient of thermal expansion than the first resin material. The wiring board according to claim 4,
The wiring board according to claim 1, wherein the first and second inorganic insulating fillers are made of the same material. The wiring board according to claim 1,
Electronic components mounted on the wiring board;
A mounting structure characterized by comprising:

Images