JP4264091B2 - Wiring board manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent the deterioration in strength due to diffusion of a component of copper of wiring layer into a brazing material of a low meting point by the heat generated in connecting an electronic component via the brazing material of a low melting point when forming a non-defect film on the wiring layer of the surface of the wiring board using a plating film of tin etc. which melts at a low temperature. <P>SOLUTION: In the wiring board 4, the electrode of the electronic component 3 is connected to an insulating substrate 1 composed of a glass ceramic via a brazing material 5 of a low melting point and the wiring layer 2 which contains copper as a main component is formed on it. In the wiring substrate 4, a heat-treated copper/tin alloy layer 6 and a heat-treated silver or gold/tin alloy layer 7 are formed on the surface of area where the electrode is connected via the brazing material 5 of a low melting point in the wiring layer 2. Thereby, the component of the copper in the wiring layer 2 can be effectively prevented from diffusing into the brazing material 5 of a low melting point when connecting the brazing material 5 of a low melting point to the wiring layer 2. <P>COPYRIGHT: (C)2006,JPO&amp;NCIPI

Description

The present invention is a wiring board on which electronic components such as a semiconductor element, a capacitor element, and a resistor are mounted via a low-melting-point brazing material such as solder, and a plating layer is deposited on the wiring layer on the surface thereof The present invention relates to a method for manufacturing a wiring board.

  Conventionally, a wiring board on which electronic components such as a semiconductor element, a capacitor element, and a resistor are mounted generally includes an insulating base made of an aluminum oxide sintered body, and tungsten and molybdenum formed from the upper surface to the lower surface of the insulating base. And a plurality of wiring layers made of a refractory metal material such as a semiconductor element, a capacitor element, a resistor, and other electronic components are mounted on the upper surface of the insulating base and each electrode of such an electronic component is mounted It is electrically connected to the wiring layer through a low melting point solder such as solder.

  Such a wiring board is mounted on the external electric circuit board by connecting a portion led to the lower surface of the insulating base of the wiring layer to the wiring conductor of the external electric circuit board via a low melting point solder such as solder. At the same time, each electrode of the electronic component mounted on the wiring board is electrically connected to a predetermined external electric circuit.

  The above-mentioned wiring board includes a nickel plating layer and a gold plating layer made of a nickel-phosphorus alloy or a nickel-boron alloy in a region where at least an electronic component is connected via a low melting point solder such as solder. This nickel plating layer makes it possible to improve the bonding of solder etc. to the wiring layer made of a refractory metal material such as tungsten, and the gold plating layer forms nickel oxide on the surface of the nickel plating layer This prevents the solderability and the like from deteriorating.

  In addition, as a method of depositing these nickel plating layer and gold plating layer, it is difficult to form a lead wire for supplying plating power to the wiring layer due to the high density of the wiring layer accompanying the miniaturization of the wiring board, Electroless methods are being used frequently.

On the other hand, the nickel plating layer, which is the base plating layer of the gold plating layer, is firmly attached to the wiring layer made of a refractory metal material such as tungsten or molybdenum, and cracks and pinholes due to the stress inherent in the nickel plating layer. For example, a heat treatment at 800 ° C. to 1000 ° C. is performed for the purpose of suppressing plating film defects such as nickel crystal growth. As a result, the number of cracks and pinholes in which the plating solution tends to remain is extremely small in the nickel plating layer, so that the plating solution that remains due to heat when the electronic component is connected to the wiring layer via solder or the like is removed from the gold plating layer. It exudes to the top, and it becomes difficult for the problem that it forms a spot-like blotch to cause poor appearance.
Japanese Patent Laid-Open No. 10-102266 JP 2001-131774 A

  In the recent advanced information age, the frequency band used for signals is increasingly shifting to the high frequency band. In a high-frequency wiring board that transmits such a high-frequency signal, the resistance of the conductor forming the wiring layer is required to be low in order to transmit the high-frequency signal at high speed, and the insulating substrate has a lower dielectric constant. A rate is required.

  However, refractory metals such as tungsten and molybdenum used in conventional wiring layers have a large conductor resistance, so the signal propagation speed is slow, and signal propagation in a high frequency region of 30 GHz or more is difficult. It is necessary to use a low resistance metal such as copper, silver or gold in place of such a metal such as tungsten or molybdenum.

  For this reason, recently, the use of glass ceramics obtained by firing a mixture of glass and ceramics (inorganic filler) as an insulating substrate has attracted attention. Glass ceramics are suitable for high-frequency insulating substrates because of their low dielectric constant, and can be fired at a low temperature of 800 ° C. to 1000 ° C., so that low resistance metals such as copper, silver, and gold can be used as wiring layers. There is an advantage.

  In addition, as a low resistance metal used as a wiring layer, it has become mainstream to use the conductor which has copper which was excellent in the high frequency characteristic as a main component.

  However, the copper-based conductors used in these glass ceramics contain a large amount of glass components in which the plating layer is difficult to be deposited, and many of the glass components are exposed on the surface, resulting in a rough surface. In addition, a setter component that is installed on the upper surface of the insulating base during firing and serves to prevent warping of the insulating base is often attached to the surface of the wiring layer. There was a problem that the nickel plating layer could not be uniformly applied to the whole.

  Therefore, the glass and deposits on the surface of the wiring layer are chemically removed by immersing them in a glass etching solution containing fluoride as a main component, or physically removed with a blasting device or the like. In appearance, a nickel plating layer is uniformly applied over the entire surface of the wiring layer.

  However, even in the removal of these chemical and physical glasses and deposits, the processing conditions are limited because it is necessary to avoid a decrease in the strength of the insulating substrate and wiring layer. It could not be removed completely. Therefore, a trace amount of glass and deposits remain on the surface of the wiring layer, and this trace amount of remaining glass and deposits inhibits the initial plating deposition, so the nickel plating layer has high stress. Therefore, when the surface of the nickel plating layer is observed with a scanning electron microscope, there is a problem that fine crack-like abnormal precipitates are formed in spots.

  The plating solution tends to remain in the fine crack-like abnormal deposits, and the plating solution remaining here is gold plated on the nickel plating layer by heat when the electronic component is connected to the wiring layer via solder or the like. There is a problem that the surface of the layer oozes out and a spot-like blot is formed, resulting in poor appearance.

In order to suppress this abnormal precipitation portion, for example, heat treatment may be applied. However, if heat treatment at 800 ° C. to 1000 ° C. necessary for crystal growth of the nickel plating layer is applied, the wiring layer made of copper may have a blistering or the like. There was a problem that the problem was triggered.
For this reason, after performing tin plating, solder plating, or lead substitute solder that can grow crystals with a low melting point, heat treatment is performed to form a defect-free film, preventing exudation and spotted spots from occurring In general, the copper component in the wiring layer mainly composed of copper, such as solder, is caused by the heat at the time of mounting a low melting point soldering material such as solder or the heat at the time of remounting (repair). There was a problem that it diffused into the low melting point brazing material and deteriorated the bondability.

  The present invention has been devised in view of the above-described problems in the prior art, and its purpose is to blot the surface other than the region where the wiring layer is connected via a low-melting-point brazing material such as solder. Even when a film that grows at a temperature lower than that of nickel is formed on the surface of the wiring layer in order to prevent appearance defects due to protrusions and spotted spots, electronic components are soldered to the wiring layer. Provided is a method of manufacturing a wiring board capable of preventing the copper component in a wiring layer mainly composed of copper from diffusing into a low melting point brazing material such as solder due to heat at the time of connection via the low melting point brazing material. There is.

The method for manufacturing a wiring board according to the present invention includes an insulating base made of glass ceramic on which an electronic component is mounted, a wiring layer mainly composed of copper formed on the insulating base, and the wiring layer formed on the wiring layer. A method of manufacturing a wiring board having a copper-tin alloy layer and a silver-tin alloy, wherein a thickness of 0.5 to 5 μm is formed on the surface of the region of the wiring layer to which the electrodes of the electronic component are electrically connected. A copper-plated alloy layer and a silver-tin alloy layer are sequentially formed on the wiring layer by sequentially forming a tin-plated layer having a thickness of 0.13 and a silver-plated layer having a thickness of 0.13 to 1.3 μm and heat-treating it. To do.

Preferably, in the method for manufacturing a wiring board, a ratio of the thickness of the silver plating layer to the thickness of the tin plating layer is 1/4.

The method of manufacturing a wiring board according to the present invention includes an insulating base made of glass ceramic on which electronic components are mounted, a wiring layer mainly composed of copper formed on the insulating base, and the wiring layer formed on the wiring layer. A method of manufacturing a wiring board having a copper-tin alloy layer and a gold-tin alloy, wherein a thickness of 0.5 to 5 μm is formed on a surface of the wiring layer region to which the electrodes of the electronic component are electrically connected. A copper-plated alloy layer and a gold-tin alloy layer are sequentially formed on the wiring layer by sequentially forming a tin-plated layer having a thickness of 0.4 to 4.1 μm and a heat treatment. To do.

  As described above, according to the wiring board and the manufacturing method thereof of the present invention, the wiring layer forms a bleed or spotted stain on the surface other than the region where the wiring layer is connected via the low melting point brazing material such as solder. In order to prevent the occurrence of the above, even when a film that grows at a temperature lower than that of nickel is formed on the surface of the wiring layer, the electronic component is connected to the wiring layer via a low melting point solder such as solder. It was possible to provide a wiring board capable of preventing the copper component in the wiring layer containing copper as a main component from being diffused into a low melting point solder such as solder and a method for manufacturing the same.

Next, a description of an embodiment of a wiring board and a manufacturing method thereof accompanying with reference to the drawings in detail the present invention.

FIG. 1 shows an example of an embodiment in which a wiring board according to an embodiment of the present invention is applied to a package for housing a semiconductor element for housing a semiconductor element. 1 is an insulating substrate, 2 is a wiring layer, 3 is an electron Components 4 are a wiring board for mounting an electronic component 3 such as a semiconductor element, which is composed of an insulating substrate 1 and a wiring layer 2, 5 is a low melting point brazing material, and 8 is a lid.

  The insulating substrate 1 is formed by sintering a glass ceramic green sheet in which glass powder, filler powder (ceramic powder), and an organic binder, plasticizer, organic solvent and the like are mixed.

  Examples of the glass component include SiO 2 —B 2 O 3, SiO 2 —B 2 O 3 —Al 2 O 3, SiO 2 —B 2 O 3 —Al 2 O 3 —MO (where M represents Ca, Sr, Mg, Ba or Zn), SiO 2 —Al 2 O 3 —M 1 O— M2O system (provided that M1 and M2 are the same or different and represent Ca, Sr, Mg, Ba or Zn), SiO2-B2O3-Al2O3-M1O-M2O system (where M1 and M2 are the same as above), SiO2-B2O3-M32O system (where M3 represents Li, Na or K), SiO2-B2O3-Al2O3-M32O system (where M3 is the same as above), Pb glass, Bi glass, etc. It is done.

  Examples of the filler include at least one selected from Al2O3, SiO2, ZrO2 and an alkaline earth metal oxide, TiO2 and an alkaline earth metal oxide, Al2O3 and SiO2. Examples thereof include complex oxides (for example, spinel, mullite, cordierite) and the like.

  The mixing ratio of these glass and filler is preferably 40:60 to 99: 1 by mass ratio.

  As the organic binder blended in the glass ceramic green sheet, those conventionally used for ceramic green sheets can be used. For example, acrylic (acrylic acid, methacrylic acid or ester homopolymer or copolymer) A polymer, specifically an acrylic ester copolymer, a methacrylic ester copolymer, an acrylic ester-methacrylic ester copolymer, etc.), polyvinyl butyral, polyvinyl alcohol, acrylic-styrene, polypropylene carbonate, Examples include cellulose-based homopolymers or copolymers.

  The glass ceramic green sheet is obtained by adding a predetermined amount of plasticizer and solvent (organic solvent, water, etc.) to the glass powder, filler powder, and organic binder as necessary to obtain a slurry, which is then used as a doctor blade, rolled, calender. It can be obtained by molding to a thickness of about 50 μm to 500 μm by a roll, a die press or the like.

  The glass ceramic green sheet thus obtained is subjected to cutting, punching, or the like to obtain an appropriate shape, and after stacking a plurality of these, the organic components are removed and fired. The organic component is removed by heating the laminate in a temperature range of 100 ° C. to 800 ° C. to decompose and volatilize the organic component. The firing temperature varies depending on the glass ceramic composition, but is usually in the range of about 800 ° C to 1100 ° C. Firing is usually performed in the air, but when copper is used as the conductor material, organic components are removed in a nitrogen atmosphere containing water vapor at 100 ° C. to 700 ° C., and then the firing is performed in a nitrogen atmosphere.

  The insulating substrate 1 has a large number of wiring layers 2 deposited from the mounting portion on the upper surface to the lower surface, and the electrode of the electronic component 3 has a low melting point such as solder on the portion exposed to the mounting portion of the wiring layer 2. The part electrically connected through the brazing material 5 and led to the lower surface is electrically connected to the external electric circuit through a low melting point brazing material such as solder.

  The wiring layer 2 is made of, for example, copper powder and 1% by weight or less of glass, and a metal paste obtained by adding and mixing an appropriate organic binder and solvent to the ceramic green sheet serving as the insulating substrate 1 is previously known in advance. The insulating substrate 1 is applied from the upper surface to the lower surface by printing and applying a predetermined pattern by a printing method.

  The wiring layer 2 contains glass that has moved and diffused from the insulating substrate 1 to the wiring layer 2 during firing, and the surface of the wiring layer 2 has a lot of glass that has moved and diffused in this way. . Furthermore, a small amount of fired deposits such as setters adhered during firing are present on the surface of the wiring layer 2.

  In addition, as shown in the enlarged cross-sectional view of the main part in FIG. 2, the wiring layer 2 is heat-treated at least on the surface of the region where the electrode of the electronic component 3 is connected via the low melting point brazing material 5. A copper-tin alloy layer 6 and a heat-treated silver or gold-tin alloy layer 7 are successively deposited.

  Here, the low melting point brazing material 5 is a eutectic that melts at a temperature of about 200 ° C. to 300 ° C., which serves to electrically and mechanically connect the wiring layer 2 to the electronic component 3 and the external electric circuit. An alloy.

According to the wiring board 4 according to the present embodiment, the wiring layer 2 mainly composed of copper, in which the electrodes of the electronic component 3 are connected to the insulating base 1 made of glass ceramics through the low melting point brazing material 5 is formed. In the wiring substrate 4 thus formed, the surface of a region of the wiring layer 2 where the electrodes are connected via the low melting point brazing material 5 is subjected to heat-treated copper-tin alloy layer 6 and heat-treated silver or gold and tin. It is important that the alloy layers 7 are formed sequentially.

  This is because the heat treated copper tin alloy layer 6 is formed by the copper component in the wiring layer 2 containing copper as a main component by the heat generated when the low melting point brazing material 5 is connected to the wiring layer 2. Since it is possible to effectively prevent diffusion into the material 5, the main component is copper due to heat at the time of mounting a low melting point soldering material such as solder or heat at the time of remounting (repair). It is possible to effectively prevent the copper component in the wiring layer 2 from diffusing into the low-melting-point brazing material 5 such as solder and deteriorating the bondability, and connect the electronic component 3 to the wiring layer 2 via solder or the like. It is because it becomes possible to make it.

Further, the heat-treated silver or gold-tin alloy layer 7 is formed on the surface of the heat-treated copper-tin alloy layer 6 while the low-melting-point brazing material, silver Alternatively, the melting point of the alloy layer of gold and tin, the copper tin alloy layer, and the copper in the wiring layer can be sequentially increased, and as a result, the copper component in the wiring layer mainly composed of copper can be diffused. This is because it can be effectively suppressed.
According to the above wiring board, the heat treated copper tin alloy layer and the heat treated silver or gold and tin alloy layer are formed on the surface of the region of the wiring layer where the electrodes are connected via the low melting point brazing material. Because the melting point of the copper tin alloy layer and the silver or gold and tin alloy layer is higher than the mounting temperature, the copper tin alloy layer and the silver or gold and tin alloy layer are formed at the mounting temperature. Effectively prevent copper components in the copper-based wiring layer from diffusing into the low-melting-point brazing material when connecting low-melting-point brazing material to the wiring layer because there is no chemical change due to heat. Is possible. As a result, the copper component in the wiring layer mainly composed of copper diffuses into the low-melting-point brazing material such as solder due to the heat at the time of mounting the low-melting-point brazing material such as solder or the heat at the time of remounting (repair). It is possible to effectively prevent deterioration of the bondability. In addition, since an alloy layer of silver or gold and tin is formed on the copper tin alloy layer, the low melting point brazing material, silver or gold and tin The alloy layer, the copper-tin alloy layer, and the copper in the wiring layer can be configured so that the melting point becomes higher in order.
As a result, it is possible to more effectively suppress the diffusion of the copper component in the wiring layer mainly composed of copper.
Here, the mounting temperature refers to the surface of the region where the electrodes are connected via the low melting point brazing material on the wiring layer mainly composed of copper, and the heat-treated copper tin alloy layer and the heat-treated silver or gold This is the temperature of the wiring board when an electronic component is mounted on the wiring layer via a low melting point solder such as solder on the wiring board on which an alloy layer with tin is formed.

Furthermore, in the wiring substrate 4 according to the present embodiment, the copper tin alloy layer 6 is formed by diffusing copper of the wiring layer 2 by a heat treatment in a tin plating layer deposited on the surface of the wiring layer 2, and silver or The alloy layer 7 of gold and tin is desirably formed by diffusing tin of the tin plating layer by heat treatment on the silver plating layer or the gold plating layer deposited on the surface of the tin plating layer.
According to the wiring board according to the present embodiment, the copper-tin alloy layer is formed by diffusing copper of the wiring layer by heat treatment in the tin plating layer deposited on the surface of the wiring layer, and is formed of silver or gold and tin. When the alloy layer is formed by diffusing tin of the tin plating layer by heat treatment on the silver plating layer or gold plating layer deposited on the surface of the tin plating layer, the alloy layer is mounted with a low melting point brazing material. On the other hand, a low melting point brazing material, an alloy layer of silver or gold and tin, a copper-tin alloy layer, and a copper layer in the wiring layer can be configured so that the melting point becomes higher, and the wiring layer mainly composed of copper. It becomes possible to effectively suppress the diffusion of the copper component therein. As a result, the copper component in the wiring layer mainly composed of copper diffuses into the low-melting-point brazing material such as solder due to the heat at the time of mounting the low-melting-point brazing material such as solder or the heat at the time of remounting (repair). It is possible to effectively prevent deterioration of the bondability.

  In this case, the low melting point brazing material, the silver / gold / tin alloy layer, the copper tin alloy layer, and the copper in the wiring layer have a higher melting point in order than the low melting point brazing material. As a result, it becomes possible to effectively suppress the diffusion of the copper component in the wiring layer mainly composed of copper, so that when the low melting point brazing material 5 is connected to the wiring layer 2, the copper is removed. It becomes possible to effectively prevent the copper component in the wiring layer 2 as a main component from diffusing into the low melting point brazing material 5, and as a result, heat at the time of mounting a low melting point brazing material such as solder, It becomes possible to effectively prevent the copper component in the wiring layer containing copper as a main component from diffusing into a low melting point solder such as solder and deteriorating the bonding property due to heat during mounting (repair). Because.

  Of the alloy layer 7 of silver or gold and tin, the tin-silver alloy layer has a high melting point of silver, so that a relatively small amount of silver can be effectively used in the wiring layer 2 mainly composed of copper. A barrier layer that prevents the copper component from diffusing into the low melting point brazing material 5 can be formed.

  Further, according to the tin-gold alloy layer, since the solderability and corrosion resistance of gold are extremely excellent, the solderability and corrosion resistance are excellent even after alloying.

In addition, according to the method of manufacturing the wiring board according to the present embodiment, the step of forming the wiring layer 2 mainly composed of copper on the insulating substrate 1 made of glass ceramics, and the electrode of the electronic component 3 in the wiring layer 2 are provided. A step of sequentially depositing a tin plating layer and a silver plating layer or a gold plating layer on the surface of the region connected via the low melting point brazing material 5, and then 50 ° C. or more from the melting point of the low melting point brazing material 5 It is important to include a step of heat-treating the tin plating layer and the silver plating layer or the gold plating layer at a temperature higher by 100 ° C.
According to the above method for manufacturing a wiring board, a wiring layer mainly composed of copper is formed on an insulating base made of glass ceramics, and electrodes of electronic components in the wiring layer are connected via a low melting point brazing material. A step of sequentially depositing a tin plating layer and a silver plating layer or a gold plating layer on the surface of the region to be coated, and then the tin plating layer and the silver at a temperature 50 to 100 ° C. higher than the melting point of the low melting point brazing material. A plating layer or a gold plating layer is subjected to a heat treatment step, so that a finer metal layer that suppresses the occurrence of defects such as pinholes in the process of alloying the silver plating layer or the gold plating layer with tin And the formation of a copper-tin alloy layer having a higher melting point than that of an alloy layer of silver or gold and tin, so that the electrodes of the wiring layer can be connected via a low-melting-point brazing material such as solder. Outside the region to be joined It is possible to effectively prevent appearance defects due to the formation of spots or spotted spots on the surface, and also when copper is bonded to the wiring layer via a low melting point brazing material. Thus, it is possible to effectively prevent the copper component in the wiring layer mainly composed of the heat diffusion into the low melting point brazing material such as solder.

  This is because the copper-tin alloy layer 6 and the alloy layer 7 of silver or gold and tin have at least the electrodes of the electronic component 3 having a low melting point on the surface of the wiring layer 2 as shown in the enlarged sectional view of the main part in FIG. After sequentially depositing a tin plating layer 9 and a silver plating layer or a gold plating layer 10 on the surface of the region connected via the brazing material 5, for example, 50 ° C. from the melting point of the low melting point brazing material 5 in a nitrogen atmosphere. The copper-tin alloy layer 6 formed by diffusing the copper of the wiring layer 2 into the tin-plated layer 9 and the tin of the tin-plated layer 9 are silver-plated or Silver or gold and tin alloy layer 7 formed by diffusing into gold plating layer 10 is obtained. At that time, the film thickness ratio of the tin plating layer 9 and the silver plating layer or the gold plating layer 10 is the temperature at which the copper tin alloy layer 6 and the alloy layer 7 of silver or gold and tin are formed (hereinafter referred to as the alloying temperature). Various selections can be made according to the above. This alloying temperature is selected as a temperature that is 50 ° C. to 100 ° C. higher than the melting point of the low melting point brazing material 5 when the electronic component 3 is mounted on the wiring board 4 via the low melting point brazing material 5.

  For example, if the melting point of the low melting point brazing material 5 is 250 ° C., the alloying temperature may be set to 300 ° C. to 350 ° C., which is 50 ° C. to 100 ° C. higher than the melting point. Therefore, since the melting point of the copper tin alloy layer 6 and the alloy layer 7 of silver or gold and tin formed at 300 ° C. to 350 ° C. is higher than that of the low melting point brazing material 5, the heat treated copper tin alloy layer 6 and the heat-treated alloy layer 7 of silver or gold and tin effectively function as a barrier layer with respect to the copper in the wiring layer 2, and on the surface of the alloy layer 7 of silver or gold and tin. This is because it is possible to effectively prevent the copper component in the wiring layer 2 mainly composed of copper from diffusing into the low melting point brazing material 5 mounted at a temperature of 250 ° C.

  In addition, it is possible to effectively prevent the components of the low melting point brazing material 5 from diffusing into the wiring layer 2 by the same action.

  On the other hand, when the alloying temperature is lower than the melting point of the low melting point brazing material 5 by less than 50 ° C., the heat-treated copper-tin alloy layer 6 and the heat-treated alloy layer 7 of silver or gold and tin 7 Since the difference in melting point between the low melting point brazing material 5 and the low melting point brazing material 5 is small, the diffusion of the copper component in the wiring layer 2 mainly composed of copper into the low melting point brazing material 5 is effectively prevented when the electronic component 3 is mounted. It causes a problem that it cannot be done. When the alloying temperature is higher than the melting point of the low melting point brazing material 5 by 100 ° C., a thermal load is applied to the insulating substrate 1 to thereby apply the copper component in the wiring layer 2 and the copper tin alloy layer 6. As a result, the insulative property of the insulating base 1 is deteriorated due to diffusion of tin in the tin plating layer 9, which should become, into the insulating base 1.

  Furthermore, after determining the alloying temperature, the film thicknesses of the tin plating layer 9 and the silver plating layer or the gold plating layer 10 are determined. This thickness ratio is such that the tin-plated layer 9 and the silver-plated layer or gold-plated layer 10 are fully alloyed into the copper-tin alloy layer 6 and the silver- or gold-tin alloy layer 7 at the selected alloying temperature. Therefore, for example, when the tin-silver alloy layer 7 is formed from the tin-plated layer 9 and the silver-plated layer 10, the tin-plated layer 9 and the silver-plated layer are formed if the alloying temperature is 350 ° C. The copper tin alloy layer 6 and the tin silver alloy layer 7 can be continuously formed by setting the film thickness of 10 to a ratio of 4: 1.

  If the thickness of the tin plating layer 9 is less than 0.5 μm, the effect of preventing the copper component in the wiring layer 2 containing copper as a main component from diffusing into the low melting point brazing material 5 cannot be obtained. On the other hand, if it is attempted to deposit more than 5 μm, the plating takes a long time. Therefore, the thickness of the tin plating layer 9 is 0.5 μm to 5 μm, preferably 1 μm to 2 μm. The thickness of the silver plating layer or the gold plating layer 10 can be determined by the ratio with the thickness of the tin plating layer 9 according to the temperature at which the plating film is alloyed. For example, taking the case where the tin-silver alloy layer 7 is formed from the tin plating layer 9 and the silver plating layer 10 as an example, if the alloying temperature is 350 ° C., the film of the tin plating layer 9 and the silver plating layer 10 By setting the thickness to a ratio of 4: 1, the copper tin alloy layer 6 and the tin silver alloy layer 7 can be continuously formed.

In the method for manufacturing a wiring board according to the present embodiment , the tin plating layer 6 is deposited on the surface of the wiring layer 2 by an electroless method. The electroless tin plating solution for depositing the tin plating layer 6 by an electroless method is not particularly limited, and various types can be used. Specifically, a substituted tin plating solution using cyan having a tin ion concentration of 1 g / L to 50 g / L, an electroless tin plating solution using a disproportionation reaction, or the like can be used. The silver plating layer or the gold plating layer 7 is deposited on the surface of the tin plating layer 6 by an electroless method. The electroless silver plating solution or the electroless gold plating solution for depositing the silver plating layer or the gold plating layer 7 by an electroless method is not particularly limited, and various types can be used. Specifically, a cyan bath or a thiosulfate bath having a silver ion concentration of 5 g / L to 50 g / L or a cyan bath having a gold ion concentration of 1 g / L to 10 g / L can be used.

Thus, according to the wiring board 4 according to the present embodiment, the electrodes of the electronic component 3 are electrically and mechanically connected to the wiring layer 2 formed on the upper surface of the insulating base 1 via the low melting point brazing material 5. Thereafter, a lid 8 made of metal or ceramic is joined to the upper surface of the insulating base 1 via a sealing material such as glass, resin, or brazing material, and the electronic component 3 is placed inside the container made of the insulating base 1 and the lid 8. Is hermetically accommodated to form a semiconductor device.

  Note that the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the scope of the present invention. For example, in the above-described example, the wiring board of the present invention is applied to a semiconductor element housing package for housing semiconductor elements, but may be applied to other uses such as a hybrid integrated circuit board.

  Hereinafter, the present invention will be described in detail by way of specific examples, but the present invention is not limited to the following specific examples.

  After forming a thin tin layer using a substitution tin plating solution using cyan on the electrode composed of a copper-based wiring layer formed on an insulating substrate made of glass ceramics, a disproportionation reaction was used. After forming a tin plating layer with a thickness of 2 μm using an electroless tin plating solution, and then forming a silver plating layer with a thickness of 0.5 μm using a cyan bath, the alloying temperature and this electrode are connected. As shown in Table 1, heat treatment was performed for 30 seconds at each alloying temperature of 0 to 150 ° C. as shown in Table 1. An electronic component using the 90% Sn-7.5% Bi-2% Ag-0.5% Cu solder ball having a melting point of 245 [deg.] C. as the low melting point solder material on the wiring boards of prototype numbers 1 to 7 produced in this manner. A semiconductor element was mounted, and the bondability was determined from the strength when the semiconductor element was peeled off and the mode of the peeled surface. Moreover, as the repairability, the solderability when a semiconductor element once mounted was repaired (re-mounted) was also evaluated.

Further, a voltage was applied between independent wiring patterns composed of wiring layers on the wiring board, and the insulating properties of the wiring board were also evaluated. The results are shown in Table 1.

  Regarding the bondability in Table 1, “○” indicates that the fracture interface is inside the solder and 100% fracture inside the solder in the solder ball shear test, so the solder / plating interface is very strong and excellent in solder jointability. Indicates that Further, “Δ” indicates that although a part of the underlying copper-tin alloy layer is exposed at the fracture interface in the solder ball shear test, there is no problem in strength, and there is no practical problem. In addition, “x” indicates that the copper tin alloy layer is exposed at the fracture interface in the solder ball shear test and the strength is weak, so that it cannot be used practically.

As for repairability, the solder ball shear test was evaluated after repeating re-mounting three times, and the fracture mode was confirmed while comparing the initial bonding state.
The evaluation criteria for this break mode was the same as the bondability.

  For insulation, a voltage of 10 V is applied between wiring patterns composed of wiring layers having independent L / S (L: line width, S: spacing between line widths) of 100 μm / 100 μm on the wiring board, The insulation between patterns was measured using an insulation resistor, and “○” indicates that the measured value was 106Ω or higher and there was no practical problem, and “X” indicates that the level was less than 106Ω.

As is apparent from the results in Table 1, the difference between the alloying temperature and the melting point of the low melting point brazing material is 0 ° C. No. 1 had a problem in bondability and repairability (indicated by x in the column of bondability and repairability in the table). In addition, the difference between the alloying temperature and the melting point of the low melting point brazing material is 25 ° C. No. 2 had a problem in bondability and repairability. (Indicated by Δ in the column of bondability and repairability in the table). In addition, the difference between the alloying temperature and the melting point of the low melting point brazing material is 150 ° C. No. 7 had good bondability and repairability, but had problems due to deterioration of insulation properties (indicated by Δ in the column of bondability and repairability in the table, and x in the column of insulation).
Further, the difference between the alloying temperature and the melting point of the low melting point brazing material is 125 ° C. In No. 6, the bondability and repairability were good, but the insulation was deteriorated (indicated by Δ in the column of insulation in the table).

  On the other hand, the sample Nos. 5 and 75 ° C. and 100 ° C. in which the difference between the alloying temperature and the melting point of the low-melting-point brazing material is a wiring board manufactured by the method for manufacturing a wiring board of the present invention. 3, 4 and 5 were excellent in both bonding and insulating properties.

  Further, the repairability was excellent in the fracture mode, and the joining state was excellent with no change from the initial state (indicated in the columns of joining property, repairing property, and insulating property in the table).

Next, as a wiring board of trial production numbers 8 to 17, a tin plating layer is formed to 0.1 to 6 μm using a methanesulfonic acid bath on an electrode composed of a wiring layer mainly composed of copper formed on an insulating base made of glass ceramics. Next, after forming a silver plating layer with a film thickness of 0.025 to 1.5 μm using a cyan bath, the difference between the alloying temperature and the melting point of the low melting point brazing material is 75 ° C. And heat treatment for 30 seconds. Evaluation similar to the wiring board of trial production numbers 1-7 was performed to the wiring board produced in this way. The results are shown in Table 2.

As can be seen from the results in Table 2, the sample No. In No. 8, problems were observed in the bondability and repairability (indicated by Δ to x in the column of bondability and repairability in the table).
Further, Sample No. with a tin plating layer thickness of 0.3 μm was used. No. 9 was a level where there was no problem in strength although a part of the underlying copper-tin alloy layer was exposed at the fracture interface, and there was no problem in practical use (indicated by Δ in the column of bondability and repairability in the table) ). In addition, Sample No. with a tin plating layer thickness of 5.5, 6.0 μm. Nos. 16 and 17 had good bondability and repairability, but a long time of 3 to 4 hours was required for forming the tin plating layer.

  In contrast, Sample Nos. With the tin plating layer thicknesses of 0.5, 1, 2, 3, 4 and 5 μm were used. Nos. 10, 11, 12, 13, 14, and 15 were excellent both in terms of bondability and repairability (indicated by a circle in the column of bondability and repairability in the table).

  For all of the wiring boards of the above examples and comparative examples, 90% Sn-7.5% Bi-2% Ag-0.5% Cu solder having a melting point of 245 [deg.] C. is used as a low melting point brazing material, and wettability is achieved by dipping. As a result, the solder wettability of all the wiring boards was good. Furthermore, no whisker was generated on any of the wiring boards.

Next, a thin layer of tin is formed on the electrode composed of a copper-based wiring layer formed on an insulating substrate made of glass ceramics using a substitution tin plating solution using cyanide, and then a disproportionation reaction is performed. After forming a tin plating layer with a film thickness of 2 μm using an electroless tin plating solution using, and then forming a gold plating layer with a thickness of 1.6 μm using a cyan bath, the alloying temperature and this electrode As shown in Table 3, a heat treatment was performed for 30 seconds at each alloying temperature where the difference from the melting point of the low melting point brazing material connected to was 0 to 150 ° C. Evaluations similar to the wiring boards of prototype numbers 1 to 7 were performed on the wiring boards of prototype numbers 18 to 24 thus fabricated. The results are shown in Table 3.

  As is apparent from the results in Table 3, the difference between the alloying temperature and the melting point of the low melting point brazing material is 0 ° C. No. 18 had problems in bondability and repairability (indicated by x in the column of bondability and repairability in the table). In addition, the difference between the alloying temperature and the melting point of the low melting point brazing material is 25 ° C. No. 19 had problems in bondability and repairability. (Indicated by Δ in the column of bondability and repairability in the table). In addition, the difference between the alloying temperature and the melting point of the low melting point brazing material is 150 ° C. In No. 24, the bondability and repairability were good, but there was a problem due to the deterioration of the insulation (indicated by Δ in the column of bondability and repairability in the table and x in the column of insulation). Further, the difference between the alloying temperature and the melting point of the low melting point brazing material is 125 ° C. In No. 23, the bondability and repairability were good, but the insulation was deteriorated (indicated by Δ in the column of insulation in the table).

  On the other hand, the sample Nos. 5 and 75 ° C. and 100 ° C. in which the difference between the alloying temperature and the melting point of the low-melting-point brazing material is a wiring board manufactured by the method for manufacturing a wiring board of the present invention. Nos. 20, 21 and 22 were excellent both in terms of bondability and insulation.

Further, the repairability was excellent in the fracture mode, and the joining state was excellent with no change from the initial state (indicated in the columns of joining property, repairing property, and insulating property in the table).

In addition, as a wiring board of prototype numbers 25 to 34, a thin tin layer using a substitution tin plating solution using cyan for an electrode comprising a wiring layer mainly composed of copper formed on an insulating base made of glass ceramics. Then, a tin plating layer is formed to a thickness of 0.1 to 6 μm using an electroless tin plating solution utilizing a disproportionation reaction, and then a gold plating layer is formed to a thickness of 0.08 to 4.9 μm using a cyan bath. After forming with a film thickness, heat treatment was performed for 30 seconds at a temperature at which the difference between the alloying temperature and the melting point of the low melting point brazing material was 75 ° C. Evaluation similar to the wiring board of trial production numbers 1-7 was performed to the wiring board produced in this way. The results are shown in Table 4.

  As can be seen from the results in Table 4, the sample No. No. 25 had problems in the bondability and repairability (indicated by Δ to x in the column of bondability and repairability in the table). Further, Sample No. with a tin plating layer thickness of 0.3 μm was used. No. 26 was a level where there was no problem in strength, although a part of the underlying copper-tin alloy layer was exposed at the fracture interface, and there was no problem in practical use (indicated by Δ in the column of bondability and repairability in the table) ). In addition, Sample No. with a tin plating layer thickness of 5.5, 6 μm. Although 33 and 34 were both good in bondability and repairability, it took 3 to 4 hours to form a tin plating layer.

  In contrast, Sample Nos. With the tin plating layer thicknesses of 0.5, 1, 2, 3, 4 and 5 μm were used. Nos. 27, 28, 29, 30, 31, and 32 were excellent in terms of both bondability and repairability (indicated by a circle in the column of bondability and repairability in the table).

For all of the wiring boards of the above examples and comparative examples, 90% Sn-7.5% Bi-2% Ag-0.5% Cu solder having a melting point of 245 [deg.] C. is used as a low melting point brazing material, and wettability by dipping. As a result, the solder wettability of all the wiring boards was good.
Furthermore, no whisker was generated on any of the wiring boards.

It is sectional drawing which shows an example of embodiment of the wiring board of this invention. It is a principal part expanded sectional view of the wiring board shown in FIG. It is a principal part expanded sectional view of the wiring board for demonstrating the manufacturing method of the wiring board of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Insulation base | substrate 2 ... Wiring layer 3 ... Electronic component 4 ... Wiring board 5 ... Low melting point brazing material 6 ... Copper tin alloy layer 7 ... · Silver or gold and tin alloy layer 8 ··· Lid 9 ··· Tin plating layer
10 ... Silver plating layer or gold plating layer

Claims (3)

An insulating substrate made of glass ceramic on which electronic parts are mounted, a wiring layer mainly composed of copper formed on the insulating substrate, and a copper tin alloy layer and a silver tin alloy formed on the wiring layer A method for manufacturing a wiring board, comprising: a tin plating layer having a thickness of 0.5 to 5 μm on a surface of a region of the wiring layer to which an electrode of the electronic component is electrically connected; A method for manufacturing a wiring board, wherein a silver-plated layer having a thickness of 3 μm is sequentially formed and heat-treated to thereby sequentially form a copper-tin alloy layer and a silver-tin alloy layer on the wiring layer . The method of manufacturing a wiring board according to claim 1, wherein a ratio of the thickness of the silver plating layer to the thickness of the tin plating layer is ¼. An insulating substrate made of glass ceramic on which electronic parts are mounted, a wiring layer mainly composed of copper formed on the insulating substrate, and a copper-tin alloy layer and a gold-tin alloy formed on the wiring layer A method for manufacturing a wiring board, comprising: a tin plating layer having a thickness of 0.5 to 5 μm on a surface of a region of the wiring layer to which an electrode of the electronic component is electrically connected; and 0.4 to 4. A method for manufacturing a wiring board, in which a gold-plated layer having a thickness of 1 μm is sequentially formed and heat-treated to sequentially form a copper-tin alloy layer and a gold-tin alloy layer on the wiring layer.

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