JP4965102B2 - Conductive paste composition for via hole filling - Google Patents

Description

  The present invention relates to a conductive paste composition for filling via holes, and more particularly to a conductive paste composition for filling via holes of a multilayer wiring board formed by laminating a plurality of wiring boards.

  Advances in the highly information-oriented society have led to faster information processing in electronic devices (higher operating frequency) and wider frequency bands for information communications (broadband). There is a need for a wiring board. Further, the wiring board material is required to have a low relative dielectric constant and dielectric loss tangent.

  As this high-density multilayer wiring board, a buildup multilayer board in which buildup layers made of a photosensitive epoxy resin are successively stacked above and below a core layer made of a glass epoxy board has been proposed since the 1990s. This build-up multilayer board is used in many electronic devices today because fine wiring is easier compared to conventional multilayer boards.

  However, in the build-up multilayer wiring board, it is necessary to ensure the insulation reliability of the board. In comparison, there is a problem that the via wiring for connecting the layers is formed by copper plating, so that the via cannot be formed on the via in the manufacturing process. Therefore, in the build-up multilayer wiring board, a limit has begun to appear in order to cope with the further higher density demanded in recent years.

  As a solution to these problems, a coreless all-layer IVH (Intermediate Via Hole) substrate that has a high degree of freedom in wiring design and excellent transmission characteristics has recently attracted attention. Via wiring for connecting each layer in the coreless all-layer IVH substrate is formed of a conductive paste composition. Therefore, it is possible to form a via-on-via structure and a pad-on-via structure in which a via is formed on the via, and sufficiently meet the recent demand for higher density.

  The conductive paste composition for filling via holes is generally composed of electroparticles, a resin and a solvent. The conductive paste composition for filling a via hole is produced by roughly kneading each of these components with a planetary mixer, kneading with a three roll, and defoaming with a planetary mixer.

  The conductive paste composition for filling via holes is roughly classified into a metal pressure contact paste and a metal diffusion paste. The metal pressure contact paste is intended to conduct electricity by contacting metal particles due to solvent volatilization, resin curing shrinkage, and lamination pressure. As the metal particles in the metal pressure contact paste, silver powder, copper powder, silver-coated copper powder or the like is used.

  The metal diffusion paste contains metal particles that melt at a temperature lower than the laminating temperature and diffuse into the copper foil, which is a conductor pattern, and the metal particles are diffused and alloyed by the solvent volatilization and laminating pressure to achieve conduction. is there. For this reason, high connection reliability can be expected in the metal diffusion paste.

  The metal particles used in the metal diffusion paste include eutectic solder (Sn / Pb: mp 183 ° C.), Pb-free solder powder (for example, Sn / Ag / Cu: mp 220 ° C.), Sn plating (Sn: mp 232 ° C.) Cu core , Sn plating Ag core and the like. Of these, eutectic solder contains Pb and therefore cannot be used because it has a large environmental load, and Sn-plated Cu core and Sn-plated Ag core are not preferred because of high cost. Therefore, Pb-free solder powder (lead-free solder particles) is often used as the metal particles used in the metal diffusion paste.

  As a conventional technique related to a metal diffusion paste, Patent Document 1 describes a conductive composition filled in a via hole provided in an insulating base material in a printed circuit board. This conductive composition is made of an alloy of tin and silver, and this tin forms a solid phase diffusion phase with a metal that forms a conductor pattern in a printed circuit board, and is electrically connected. In this case, it is described that since the electrical connection between the conductor patterns is not performed by contact conduction, the interlayer connection resistance value hardly changes and the reliability of the interlayer connection can be prevented from being lowered.

Patent Document 2 describes a wiring board including an insulating substrate, a conductor wiring layer, and a via hole conductor. As the conductive paste for forming the via-hole conductor, in the example of Patent Document 2, a conductive paste containing silver-coated copper powder, a Pb—Sn alloy, an epoxy resin, and a solvent is described. In the present invention, the molten tin component reacts with the copper component by heating during the production of the wiring board, and an intermetallic compound such as Cu ₃ Sn is generated. Further, it is described that the intermetallic compound can firmly bond the copper powder or between the copper powder and the conductor wiring layer to improve heat resistance and conductivity.

Patent Document 3 describes a lead-free solder paste obtained by mixing a lead-free solder powder and a solder flux.
Japanese Patent No. 3473601 Japanese Patent No. 3187373 Japanese Patent No. 3074649

  However, the conductive composition described in Patent Document 1 contains tin and silver and, in some cases, an organic solvent, but does not contain a resin. For this reason, it is difficult to fill the via hole with a good yield with a normal printing means, and it is necessary to employ a special printing method.

  Moreover, the conductive paste described in Patent Document 2 uses a lead-containing solder. Such a lead-containing solder has a problem because when the wiring board using the lead-containing solder is discarded, the lead may be eluted from the board and the groundwater may be contaminated. . In addition, the electronic component goes backward in the direction of making Pb free.

  Moreover, the lead-free solder paste described in Patent Document 3 does not contain a resin. Therefore, as in the case of the above-mentioned Patent Document 1, it is necessary to adopt a special printing technique when filling the via hole.

  Further, from the viewpoint of producing a higher performance wiring substrate, the conductive paste composition in the via hole is required to be highly metal diffusion bonded and have a very low resistance value.

  Therefore, the present invention is preferable from the viewpoint that the via hole can be filled by a normal printing method (for example, a screen printing method) and does not contain lead, so that environmental load is reduced. It is an object of the present invention to provide a conductive paste composition for filling via holes, in which defects are not generated in the via holes, the connection reliability of the via holes is high, and the resistance value of the via holes can be extremely reduced.

  The present invention will be described below. In order to facilitate understanding of the present invention, reference numerals in the accompanying drawings are appended in parentheses, but the present invention is not limited to the illustrated embodiment.

  The first aspect of the present invention comprises an insulating base material (10) made of a thermoplastic resin composition, and a conductor pattern (20) provided on the insulating base material, and a conductive paste composition on the insulating base material (10). A wiring board (100) formed with via holes (30) filled with an object (40) is overlapped with the wiring boards (100), or different from the wiring board (100). A conductive paste composition (filled in the via hole) in a multilayer wiring board (200) which is alternately laminated with a wiring board (300) made of a material other than the plastic resin composition, and is laminated by heat fusion or sequentially laminated. 40) comprising conductive powder and a binder component, wherein the mass ratio of the conductive powder and the binder component is 90/10 or more and less than 98/2, and the conductive powder comprises the first alloy particles and First The first alloy particles are non-lead solder particles having a melting point of 180 ° C. or higher and lower than 260 ° C., and the second metal particles are selected from the group consisting of Au, Ag, and Cu. At least one kind, a mass ratio of the first alloy particles to the second metal particles is 76/24 or more and less than 90/10, and the binder component is a polymerizable monomer that is cured by heating. A conductive paste composition for filling via holes, wherein the melting point of the lead-free solder particles is included in the curing temperature range of the binder component.

  According to the first aspect of the present invention, there is provided a conductive paste composition for filling via holes, which can be filled into the via holes (30) by a normal printing technique and is preferable from the viewpoint of reducing environmental load because it does not contain lead. Can be provided. Further, by using the lead-free solder particles and the binder component such that the melting point of the lead-free solder particles is included in the curing temperature range of the binder component, the solder component causes the second metal particles and the conductor pattern (20) to be formed. Highly metal diffusion bonding is performed with the metal to be formed. As a result, the multilayer wiring board (200) using the conductive paste composition for filling via holes of the present invention has a very small resistance value of via holes and is excellent in moisture absorption heat resistance, connection reliability, and conductor adhesive strength. It becomes. Here, “metal diffusion bonding” means that the tin in the lead-free solder particles becomes the second metal particles and / or the conductor pattern (20) when the melting point of the alloy composed of the lead-free solder particles is exceeded. It diffuses in the metal forming the metal to form a new alloy.

  In the first aspect of the present invention, the average particle size of the first alloy particles and the second metal particles is preferably 10 μm or less. By doing so, the conductive paste composition can be easily introduced into the via hole (30), and metal diffusion bonding can be easily caused. The average particle size difference between the first alloy particles and the second metal particles is preferably 2 μm or less. By doing so, metal diffusion bonding can be easily caused.

  In the first present invention, the binder component is preferably a mixture of an alkenylphenol compound and maleimides. In the first invention, the first alloy particles are Sn—Cu, Sn—Sb, Sn—Ag—Cu, Sn—Ag—Cu—Bi, Sn—Ag—In, Sn—Ag—In—Bi, One or more lead-free solder particles selected from the group consisting of Sn—Zn, Sn—Zn—Bi, and Sn—Ag—Bi are preferable. By using those exemplified as the binder component and the non-lead solder particles, the melting point of the non-lead solder particles is included in the curing temperature range of the binder component, and the solder component and the second metal particles and Metal diffusion bonding can be performed between the metal forming the conductor pattern (20).

In the first invention, the alkenylphenol compound is dimethallylbisphenol A, the maleimide is bismaleimide, and the molar ratio of dimethallylbisphenol A and bismaleimide is preferably 30/70 or more and less than 70/30. . By using such a binder component, it is possible to make the conductor adhesive force better.
The second aspect of the present invention comprises an insulating base material (10) made of a thermoplastic resin composition, and a conductor pattern (20) provided on the insulating base material, and a conductive paste composition on the insulating base material (10). A wiring board (100) formed with via holes (30) filled with an object (40) is overlapped with the wiring boards (100), or different from the wiring board (100). A conductive paste composition (filled in the via hole) in a multilayer wiring substrate (200), which is alternately laminated with a wiring substrate (300) made of a material other than the plastic resin composition, and laminated or sequentially laminated by thermal fusion ( 40) comprising conductive powder and a binder component, wherein the mass ratio of the conductive powder and the binder component is 90/10 or more and less than 98/2, and the conductive powder comprises the first alloy particles and First The first alloy particles are non-lead solder particles having a melting point of 180 ° C. or higher and lower than 260 ° C., and the second metal particles are selected from the group consisting of Au, Ag, and Cu. The mass ratio of the first alloy particles and the second metal particles is 76/24 or more and less than 90/10, and the binder component is a mixture containing maleimides. A conductive paste composition for filling via holes.

  The conductive paste composition for filling via holes of the present invention can be filled in via holes by a normal printing method, and is preferable from the viewpoint of reducing environmental burden because it does not contain lead. Further, by using the lead-free solder particles and the binder component such that the melting point of the lead-free solder particles is included in the curing temperature range of the binder component, the solder component forms the second metal particles and the conductor pattern. Highly metal diffusion bonding between the two. As a result, the multilayer wiring board using the conductive paste composition for filling via holes of the present invention can have a very small resistance value of the via holes, and also has moisture absorption heat resistance, connection reliability, and conductor adhesion. It can be excellent in strength.

Hereinafter, the present invention will be described based on embodiments shown in the drawings.
<Use of conductive paste composition for filling via hole>
FIG. 1 schematically shows a general manufacturing process of a multilayer wiring board 200 in which the conductive paste composition for filling via holes of the present invention is used. FIGS. 1A to 1G are views showing a process of manufacturing a multilayer wiring board 200a by superimposing a plurality of wiring boards 100a provided with an insulating base material 10 made of a thermoplastic resin composition. 1 (h) to 1 (l) show a multilayer structure in which a wiring board 100b provided with an insulating base material 10 made of a thermoplastic resin composition and a wiring board 300 made of a material other than the thermoplastic resin composition are alternately stacked. It is the figure which showed the process of manufacturing the wiring board 200b. The conductive paste composition 40 for filling via holes of the present invention electrically connects 20 parts of the conductor pattern in the multilayer wiring board 200 by filling the via holes 30 in the multilayer wiring board 200 manufactured by these processes. The via hole to be formed is formed. The process shown in FIG. 1 is an example of a method for producing a multilayer wiring board 200 in which the via hole filling conductive paste composition 40 of the present invention is used, and the via hole filling conductive paste composition 40 of the present invention includes: The multilayer wiring board 200 is not limited to the multilayer wiring board 200 manufactured by these manufacturing methods, and is laminated by thermocompression bonding by heating at a temperature higher than the melting point of the first alloy particles in the conductive paste composition for filling via holes. It can also be used in multilayer wiring boards.

<Conductive paste composition for via hole filling>
The conductive paste composition for filling via holes of the present invention contains conductive powder and a binder component.

(Conductive powder)
The conductive powder used in the present invention is composed of first alloy particles and second metal particles.

  The first alloy particles are non-lead solder particles having a melting point of 180 ° C. or higher and lower than 260 ° C. Examples of such lead-free solder particles include Sn—Cu, Sn—Sb, Sn—Ag—Cu, Sn—Ag—Cu—Bi, Sn—Ag—In, Sn—Ag—In—Bi, and Sn—. Zn, Sn-Zn-Bi, and Sn-Ag-Bi can be mentioned. These lead-free solder particles are reliable in the effect of metal diffusion of tin. As the first alloy particles, a mixture of two or more of these non-lead solder particles can also be used.

  The second metal particles are at least one or more metal particles selected from the group consisting of Au, Ag, and Cu. The second metal particle is a particle formed of a metal having a low electric resistance value, and bears the electric conductivity of the via hole. The second metal particles have a higher melting point than the first alloy particles, and have a role of maintaining the viscosity of the conductive paste composition during heating.

  The mixing ratio of the first alloy particles and the second metal particles in the conductive powder is “76/24” or more and less than “90/10” by mass ratio (“first alloy particles” / “second” Metal particles "). If the amount of the first alloy particles is too large beyond this range, the viscosity of the conductive paste composition is greatly reduced when the substrate is heated and laminated, and the conductive paste composition 40 flows out from the via hole 30. There is a risk that.

  The average particle diameter of the first alloy particles and the second metal particles is preferably 10 μm or less. By setting the first alloy particles to such a particle size, the conductive paste composition 40 can be easily filled into the via hole 30 and metal diffusion can easily occur. Moreover, the effect which adjusts the viscosity of the electrically conductive paste composition at the time of carrying out heating lamination | stacking of a board | substrate by using a 2nd metal particle as such a particle size becomes favorable.

  The average particle size difference between the first alloy particles and the second metal particles is preferably 2 μm or less. By aligning the particle diameters as much as possible, metal diffusion bonding can be easily generated.

(Binder component)
The binder component used in the present invention is a mixture of polymerizable monomers that are cured by heating. Examples of such a binder component include a mixture of an alkenylphenol compound and maleimides. In addition, even if the alkenylphenol compound and / or maleimide is a polymer compound, it can be included in the polymerizable monomer of the present invention as long as it is cured by crosslinking reaction by heating. And

  Examples of the alkenylphenol compound include alkenylphenol compounds having at least two alkenyl groups in the molecule, that is, phenolic compounds in which a part of the hydrogen atoms of the aromatic ring are substituted with alkenyl groups. Specifically, examples of such alkenylphenol compounds include compounds in which an alkenyl group is bonded to bisphenol A or a phenolic hydroxyl group-containing biphenyl skeleton. More specifically, 3,3′-bis (2-propenyl) -4,4′-biphenyldiol, 3,3′-bis (2-propenyl) -2,2′-biphenyldiol, 3,3 ′ Dialkenyl biphenyldiol compounds such as -bis (2-methyl-2-propenyl) -4,4'-biphenyldiol and 3,3'-bis (2-methyl-2-propenyl) -2,2'-biphenyldiol 2,2-bis [4-hydroxy-3- (2-propenyl) phenyl] propane, 2,2-bis [4-hydroxy-3- (2-methyl-2-propenyl) phenyl] propane (hereinafter “ And dialkenyl bisphenol compounds such as “dimethallyl bisphenol A”). Among these, it is preferable to use dimethallyl bisphenol A as the alkenylphenol compound from the viewpoint that the raw material cost is low and stable supply is possible. The structural formula of dimethallylbisphenol A is shown in Formula 1.

  Examples of maleimides include maleimide compounds having at least two maleimide groups in the molecule. Specific examples thereof include bismaleimides such as bis (4-maleimidophenyl) methane and tris (4-maleimidophenyl) methane. And trismaleimide such as bis (3,4-dimaleimidophenyl) methane, and polymaleimide such as poly (4-maleimidostyrene). Among these, as maleimides, it is preferable to use bis (4-maleimidophenyl) methane because raw material costs are low and stable supply is possible. The structural formula of bis (4-maleimidophenyl) methane is shown in Formula 2.

  In this binder component, the molar ratio of the alkenylphenol compound and maleimide is preferably “30/70” or more and less than “70/30” (“alkenylphenol compound” / “maleimides”). If this range is exceeded and either component in the binder component is too much, the resulting resin becomes brittle and the adhesive strength between the conductive paste composition 40 and the conductor pattern 20 parts is reduced.

  The curing reaction of the binder component will be described below. The alkenyl group in the alkenylphenol compound undergoes alternating copolymerization and / or addition reaction with the ethylenically unsaturated group of the maleimide compound, and the phenolic hydroxyl group also undergoes addition reaction with the ethylenically unsaturated group of the maleimide group. Hereinafter, the curing mechanism of dimethallylbisphenol A and bis (4-maleimidophenyl) methane exemplified as the binder component will be specifically described. First, in the stage heated to 120-180 degreeC, the linear polymer shown by the following formula | equation 3 is obtained.

  Furthermore, when heated to 200 ° C. or higher, for example, a three-dimensionally crosslinked polymer represented by the following formula 4 is obtained.

  In the present invention, the curing by the three-dimensional crosslinking of the binder component promotes the metal diffusion of the solder component to the metal forming the second metal particles and / or the conductor pattern 20, thereby increasing the level of the metal. It is believed that a diffusion bond is formed. That is, when the binder component is cured, pressure is applied to the first alloy particles and the second metal particles in the via hole 30, whereby the solder component is diffused into the metal that forms the metal particles and the conductor pattern 20. Is believed to be promoted. FIG. 2 shows how the elastic modulus of the binder component changes with temperature. The elastic modulus of the monomer mixture decreases with increasing temperature. However, the elastic modulus suddenly increases due to the formation of the linear polymer represented by Formula 3 at 120 to 180 ° C. (From the graph of “monomer mixture” in FIG. 2, “after crosslinking”). It becomes a graph of.) Thereafter, the linear polymer is considered to change into a three-dimensionally crosslinked polymer represented by Formula 4 at 200 ° C. or higher. The graph after crosslinking tends to decrease with increasing temperature. However, a constant elastic modulus is maintained without melting even in a high temperature region.

  Thus, when the lead-free solder particles are melted at 180 to 260 ° C., the binder component undergoes a curing reaction to maintain a certain elastic modulus. As described above, it is considered that a metal diffusion bonding occurs in the conductive paste composition 40 for filling a via hole according to the present invention by applying pressure to the melted lead-free solder particles due to curing of the binder. And the multilayer wiring board 200 using the conductive paste composition 40 of the present invention has a very low resistance value of the via hole, and has excellent moisture absorption heat resistance, connection reliability, and conductor adhesive strength. It is considered to be.

  From such a viewpoint, the binder component needs to be cured at the stage where the solder particles are dissolved, and the melting point of the lead-free solder particles needs to be included in the curing temperature range of the binder component. On the other hand, when the melting point of the lead-free solder particles is too high compared to the curing temperature range of the binder component, the lead-free solder particles are not yet melted at the stage where the binder component is cured. The effect of being promoted cannot be enjoyed. In addition, when the melting point of the non-lead solder particles is too low as compared with the curing temperature range of the binder component, the dissolved solder component may protrude from the via hole.

  In addition, the curing temperature range of the binder component was measured by the generation temperature of an exothermic peak measured by differential scanning calorimetry (DSC) at a temperature rising rate of 10 ° C./min.

  As described above, the conductive paste composition 40 for filling a via hole of the present invention contains a conductive powder and a binder component. The mixing ratio of the conductive powder and the binder component is “90 / 10 "or more and less than" 98/2 "(" conductive powder "/" binder component "). If the amount of the conductive powder is too small beyond this range, the electrical resistance value of the conductive paste filled in the via hole will increase. If the amount of the conductive powder is too large beyond this range, the workability of printing and filling the conductive paste composition 40 into the via hole 30 is deteriorated, and the conductive paste composition 40 and 20 parts of the conductive pattern are also obtained. And the adhesive strength will decrease.

<Insulating base material 10 made of thermoplastic resin composition>
The thermoplastic resin composition forming the insulating substrate 10 made of a thermoplastic resin composition is a mixture of a polyaryl ketone resin and an amorphous polyetherimide resin having a crystal melting peak temperature (Tm) of 260 ° C. or higher. It is preferable to use a composition. Note that the polyaryl ketone resin and the amorphous polyetherimide resin are compatible systems, and these mixed compositions have one crystal melting peak temperature. That is, in the above, it means that one crystal melting temperature of the mixed composition of the polyaryl ketone resin and the amorphous polyetherimide resin is 260 ° C. or higher.

  This polyaryl ketone resin is a thermoplastic resin having an aromatic nucleus bond, an ether bond and a ketone bond in its structural unit, and representative examples include polyether ketone, polyether ether ketone, polyether ketone ketone, etc. Of these, polyetheretherketone is preferred. Polyether ether ketone is commercially available as “PEEK151G”, “PEEK381G”, “PEEK450G” (all are trade names of VICTREX), and the like.

  The amorphous polyetherimide resin is an amorphous thermoplastic resin containing an aromatic nucleus bond, an ether bond and an imide bond in the structural unit, and is not particularly limited. Polyetherimide is commercially available as “Ultem CRS 5001”, “Ultem 1000” (both are trade names of General Electric).

  The mixing ratio of the polyaryl ketone resin and the amorphous polyetherimide resin is 30% by mass or more and 70% by mass or less of the polyaryl ketone resin in consideration of adhesion to other wiring substrates 100 and 300 to be laminated. It is preferable to use a mixed composition containing an amorphous polyetherimide resin and inevitable impurities. Here, the reason why the content of the polyaryl ketone resin is limited to 30% by mass or more and 70% by mass or less is that when the content of the polyaryl ketone resin is too high, the crystallinity of the thermoplastic resin composition is high. This is because the lamination property at the time of multilayering is lowered, and if the content of the polyaryl ketone resin is too low, the crystallinity itself of the thermoplastic resin composition as a whole is lowered, and the crystal melting peak temperature is 260 ° C. It is because reflow heat resistance falls even if it is above.

  This thermoplastic resin composition may contain an inorganic filler. There is no restriction | limiting in particular as an inorganic filler, Any well-known thing can be used. Examples thereof include talc, mica, mica, glass flake, boron nitride (BN), plate-like carbon cal, plate-like aluminum hydroxide, plate-like silica, and plate-like potassium titanate. These may be added singly or in combination of two or more. In particular, a scale-like inorganic filler having an average particle size of 15 μm or less and an aspect ratio (particle size / thickness) of 30 or more can keep the linear expansion coefficient ratio in the plane direction and the thickness direction low, and the thermal shock cycle test. This is preferable because generation of cracks in the substrate at the time can be suppressed.

  The added amount of the inorganic filler is preferably 20 parts by mass or more and 50 parts by mass or less with respect to 100 parts by mass of the thermoplastic resin. This is because if the amount of the inorganic filler added is too large, a problem of poor dispersion of the inorganic filler occurs, and the linear expansion coefficient tends to vary or the strength tends to decrease. In addition, if the amount of the inorganic filler added is too small, the effect of reducing the linear expansion coefficient and improving the dimensional stability is small, which is caused by the difference in the linear expansion coefficient with the other wiring substrate 300 or the conductive pattern 20 in the reflow process. This is because internal stress is generated, and the substrate is warped and twisted.

  In addition, the thermoplastic resin composition has various additives other than other resins and inorganic fillers, such as a stabilizer, an ultraviolet absorber, a light stabilizer, a nucleating agent, a colorant, and a lubricant, to the extent that the properties are not impaired. In addition, flame retardants and the like may be appropriately contained. As a method of adding various additives including these inorganic fillers, a known method, for example, the following methods (a) and (b) can be used.

  (A) Various additives were mixed with a polyaryl ketone resin and / or an amorphous polyetherimide resin base material (base resin) at a high concentration (typically about 10 to 60% by mass). A method of preparing a master batch separately, adjusting the concentration of the master batch and mixing the resin, and mechanically blending it using a kneader or an extruder. (B) A method in which various additives are mechanically blended directly with a resin to be used using a kneader or an extruder. Among these methods, the method (a) is preferable from the viewpoint of dispersibility and workability. Further, the surface of the insulating base material 10 made of the thermoplastic resin composition may be appropriately subjected to corona treatment or the like for the purpose of improving the lamination property.

<The manufacturing method of the wiring board 100a provided with the insulating base material 10 which consists of a thermoplastic resin composition>
1A to 1E show a process for manufacturing a single-layer wiring board 100a. First, as shown to Fig.1 (a), the insulating base material 10 which consists of a thermoplastic resin composition is prepared. The insulating substrate 10 is preferably in the form of a film, a thin plate or a sheet. As a forming method, a known method such as an extrusion casting method using a T die or a calendar method can be adopted, and the method is particularly limited. However, an extrusion casting method using a T-die is preferable from the viewpoints of sheet formability and stable productivity. The molding temperature in the extrusion casting method using a T-die is appropriately adjusted depending on the flow characteristics and film-forming properties of the resin used, but is generally polyaryl ketone resin and amorphous having a crystal melting peak temperature of 260 ° C. or higher. In the case of a mixed composition of a conductive polyetherimide resin, the temperature is 360 to 400 ° C. In addition, it is necessary to form an amorphous film by rapidly forming a film during extrusion casting. Thereby, since the area | region where an elasticity modulus falls in 170-230 degreeC vicinity is expressed, thermoforming and heat fusion in this temperature range are attained. Specifically, the elastic modulus starts to decrease at around 170 ° C., and thermoforming and heat fusion are possible at around 200 ° C. The graph shown in FIG. 3 is obtained by measuring the elastic modulus at a temperature rising rate of 3 ° C./min. When the temperature rising rate is 10 ° C./min, the transition from amorphous to crystalline is delayed. In the vicinity of 230 ° C., the elastic modulus is the lowest.

  Subsequently, as shown in FIG.1 (b), metal foil is affixed on the surface of the insulating base material 10 which consists of a thermoplastic resin composition. As described above, since the insulating base material 10 made of the thermoplastic resin composition is in an amorphous state, the crystallization of the thermoplastic resin does not proceed greatly, and it takes a relatively short time at a temperature slightly above the glass transition temperature. Thus, the metal foil can be attached without causing crystallization of the insulating base material. Further, when forming the insulating base material 10, a copper foil may be laminated at the same time as shown in FIG.

  Next, as shown in FIG. 1C, a via hole 30 is formed at a predetermined position of the insulating base 10 using a laser or a mechanical drill. Next, as shown in FIG. 1D, a conductor pattern 20 is formed by a normal method such as applying a resist to the surface of the metal foil in a circuit pattern, etching, and removing the resist. In addition, after forming a via hole, a copper foil may be affixed and the conductor pattern 20 may be formed, and after forming the conductor pattern 20, a via hole may be formed. It is not limited. Next, the via hole 30 is filled with the conductive paste composition 40 by a normal printing method such as screen printing, and a single-layer wiring board 100a as shown in FIG.

<Behavior of elastic modulus with respect to temperature of insulating substrate 10 made of thermoplastic resin composition>
Here, the behavior of the elastic modulus with respect to the temperature of the insulating substrate 10 made of the thermoplastic resin composition will be described. As a thermoplastic resin composition, a mixed composition of a polyaryl ketone resin and an amorphous polyetherimide resin having a crystal melting peak temperature (Tm) of 260 ° C. or higher, particularly a polyether as a polyaryl ketone resin The behavior of the elastic modulus with respect to temperature of the insulating base material 10 when ether ketone is used is shown in FIG.

  “Before lamination” is a graph showing the behavior of the elastic modulus with respect to the temperature of the insulating base material 10 before lamination as the multilayer wiring board 200. Also, “after lamination” is displayed as a graph showing the behavior of the elastic modulus with respect to the temperature of the insulating base material 10 after the multilayer wiring board 200 is formed by heating and pressurizing under predetermined conditions. . In the state before lamination, as described above, the insulating base material 10 is formed into an amorphous film by rapid cooling. Therefore, the elastic modulus is sufficiently lowered in a relatively low temperature region of around 200 ° C. Thereby, the insulating base material 10 before lamination can be thermoformed and heat-sealed at a relatively low temperature.

  The insulating base material 10 formed into an amorphous film changes to crystallinity by heating and pressure molding under predetermined conditions when the multilayer wiring base material 200 is manufactured. Along with this, the elastic modulus of the insulating base material 10 is greatly changed to behave as shown in the graph after lamination in FIG. As a result, the effect of promoting metal diffusion bonding is demonstrated as will be described below, and the resistance value of the via hole of the multilayer wiring board 200 can be made extremely small, as well as moisture absorption heat resistance and connection reliability. In addition, it is considered that the adhesive strength of the conductor can be excellent.

  Next, how metal diffusion bonding is promoted will be described. Here, the relationship between the lead-free solder particles in the conductive paste composition 40 and the insulating substrate 10 made of the thermoplastic resin composition is important, and storage of the thermoplastic resin composition at the melting point of the lead-free solder particles. The elastic modulus is preferably 10 MPa or more and less than 5 GPa. In addition, when the mixed composition of polyether ether ketone and amorphous polyether imide, which is the above-described preferred form, is used as the thermoplastic resin composition forming the insulating base material 10 made of the thermoplastic resin composition. As shown in FIG. 3, the storage elastic modulus of the thermoplastic resin composition at the melting point of the lead-free solder particles of 180 ° C. or higher and lower than 260 ° C. is 10 MPa or higher and lower than 5 GPa. The storage elastic modulus of the thermoplastic resin composition is a value measured using a viscoelasticity evaluation apparatus at a measurement frequency of 1 Hz and a temperature increase rate of 3 ° C./min.

  As described above, the thermoplastic resin composition has a storage elastic modulus of 10 MPa or more and less than 5 GPa at the melting point of the lead-free solder particles. It means that a certain degree of elastic modulus is maintained without being melted while having flexibility.

  Thus, by giving the thermoplastic resin composition a certain degree of flexibility at the melting point of the lead-free solder particles, the conductive paste composition 40 and the thermoplastic resin composition can be compatible with each other, and the conductive Adhesiveness between the insulating paste composition 40 and the insulating substrate 10 made of the thermoplastic resin composition is improved. In addition, when the wiring substrate 100 is laminated by thermal fusion, the conductive paste composition 40 is maintained by maintaining a certain degree of elastic modulus without melting the thermoplastic resin composition at the melting point of the lead-free solder particles. Can be clamped by the thermoplastic resin composition which is the side surface of the via hole, and pressure can be applied to the conductive paste composition 40. Thereby, it is considered that the tin component in the lead-free solder particles can diffuse into the metal forming the second metal particles and / or the conductor pattern 20 to form a metal diffusion bonding.

<Wiring board 300 made of a material other than the thermoplastic resin composition>
The wiring substrate 300 made of a material other than the thermoplastic resin composition includes a glass epoxy substrate (FR4 substrate), a two-layer polyimide substrate, a pseudo two-layer polyimide substrate, a three-layer polyimide substrate, an LCP (liquid crystal polymer) substrate, and an LTCC (low temperature fired ceramic). ) A substrate can be used. Two or more of these wiring boards 300 may be laminated together to form the multilayer board 200.

  A method for manufacturing a glass epoxy substrate (FR4 substrate) will be described. First, an insulating base material (prepreg) in which a glass cloth is impregnated with a thermosetting resin to form a semi-cured state (B stage) is prepared. Next, a through-hole penetrating the insulating base material is formed at a predetermined position of the insulating base material using a laser or a mechanical drill, and this is used as a via hole. Next, a conductive paste is filled into the via hole by screen printing or the like. Then, if necessary, the conductive paste is solidified by heating to volatilize the solvent. The conductive paste used for the wiring substrate 300 is not particularly limited, and a general conductive paste used for filling via holes can be used. Moreover, the conductive paste composition 40 used in the wiring base material 100 can also be used as the conductive paste used for the wiring board 300. Next, if necessary, the dried and solidified product of the conductive paste protruding on the surface of the insulating base material is removed by mechanical polishing or the like, and copper foil is applied to one or both surfaces of the insulating base material. The insulating substrate is completely cured simultaneously with thermocompression bonding (C-stage). Next, the copper foil is patterned by etching to form a conductor pattern. From the above, it is possible to manufacture the wiring substrate 300 made of a material other than the thermoplastic resin composition using the glass epoxy substrate.

  The “B stage” of the above-described epoxy resin refers to a semi-cured state in which the reaction proceeds to some extent when a resin and a curing agent are mixed. At this stage, most of it is no longer dissolved in the solvent, but when heated, it dissolves and the reaction proceeds further. The “C stage” refers to a completely cured state that is insoluble and infusible at the final stage of the reaction.

  A method for manufacturing a liquid crystal polymer (LCP) substrate will be described. First, an insulating substrate made of LCP is prepared. As the LCP, LCPI type (liquid crystal transition temperature: 350 ° C.), LCP II type (liquid crystal transition temperature: 300 ° C.), or the like can be used. As the insulating substrate made of LCP, a film shape, a thin plate shape, or a sheet shape is preferable. The molding method is preferably a known method, for example, an extrusion casting method using a T die, a calendar method, an inflation molding method, or the like, and is not particularly limited. Considering, an extrusion casting method using a T die is preferable. The molding temperature in the extrusion casting method using a T-die is appropriately adjusted depending on the fluidity and film-forming property of the resin used, but is generally 400 to 420 ° C. for the LCPI type resin and 350 for the LCP II type resin. ~ 370 ° C. The copper foil is affixed at the time of film formation, and then a via hole is formed in the insulating base material and patterned to form a conductor pattern, which is the same as in the above-described method for manufacturing a glass epoxy substrate.

  A two-layer polyimide substrate in which a polyimide layer is formed on a copper foil by a casting method or a casting method, a pseudo two-layer polyimide substrate in which a thermoplastic polyimide layer is bonded as an adhesive layer between a polyimide film and a copper foil, and a polyimide film A three-layer polyimide substrate using a thermosetting adhesive between copper foils can also be manufactured by the same manufacturing method as the above-described glass epoxy substrate and LCP substrate.

  The LTCC (low temperature fired ceramic) substrate was produced by forming via holes in an LTCC (low temperature fired ceramic) substrate before firing, filling the via holes with Ag paste, and applying Ag paste wiring to the surface layer and firing.

<Method for Manufacturing Multilayer Wiring Board 200>
1E to 1G show the manufacturing process of the multilayer wiring board 200a. As shown in FIG. 1F, a plurality of produced single-layer wiring boards 100a are overlapped. In the illustrated form, three single-layer wiring boards 100a are overlaid. In addition, the lowermost substrate is superposed in a different direction so that the conductor pattern 20 is formed outside the multilayer substrate. Specifically, as shown in FIG. 4, the cushioning film 51, which has three cushion films 51 and wiring substrates 100 a having elasticity and releasability from the lower side, are stacked on the laminated jig 50 with a built-in heater. After that, the pressing jig 52 is pressed down in the direction of the arrow shown in the drawing, so that the three wiring substrates 100a are thermocompression bonded, and these are laminated and integrated to form the multilayer wiring board 200a. As the lamination conditions of each layer, from the viewpoint of effectively causing metal diffusion bonding, it is preferable that the temperature is 200 ° C. or more and less than 260 ° C., the pressure is 3 MPa or more and less than 8 MPa, and the press time is 10 minutes or more and less than 40 minutes.

  1 (h) to (l) show a multilayer structure in which a wiring board 100b provided with an insulating base material 10 made of a thermoplastic resin composition and a wiring board 300 made of a material other than the thermoplastic resin composition are alternately stacked. It is the figure which showed the process of manufacturing the wiring board 200b. First, as shown in FIG.1 (h), the insulating base material 10 which consists of a thermoplastic resin composition is prepared. The molding method is the same as in the case of FIG. Next, as shown in FIG. 1 (i), a via hole 30 is formed at a predetermined position of the insulating substrate 10 using a laser or a mechanical drill. Then, the formed via hole 30 is filled with the conductive paste composition 40 by a normal printing method such as screen printing, and a single-layer wiring board 100b as shown in FIG. 1 (j) is manufactured.

  Next, as shown in FIG. 1 (k), the manufactured single-layer wiring board 100b and the wiring board 300 made of a material other than the thermoplastic resin composition different from the wiring board 100b are alternately stacked. In the illustrated embodiment, the wiring board 300 made of a material other than the thermoplastic resin is disposed on both sides of the wiring board 100b in the middle.

  Then, under predetermined conditions, the layers are heat-sealed to produce a multilayer wiring board 200b as shown in FIG. The lamination method and lamination conditions are the same as the method and conditions shown in FIG.

  In addition, in the manufacturing method shown to Fig.1 (a)-(g), the conductor pattern 20 is formed in the single side | surface of the single layer wiring board 100a, and also shown to FIG.1 (h)-(l). In the manufacturing method, the conductor pattern 20 is formed on both surfaces of the wiring board 300 made of a material other than the thermoplastic resin composition without forming the conductor pattern 20 on the single-layer wiring board 100b, but the multilayer wiring board 200a to be manufactured is formed. As long as the conductor pattern 20 is formed at a desired position in 200b, the position where the conductor pattern is formed in the single-layer wiring boards 100a, 100b, 300 is not particularly limited, and can be changed as appropriate.

<Example 1>
(Preparation of insulating substrate 10)
For 100 parts by mass of a resin mixture composed of 40% by mass of a polyether ether ketone resin (PEEK450G, Tm = 335 ° C.) and 60% by mass of an amorphous polyetherimide resin (Ultem 1000), an average particle diameter of 5 μm and an average A thermoplastic resin composition obtained by mixing 39 parts by mass of synthetic mica having an aspect ratio of 50 was melt-kneaded and rapidly cooled to form an insulating substrate 10 made of an amorphous film having a thickness of 100 μm. The crystal melting peak temperature (Tm) was 335 ° C. when this amorphous film was measured using a differential scanning calorimeter while raising the temperature at 10 ° C./min.

(Preparation of conductive paste composition for via hole filling)
Sn-Ag-Cu alloy particles (average particle size 5.55 μm, melting point 220 ° C., Sn: Ag: Cu (mass ratio) = 96.5 : 3: 0.5) 76% by mass and Cu particles (average particle size 5 μm) ) 3 mass of a mixture of polymerizable monomers mixed at a ratio of 50 mass% of dimethallylbisphenol A and 50 mass% of bis (4-maleimidophenyl) methane with respect to 97 mass parts of the conductive powder mixed at a ratio of 24 mass%. And 7.2 parts by mass of γ-butyrolactone as a solvent were added and kneaded with three rolls to prepare a conductive paste composition.

(Production of single-layer wiring board 100a)
A copper foil having a thickness of 12 μm was attached to the insulating base material 10 produced above by thermocompression bonding at 205 ° C., 5 MPa for 10 minutes. Next, a via hole having a diameter of 100 μm penetrating the insulating base material was formed using a laser at a desired position of the insulating base material. Then, the conductive paste composition prepared above was filled in this via hole by screen printing. After filling, the conductive paste was dried and solidified by heating at 125 ° C. for 45 minutes to evaporate the solvent. Thereafter, a conductor pattern was formed on the copper foil by a photolithographic method to produce a single-layer wiring board 100a.

(Preparation of multilayer wiring board 200a)
Three single-layer wiring boards 100a obtained as described above are prepared, stacked so that the positions of the via portions match, and stacked by vacuum pressing at a temperature of 230 ° C., 5 MPa for 30 minutes, whereby the insulating substrate 10 is crystallized. A three-layer multilayer wiring board 200a having a layer thickness of 0.3 mm was produced.

<Example 2>
A conductive paste composition was prepared in the same manner as in Example 1 except that the conductive powder in the conductive paste composition in Example 1 was 95 parts by mass and the mixture of polymerizable monomers was 5 parts by mass. A single-layer wiring board 100a and a multilayer wiring board 200a were produced.

<Example 3>
In the same manner as in Example 1 except that the conductive powder in the conductive paste composition in Example 1 was mixed at a ratio of 85% by mass of Sn—Ag—Cu alloy particles and 15% by mass of Cu particles, A conductive paste composition was prepared to produce a single-layer wiring board 100a and a multilayer wiring board 200a.

<Example 4>
(Production of single-layer wiring board 100b)
In Example 1, a single-layer wiring board 100b was produced in the same manner as in Example 1 except that the copper foil was not attached to the insulating base material 10.
(Production of glass epoxy substrate (FR4))
A glass cloth was impregnated with an epoxy resin composition to prepare a semi-cured (B stage) prepreg having a thickness of 100 μm. Via holes were formed by laser at predetermined locations of the prepreg, and the conductive paste composition prepared in Example 1 was filled into the via holes by screen printing. After filling, the conductive paste was dried and solidified by heating at 125 ° C. for 45 minutes to evaporate the solvent.
Then, a 12 μm thick copper foil was attached to both surfaces of the prepreg by thermocompression bonding at 180 ° C. and 5 MPa for 30 minutes, and at the same time, the epoxy resin was completely cured (C stage). Next, a conductive pattern was formed on the copper foil by a photolithographic method to produce a glass epoxy substrate.
(Preparation of multilayer wiring board 200b)
Prepare one single-layer wiring board 100b obtained above and two glass epoxy boards, and stack them alternately so that the positions of the via portions match, at a temperature of 230 ° C., 5 MPa, 30 minutes, Lamination was performed by vacuum pressing to produce a three-layer multilayer wiring board 200b having a layer thickness of 0.3 mm in which the insulating base material 10 was crystallized.

<Example 5>
In Example 4, a multilayer wiring substrate 200b was manufactured in the same manner as in Example 4 except that a liquid crystal polymer substrate was used instead of the glass epoxy substrate. A method for producing a liquid crystal polymer substrate will be described below.
(Manufacturing method of liquid crystal polymer substrate)
The LCPI mold was extruded at 420 ° C. by an extrusion casting method using a T die, and at the same time, a copper foil having a thickness of 12 μm was attached to both sides. Thereafter, in the same manner as in the above glass epoxy substrate, a via hole was formed, and the conductive paste composition was filled and dried to form a conductor pattern, thereby obtaining a liquid crystal polymer substrate having a thickness of 0.1 mm.

<Example 6>
In Example 4, a multilayer wiring substrate 200b was obtained in the same manner as in Example 4 except that a three-layer polyimide substrate was used instead of the glass epoxy substrate. A method for producing a three-layer polyimide substrate will be described below.
(Method for producing a three-layer polyimide substrate)
A thermosetting adhesive layer is thinly coated on both sides of a 35 μm polyimide film, dried and solidified to such an extent that the adhesive layer does not cure, and a via hole is formed in a predetermined portion of the polyimide film with the adhesive layer. The conductive paste composition prepared in Example 1 was filled by screen printing. After filling, the conductive paste was further dried by heating under conditions of 125 ° C. and 45 minutes at which the adhesive layer did not cure, and the solvent was evaporated.
Then, a 12 μm thick copper foil was attached to both sides of the polyimide film with an adhesive layer on which vias were formed by thermocompression bonding at 180 ° C. and 5 MPa for 30 minutes, and at the same time, the epoxy resin was completely cured (C stage). ). Next, a conductor pattern was formed on the copper foil by a photolithographic method to produce a three-layer polyimide double-sided substrate having a thickness of 60 μm.

<Example 7>
In Example 4, a multilayer wiring board 200b was obtained in the same manner as in Example 4 except that LTCC was used instead of the glass epoxy board. The manufacturing method of LTCC is demonstrated below.
(Manufacturing method of LTCC)
Via holes are formed in an LTCC (low temperature fired ceramic) substrate before firing, Ag paste is filled into the via holes, Ag paste wiring is applied to the front and back layers of the substrate before firing, and firing is performed to produce an LTCC double-sided substrate. .

<Comparative Example 1>
A conductive paste composition was prepared in the same manner as in Example 1, except that the conductive powder in the conductive paste composition in Example 1 was 98 parts by mass and the mixture of polymerizable monomers was 2 parts by mass. A single-layer wiring board 100a and a multilayer wiring board 200a were produced.

<Comparative example 2>
A conductive paste composition was prepared in the same manner as in Example 1 except that the conductive powder in the conductive paste composition in Example 1 was 89 parts by mass and the mixture of polymerizable monomers was 11 parts by mass. A single-layer wiring board 100a and a multilayer wiring board 200a were produced.

<Comparative Example 3>
In the same manner as in Example 1 except that the conductive powder in the conductive paste composition in Example 1 was mixed at a ratio of 75% by mass of Sn—Ag—Cu alloy particles and 25% by mass of Cu particles, A conductive paste composition was prepared to produce a single-layer wiring board 100a and a multilayer wiring board 200a.

<Comparative example 4>
In the same manner as in Example 1 except that the conductive powder in the conductive paste composition in Example 1 was mixed at a ratio of 91% by mass of Sn—Ag—Cu alloy particles and 9% by mass of Cu particles, A conductive paste composition was prepared to produce a single-layer wiring board 100a and a multilayer wiring board 200a.

<Reference Example 1>
A conductive paste composition was prepared in the same manner as in Example 1 except that the average particle diameter of the Sn—Ag—Cu alloy particles in the conductive paste composition in Example 1 was set to 15 μm. The wiring board 100a and the multilayer wiring board 200a were produced.

<Reference Example 2>
A conductive paste composition was prepared in the same manner as in Example 1 except that the average particle size of Cu particles in the conductive paste composition in Example 1 was set to 15 μm. A wiring board 200a was produced.

<Reference Example 3>
A conductive paste composition was prepared in the same manner as in Example 1 except that the average particle size of Cu particles in the conductive paste composition in Example 1 was 3.5 μm, and a single-layer wiring board 100a was prepared. And the multilayer wiring board 200a was produced.

<Reference Example 4>
A conductive paste composition was prepared in the same manner as in Example 1 except that the average particle diameter of the Sn—Ag—Cu alloy particles in the conductive paste composition in Example 1 was 8 μm. The wiring board 100a and the multilayer wiring board 200a were produced.

<Reference Example 5>
Except that the mixture of polymerizable monomers in the conductive paste composition in Example 1 was mixed in a proportion of 25% by mass of dimethallyl bisphenol A and 75% by mass of bis (4-maleimidophenyl) methane. In the same manner as in Example 1, a conductive paste composition was prepared to produce a single-layer wiring board 100a and a multilayer wiring board 200a.

<Reference Example 6>
Except that the mixture of polymerizable monomers in the conductive paste composition in Example 1 was mixed at a ratio of 75% by mass of dimethallyl bisphenol A and 25% by mass of bis (4-maleimidophenyl) methane. In the same manner as in Example 1, a conductive paste composition was prepared to produce a single-layer wiring board 100a and a multilayer wiring board 200a.

<Comparative Example 5>
For comparison, a conductive paste and a multilayer wiring board described in Patent Document 2 were produced.
(Preparation of conductive paste)
60% by mass of silver-coated copper powder (average particle size 5 μm, silver content 6% by mass) and Pb—Sn alloy (average particle size 10 μm, Pb: Sn mass ratio = 38: 62, melting point = about 183 ° C.) 40% by mass 4 parts by weight of epoxy resin and 2.0 parts by weight of 2-octanol as a solvent were added to 96 parts by weight of the metal component mixed at a ratio of%, and kneaded with three rolls to prepare a conductive paste.
(Production of multilayer wiring board)
A via hole having a diameter of 200 μm was formed by microdrilling on a B-stage insulating sheet comprising 40% by volume of polyphenylene ether resin and 60% by volume of silica, and the conductive paste composition prepared above was formed in the via hole. Filled. Then, a conductive wiring layer made of a copper foil having a thickness of 12 μm is bonded to both sides of the B-stage insulating sheet embedded with the conductive paste so as to sandwich both ends of the via-hole conductor by a transfer method, and then 200 Heat treatment was performed at 1 ° C. for 1 hour. Next, a conductor pattern was formed on the copper foil by a photolithographic method to produce a single layer substrate. The four single-layer substrates were stacked so that the positions of the via portions were aligned and laminated by vacuum pressing at a temperature of 200 ° C. and 5 MPa for 30 minutes to produce a four-layer multilayer wiring substrate.

<Comparative Example 6>
(Preparation of pressure contact paste)
A conductive paste composition was prepared by adding 10 parts by weight of a binder and 7 parts by weight of γ-butyrolactone as a solvent to 90 parts by weight of Ag particles (average particle size 5 μm) and kneading them with three rolls. As the binder, a mixture of polymerizable monomers mixed in a proportion of 50% by mass of dimethallylbisphenol A and 50% by mass of bis (4-maleimidophenyl) methane used in Example 1 was used.
(Production of multilayer wiring board)
Using the above-mentioned pressure contact paste, a single-layer wiring board 100a and a multilayer wiring board 200a were produced in the same manner as in Example 1.

<Evaluation method>
The following evaluation was performed on the multilayer wiring board produced above. Each evaluation result is shown in Table 1.
(Appearance of via cross section)
The via portion of the obtained multilayer wiring board was subjected to cross-sectional SEM observation and evaluated according to the following criteria.
○: Metal particles are not found. There are no filling defects.
X: Metal particles can be confirmed. Or, metal particles are not found, but there are filling defects.

(Hygroscopic heat resistance)
The obtained multilayer wiring board is dried at 125 ° C. for 4 hours. Then, the treatment in a constant temperature and humidity chamber of 30 ° C. and a humidity of 85% for 96 hours was repeated twice, followed by heating in a reflow furnace having a peak temperature of 250 ° C. The obtained multilayer wiring board was evaluated according to the following criteria.
◯: There is no peeling at the laminated interface between the substrates, and no swelling occurs in the via hole.
X: Peeling occurred at the laminated interface between the substrates and / or swelling occurred in the via hole.

(Resistance value before test)
In the test pattern portion where wiring was applied from the uppermost layer to the lowermost layer of the obtained multilayer wiring board, the following criteria were evaluated.
○: Resistance value is less than 1 × 10 ⁻⁴ Ωcm ×: Resistance value is 1 × 10 ⁻⁵ Ωcm or more

(Connection reliability)
The following two connection reliability tests were performed on the multilayer wiring board subjected to the above-described treatment for moisture absorption heat resistance.

-Migration resistance test DC50V was applied for 240 hours in a constant temperature and humidity chamber of 85 ° C and humidity of 85%. The obtained multilayer wiring board was evaluated according to the following criteria. “Migration” refers to a phenomenon in which CuO is formed and short-circuited between conductor patterns made of copper, for example.
○: The insulation resistance value did not decrease.
X: The insulation resistance value decreased.

Thermal shock test A cycle of 9 minutes at -25 ° C and 9 minutes at 125 ° C was repeated 1000 times.
The obtained multilayer wiring board was evaluated according to the following criteria. The resistance change rate is a value represented by “| resistance value before test−resistance value after test | / resistance value before test” × 100 (%).
○: The rate of change in resistance is less than 20% at both normal temperature and constant temperature (25 ° C.).
X: The rate of change in resistance is 20% or more at either room temperature or constant temperature (25 ° C.).

(Conductor adhesive strength)
A wire was soldered to the conductor pattern portion exposed on the multilayer wiring board, the wire was pulled up, and the strength when the conductor pattern portion was peeled was measured.
A: The strength was 1 N / mm or more.
X: The strength was less than 1 N / mm.

  (Evaluation results)

  The multilayer wiring board using the conductive paste composition for filling via holes of the present invention showed good results in all evaluation items (Examples 1 to 7). On the other hand, in Comparative Example 1, since the amount of the binder component in the conductive paste composition is small, the appearance of the via cross section, the moisture absorption heat resistance, the resistance value before the test, and the conductor adhesion strength are inferior. It was. This is considered to be because the binder component is small, the screen printability to via holes is poor, a number of via defects are generated, and the effect of promoting metal diffusion bonding is small.

  Moreover, in comparative example 2, since there was too much quantity of the binder component in an electrically conductive paste composition, the result inferior in the resistance value before a test and conductor adhesive strength was shown. It is considered that the metal diffusion bonding was not sufficiently generated because the amount of the binder component was too large.

  Moreover, in Comparative Example 3, since the ratio of the first alloy particles in the conductive powder in the conductive paste composition was small, inferior results were obtained in the appearance of the via cross section and the migration resistance test. This is probably because the first alloy particles have strong migration resistance, and this ratio is reduced, and ion migration of the second metal particles is likely to occur.

  Moreover, in Comparative Example 4, since the ratio of the first alloy particles in the conductive powder in the conductive paste composition was large, an inferior result was shown in the resistance value before the test. It is considered that the first alloy particles have a higher resistance value than the second metal particles, and thus the resistance value of the multilayer wiring board is increased.

  In Reference Example 1, the particle diameter of the first alloy particles is too large. In Reference Example 2, the particle diameter of the second metal particles is too large. In Reference Examples 3 and 4, Since the particle size difference between the first alloy particles and the second metal particles is too large, the appearance of the via cross section and the resistance value before the test were inferior. In Reference Examples 1 to 4 in which the particle sizes and particle size differences of the first alloy particles and the second metal particles are outside the preferable range of the present invention, it is considered that metal diffusion bonding is less likely to occur.

  In Reference Example 5, since the amount of maleimides in the binder component is too large, in Reference Example 6, the amount of alkenylphenol compound in the binder component is too large, resulting in a brittle resin and conductive adhesive strength. Was inferior.

  Although the comparative example 5 is an example using the electrically conductive paste composition of patent document 2, it was inferior in the external appearance of a via | veer cross section, moisture absorption heat resistance, and conductor adhesive strength. This is because the insulating base material is a thermosetting PPE resin and the binder component in the conductive paste composition is an epoxy resin, so that the pressure for the solder component to diffuse into the metal particles and the conductor pattern portion is reduced. This is probably because the metal diffusion bonding did not occur sufficiently. Moreover, since the curing temperature of the thermosetting PPE resin is 150 to 200 ° C., if the solder component in Comparative Example 5 is changed to lead-free solder having a melting point of 200 ° C. or higher, the metal diffusion becomes more difficult, resulting in inferior results. It will be shown.

  Comparative Example 6 is an example in which a metal pressure welding paste is used instead of the metal diffusion paste, but the appearance of the via cross section, the migration resistance test, the thermal shock test, and the conductor adhesive strength are inferior.

  While the present invention has been described in connection with embodiments that are presently the most practical and preferred, the present invention is not limited to the embodiments disclosed herein. However, the conductive paste composition for filling via holes can be changed as appropriate without departing from the spirit or concept of the invention that can be read from the claims and the entire specification. Must be understood as encompassed by.

It is the figure which showed the outline | summary of the manufacturing method of the multilayer wiring board 200 using the electrically conductive paste composition 40 for via-hole filling of this invention. It is the figure which showed a mode that the elasticity modulus of a binder component changed with temperature. It is the figure which showed a mode that the elasticity modulus of the specific thermoplastic resin composition which comprises the insulating base material 10 changes with temperature. It is a conceptual diagram of the lamination jig | tool 50 for manufacturing the multilayer wiring board 200 by thermocompression bonding the wiring board 100. FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Insulation base material which consists of thermoplastic resins 20 Conductive pattern 30 Via hole 40 Conductive paste composition for via hole filling 100a, 100b Single-layer wiring board 200a, 200b Multi-layer wiring board 50 Lamination jig 51 Cushion film 52 Pressing jig

Claims (6)

  An insulating substrate made of a thermoplastic resin composition, a wiring board comprising a conductor pattern provided on the insulating substrate, and a via hole filled with a conductive paste composition is formed on the insulating substrate. A multilayer wiring board in which a plurality of wiring boards are superposed on each other or alternately superposed on a wiring board made of a material other than a thermoplastic resin composition, which is different from the wiring board, and laminated or sequentially laminated by thermal fusion. In the conductive paste composition filled in the via hole,
  A conductive powder and a binder component, wherein a mass ratio of the conductive powder and the binder component is 90/10 or more and less than 98/2;
  The conductive powder comprises first alloy particles and second metal particles,
The first alloy particles are non-lead solder particles having a melting point of 180 ° C. or higher and lower than 260 ° C .;
The second metal particles are at least one selected from the group consisting of Au, Ag, Cu, and a mass ratio of the first alloy particles to the second metal particles is 76/24 or more 90 / Less than 10,
  The binder component is a mixture containing maleimides,
A conductive paste composition for filling via holes. An insulating substrate made of a thermoplastic resin composition, a wiring board comprising a conductor pattern provided on the insulating substrate, and a via hole filled with a conductive paste composition is formed on the insulating substrate. A multilayer wiring board in which a plurality of wiring boards are superposed on each other or alternately superposed on a wiring board made of a material other than a thermoplastic resin composition, which is different from the wiring board, and laminated or sequentially laminated by thermal fusion. In the conductive paste composition filled in the via hole,
A conductive powder and a binder component, wherein a mass ratio of the conductive powder and the binder component is 90/10 or more and less than 98/2;
The conductive powder comprises first alloy particles and second metal particles,
The first alloy particles are non-lead solder particles having a melting point of 180 ° C. or higher and lower than 260 ° C .;
The second metal particles are at least one selected from the group consisting of Au, Ag, Cu, and a mass ratio of the first alloy particles to the second metal particles is 76/24 or more 90 / Less than 10,
The binder component is a mixture of polymerizable monomers that are cured by heating, and the melting point of the lead-free solder particles is included in the curing temperature range of the binder component.
A conductive paste composition for filling via holes. The conductive paste composition for filling via holes according to claim 1 or 2 , wherein the binder component is a mixture of an alkenylphenol compound and maleimides. 4. The conductive paste for filling via holes according to claim 1, wherein an average particle size of the first alloy particles and the second metal particles is 10 μm or less, and an average particle size difference is 2 μm or less. Composition. The first alloy particles are Sn—Cu, Sn—Sb, Sn—Ag—Cu, Sn—Ag—Cu—Bi, Sn—Ag—In, Sn—Ag—In—Bi, Sn—Zn, Sn— The conductive paste composition for filling via holes according to any one of claims 1 to 4 , wherein the conductive paste composition is filled with one or more lead-free solder particles selected from the group consisting of Zn-Bi and Sn-Ag-Bi. The alkenylphenol compound is dimethallylbisphenol A,
The maleimide is bis (4-maleimidophenyl) methane;
The conductive paste composition for filling via holes according to any one of claims 3 to 5 , wherein a molar ratio of the dimethallyl bisphenol A and the bis (4-maleimidophenyl) methane is 30/70 or more and less than 70/30. .

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