JP2001093330A - Through-hole conductor forming conductive paste and its manufacturing method as well as both-side printed wiring board using through-hole conductor forming conductive paste - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a through-hole conductor forming conductive paste superior in through- hole passing and soldering performance and its manufacturing method as well as a both-side printed wiring board using the through-hole conductor forming conductive paste. SOLUTION: A through-hole conductor forming conductive paste comprises containing sulfonic acid based hardening agent, binder, conductive powder formed of copper powder or copper alloy powder having almost all surfaces coated with silver while leaving exposed portions, and organic solvent; and a manufacture of the through-hole conductor forming conductive paste comprises coating almost all surfaces of copper powder or copper alloy powder with silver while leaving exposed portions and then uniformly mixing sulfonic acid hardening agent, binder and organic solvent added thereto; as well as a both-side printed wiring board comprises forming through-holes passing through a printed board having electric circuits on both sides, conducting the electric circuits on both sides through the through-holes with the above-described conductive paste or the conductive paste manufactured in the above- described method, and passing a portion of a through-hole conductor therethrough to form pin-insertion holes.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a conductive paste for forming a through-hole conductor which has good through-hole penetrability and can be soldered, a method of manufacturing the same, and a conductive paste for forming a through-hole conductor. Related to a double-sided printed wiring board.

[0002]

2. Description of the Related Art Conventionally, as a method of forming an electric circuit (wiring conductor) such as a printed wiring board or an electronic component, electronic materials,
As described on pages 42 to 46 of the October 1994 issue, a conductive powder of gold, silver, copper, carbon, or the like is used, and a binder, an organic solvent, and additives as needed are added thereto to form a paste. A method of applying or printing a mixed conductive paste is generally known. Particularly in a field where high conductivity is required, gold powder or silver powder is generally used.

As shown in FIG. 1, conduction of an electric circuit on both the front surface and the back surface of a wiring board substrate is achieved by plating 2 in a through hole 1 or filling a conductive paste 3 in this method. In order to insert the pin 4, the plating 2 is generally applied to the inside of the through hole 1 to conduct electricity. However, the plating 2 has to be applied to the inner wall of the through hole 1 and thus has the disadvantage that the number of steps, time and lining cost are increased. On the other hand, when the conductive paste 3 is used, there is a possibility that the through hole 1 may be closed after the filling, drying and curing steps, or the solderability is poor when soldering with the solder 5. There is. If through hole 1 is closed,
If the pin 4 is forcibly inserted, as shown in FIG. 2, the pin 4 may pierce the conductive paste 3 in the portion blocking the through hole 1, causing a crack 6 to occur, and the front surface and the back surface may not be conductive.

In order to solve the above-mentioned drawbacks, studies have been made on the shape of the binder and its hardener or conductive powder. However, the initial properties, through-hole penetration and solderability are poorly balanced and sufficient effects are obtained. Was not what you get. In FIGS. 1 and 2, reference numeral 7 denotes a wiring board base material.

[0005]

SUMMARY OF THE INVENTION The first aspect of the present invention is to provide a conductive paste for forming a through-hole conductor which has excellent through-hole penetration and solderability.
The inventions according to claims 2 and 3 provide a conductive paste for forming a through-hole conductor, which is particularly excellent in the effect of improving the through-hole penetration property.
The inventions according to Claims 4 and 5 are particularly excellent in the effect of improving solderability among the inventions according to Claim 1, and Claim 1
Another object of the present invention is to provide a conductive paste for forming a through-hole conductor, which is excellent in the effect of improving conductivity in addition to the invention of (1).

The invention according to claim 6 provides a method for producing a conductive paste for forming a through-hole conductor, which is excellent in through-hole penetration and solderability. According to a seventh aspect of the present invention, by using the conductive paste for forming a through-hole conductor, the electric circuit on both the front and back surfaces is conducted, and the pin insertion hole is formed through the through-hole conducting portion. A printed wiring board is provided.

[0007]

The present invention comprises a sulfonic acid-based curing agent, a binder, a conductive powder whose surface is substantially covered with silver by exposing a part of copper powder or copper alloy powder, and an organic solvent. And a conductive paste for forming a through-hole conductor. The present invention also relates to the conductive paste for forming a through-hole conductor, wherein the binder is an epoxy resin or a phenol resin. The present invention also relates to the conductive paste for forming a through-hole conductor, wherein the sulfonic acid-based curing agent is 0.05 to 10% by weight based on 90 to 99.95% by weight of the solid phenol resin. In addition, the present invention provides the conductive paste for forming a through-hole conductor, wherein the blending ratio of the binder and the conductive powder is 5 to 15% by weight of the binder and 85 to 95% by weight of the conductive powder based on the solid content of the conductive paste. About.

Further, the present invention provides a conductive powder which is a flat conductive powder having an aspect ratio of 3 to 20 and an average major particle diameter of 5 to 30 μm and an exposed area of copper powder or copper alloy powder of 10 to 60%. The present invention relates to the conductive paste for forming a through-hole conductor. Further, the present invention is characterized in that after part of the copper powder or copper alloy powder is exposed and the surface is substantially covered with silver, a sulfonic acid-based curing agent, a binder and an organic solvent are added and uniformly mixed. The present invention relates to a method for producing a conductive paste for forming a through-hole conductor. Furthermore, the present invention forms a through hole penetrating a printed wiring board having an electric circuit on both sides, and the conductive paste for forming a through hole conductor or the conductive paste for forming a through hole conductor manufactured by the method described above, The present invention relates to a double-sided printed wiring board having a pin insertion hole formed by conducting electric circuits on both sides through the through hole and penetrating a conductor portion of the through hole.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION As a sulfonic acid-based curing agent, a solution mixed with water at a ratio of 1: 1 has a pH of 5 to 8.8 and a dissociation temperature of 60 to 1 because of its function as a phenol resin curing agent.
Those having a temperature range of 30 ° C. are preferred, and the pH is 5.5 to 5.5.
7.5, and those having a dissociation temperature in the range of 65 to 120 ° C are more preferable. Representative examples thereof include p-toluenesulfonic acid [formula (a)], dinonylnaphthalenesulfonic acid [general formula (b)], dinonylnaphthalenedisulfonic acid [general formula (c)], dodecylbenzenesulfonic acid [Formula (d)], their block types, and the like.

[0010]

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[0011] The amount of the curing agent added is such that
From the viewpoints of resistance value, variation thereof, and the like, the content is preferably in the range of 0.05 to 10% by weight with respect to 90 to 99.95% by weight of the solid phenol resin.
More preferably, it is in the range of 0.1 to 5% by weight with respect to 99.9% by weight.

If the through-hole is formed using a conductive paste to which a sulfonic acid-based curing agent is added, the through-hole penetration is improved. This is because the sulfonic acid-based curing agent has a strong function as an acid, and because of the low dissociation temperature, the temperature in the dryer after drying rises at an early stage where the paste viscosity decreases and the binder hardens. It is considered that since the morphological change easily proceeds, the through-hole penetration is improved.

As the copper powder or copper alloy powder, it is preferable to use a powder produced by an atomizing method, and the smaller the particle size, the better, for example, the powder having an average particle size of 1 to 20 μm, preferably 1 to 10 μm. It is preferable to use, because even if the surface is coated with silver and then flattened, it can be easily dispersed uniformly in the conductive powder.

[0014] There are methods such as displacement plating, electroplating, and electroless plating for coating the surface of copper powder or copper alloy powder with silver, and the copper powder or copper alloy powder has high adhesion to silver and running. Since the cost is low, it is preferable to cover with displacement plating. The amount of silver coating on the surface of the copper powder or copper alloy powder is 5 to 25% by weight based on the copper powder or copper alloy powder from the viewpoints of migration resistance, cost, and improvement in conductivity.
Is more preferable, and the range of 10 to 23% by weight is more preferable.

The conductive powder used in the present invention is a silver-coated copper powder or a silver-coated copper alloy powder in which a part of the above-mentioned copper powder or copper alloy powder is exposed and the surface is substantially covered with silver. Yes,
If a copper powder or a copper alloy powder that is entirely covered with silver without exposing a part thereof is used, the solderability is deteriorated and the object of the present invention cannot be achieved. In addition, it is not preferable to use a material whose entire surface is coated with silver, because the migration property is deteriorated. The exposed area of the copper powder or copper alloy powder is 10 to 60% in terms of solderability, oxidation of exposed portions, conductivity, etc.
Is preferable, and the range of 25 to 55% is more preferable. Note that, as the copper alloy powder, an alloy of copper and tin, copper and zinc, or the like is preferably used.

If the conductive powder has few contact points, the resistance tends to increase. Therefore, in order to increase the contact area between the conductive particles and obtain high conductivity, it is preferable to apply an impact to the conductive powder to deform the particles into a flat shape. The flat conductive powder in the present invention is a conductive powder composed of fine particles that are almost flat in shape and, for example, flaky conductive powder. As the flat conductive powder, it is preferable to use a conductive powder having an aspect ratio of 3 to 20 and an average particle diameter of the major axis of 5 to 30 μm, and an aspect ratio of 5 to 15 and an average particle diameter of the major axis of 5 to 5 μm.
It is more preferable to use a conductive powder of 20 μm.

In the case of conductive powder having an aspect ratio of less than 3 and a long diameter of less than 5 μm, a sufficient contact area between the conductive particles cannot be obtained, and the conductivity tends to decrease. In addition, conductive powder having an aspect ratio of more than 20 and an average long particle diameter of more than 30 μm tends to impair printability. The average particle size mentioned above can be measured by a laser scattering type particle size distribution measuring device. In the present invention, the measurement was performed using a master sizer (manufactured by Malvern) as the device.

The aspect ratio in the present invention refers to the ratio of the major axis to the minor axis (major axis / minor axis) of the conductive powder particles. In the present invention, the particles of the conductive powder are mixed well in the curable resin having a low viscosity, and the resin is cured while allowing the particles to settle by standing, and the obtained cured product is cut in the vertical direction. The shape of the particles appearing on the cut surface is observed under magnification with an electron microscope, and the major axis / minor axis of each particle is obtained for at least 100 particles, and the average value thereof is defined as the aspect ratio.

Here, the minor axis is selected so that a particle appearing on the cut surface sandwiches a combination particle of two parallel lines contacting the outside of the particle, and two of the combinations having the shortest interval are selected. The distance between the parallel lines. On the other hand, the major axis is the two parallel lines perpendicular to the parallel line that determines the minor axis, and is the distance between the two parallel lines that are the longest among the combinations of the two parallel lines that contact the outside of the particle. is there. The rectangle formed by these four lines is sized to fit the particle exactly inside it. The specific method used in the present invention will be described later.

As the binder, an organic adhesive component such as an epoxy resin or a phenol resin, and, if necessary, a saturated polyester resin or a phenoxy resin are used. The ratio of the epoxy resin and the phenol resin is 5 to 30% by weight of the epoxy resin and 70 to 9% of the phenol resin.
The range of 5% by weight is preferable, and the epoxy resin is 10 to 25%.
More preferably, the weight percent and the phenolic resin are in the range of 75 to 90 weight percent. When the epoxy resin is less than 5% by weight,
The adhesive strength between the paste and the copper foil tends to decrease, and when the epoxy resin exceeds 30% by weight, the conductivity tends to decrease. It is preferable that a saturated polyester resin, a phenoxy resin, and the like, which are used as needed, be contained in the binder in an amount of 15% by weight or less.

The compounding ratio of the binder to the conductive powder is preferably 5 to 15% by weight of the binder and 85 to 95% by weight of the conductive powder, and 7 to 13% by weight of the binder and 87 to 93% by weight of the conductive powder. The range is more preferred. When the conductive powder is less than 85% by weight, the solderability and the conductivity tend to decrease, and when the conductive powder exceeds 95% by weight,
The adhesive strength between the paste and the copper foil tends to decrease.

As the organic solvent contained in the conductive paste, terpineol, benzyl alcohol, ethyl carbitol, ethyl carbitol acetate, butyl cellosolve and the like are used. Further, the conductive paste can be obtained by adding an antifoaming agent or a defoaming agent as required in addition to the above-mentioned materials, and mixing them uniformly. An antifoaming agent, a defoaming agent, etc. are added as necessary. If added, the content of the defoaming agent, the defoaming agent, etc. is 0.005 to 100 parts by weight of the conductive powder. Preferably it is in the range of 10 parts by weight.

Next, a double-sided printed wiring board in which electric circuits are formed on both the front surface and the rear surface, the electric circuits on both surfaces are conducted through through holes, and pin insertion holes are formed by penetrating through conductor portions of the through holes will be described in detail. I do.

The base material used for the double-sided printed wiring board for forming the electric circuit and the through hole includes a paper phenol laminate, a glass epoxy laminate, a composite laminate using a glass nonwoven fabric and a glass cloth, a polyamideimide laminate, and the like. , A film of polyethylene terephthalate or the like, a film of polyester or polyamide imide, or the like. The method for forming an electric circuit using a conductive paste on these substrates is not particularly limited, but a screen printing method, a method using a dispenser controlled by a computer, and the like are preferable in terms of workability, productivity, and the like.

The double-sided printed wiring board according to the present invention is obtained by the following method. The conductive paste for forming a through-hole conductor according to the present invention is applied or filled in all the through-holes of the substrate from which the electric circuit has been etched out. The application or filling includes screen printing, filling with pins, syringes, or the like. The base material coated or filled in the through holes is subjected to a heat treatment at 40 to 160 ° C.

The double-sided printed wiring board thus obtained has through holes penetrating therethrough and is capable of being soldered, so that the front and back surfaces of the wiring board are electrically connected and a pin insertion hole is formed. be able to. Further, in the through holes other than the pin insertion holes, conduction between the front surface and the back surface is obtained by the conductive paste, so that all the through holes other than the pin insertion holes and the pin insertion holes can be formed by the same operation using the conductive paste. Therefore, in the conventional wiring board using the conductive paste, the pin insertion hole and the through hole other than the pin insertion hole cannot be formed by the same operation. A double-sided printed wiring board having through holes other than holes formed by the same operation is obtained.

[0027]

The present invention will be described below with reference to examples. Example 1 Bisphenol A type epoxy resin (oiled shell epoxy)
10 parts by weight of Epicoat 834 (trade name, manufactured by Co., Ltd.) and 40 parts by weight of a solid obtained by removing the solvent of a resole-type phenol resin (Retop PL-2211 NV60, trade name, manufactured by Gunei Chemical Co., Ltd.) are converted to benzyl alcohol Kanto Chemical Co., Ltd.
(Special grade), 25 parts by weight in advance, and then cooled to room temperature, and then a dodecylbenzenesulfonic acid-based curing agent (manufactured by Kusumoto Kasei Co., Ltd., trade name 5225 NV25) 0.4
The parts by weight were added and uniformly mixed to obtain a resin composition.

Next, spherical copper powder (manufactured by Nippon Atomize Processing Co., Ltd., trade name: SF-Cu) produced by an atomizing method and having an average particle size of 5.4 μm was washed with dilute hydrochloric acid and pure water, and then washed with water 1
8 AgCN (Wako Pure Chemical Industries, Ltd., reagent) per liter
0 g and a plating solution containing 75 g of NaCN (manufactured by Wako Pure Chemical Industries, Ltd.), displacement plating is performed so that the amount of silver is 17% by weight with respect to the spherical copper powder, washed with water, dried, and dried with silver-plated copper. Powder was obtained.

Thereafter, 450 g of the silver-plated copper powder obtained above and 4 kg of zirconia balls having a diameter of 10 mm were put into a 2 liter ball mill container, and rotated for 1 hour and 30 minutes to deform the shape. A flaky silver-plated copper powder having an average particle diameter of 6.2 and a major axis of 7.8 μm was obtained. Ten particles of the obtained silver-plated copper powder were taken out and quantitatively analyzed by a scanning Auger electron spectrometer to examine the exposed area of the copper powder. The average was 52% in the range of 23 to 58%. The silver coating amount on the surface of the copper powder is
It was 17% by weight based on the copper powder.

Next, 450 g of the flaky silver-plated copper powder was added to 75.4 g of the resin composition obtained above, and the mixture was uniformly mixed and dispersed with a stirrer and a three-roll mill to obtain a conductive paste. In addition, diethylene glycol monoethyl ether (Kanto Chemical Co., Ltd.)
(Special grade, special grade) was added and uniformly mixed and dispersed by a stirrer to obtain a conductive paste for printing. The proportion of the dodecylbenzenesulfonic acid-based curing agent was 0.3% by weight based on the phenol resin, and the blending ratio of the conductive powder and the binder in the conductive paste was 90% by weight of the conductive powder and 10% by weight of the binder. Was.

Next, using the conductive paste obtained above, a paper phenol copper-clad laminate having a through hole having a thickness of 1.6 mm and a diameter of 0.85 mm (manufactured by Hitachi Chemical Co., Ltd.)
After etching and removing the copper foil (trade name: MCL-437F), as shown in FIG. 3, a conductive paste is filled in the through-holes 1 and printed and connected between the through-holes 1 in the air for 60 hours. Heat treatment was performed at 160 ° C. for 40 minutes at 160 ° C. for 1 hour to obtain a double-sided printed wiring board. In FIG. 3, reference numeral 8 denotes a paper phenol copper-clad laminate.

As a result of evaluating the characteristics of the obtained wiring board, 6
Percentage of through holes per hole is 100%
And the resistance value per through hole is 27.6 m
Ω / hole and insulation resistance between adjacent through holes is 1
It was 010Ω or more. As a result of conducting a solder heat resistance test, a temperature cycle test, and a wet and medium load test of the wiring board, the resistance change rate of the solder heat resistance test was +22.1, and the resistance change rate of the temperature cycle test was + 24.2%. The insulation resistance between the through holes in the wet and medium load test was 108Ω or more.

The solder heat resistance test was performed by dipping the solder bath heated to 260 ° C. for 5 seconds 5 times, and the temperature cycle was −65.
One cycle from 30 minutes at 30 ° C. to 30 minutes at 125 ° C.
The 0-cycle, medium humidity load test was carried out at 40 ° C. and 95% RH for 1000 hours by applying a voltage of 50 V between adjacent lines.

The solderability was also evaluated. A flux was applied to the conductive paste on the through holes, and soldering was performed thereon. After cooling, a cellophane tape was stuck on the solder adhered to the conductive paste, and peeled off at an angle of 90 ° C. As a result, no peeling of the solder from the conductive paste was observed. Furthermore, as a result of observing the cross section of the soldered through-hole, it was confirmed that solder was attached to the conductive paste.

Further, a flux was applied to the conductive paste on the through holes, and the wiring board was floated on the upper surface of the solder bath with the pins inserted into the component holes, and soldered to the component holes. After cooling, the conduction between the front and back surfaces of the wiring board and the pins was confirmed. As a result, a current of 10 mA could be confirmed to flow. , And it was confirmed that the pins were fixed by the solder.

The specific method of measuring the aspect ratio in this embodiment is described below. 8 g of a base material (No. 20-8130) of a low-viscosity epoxy resin (manufactured by Buehler Co.) and 2 g of a curing agent (No. 20-8132) are mixed, and 2 g of conductive powder is mixed and dispersed well, and the mixture is left as it is. After degassing in vacuo at ℃, the particles were allowed to stand at 30 ℃ for 6 to 8 hours to settle and harden the particles. Thereafter, the obtained cured product was cut in the vertical direction, the cut surface was magnified 2000 times with an electron microscope, and the major axis / minor axis was determined for 100 particles that appeared on the cut surface. Ratio.

Example 2 Bisphenol A type epoxy resin 12 used in Example 1
38 parts by weight of the resol-type phenol resin and solidified by removing the solvent of the resol-type phenol resin are heated and dissolved in 25 parts by weight of benzyl alcohol in advance, then cooled to room temperature, and then a dinonylnaphthalenedisulfonic acid-based curing agent (Kusumoto Kasei Co., Ltd.
(Trade name: X49-110, NV25) (2 parts by weight) and uniformly mixed to obtain a resin composition.

To 77 g of this resin composition, 367 g of the flaky silver-plated copper powder obtained in Example 1 was added and uniformly mixed in the same manner as in Example 1, and 120 g of diethylene glycol monoethyl ether used in Example 1 was further added. Was added and uniformly mixed to obtain a conductive paste for printing. The ratio of the dinonylnaphthalenedisulfonic acid-based curing agent was 1.3% by weight based on the phenol resin, and the ratio of the conductive powder to the binder in the conductive paste was 88% by weight of the conductive powder and 12% by weight of the binder. Was.

Next, a double-sided printed wiring board was manufactured through the same steps as in Example 1, and its characteristics were evaluated. as a result,
The ratio of through holes per 60 holes of the obtained wiring board was 100%, and the resistance per through hole was 26.7 mΩ / hole. As a result of conducting a solder heat resistance test, a temperature cycle test, and a humidity and medium load test of the wiring board, the resistance change rate in the solder heat resistance test was +19.
4, and the resistance change rate in the temperature cycle test was +27.7.
%, And the insulation resistance between the through holes in the wet and medium load test was 108 Ω or more.

The solderability was also evaluated. as a result,
A cellophane tape was stuck on the solder and peeled off at an angle of 90 ° C. However, no peeling of the solder was observed from the conductive paste, and it was confirmed from the cross-sectional observation that the solder was on the conductive paste. In addition, through the same process as in Example 1, a pin was inserted into the component hole and soldered. After cooling, conduction between the front and back surfaces of the wiring board and the pin was confirmed. As a result, a current of 10 mA could flow. From the result of observing the cross section of the through hole of the component hole into which the pin was inserted, it was confirmed that the solder was attached on the conductive paste and the pin was fixed by the solder.

Comparative Example 1 Bisphenol A type epoxy resin 10 used in Example 1
40 parts by weight of a solid by removing the solvent of the resol-type phenolic resin and 40 parts by weight were dissolved in 25 parts by weight of benzyl alcohol in advance by heating and uniformly mixed to obtain a resin composition. 450 g of the flaky silver-plated copper powder obtained in Example 1 was added to 75.04 g of this resin composition, and the same process as in Example 1 was performed to obtain a conductive paste for printing. Next, Example 1
As a result of producing a double-sided printed wiring board through the same steps as described above and evaluating its characteristics, the ratio of through holes per 60 holes of the obtained wiring board was as low as 4%.
The resistance value per through hole is 62.8 mΩ.
/ It became high with a hole.

A flux is applied to the conductive paste on the through-holes of the wiring board of which the through-hole does not penetrate, and the wiring board is placed on the upper surface of the solder bath with the pins inserted into the component holes. It was floated and soldered to the component holes. After cooling, the continuity between the front and back surfaces of the wiring board was confirmed. However, a current of 10 mA did not flow, and the cross section of the through hole of the component hole into which the pin was inserted was observed. As shown in FIG. Occurred. Therefore, each test was not performed.

[0043]

According to the present invention, the conductive paste for forming a through-hole conductor has excellent through-hole penetration and solderability. The conductive paste for forming a through-hole conductor according to claims 2 and 3 is particularly excellent in the effect of improving the through-hole penetrability of the conductive paste for forming a through-hole conductor according to claim 1. The conductive paste for forming a through-hole conductor according to claims 4 and 5 is particularly excellent in the effect of improving solderability among the conductive paste for forming a through-hole conductor according to claim 1, and the through-hole conductor according to claim 1 In addition to the conductive paste for forming, it has an excellent effect of improving conductivity.

The conductive paste for forming a through-hole conductor obtained by the method according to claim 6 has excellent through-hole penetration and solderability. In the double-sided printed wiring board according to claim 7, by using the conductive paste for forming a through-hole conductor, an electric circuit on both the front surface and the rear surface is conducted, and a pin insertion hole is formed by penetrating the through-hole conducting portion. can do.

[Brief description of the drawings]

FIG. 1 is a partial cross-sectional view showing an example of a through-hole connection method for a double-sided printed wiring board.

FIG. 2 is a partial cross-sectional view showing a state in which a pin is inserted into a pin insertion hole of a double-sided printed wiring board and a crack has occurred in a conductive paste.

FIG. 3 is a plan view showing a state in which a conductive paste is filled in through holes of a paper phenol copper-clad laminate in which a copper foil on a surface is removed by etching and printed between the through holes.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Through hole 2 Plating 3 Conductive paste 4 Pin 5 Solder 6 Crack 7 Wiring board base material 8 Paper phenol copper clad laminate

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) H05K 1/11 H05K 1/11 NF term (Reference) 4E351 AA01 AA03 AA04 BB31 BB49 CC11 CC22 DD04 DD05 DD21 DD52 DD54 DD56 EE02 EE15 EE16 EE27 GG06 GG16 5E317 AA24 BB02 BB03 BB12 BB14 BB18 CC08 CC22 CC25 CD21 CD25 CD27 CD32 GG07 GG11 5G301 DA03 DA06 DA42 DA55 DA57 DD01 DE01

Claims (7)

[Claims] 1. A through-hole conductor for forming a through-hole conductor comprising a sulfonic acid-based curing agent, a binder, a conductive powder whose surface is substantially covered with silver by exposing a part of a copper powder or a copper alloy powder, and an organic solvent. Conductive paste. 2. The conductive paste for forming a through-hole conductor according to claim 1, wherein the binder is an epoxy resin or a phenol resin. 3. A sulfonic acid-based curing agent is used in an amount of 0.05 to 99.95% by weight based on 90 to 99.95% by weight of a solid phenol resin.
3. The conductive paste for forming a through-hole conductor according to claim 1, which is 10% by weight. 4. The compounding ratio of the binder and the conductive powder is such that the binder is 5 to 15% by weight based on the solid content of the conductive paste.
4. The conductive paste for forming a through-hole conductor according to claim 1, wherein the conductive powder is 85 to 95% by weight. 5. The conductive powder according to claim 1, wherein the conductive powder is a flat conductive powder having an aspect ratio of 3 to 20 and an average long diameter of 5 to 30 μm, and an exposed area of copper powder or copper alloy powder of 10 to 60%. 5. The conductive paste for forming a through-hole conductor according to 2, 3, or 4. 6. A method in which a part of copper powder or copper alloy powder is exposed to cover the surface with silver, and then a sulfonic acid-based hardener, a binder and an organic solvent are added and uniformly mixed. A method for producing a conductive paste for forming a through-hole conductor. 7. A conductive paste for forming a through-hole conductor according to claim 1 or a method according to claim 6, wherein a through-hole penetrating a printed wiring board having electric circuits on both sides is formed. A double-sided printed wiring board, comprising: a conductive paste for forming a through-hole conductor, wherein electrical circuits on both sides are conducted through the through-hole and a pin insertion hole is formed through the through-hole conductor.