JP2000196226A - Composite material for electric circuit formation and its use - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a composite material for electric circuit formation which realizes fine pitch and enables formation of a printed wiring board which is excellent in adhesion property with a base and in heat resistance property. SOLUTION: The composite material for electric circuit formation comprises a supporter and a conductive fine particle group 23 provided on a supporter to be detached. Preferable size of the conductive fine particle group 23 is in the range of 0.1 to 5.0 μm in a thickness direction of a composite material, and preferable surface roughness (Rz) of a surface provided with the conductive fine particle group 23 is in the range of 0.5 to 10.0 μm. A lamination board is formed by joining the composite material for electric circuit formation to a base surface. A lamination board is formed by removing a supporter alone after the composite material for electric circuit formation is joined to a base surface. A printed wiring board is formed by using the composite material for electric circuit formation.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a novel composite material for forming an electric circuit and its use. More specifically, the present invention relates to a composite material for forming an electric circuit suitable for forming a printed wiring board.

[0002]

2. Description of the Related Art In recent years, with the miniaturization and high density of electronic equipment, the circuit width and circuit interval of a printed wiring board used have become thinner year by year, and accordingly, they are used for wiring formation. The thickness of the metal foil is also 35 μm, from 18 μm to 1
The thickness tends to be reduced to 2 μm. When such a metal foil is used, for example, a printed wiring board is manufactured by a process (panel plating method) as shown in FIG.
Specifically, as shown in FIG. 4A, a circuit-forming metal foil 2 is adhered to a substrate 1 made of an insulating resin to form a laminate. Next, as shown in FIG. 4B, a via hole 3 is formed by drilling or irradiating a laser beam on the laminated board in order to conduct the upper circuit and the lower circuit. Electroless plating and electrolytic plating are performed on the surface of the via hole and the surface of the insulating resin layer thus formed, and a plating layer 4 is formed as shown in FIG. Next, a resist 5 for forming a circuit is formed on the surface of the plating layer 4 obtained as shown in FIG. 4D, and the plating layer 4 and the metal foil 2 for forming a circuit other than the circuit are formed.
Is removed by etching as shown in FIG. 4 (e), and then the resist is removed as shown in FIG. 4 (f) to form a circuit 6.

When a printed wiring board is formed by such a panel plating method, a circuit having a fine pitch can be formed as the thickness of the metal foil on the surface becomes thinner. ing.

There is also known a method of directly forming a printed wiring board without using a metal foil. in this way,
For example, a printed wiring is manufactured by a process (pattern plating method) as shown in FIG. First, FIG.
As shown in (a), a substrate 11 made of an insulating resin
Drilling or irradiating a laser to make a hole,
A via hole 12 is formed as shown in FIG. Next, after forming a resist 13 for forming a circuit in a pattern as shown in FIG. 5C, a plating layer 14 is formed by electroless plating and electrolytic plating as shown in FIG. 5D. . Thereafter, as shown in FIG. 5E, the circuit 13 is formed by removing the resist 13 on the surface.

[0005] This pattern plating method has an advantage that the surface plating layer can be thinned and the process is simple.

When a printed wiring board is formed by a method using a metal foil (panel plating method) as described above, it is difficult to handle an extremely thin metal foil.
When a laminated board is formed by bonding with an insulating substrate, the laminate may be broken or wrinkled. Also, in the panel plating method, when drilling a via hole directly by laser drilling, burrs may occur at the end of the metal foil in the via hole part, and plating growth of this burr part, Since it is faster than the plating growth of the flat portion of the metal foil, the burrs are enlarged, which may cause problems such as poor adhesion with the resist for forming a circuit and insufficient etching. The generation of such burrs and the enlargement of the burrs is achieved by providing a support on a conventional ultrathin metal foil and peeling the support to form a composite foil (peelable metal foil).
Even when used for forming an electric circuit, there has been a similar problem. For this reason, it is necessary to remove the metal foil in the perforated portion in advance by etching or the like, and there has been a problem that the perforation process becomes complicated.

Further, a printed wiring board which does not always satisfy even by a method using no metal foil (such as the pattern plating method) has not been obtained. For example, when manufacturing a printed wiring board by these methods, the surface of the insulating resin substrate should be roughened by chemical or physical means in advance to increase the adhesion between the insulating resin and the circuit. However, even if the surface is roughened, there is a disadvantage that the adhesion strength between the formed wiring layer and the insulating resin is insufficient. In addition, the heat resistance of the obtained printed wiring board is not always satisfactory, and therefore, when the printed wiring board is subjected to a heat treatment such as a soldering treatment or a solder resist treatment, and the electronic component is mounted, the wiring layer and the base layer are not bonded. There has been a problem that the adhesion to the material is weakened and the wiring layer is peeled off. Furthermore, since the formed metal layer is fragile, there has been a problem such as disconnection when a bending stress is applied to the printed wiring board.

The present inventors have conducted intensive studies in view of such prior art, and found that a composite material for forming an electric circuit, comprising a support and a group of conductive fine particles detachably provided on the support, was developed. It has been found that the use of such a composition solves all of the above problems and that a printed wiring board having a fine pitch can be formed, and the present invention has been completed.

[0009]

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems, and an electric circuit capable of forming a printed wiring board capable of forming a fine pitch and having excellent adhesion to a substrate and excellent heat resistance. It is intended to provide a forming composite material.

[0010]

SUMMARY OF THE INVENTION The composite material for forming an electric circuit according to the present invention is characterized by comprising a support and a group of conductive fine particles detachably provided on the support.

The size of the conductive fine particles is preferably in the range of 0.1 to 5.0 μm in the thickness direction of the composite material.

The surface roughness (Rz) of the surface of the composite material for forming an electric circuit, on which the conductive fine particles are provided, is 0.5-1.
It is preferably in the range of 0.0 μm.

The laminate according to the present invention is obtained by bonding the above-mentioned composite material for forming an electric circuit to the surface of a base material.
As such a laminate according to the present invention, a laminate with a support joined to the surface of the substrate, the composite material for forming an electric circuit,
And a laminate without a support obtained by removing only the support from the laminate with the support. Furthermore, a printed wiring board according to the present invention is formed using the composite material for forming an electric circuit.

[0014]

DETAILED DESCRIPTION OF THE INVENTION Hereinafter, the present invention will be described specifically.

[Composite Material for Forming an Electric Circuit] FIG. 1 is a schematic sectional view showing an optimal embodiment of the composite material for forming an electric circuit according to the present invention. In this embodiment, the electric circuit forming composite material 21 is characterized by comprising a support 22 and a group of conductive fine particles 23 detachably provided on the support.

Examples of the support 22 include a copper foil, a copper alloy foil, an aluminum foil, a composite metal foil having an aluminum foil surface coated with copper, a composite metal foil having an aluminum foil surface coated with zinc, Metal foil such as stainless steel foil,
Examples include a sheet made of a synthetic resin such as polyimide, polyester, polyurethane, and Teflon, and a sheet made of an inorganic material.

The thickness of the support 22 is 5-20.
0 μm, preferably 18-70 μm is desirable.

The conductive fine particles constituting the conductive fine particle group 23 are not particularly limited as long as they are conductive, and specifically, metals such as copper, silver, gold, platinum, zinc, nickel and the like, Alloy of metals, indium oxide,
Examples include inorganic compounds such as tin oxide and organic compounds such as polyaniline.

The conductive fine particle group 23 may be composed of a single conductive fine particle as described above, or may be composed of a fine particle of a mixture of two or more conductive substances.

The size (d) of the conductive fine particles in the thickness direction is 0.1 to 5.0 μm, preferably 0.2 to 5.0 μm.
To 2.0 μm, more preferably 0.5 to 1.0 μm.

The shape of the conductive fine particles is not particularly limited, and may be, for example, a sphere, a tuft, a lump, a mustache, a dendrite, or the like.

It is desirable that at least some of the conductive fine particles in the conductive fine particle group 23 are not joined to each other. For this reason, the conductive fine particle group 23 may be one in which conductive fine particles are scattered, and the conductive fine particles 23 are scattered so that an aggregate of conductive fine particles detachably bonded to each other does not bond to each other. The conductive fine particles and the aggregate of the conductive fine particles detachably bonded to each other may be interspersed so as not to be bonded to each other. In addition, such a conductive fine particle group 23 cannot be handled or taken out by itself, such as a film or a foil.

The conductive fine particle group 23 is provided on the surface of the support 22 so as to be detachable from the support 22. For this reason, when the composite material for forming an electric circuit according to the present invention is used, for example, when adhering to an insulating substrate to produce a laminate, only the support is easily detached, and the conductive fine particles are placed on the insulating substrate. Groups can be provided.

The composite material for forming an electric circuit according to the present invention has a surface roughness (Rz) of 0.5 to 10.0 μm, preferably 1 to 5 μm, on the surface provided with the conductive fine particles.
m, more preferably in the range of 2.0 to 4.5 μm. The surface roughness in the present invention is JI
It is measured according to the method described in SC 6515 or IPC-TM-650.

The method for producing the composite material for forming an electric circuit according to the present invention is not particularly limited. For example, conductive fine particles may be formed on the support by electrolytic plating, electroless plating or the like. By forming and adhering, the composite material for forming an electric circuit according to the present invention can be manufactured. Alternatively, it can be produced by applying an organometallic compound such as an alkoxide on the support and hydrolyzing it. Furthermore, it can also be obtained by applying a suspension in which the conductive fine particles are dispersed on a support, or by spraying the conductive fine particles with a spray or the like and bonding the conductive fine particles to the support.

For example, when electrodeposited copper electrodeposited fine particles as a conductive fine particle on a support, it is produced as follows.

Cathodic electrolysis is performed using a plating bath,
Electroconductive fine particles are deposited on the support. The current density at the time of the cathodic electrolysis is appropriately selected depending on the bath composition. For example, the cathodic electrolysis is performed at a current density of 1 to 50 A / dm ² . As the plating bath, a copper pyrophosphate plating bath, a copper cyanide plating bath, an acidic copper sulfate plating bath, or the like is used, and preferably, an acidic copper sulfate plating bath is used.

For example, when an acidic copper sulfate plating bath is used, additives such as α-naphthoquinoline, dextrin, glue, PVA, triethanolamine and thiourea may be added to the plating bath if necessary. 0.5-20ppm
May be added. When such an additive is added, the shape of the primary particles constituting the obtained copper electrodeposit fine particles can be controlled.

Specific examples of the composite material for forming an electric circuit according to the present invention include combinations shown in Table 1.

[0030]

[Table 1] The composite material for forming an electric circuit according to the present invention is desirably subjected to a treatment capable of removing only the support. In addition, the "treatment capable of detaching only the support" means that the support and the conductive fine particles are adhered without detachment in a use state before forming the electric circuit, and the support is used during the formation of the electric circuit. This refers to a process in which only desorption occurs.

Examples of such treatment include providing a release layer between the conductive fine particles and the support, and dissolving and removing the support without damaging the conductive fine particles.

The release layer is not particularly limited as long as it has an adhesive strength such that the conductive fine particles are not easily detached and adheres to the support. For example, when the support is a metal foil, a release layer composed of an inorganic compound such as an oxide of a metal constituting the support or a metal different from the metal species forming the support, or a sulfide is used. . Specifically, when the support is a copper foil, a release layer made of a chromium alloy, copper sulfide, or the like is used. Further, when the support is an aluminum foil or an aluminum alloy foil, it is hardly possible to electrodeposit a group of copper particles on these surfaces, or the bonding strength between these surfaces and the electrodeposited copper particles is too low. A release layer made of, for example, is used. When a surface zinc plating support is used, it is preferable to use a copper pyrophosphate plating bath for electrodeposition of the conductive fine particles since zinc dissolves in the acidic plating bath. Further, as the release layer, an organic release layer made of a nitrogen-containing compound such as triazole, carboxybenzotriazole, imidazole, or the like, a sulfur-containing compound such as thiocyanurate, or a carboxylic acid such as oleic acid can be used.

Further, when the composite material for forming an electric circuit according to the present invention is bonded to a base resin,
It is preferable that the conductive fine particles be treated so as not to be completely buried in the base resin.

Examples of such a treatment include forming a cover plating layer (copper cover plating layer) on the surface of the conductive fine particles. Further, the surface of the conductive fine particles may be subjected to a rust prevention treatment. [Laminated Board and Printed Wiring Board] The laminated board according to the present invention is formed using the above-described composite material for forming an electric circuit according to the present invention.

Specifically, it can be obtained by bonding the composite material for forming an electric circuit to an insulating resin substrate such that the conductive fine particles face the insulating resin substrate.

The insulating resin substrate is not particularly limited, and may be a glass epoxy substrate, a glass polyimide substrate, a glass polyester substrate, an aramid epoxy substrate, an FR-4 substrate, a paper-phenol substrate, Paper-epoxy substrates and the like.

The bonding between the composite material for forming an electric circuit and the insulating resin substrate is usually performed at a temperature of 155 to 230 ° C. and a temperature of 15 to 1
It is desirable to apply a pressure of 50 kgf / cm ² .

Further, in the laminate according to the present invention, after the conductive fine particles of the composite material for forming an electric circuit are bonded to the insulating resin substrate, only the support may be detached.

In the present invention, the composite material for forming an electric circuit bonded to an insulating resin substrate is sometimes called a laminated plate with a support, and the support is detached from the laminated plate with a support. What was made may be called a laminated plate without a support.

Examples of the method for removing only the support include a method for removing the support and a method for removing the support by polishing or dissolving.

When only the support is peeled, the composite material for forming an electric circuit according to the present invention has a peel strength of the support of 1 to 300 gf / cm according to JIS-C-6481, and practically 5 to 5 gf / cm. 1
It is desirable to be in the range of 00 gf / cm. When the peel strength of the electric circuit forming composite material is in the above range, when forming a laminate using the electric circuit forming composite material of the present invention,
Only the support can be easily separated from the composite material for forming an electric circuit. As described above, when only the support is separated, it is preferable that the above-described separation layer is formed between the support and the conductive fine particle group.

When the support is removed by polishing or dissolving, the support of a metal foil such as a copper foil, an aluminum foil and an aluminum alloy foil is etched or dissolved by an acid or alkali. Can be removed. The support of the synthetic resin sheet can be removed by dissolving the synthetic resin in an organic solvent.

The printed wiring board according to the present invention can be obtained by forming printed wiring on such a laminated board. The method for forming the printed wiring is not particularly limited, and for example, a panel plating method, a pattern plating method, or the like can be adopted.

In the panel plating method, a printed wiring board is manufactured through, for example, a manufacturing process shown in FIG. Specifically, first, as shown in FIG. 2 (a), after bonding the composite material for forming an electric circuit to an insulating resin substrate,
After removing only the support, the laminate 31 having the conductive fine particle group 23 on the surface is irradiated with a laser, and a hole is formed as shown in FIG. 2B to form a via hole 32. Electroless plating and electrolytic plating are performed on the surface of the via hole and the surface of the insulating resin layer thus formed, and a plating layer 33 is formed as shown in FIG. 2C. On the surface of the obtained plating layer 33, a resist 34 for forming a circuit is formed in a pattern as shown in FIG. 2D, and as shown in FIG.
3 is removed by etching, and then the resist is removed as shown in FIG.

In the printed wiring board according to the present invention, since the conductive fine particles of the composite material for forming an electric circuit as described above are provided on the surface of the insulating resin layer, the formed circuit is thin and the fine pitch is reduced. A circuit having the same.
In addition, since the conductive fine particles of the composite material for forming an electric circuit are provided on the surface of the insulating resin layer, burrs may be generated at the end of the via hole during laser processing, such as when using metal foil. Therefore, problems such as an enlarged burr portion at the end of the via hole, poor adhesion of the resist, and insufficient etching do not occur. Therefore, it is not necessary to remove the perforated portion by etching or the like in advance. In addition, such laser drilling can be performed using a laser having an output lower than that of a conventionally proposed laser.

In the pattern plating method, a printed wiring board is manufactured through, for example, a manufacturing process shown in FIG. Specifically, as shown in FIG. 3A, the laminated plate 41 provided with the conductive fine particles 23 on the surface of the insulating resin layer is directly irradiated with a laser to form a hole.
A via hole 42 is formed as shown in FIG.
Next, as shown in FIG. 3 (c), electroless plating is applied to the entire surface including the inside of the via hole to form a plating layer 43, and then, as shown in FIG. 3 (d), a resist 44 for forming a circuit is formed. Is formed in a pattern, and a circuit 45 having a predetermined thickness is formed by electrolytic plating as shown in FIG. After that, the resist 44 on the surface is removed, and the entire surface is further etched. In particular, the electroless plating layer 43 and the conductive fine particle group other than the circuit are removed by etching (this may be referred to as flash etching). The circuit 45 is formed as shown in FIG. In this process, tin plating or solder plating may be applied to the circuit surface before the removal of the resist to form an etching resist.

By using either the panel plating method or the pattern plating method, a printed wiring board having excellent adhesion between the formed wiring layer and the insulating resin and excellent heat resistance can be produced. Can be.

In the present invention, the printed wiring board as described above is used as a substrate with an inner circuit, and the composite material for an electric circuit according to the present invention is bonded via an insulating resin layer. The support is removed from the composite material for forming a circuit, the conductive fine particles are provided on the surface of the insulating resin layer, then the via hole and the circuit are formed, and plating is performed to obtain a double-sided printed wiring board. it can.

By repeating such operations, a multilayer printed wiring board can be obtained.

[0050]

As the composite material for forming an electric circuit of the present invention, a very thin group of conductive fine particles is provided on the surface of the insulating resin layer, so that the insulating resin layer is drilled, laser-processed or similar. The method eliminates problems such as generation of burrs at the time of boring a printed wiring board. Moreover, the boring process can be performed even if the laser output is weaker than the conventionally proposed output. Further, when such a composite material for forming an electric circuit of the present invention is used, the thickness of the circuit can be reduced, so that a printed wiring board having a fine pitch can be efficiently produced. Moreover, when the composite material for forming an electric circuit of the present invention is used, a sufficient adhesive force can be provided between the insulating resin layer and the circuit.

[0051]

Hereinafter, the present invention will be described based on examples.
The present invention is not limited to these Examples.

[0052]

Example 1 An electrolytic copper foil having a thickness of 35 μm was prepared as a support metal foil, and its glossy surface was washed for 30 seconds in a cleaning solution containing sulfuric acid at a concentration of 100 g / l. After washing with sulfuric acid, the copper foil was washed with water.

Next, the copper foil was immersed in a 10 g / l aqueous solution of ammonium sulfide for 10 seconds at a liquid temperature of 30 ° C. to form a copper sulfide release layer on the glossy surface of the copper foil. Copper sulfide release layer
After washing with purified water for 10 seconds, the copper foil was immersed in a copper concentration of 20 g.
/ L, a sulfuric acid concentration of 70 g / l, and a plating bath having a solution temperature of 40 ° C., electrolysis was performed at a current density of 20 A / dm ² for 5 seconds, and the conductive fine particles of copper were electrodeposited on the surface of the release layer.

The composite foil having the conductive fine particles formed as described above has a copper concentration of 75 g / l and a sulfuric acid concentration of 80 g / l.
Using a plating bath of g / l and a liquid temperature of 50 ° C., electrolysis was performed at a current density of 30 A / dm ² for 10 seconds to form a copper-plated plating layer on the conductive fine particles.

The composite material for forming an electric circuit thus obtained was subjected to a rinsing treatment, a rust preventive treatment, and a drying treatment.

The size of the conductive fine particles having the overlaid plating layer was 1.5 μm in the thickness direction of the composite material for forming an electric circuit.

The surface roughness (Rz) of the surface on which the conductive fine particle group having the overlaid plating layer was formed was 2.9 μm. [Laminated plate] The obtained composite material for forming an electric circuit was
Four 0.1 mm thick FR-4 prepregs are laminated so that the conductive fine particles having a cover plating layer and the prepreg face each other, and are pressed at 175 ° C. and 25 kg / cm ² for 60 minutes. -Heating was performed to produce a laminate.

After the copper support was peeled off from the obtained laminate, the entire surface of the laminate was subjected to electroless plating with copper, and further subjected to electrolytic plating.
After forming a 5 μm copper layer, a patterned resist was formed, followed by etching to prepare an evaluation sample having a 10 mm wide circuit, and the peel strength was evaluated in accordance with JIS C 6481. When the peeling strength between the circuit of the evaluation sample obtained and the substrate (FR-4) was measured, the peeling strength was 1.43 kg / cm.
The formed circuit had sufficient adhesive strength to the substrate. Heat resistance The obtained evaluation sample was floated in a solder bath at 160 ° C. for 20 seconds, and the peel strength between the substrate and the circuit was measured.

As a result, the peel strength was 1.43 kg / c.
m, the peel strength was almost unchanged from that before the solder float, and it was found that the obtained evaluation sample had excellent heat resistance. [Printed Wiring Board] The obtained composite material for forming an electric circuit was laminated on four FR-4 prepregs having a thickness of 0.1 mm so that the conductive fine particles and the prepreg faced each other.
The composite was pressed and heated at 25 ° C. and 25 kg / cm ² for 60 minutes to bond the electric circuit forming composite material and the prepreg, thereby producing a laminate.

After removing the support from the laminate and providing a group of conductive fine particles on the prepreg, a hole was formed using a carbon dioxide gas laser. No burrs were observed at the hole. Was.

Next, electroless plating of copper is performed on the entire surface of the laminate, and further electrolytic plating is performed, so that a total thickness of 1
An 8 μm copper layer was formed. A resist is formed on the laminate thus obtained and then etched to obtain a line width / line interval = 3.
A circuit of 0 μm / 30 μm was formed. The etching property at this time was good, and it was found that the produced composite material for forming an electric circuit was very excellent in forming a fine circuit.

[0062]

Example 2 An electrolytic copper foil having a thickness of 35 μm was prepared as a support metal foil, and its glossy surface was washed for 30 seconds in a cleaning solution containing sulfuric acid at a concentration of 100 g / l. After washing with sulfuric acid, the copper foil was washed with purified water. Liquid temperature 40
It was immersed in a triazinethiol aqueous solution having a concentration of 5 g / l at 30 ° C. for 30 seconds to form an organic release layer on the surface of the support copper foil.

Next, the surface of the formed organic release layer is
After washing with water, copper concentration 10g / l, sulfuric acid concentration 170g /
1, using a plating bath having a liquid temperature of 30 ° C. and a current density of 15 A /
dm ^TwoElectrolysis for 8 seconds to remove copper conductive fine particles
Electrodeposition was performed on the delamination surface. Furthermore, when the copper concentration is 75 g / l,
With a sulfuric acid concentration of 80 g / l and a liquid temperature of 50 ° C.
Using plating bath, current density 30A / dm^TwoFor 30 seconds
Electrolyze and form a copper plating layer on the conductive fine particles.
Done.

The thus obtained composite material for forming an electric circuit was subjected to a rinsing treatment, a rustproofing treatment and a drying treatment.

The size of the conductive fine particles having the overlaid plating layer was 1.0 μm in the thickness direction of the composite material for forming an electric circuit.

The surface roughness (Rz) of the surface on which the conductive fine particles having the overlaid plating layer were formed was 2.2 μm. [Laminated plate] The obtained composite material for forming an electric circuit was
The conductive fine particles having the overlaid plating layer and the prepreg are laminated on four FR-4 prepregs having a thickness of 0.1 mm so that the prepregs face each other, and pressed and heated at 175 ° C. and 25 kg / cm ² for 60 minutes. Thus, a laminated plate was produced.

After the copper support was peeled off and removed from the obtained laminate, the entire surface of the laminate was subjected to electroless plating with copper, and further subjected to electrolytic plating, so that a total thickness of 3 mm was formed on the surface of the laminate.
After forming a 5 μm copper layer, a patterned resist was formed and then etched to prepare an evaluation sample having a 10 mm wide circuit, and the peel strength was evaluated in accordance with JIS C 6481. When the peel strength between the circuit of the evaluation sample obtained and the substrate (FR-4) was measured, the peel strength was 1.35 kg / cm.
The formed circuit had sufficient adhesive strength to the substrate. Heat resistance The obtained evaluation sample was floated in a solder bath at 160 ° C. for 20 seconds, and the peel strength between the substrate and the circuit was measured.

As a result, the peel strength was 1.35 kg / c.
m, the peel strength was almost unchanged from before the solder float, and it was found that the obtained evaluation sample had excellent heat resistance. [Printed Wiring Board] The obtained composite material for forming an electric circuit was laminated on four FR-4 prepregs having a thickness of 0.1 mm so that the conductive fine particles and the prepreg faced each other.
The composite was pressed and heated at 25 ° C. and 25 kg / cm ² for 60 minutes to bond the electric circuit forming composite material and the prepreg, thereby producing a laminate.

After removing the support from the laminate and providing a group of conductive fine particles on the prepreg, a hole was formed using a carbon dioxide gas laser. No burrs were observed at the hole.

Next, electroless plating of copper is performed on the entire surface of the laminate, and then electrolytic plating is performed.
An 8 μm copper layer was formed. The laminate thus obtained was etched to form a circuit having a line width / line interval of 30 μm / 30 μm. The etching property at this time is good,
It was found that the produced composite material for forming an electric circuit was excellent in forming a fine circuit.

[0071]

Example 3 An electrolytic copper foil having a thickness of 35 μm was prepared as a support metal foil, and its glossy surface was washed for 30 seconds in a cleaning solution containing sulfuric acid at a concentration of 100 g / l. After the sulfuric acid washing, the copper foil was washed with water for 30 seconds.

The glossy surface of the washed copper foil was immersed in an aqueous solution of triazinethiol having a liquid temperature of 40 ° C. and a concentration of 5 g / l for 30 seconds to form an organic release layer on the surface of the support copper foil.

Next, using a plating bath (solution temperature of 40 ° C.) in which copper was dissolved at a concentration of 15 g / l, cobalt was dissolved at a concentration of 5 g / l, and nickel was dissolved at a concentration of 5 g / l, a current density of 30 g was used.
Electrolysis was performed at A / dm ² for 2 seconds, and conductive fine particles made of a copper-cobalt-nickel alloy were electrodeposited on the surface of the organic release layer.

The composite foil on which the conductive fine particles were electrodeposited was further subjected to a current density of 3 A / dm using a plating bath (solution temperature: 50 ° C.) in which cobalt was dissolved at a concentration of 8 g / l and nickel at a concentration of 18 g / l. Electrolysis was performed for 5 seconds at ² to form a cobalt-nickel alloy overlay plating layer on the conductive fine particles of the copper-cobalt-nickel alloy.

The electric circuit forming composite material thus obtained was subjected to a rinsing treatment, a rust prevention treatment, and a drying treatment.

The size of the conductive fine particles having the overlaid plating layer was 3.5 μm in the thickness direction of the composite material for forming an electric circuit.

The surface roughness (Rz) of the surface on which the group of conductive fine particles was formed was 3.2 μm. [Laminated plate] The obtained composite material for forming an electric circuit was
On four FR-4 prepregs each having a thickness of 0.1 mm, the conductive fine particles and the prepreg were laminated so as to face each other, and were heated at 175 ° C and 25 ° C.
The laminate was prepared by applying pressure and heat for 60 minutes under the condition of kg / cm ² to bond the composite material for forming an electric circuit and the prepreg.

After the copper support was peeled off and removed from the obtained laminate, the entire surface of the laminate was subjected to electroless plating of copper, and further subjected to electrolytic plating, so that a total thickness of 3 mm was formed on the surface of the laminate.
After forming a 5 μm copper layer, a resist pattern was formed and etched to prepare an evaluation sample having a 10 mm wide circuit, and the peel strength was evaluated in accordance with JIS C 6481. When the peel strength between the circuit of the evaluation sample obtained and the substrate (FR-4) was measured, the peel strength was 1.50 kg / cm.
The formed circuit had sufficient adhesive strength to the substrate. Heat resistance The obtained evaluation sample was floated in a solder bath at 160 ° C. for 20 seconds, and the peel strength between the substrate and the circuit was measured.

As a result, the peel strength was 1.50 kg / c.
m, and the peel strength was hardly changed as compared with that before the solder float, indicating that the obtained evaluation sample was excellent in heat resistance. [Printed Wiring Board] The obtained composite material for forming an electric circuit was laminated on four FR-4 prepregs each having a thickness of 0.1 mm, and laminated so that the conductive fine particles and the prepreg faced each other.
The composite material for forming an electric circuit was bonded to the prepreg by pressing and heating at 75 ° C. and 25 kg / cm ² for 60 minutes to prepare a laminate.

After the support was removed from the laminate, a hole was formed using a carbon dioxide gas laser. No burrs were observed at the hole.

Next, electroless plating of copper is performed on the entire surface of the laminated plate, and further, electrolytic plating is performed.
An 8 μm copper layer was formed. The laminate thus obtained is etched to form a circuit having a line width / line interval of 30 μm / 30 μm. The etching property at this time is good,
It was found that the produced composite material for forming an electric circuit was excellent in forming a fine circuit.

[Brief description of the drawings]

FIG. 1 is a schematic cross-sectional view showing one embodiment of a composite material for forming an electric circuit according to the present invention.

FIG. 2 is a schematic sectional view illustrating a method for manufacturing a printed wiring board according to the present invention.

FIG. 3 is a schematic sectional view showing another method for manufacturing a printed wiring board of the present invention.

FIG. 4 is a schematic sectional view showing a conventionally known method for manufacturing a printed wiring board.

FIG. 5 is a schematic cross-sectional view showing another conventionally known method for manufacturing a printed wiring board.

[Explanation of symbols]

 21: composite material for forming an electric circuit 22: support 23: conductive fine particles

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Kenichiro Iwagiri 656-2 Kamakurabashi, Ageo City, Saitama Prefecture Inside the Copper Foil Division, Mitsui Kinzoku Mining Co., Ltd. (72) Inventor Takuya Yamamoto 656 Kamakurabashi, Ageo City, Saitama Prefecture -2 Inside the Copper Foil Division, Mitsui Metal Mining Co., Ltd. (72) Inventor, Tsutomu Higuchi 655-2 Kamakurabashi, Ageo City, Saitama

Claims (7)

[Claims] 1. A composite material for forming an electric circuit, comprising: a support; and a group of conductive fine particles detachably provided on the support. 2. The composite material for forming an electric circuit according to claim 1, wherein the size of the conductive fine particles is in the range of 0.1 to 5.0 μm in the thickness direction of the composite material. . 3. The electric circuit according to claim 1, wherein the surface provided with the group of conductive fine particles has a surface roughness (Rz) in a range of 0.5 to 10.0 μm. For composite materials. 4. The composite material for forming an electric circuit according to claim 1, wherein a release layer is provided between the support and the group of conductive fine particles. 5. A laminate, wherein the composite material for forming an electric circuit according to claim 1 is bonded to a surface of a base material such that the conductive fine particles face the base material. 6. The composite material for forming an electric circuit according to claim 1, which is bonded to the surface of the base material such that the conductive fine particles face the base material, and then only the support is removed. A laminate having a conductive fine particle group provided on the surface of a base material. 7. A printed wiring board formed using the composite material for forming an electric circuit according to claim 1.