JPH0493368A - Conductive coating material, and printed circuit board and electromagnetically shielded flexible printed circuit substrate using the coating material - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention]

[0001]

[Industrial application field]

The present invention is a conductive paint in which metallic copper powder is dispersed in a phenolic resin, and more specifically, it is used for jumper circuits of printed wiring boards, electromagnetic shielding, etc., and is particularly suited for use in electrical conductivity, adhesion with copper foil, and soldering heat resistance. Conductive paint with excellent properties
The present invention also relates to a printed circuit board using the conductive paint and a durable flexible printed circuit structure with electromagnetic shielding. [0002]

BACKGROUND OF THE INVENTION Conventionally, copper-clad laminated insulating substrates have been widely used as substrates for printed circuits on which ICs, MSIs, LSIs, etc. are mounted. [0003] In order to effectively utilize the printed circuit formed on such a copper-clad laminated insulating substrate, a bypass jumper circuit is provided on the printed circuit. [0004] In this jumper circuit, a resist film is formed over the entire unconnected circuit portion between copper foil circuits in a printed circuit, and then the jumper circuit jumps over the portion where the resist film is formed to connect between the copper foil circuits to be connected. It is formed by screen printing using conductive silver paint (hereinafter referred to as silver paste). However, silver paste is expensive. Also,
Various inexpensive conductive copper paints (hereinafter referred to as copper pastes) that can replace silver paste have been published, but these copper pastes mainly use thermosetting phenolic resin as a binder, so copper foil It has poor adhesion to surfaces and is unreliable for use as a conductive paint for forming jumper circuits. [0005] A shield layer is formed on the printed circuit of a printed circuit board via a ground pattern or a resist film, but when used as a conductive paint for forming such a shield layer, the copper of the ground pattern is There is a similar problem in adhesion to the foil surface. [0006] Therefore, the present inventors previously proposed a solder heat-resistant conductive paint that has good adhesion to the copper foil surface, is inexpensive, and has excellent conductivity (Japanese Patent Application No. 167229/1982). [0007] However, it has been found that the cured film formed with this conductive paint has a problem in adhesion to the non-oxidized copper foil surface. [0008] The present invention has been made to solve the above problems, and has excellent adhesion to both oxidized and non-oxidized copper foil surfaces, and has particularly good conductivity. An object of the present invention is to provide an excellent conductive paint and a printed circuit board using the conductive paint. [0009]

[Means and actions to solve the problem]

The conductive paint according to claim 1 solves the above problems, (A) 100 parts by weight of metallic copper powder (B) 5 to 30 parts by weight of resol type phenolic resin (C)
Chelate forming agent 0.5 to 4 parts by weight (D) Adhesion improver 0
．． 1 to 5 parts by weight (E) and 0.5 to 7 parts by weight of a conductivity improver are blended. [00103 In the above, the metallic copper powder may have any shape such as flake, dendritic, spherical, or irregular shape. Particle size is 100
The thickness is preferably 1 to 30 Atm, and preferably 1 to 30 Atm. Particles with a particle size of less than 1 μm are undesirable because they are easily oxidized and the conductivity of the resulting coating film decreases. [0011] The blending ratio of each component below is shown assuming that the amount of metallic copper powder is 100 parts by weight. [0012] The resol type phenolic resin binds metal copper powder and other components well, and acts effectively to maintain long-term conductivity. [0013] As the resol type phenolic resin, ordinary ones may be used, but in order to make the coating film appropriate in hardness and have good conductivity, it is necessary to use the 2-1 substituted, 2,4-2, When the infrared transmittance of the substituted product, 2,4.6-3 substituted product, methylol group, dimethylene ether, phenyl group by infrared spectroscopy is 1, m, n, a, b, c, each transmittance Between (a) l/n = 0.8~1゜2 (b) m/n = 0.8~1.2 (c) b/a = 0.8~1.2 (-) c/ A resol type phenolic resin that satisfies the following relationship: a=1.2 to 1.5 is preferable. [0014] The resol type phenolic resin is used in an amount of 5 to 30 parts by weight, preferably 9 to 20 parts by weight, based on 100 parts by weight of metallic copper powder. [0015] If the resol type phenolic resin is less than 5 parts by weight, the metallic copper powder will not be sufficiently bound, and the resulting coating film will become brittle. Moreover, when it exceeds 30 parts by weight, the conductivity decreases. [0016] The chelate forming agent is at least one kind selected from aliphatic amines such as monoethanolamine, jetanolamine, triethanolamine, ethylenediamine, triethylenediamine, and triethylenetetramine. The chelate forming agent prevents oxidation of the metallic copper powder and contributes to maintaining conductivity. [0017] The blending amount of the chelate forming agent is 0.5 to 4 parts by weight, preferably 1 to 3.5 parts by weight, based on 100 parts by weight of metallic copper powder.
Parts by weight. [0018] When the amount of the chelate forming agent is less than 0.5 parts by weight, the conductivity of the coating film decreases. On the other hand, if it exceeds 4 parts by weight, the soldering heat resistance is unfavorable. [0019] The adhesion improver includes various adhesives. [0020] As the natural resin type, rosin (gum type, tall oil type, wood type), rosin derivative, terpene resin type (terpene type, terpene phenol type), etc. are preferable. Examples of synthetic resins include petroleum resins, butyral resins,
Thermosetting materials such as phenolic resin and xylene resin, thermoplastic materials such as vinyl acetate resin, acrylic resin, cellulose, and phenoxy resin, synthetic rubber such as recycled rubber, styrene-butadiene rubber, nitrile rubber, and butyl rubber. preferable. These have the property of reducing the internal stress of the resol type phenolic resin that is the binder, or have a functional group (carboxyl group, hydroxyl group, long-chain alkyl group, etc.) that exhibits adhesive properties.

If the amount of the adhesion improver is less than 0.1 part by weight, no improvement in adhesion will be observed, and if it exceeds 5 parts by weight, the conductivity will decrease. [0022] The conductivity improver is preferably one made of a nitrogen-containing compound or a heterocyclic compound having a phenyl group, particularly a compound that can exhibit conductivity through chemical oxidative polymerization or electrolytic polymerization. [0023] Specific examples include aniline, diphenylamine, N-phenyl-p-phenylenediamine, N,N'-diphenyl-p-phenylenediamine, N-isopropyl-N'
- Alkylation such as phenyl, p-phenylenediamine, N,N'-diphenylbenzidine, aminophenol, diaminophenol, 5-tert-butyl-3,4-toluenediamine or 5-isopropyl-2,4-toluenediamine Toluenediamine, p-phenylenediamine, 1,5-naphthalenediamine, cyclohexyl-
Compounds with amino groups such as p-phenylenediamine, ortho-tolyl-β-naphthylamine, O-anisidine, 4,5-diamine, aminopyrene, chrysazine, diaminonaphthalene, pyrrole, amphoteric polypyrrolethiophene, α-bipyrrole, 3- Examples include, but are not limited to, methylthiophene, phthalocyanine, phthalocyanine metal complex, furan, selenophene, erulofen, tetrathiofulvalene, and tetracyanoquinodimethane. [0024] If the amount of these conductivity improvers is less than 0.5 parts by weight based on the metal copper powder, no improvement in conductivity will be observed (expressed in volume resistivity, it will be 1xlO-4Ω·cm or more). [0025] When the amount of the conductivity improver exceeds 7 parts by weight, not only is the conductivity saturated and no further improvement in conductivity is observed, but also, in the case of a compound having an amino group, the content It is undesirable when there is a large amount of water because gelation progresses and the pot life becomes short. It also leads to a decrease in adhesion to the copper foil surface. [0026] In addition, in order to adjust the viscosity of the conductive paint according to the present invention, an ordinary organic solvent can be used as appropriate. For example, known solvents include cellosolve acetate, carpitol, butyl carpitol, butyl cellosolve acetate, and the like. [0027] In this invention, it is preferable to use 0.1 to 2 parts by weight of the dispersant. [0028] As the dispersant, fatty acids or metal salts of fatty acids are preferred. Preferred saturated fatty acids include palmitic acid, stearic acid, and arachic acid having 16 to 20 carbon atoms, and preferred unsaturated fatty acids include seamaric acid, oleic acid, lylunic acid, and the like having 16 to 18 carbon atoms. As metal salts of fatty acids, salts of fatty acids as described above with metals such as sodium, potassium, copper, zinc, and aluminum are preferred. [0029] These dispersants promote fine dispersion of the metallic copper powder into the resin mixture. [0030] The blending amount of the dispersant is 0 to 100 parts by weight of metallic copper powder.
．． The amount is 1 to 2 parts by weight, preferably 0.3 to 1.5 parts by weight. [0031] When the amount of the dispersant is less than 0.1 part by weight, the conductivity of the coating film decreases, and on the other hand, when it exceeds 2 parts by weight, the adhesion with copper foil and soldering heat resistance are improved. ). [0032] Instead of using such a dispersant, a dispersion method such as coating the metal copper powder with an organic metal compound such as an organic diconate, titanate, aluminate, or silanate compound, or a metal acylate polymer can be used. An assignment process may also be performed. [0033] The printed circuit board according to claim 2 includes a substrate, a copper foil circuit formed on at least one surface of the substrate, and a wiring between a predetermined circuit to be connected among the copper foil circuits. a first insulating layer provided on the unconnected circuit; a jumper circuit connecting the predetermined circuits across the first insulating layer; and a second insulating layer covering a printed circuit including the jumper circuit. A printed circuit board having a jumper circuit formed with the conductive paint according to claim 1. [0034] In this printed circuit board, since the jumper circuit is formed with the conductive paint according to claim 1, the jumper circuit and the copper foil circuit have excellent adhesion, and the jumper circuit also has excellent conductivity. [0035] The printed circuit board according to claim 3 includes a substrate, a copper foil circuit including a ground pattern formed on at least one surface of the substrate, and the ground pattern on the substrate on which the copper foil circuit is formed. an insulating layer formed to cover the copper foil circuit except for at least a part of the copper foil circuit; and a conductive layer formed on the insulating layer so as to be connected to the uninsulated portion of the ground pattern. In the printed circuit board provided with the invention, the conductive layer is formed using the conductive paint according to claim 1. [0036] Since the conductive layer of this printed circuit board is formed using the conductive paint according to claim 1, it has excellent adhesion to the ground pattern and the conductive layer has excellent conductivity. [0037] Furthermore, the invention according to claim 4 relates to a flexible printed circuit structure with electromagnetic shielding. This will be explained next. [0038] Among printed circuit boards, flexible printed circuits (hereinafter referred to as FPCs) have come into widespread use, particularly for downsizing electrical equipment or incorporating circuits into complex mechanisms. Generally used FPCs require flexibility in order to be easily incorporated into equipment in view of the above-mentioned uses, but do not require durability against repeated bending. [0039] In recent years, electromagnetic interference in electrical and electronic devices has become a major problem, and as a countermeasure, it is necessary to make the casing of the device shieldable or cover the parts of the device with a shield to prevent electromagnetic waves from leaking outside. Measures are being taken to ensure that. [0040]However, looking at recent new uses of FPCs, there are many that are repeatedly bent and required to shield electromagnetic waves, such as those used in computers, word processors, and printers. In light of this current situation, conventional FPCs have poor durability against repeated bending, and furthermore, when a shield layer is provided on the FPC, the number of laminated layers increases, further worsening the bending durability. In view of the above, there is a need for an FPC that has good flexibility, has durability against repeated bending, and has an electromagnetic shielding function. [0041] The invention according to claim 4 forms a copper foil wiring circuit on the surface of a heat-resistant plastic film, and on this circuit, an undercoat layer, a shield layer coated with a conductive paste containing metal powder, and an overcoat layer (hereinafter referred to as 00 layers) are successively provided, and the ground pattern of the copper foil wiring circuit and the shield layer coated with conductive paste containing the metal powder penetrate the undercoat layer (hereinafter referred to as the UC layer) at appropriate intervals. It is configured to be electrically connected. [0042] Next, the configuration of the present invention will be further explained. [0043] The heat-resistant plastic film used in this invention is:
Films of polypropylene, crosslinked polyethylene, polyester, polyimide, polybenzimidazole, polyimideamide, fluorine-based resins such as polytetrafluorinated ethylene, polyfluorinated ethylene propylene, silicone resin having adhesive properties, and the like can be used. In particular, the film is not particularly limited as long as it can withstand the heating temperature and heating time during curing of the coating layer and conductive paint used in the present invention, and may be a heat-resistant film other than those mentioned above. [0044] The material for forming the UC layer is a liquid coating material such as a synthetic resin such as epoxy resin, epoxy/melamine resin, polyurethane, butyl rubber, or silicone elastomer, which can be screen printed, and a film material such as those mentioned above. The same type of base film is used and laminated using a roll laminator or the like. [0045] The conductive paint used in this invention is the one described in claim 1, which is suitable because it contains metal powder that can form an electromagnetic shielding layer. A paste with a sufficiently small DC resistance is required, and a sheet resistance of 0.1 Ω/mouth or less is preferable, and a paste with a resistance value higher than that cannot provide the desired shielding effect. [0046] Note that the dimension of the above-mentioned sheet resistance value means "Ω/distance between opposing sides of a square". That is, a substrate having a conductive coating film is cut into squares, and electrodes are brought into contact with opposing sides to measure the electrical resistance. That is, it means "the electrical resistance value between opposing sides of a conductive coating film". [0047] As a material forming the 00 layer, -component heat-curable silicone rubber (TS E3212.3221.325.
325-B, 3251.3251-C, 3252, manufactured by Toshiba Silicone Corporation) Two-component heat-curing silicone adhesive (two-component addition self-adhesive silicone, TSE
3360, manufactured by Toshiba Silicone Corporation, 5E1701,
CY52-237W/C5CY52-227A/B,
A material with excellent bending durability and elasticity even after heat curing treatment, such as (manufactured by Toray Silicone Co., Ltd.), is used. [0048] When the same material as the above-mentioned 00 layer is used for the UC layer, the interlaminar pressure generated during bending is alleviated due to its elasticity, preventing deterioration of the characteristics of the shield layer and further improving the bending durability. [0049] As described above, in the flexible printed circuit structure with electromagnetic wave shielding according to the invention of claim 4, the copper foil wiring circuit and the shield layer formed of conductive paste are separated by an extremely thin UC layer, and the ground pattern and the shield are separated from each other by an extremely thin UC layer. Since the layers are electrically connected, electromagnetic interference can be prevented, signal line crosstalk can be prevented, and the resistance of the ground pattern can be substantially reduced to provide electrical reinforcement. [0050] By using the above conductive paste, desired electrical characteristics can be obtained even after repeated bending over a long period of time. [0051] By using the above material for the 00 layer, the bending durability is dramatically improved. [0052] When the material of the 00 layer is used for the UC, its elasticity relieves the interlaminar pressure that occurs during bending, increasing the protective effect of the shield layer and improving the bending durability. [0053] [0053] The present invention will be described in more detail below based on Examples and Comparative Examples, but the present invention is not limited to these Examples. [0054] ''''''・1 Examples 1-4, Proportionality 1-7 Particle size 5-1
A resol type phenol resin, a fatty acid or its metal salt, a chelate forming agent, an adhesion improver, and a conductivity improver are added to 100 parts by weight of a dendritic metal copper powder having a specific surface area of 0 μm or less of 0.4 or less and a hydrogen reduction loss area of 25 or less. The mixture was mixed and kneaded to have the composition shown in Table 1, a small amount of butyl cellosolve acetate was added as a solvent, and the mixture was kneaded for 20 minutes using a triaxial roll to prepare a conductive paint. [0055] Using this conductive paint, a solder resist was printed and cured on a glass epoxy substrate by a screen printing method, and a solder resist with a width of 1 mm, a thickness of 25 ± 5 μm, and a length of 60 m was applied thereon.
Five m conductive circuits were screen printed using a 180 mesh Tetron screen, and the coating was cured by heating at 160° C. for 30 minutes using an air oven. The volume resistivity of this coating film was measured to evaluate the electrical conductivity of the coating film. The results are shown in Table 1. [0056]

[Table 11 [0057] On the other hand, after cleaning the copper foil surface of the copper-clad laminated insulating board,
Using a conductive paint, a 50 mm x 50 mm coating film was formed on the surface of the copper foil by the screen printing method, and after heating and curing the coating film in the same manner as above, JISK5400 (1
979), 11 vertical and horizontal parallel lines that are orthogonal to each other are lined up at 1 mm intervals on the coating film, and 100 squares are formed in 1 cm. The adhesion of the coating film to the copper foil surface was evaluated by determining the number of substrates of the coating film remaining on the copper foil surface when the coating film was peeled off using cellophane tape. In Table 1, the case where the number of substrates of the coating film remaining on the copper foil surface is 100 is indicated by ○, and the case where it is 99 or less is indicated by
Indicated with a mark. [0058] The solder heat resistance of the coating film was determined by forming a test piece shown in FIG.
After dipping for a second and pulling out, the surface condition was observed and evaluated. In Table 1, cases where the surface has unevenness due to thermal deformation are indicated by an x mark, and cases where there is no unevenness are indicated by an ○ mark. [0059] Method for creating a test piece (see Figure 2) (1) Using solder resist ink, place a screen on the glass epoxy substrate 11 so as to partially overlap the copper foil 12 on the glass epoxy substrate 11. A solder resist cured film 13 is formed by a printing method. (Curing conditions: 150° C., 30 minutes) (2) A cured copper paste film 14 is formed on the copper foil 12 and the cured solder resist film 13 by screen printing using a conductive paint. (Curing conditions: 150° C., 30 minutes) (3) A solder resist cured film 15 is formed on the copper paste cured film 14 by screen printing using solder resist ink. (Curing conditions: 150
℃, 30 minutes) As is clear from the table, in Examples 1 to 4, the specific compounded materials used in the present invention were appropriately combined, so the conductivity of the coating film, the copper foil surface and the coating film were Excellent adhesion and soldering heat resistance of the coating film. [00601] On the other hand, in Comparative Example 1, the conductivity improver is too small, so the conductivity is not improved, and in Comparative Example 2, the conductivity improver is too large, so the adhesion is reduced. [0061] In Comparative Example 3, since the adhesion improver was too small,
There was no improvement in adhesion and the conductivity improver was too small, so the conductivity should also be improved. Furthermore, the soldering heat resistance is also poor due to too much triethanolamine (chelate forming agent). [0062] In Comparative Example 4, there was too much adhesion improver, so the conductivity was poor, and because there was too much dispersant (potassium oleate), the adhesion to the copper foil was poor, and the soldering heat resistance was also poor. do not have. [0063] In Comparative Example 5, there was too little dispersant and too much chelate forming agent, so the adhesion to the copper foil was not improved and the soldering heat resistance was poor. [0064] In Comparative Example 6, there is too much resol-type phenolic resin, so the conductivity is poor. [0065] In Comparative Example 7, there is too much adhesion improver, so it is desired to improve the conductivity. [0066] Embodiment of Mechanics 2 and 3 FIG. 1 shows an embodiment of the printed wiring board according to claims 2 and 3. A circuit pattern is first formed on the surface of a substrate 1 made of an insulating material such as epoxy resin, phenol resin, glass fiber, or ceramics. The circuit pattern includes signal line patterns 2.2', 2'', signal lands 3, 3', a power supply pattern 4, and a ground pattern 5. Each of these patterns is formed by a known photolithography technique. Necessary patterns Signal line patterns 2, 2', 2'' between signal lands 3, 3' are lands of a predetermined circuit to be connected.
A first insulating layer 6 is provided thereon, and a jumper circuit 7 connecting the signal lands 3 and 3' is formed using conductive paint, after which a part of the area A of the ground pattern 5 is left. Then, an undercoat layer 8 is formed. This undercoat layer 8 is a solder resist layer made of a resin insulating material. The area A where the ground pattern 5 is exposed is
It is preferable to form it in as wide an area as possible on the substrate, but it is sufficient if it is formed in at least one location. This undercoat layer 8 can be easily formed by screen printing. After forming the undercoat layer 8, a conductive layer 9 is formed thereon using a conductive paint, and an overcoat layer 10 is further formed using a resin insulating material. [0067] As the conductive paint for forming the jumper circuit 7 and the conductive layer 9, the conductive paints according to Examples 1 to 4 are preferable. [0068] Q Example Straight copper foil circuit 21 (thickness 30 μm, width 1 mm, 10 units with 15 wires at 1 mm spacing being 1 unit) was applied to the surface of a polyimide film 22 with a thickness of 50 μm using an etched foil method. Formed by However, among the 15 wires, two at both ends are ground patterns. [0069] Masks are provided on the copper foil circuit 21 at regular intervals along the length direction of the ground pattern 23, and a screen (not shown) is used in which masks are provided at fixed portions at both ends of the circuit. Then, a paste made of epoxy melamine resin is applied by a printing method to form a UC layer 24 having a thickness of 30 μm. At this time, through-holes 25 are formed in the UC layer 24 in the longitudinal direction above the ground pattern 23 by the mask of the screen, and at both ends of the circuit, U are formed by the mask of the screen.
C is not applied and the circuit is left exposed. [00701 As the shield layer 27, a resin mixture (50% by weight of melamine resin, 20% by weight of polyester resin, and 30% by weight of resol type phenolic resin) is added to 100 parts by weight of dendritic metal copper powder with a particle size of 5 to 10 μm. resin mixture) 1
6 parts by weight, 10 parts by weight of a fatty acid or a metal salt of a fatty acid, and 2.5 parts by weight of a chelate forming agent, some butyl cellosolve acetate was added as a solvent, and the mixture was kneaded for 20 minutes with a triaxial roll to form a suitable mixture. A viscous conductive paint is applied to the entire surface of the UC layer 24 except for a portion of both ends using a screen printing method, and a heat treatment is performed at 150° C. for 30 minutes to harden the coating film to form a shield layer 27 with a thickness of 20 μm. to form. At this time, the conductive paint reaches the ground pattern 23 through the through hole 25, and connects the shield layer 27 and the ground pattern 2.
3 are electrically connected. [0071] Next, a one-component thermosetting silicone rubber coating material [TSE 3251, manufactured by Toshiba Silicone Corporation] was applied on the shield layer 27 by a screen printing method, and this was heated and cured at 150° C. for 1 hour to a thickness of 20 μm. 0 of
0 layer 28 is provided to obtain the electromagnetic shielding flexible printed circuit structure of the present invention. [0072] The product of the present invention made as described above is processed by using a 5 mm mandrel by ±9
No abnormality was observed even after 100,000 times of 0-degree repeated bending tests, and the test is ongoing. [0073] In addition, those using epoxy melamine resin as the OC material,
Cracks occurred after only a few dozen times. [0074] [Effect of the invention] The conductive paint according to claim 1 is cheaper than silver paste, has excellent conductivity of the paint film and adhesion of the paint film to the copper foil surface, and has excellent solderability of the paint film. Excellent heat resistance. Therefore, it is suitable for forming jumper circuits and electromagnetic shielding layers on copper foil printed circuit boards, and by immersing it in a molten solder bath, ICMSI, LSI
etc. is easy to implement. [0075] In the printed circuit board according to claim 2, since the jumper circuit is formed with the conductive paint according to claim 1, the jumper circuit and the copper foil circuit have excellent adhesion, and the jumper circuit has excellent conductivity. There is. [0076] The printed circuit board according to claim 3 has a conductive layer as described in claim 1.
Since it is formed using the conductive paint according to the above, it has excellent adhesion with the ground pattern, and since the conductive layer has excellent conductivity, it has a remarkable effect in suppressing unnecessary radiation. [0077] According to the fourth aspect of the present invention, (1) since the shield layer and the ground circuit are electrically connected, the connection of the shield (connection of the ground circuit) is completed at the same time as the terminal processing. (2)0C
By using the above-mentioned specific material, the bending durability was dramatically improved. (3) When the same material as the OC material is used for the UC, the interlaminar pressure generated during bending is alleviated, preventing deterioration of the electrical properties of the shield layer and further improving the bending durability.

[Brief explanation of the drawing]

[Figure 1] FIG. 1 is a cross-sectional view of a printed circuit board according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view of a test piece for evaluating the solder heat resistance of a coating film made of conductive paint.

FIG. 3 is a perspective view of the flexible printed circuit structure with electromagnetic shielding, cut in the longitudinal direction and with some layers peeled off.

[Explanation of symbols]

1... Board 2. 2', 2''... Signal line pattern 3.
3'... Signal land 4... Power supply pattern 5... Ground pattern 7... Jumper circuit 9... Conductive layer 21... ...Copper foil wiring circuit 22...Polyimide film 23...Ground pattern 24...UC layer 25...Through hole 26... Exposed circuit 27... Shield layer 28... OC layer

【Document name】

drawing

[Figure 1]

[Figure 2]

[Figure 3]

Claims (4)

[Claims] 1. (A) 100 parts by weight of metallic copper powder, (B) 5 to 30 parts by weight of resol type phenolic resin, (C) 0.5 to 4 parts by weight of chelate forming agent, and (D) 0.5 parts by weight of adhesion improver. A conductive paint containing 1 to 5 parts by weight (E) and 0.5 to 7 parts by weight of a conductivity improver. 2. A substrate, a copper foil circuit formed on at least one surface of the substrate, and a copper foil circuit provided on an unconnected circuit wired between predetermined circuits to be connected among the copper foil circuits. 1 insulating layer, a jumper circuit connecting the predetermined circuits across the first insulating layer, and a second insulating layer covering a circuit including the jumper circuit, the jumper circuit according to claim 1. A printed circuit board comprising the conductive paint according to item 1. 3. A copper foil circuit including a substrate and a ground pattern formed on at least one surface of the substrate;
an insulating layer formed on the substrate on which the copper foil circuit is formed so as to cover the copper foil circuit except for at least a part of the ground pattern; and an uninsulated portion of the ground pattern on the insulating layer. A printed circuit board comprising: a conductive layer formed to be connected to a conductive layer, the conductive layer being made of the conductive paint according to claim 1. 4. A copper foil wiring circuit is formed on the surface of a heat-resistant plastic film, and an undercoat layer, a shield layer coated with a conductive paste containing metal powder, and an overcoat layer are sequentially provided on the circuit, and the copper foil wiring circuit is formed on the surface of a heat-resistant plastic film. The ground pattern and the conductive paste coated shield layer containing the metal powder are electrically connected to each other by penetrating the undercoat layer at appropriate intervals, and the shield layer is made of the conductive paint according to claim 1. A flexible printed circuit structure with electromagnetic shielding characterized by: