JPS62291996A - High conductivity electric circuit and manufacture of the same - 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 [Field of the Invention] The present invention relates to a highly conductive electric circuit and a method for manufacturing the same, and more particularly, to a highly conductive electric circuit and a method for manufacturing the same. The present invention relates to an electric circuit having a transferred paint film layer and a method for manufacturing the same.

[Technical background of the invention]

Conventionally, the method of forming an electric circuit using conductive resin is to laminate a conductive coating film over the entire surface of a support film, and then cover the electric circuit using a heating plate that can heat and press only certain parts. A method of transferring to a transfer material is known. Although this method of forming electric circuits has the advantage of being able to form electric circuits at low cost, it does not allow the formation of minute circuits (less than 0.1 mm) because it uses a metal mold or rubber heating plate. There were drawbacks. Furthermore, in such a transfer method, since the circuit pattern is transferred by heating and pressing only a predetermined portion using the hot platen, the conductive coating film must have good sharpness. This breakage of the conductive coating tends to worsen as the thickness of the coating increases, so it is not possible to make the conductive coating thicker.
On the other hand, if the amount of conductive particles in the conductive coating is increased in order to obtain good conductivity, the adhesion of the conductive coating will deteriorate (because there are 9 directions, it has good conductivity, Another drawback is that it is difficult to manufacture a circuit with excellent adhesive strength.

In view of the above-mentioned points, the present inventor invented a method for forming an electric circuit by forming a circuit pattern on a transfer target using a rough adhesive and transferring a conductive coating film to this adhesive layer, and filed a patent application. (Patent Application No. 60-261366).

According to such a method of forming an electric circuit, since the adhesion of the conductive coating film is not a problem, it is possible to add a large amount of conductive particles to the conductive coating film. It has the advantage that a good electric circuit can be formed.

Such electrical circuits are often connected to other electrical circuits, electrical components, electrical equipment, etc. by soldering, but the electrical circuits transferred and formed using conductive resin as described above are The drawback was that it was impossible to connect circuits, electrical components, electrical equipment, etc. with solder. In other words, conductive resins such as conductive coatings that serve as conduction paths in electric circuits as described above are made by adding an appropriate amount of conductive particles to the resin to give it conductivity. When the amount of the conductive particles added is small, the conductivity of the conductive resin to which the conductive particles are added tends to improve as the amount of the conductive particles added increases; It is known that when the amount of particles added increases, conductivity tends to decrease due to an increase in contact resistance between particles.

Even in conductive resin, if a large amount of conductive metal particles is added, soldering becomes possible, but as mentioned above, if the amount of metal particles added is such that it can be soldered, the resistance of the electric circuit will increase. The current situation is that transfer circuits made of conductive resin that can be soldered have not been put to practical use because of the disadvantage that the value increases and the characteristic values required for the circuit cannot be satisfied.

[Summary of the invention]

The present invention has been made in view of the above points, and it is an object of the present invention to provide an electric circuit that has good conductivity and can be soldered, and a circuit forming method that can form the above-mentioned electric circuit.

Therefore, in the highly conductive electric circuit according to the present invention, the resin 10
Conductive coating film for conductive path and resin 1 basically obtained by adding 500 to 1000 parts by weight of conductive particles to 0 parts by weight
The present invention is characterized in that it has an electric circuit in which conductive coating films for solder are sequentially laminated, each of which is made up of 500 to 2000 parts by weight of conductive particles per 00 parts by weight.

Further, according to the method for manufacturing a highly conductive electric circuit according to the present invention, 500 to 2000 parts by weight of conductive particles are added to 100 parts by weight of resin on the support film 4, and immediately after heating and pressing, 500 to 1000 parts of conductive particles are added to 100 parts by weight of conductive coating film for solder and resin that exhibits easy peelability.
A circuit transfer foil on which conductive coating layers for conductive paths are successively applied by adding parts by weight is brought into contact with a circuit board on which an adhesive layer is formed in a circuit pattern, and heated and pressurized to form the circuit. The present invention is characterized in that the conductive path-forming conductive coating film and the soldering conductive coating film are transferred to an adhesive layer on a substrate to form an electric circuit.

According to the present invention, there is an advantage that a conductive coating film path for a conductive path, an electric component, an electric device, etc. can be connected by soldering to an adhesive circuit pattern previously formed on a circuit board. Further, according to the method for manufacturing a highly conductive electric circuit according to the present invention, a circuit pattern is formed using an adhesive on a circuit board, and a conductive coating film (for solder and conductive path) is transferred to this adhesive layer. Therefore, there is no need to worry about adhesive strength. Therefore, it is possible to mix a large amount of conductive particles into the conductive paint. This has the advantage that a number of possible electrical circuits can be formed.

[Detailed description of the invention]

As shown in FIG. 1, the highly conductive electric circuit according to the present invention has an adhesive layer 2 formed in a circuit pattern on a circuit board 1 by means such as screen printing. It is constructed by thermally transferring the conductive coating film 3 for conductive path and the conductive coating film 4 for solder using adhesive properties.

This circuit board 1 is not fundamentally limited in the present invention, and may be of any type as long as the adhesive layer 2 can be printed on. For example, ABS
, ASSHIPS, polyacecool, vinyl chloride,
Thermoplastic resins such as nylon, polycarbonate, and polyethylene, polyimide resins, epoxy resins, phenolic resins, polyesters (thermosetting resins such as H fat, woodblock prints,
It can be glass, ceramic slope etc.

The adhesive layer 2 formed in a circuit pattern on the circuit board 1 as described above may be an adhesive that adheres to the conductive path conductive coating film 3 and the circuit board 1 described below with good adhesive strength.
Basically, it can be anything. For example, it may be a combination of one or more of thermoplastic polyester hot melt adhesives, epoxy adhesives, alkyd adhesives, acrylic adhesives, polyamide adhesives, cellulose adhesives, urethane adhesives, rubber adhesives, rosin adhesives, etc. can.

The thickness of this adhesive layer 2 is preferably 5 to 50 μm. If it is less than 5 μm, there is a risk that the conductive coating film 3 for the conductive path will not adhere well1.On the other hand, if it exceeds 50 μm, a significant increase in adhesive strength cannot be expected, and the material may be wasted or the coating may be damaged. It is not effective because the drying of the membrane becomes slow.

The conductive coating film 3 for conductive paths formed on the adhesive layer 2 contains 500 to 10 parts of conductive particles per 100 parts by weight of resin.
00 parts by weight is added to form the basic conductive paint.

The conductive coating film described above has basic properties as a circuit transfer foil, such as being able to be transferred well to the circuit pattern adhesive layer 2 of the circuit board Fi1 and adhering with sufficient strength;
In addition, it is necessary to satisfy various conditions such as having good adhesive strength with the conductive coating film 4 for soldering and having the required conductivity for an electric circuit. be.

In order to satisfy these conditions, it is necessary to improve the resin (solvent and solute) that is the base material of the conductive coating film for solder and the conductive coating film for conductive paths, as well as the conductive particles added to this resin. It is important to select the type, etc., and it is also necessary to consider the amount of conductive particles added and the particle size. The resin serving as the base material of such a conductive paint includes a resin component (solute) that adheres well to the conductive coating film 4 for soldering, such as acrylic, polyamide, epoxy, polyether, and polyester. For example, MEK S
MIflK, ketone solvents such as cyclohexanone, aromatic hydrocarbon solvents such as toluene and xylene, IPA
, alcohol solvents such as butanol, ether solvents, ester solvents, and others such as DMF, N-
It can be a resin solution dissolved in one or more solvents such as methylpyrrolidone.

In addition, when the electric circuit formed in this way is soldered by TTS soldering, a thermoplastic resin or a thermosetting resin having a high softening point or a thermoplastic resin can be used. Examples of such a resin solution include polyether sulfone, polysulfone, polyetherimide, etc.
It can be a resin solution dissolved in one or more solvents such as IP and N-methylpyrrolidone.

The conductive particles added to the resin solution are not fundamentally limited in the present invention as long as they can be uniformly dispersed in the resin solution and impart good conductivity.

For example, gold, silver, platinum, copper, nickel, aluminum,
It can be one or more of metal particles such as tin and zinc, composites and alloy powders whose surfaces are coated with the above-mentioned metals, and carbon particles.

Such conductive particles (5 parts by weight per 100 parts by weight of H fat)
Add 00 to 1000 parts by weight. If it is less than 500 parts by weight, it will be difficult to achieve a surface resistance of 1Ω/or less, which is required for a circuit filled with conductive particles, while if it exceeds 1000 parts by weight, the resistance value will increase (conductivity will decrease). and the paint suitability (fluid viscosity) deteriorates. In the present invention, a circuit pattern is formed by the adhesive layer 2, and the conductive path-forming conductive coating layer 3 is transferred onto this circuit pattern, so that the adhesive constituting the adhesive layer 2 and the conductive path are By selecting the resin for the conductive coating layer 3, the adhesive strength can be improved. Therefore, unlike in the case of conventional circuit transfer foils, it is possible to mix conductive particles to the limit where the conductivity decreases due to contact resistance or the like. Therefore, an electric circuit with good conductivity and adhesive strength can be formed.

The particle size of the conductive particles is preferably 10 μm or less.

This is because if the thickness exceeds 10 μm, problems tend to occur during painting.

The thickness of this conductive coating film 3 for conductive paths is preferably 15
The thickness is preferably ~30 μm. If the thickness of the conductive coating film 3 for the conductive path is thinner than 15 μm, a large amount of conductive particles must be filled in order to obtain the conductivity of 1.0 Ω/hole or less required for an electric circuit. This is because, if it exceeds this value, there is a risk that the cutting quality will deteriorate and it will be difficult to form the conductive coating film 3 for conductive path corresponding to the circuit pattern of the adhesive Fi2.

Other additives such as antioxidants, dispersants, etc. can be optionally added to the conductive paint for conductive paths.

In the highly conductive electric circuit according to the present invention, as shown in FIG.
are layered.

The conductive coating film 4 for solder is formed of a conductive paint containing a higher content of metal particles than the conductive coating film 3 for conductive paths described above.

Since this conductive coating film for soldering is a part to be soldered, unlike the conductive coating film 3 for conductive paths, conductivity is not much of a problem and good solder can be formed. It is required to have good adhesive strength with the conductive coating M*3 and to be easily peeled off from the support film described below immediately after heating.

Examples of resins that satisfy these conditions include acrylic, polyamide, epoxy, dilute ether, and polyester resins, cyclized rubber,
One or more types of chlorinated rubber, rosin, etc., for example, MEK
, MIBK, ketone solvents such as cyclohexanone,
Aromatic hydrocarbon solvents such as toluene and xylene, IP
^, alcohol solvents such as butanol, ether solvents, ester solvents, etc. DMF, N
- It can be a conductive coating provided by a resin solution dissolved in one or more solvents such as methylpyrrolidone.

In particular, in the case of ordinary soldering (conducted at about 260° C.), it is necessary to use a heat-resistant resin, a thermoplastic resin with a high softening point, or a thermosetting resin.

Such resin solutions include polyether sulfone,
A resin solution can be used in which one or more heat-resistant resins such as polysulfone and polyetherimide are dissolved in one or more solvents such as DMF and N-methylpyrrolidone.

Furthermore, it is obvious that the gold particles added to this resin solution should preferably be metal particles with good solderability.

In general, metal particles having a smaller ionization tendency than hydrogen are preferred. Examples of such metal particles include gold, silver,
It can be one or more of metal particles such as platinum, copper, nickel, and tin, or composites and alloy powders whose surfaces are coated with the above metals.

Further, the amount of metal particles added to the conductive coating film 4 for solder is 500 to 2000 parts by weight based on 100 parts by weight of the resin. If the content is less than 500 parts by weight, the content of the gold-flex particles will be too small, making soldering difficult. On the other hand, if it exceeds 2000 parts by weight, the peel strength between the conductive coating film 3 for conductive paths and the supporting film will be reduced. As well as becoming inferior, they become brittle and cannot be put to practical use. Furthermore, there is also the drawback that the cost is high.

Further, the average particle diameter of the metal particles is preferably 0.3 to
The thickness is preferably 10 μm.

Basically, the thickness of the conductive coating film 4 for soldering should be sufficient for soldering. Therefore, the thickness of this conductive coating film 4 for soldering is preferably 1 μm or more.

Next, a method for manufacturing a highly conductive electric circuit according to the present invention will be explained.

FIG. 2 is a sectional view of an example of the method for manufacturing a highly conductive electric circuit of the present invention. As shown in FIG. 2, first, according to the method for manufacturing a highly conductive electric circuit according to the present invention, the circuit An adhesive layer 2 having a predetermined circuit pattern is formed on a substrate 1.

The method of forming the adhesive layer 2 is basically not limited, and can be formed by a printing method such as screen printing or gravure printing.

The type and thickness of the adhesive layer 2Q are as described above, but it is preferable that the line width or the distance between the lines of the circuit pattern formed on the circuit board 1 be narrower. Of course. In the method for manufacturing a highly conductive electric circuit according to the present invention, the above-mentioned line width or line distance is 0.5
In order to make it possible to form a circuit of less than 1.0 mm, the thickness of the wire is increased (to obtain good conductivity), and in order to form a circuit with good adhesive strength, the viscosity of the printing adhesive is reduced to 1.
It is preferable to adjust it to 0 to 400 voices. If the viscosity of the adhesive is less than 10 voids, there is a risk that the wires will be distorted, whereas if it exceeds 400 voids, it will be difficult to print circuits and patterns on the circuit board 1.

It is clear that the adhesive forming the adhesive layer 2 described above is functionally selected depending on the type of circuit board 1. For example, when using thermosetting resin as this adhesive,
The adhesive layer 2 printed on the circuit board Mj, 1 is kept in a semi-cured state, and is cured when transferring the circuit transfer foil described later or by secondary heating after transfer, to form the adhesive layer 2 for the conductive path. It is preferable that the conductive coating layer 3, the circuit board 1, and the adhesive layer 2 be bonded together with good adhesive strength.

Such a semi-cured state is preferably about 20 to 40% crosslinked. This is because if it deviates from the above-mentioned range, there is a possibility that the adhesive strength between the circuit board 1 and the conductive path-forming conductive coating film 3 will decrease.

In this way, after forming the adhesive layer 2 on the circuit pattern, the conductive coating film 4 for solder, which exhibits easy peelability immediately after heating and pressurizing, is formed.
and a circuit transfer foil 6 in which a conductive coating film 3 for a conductive path is sequentially laminated on a support film 5 is superimposed on the circuit board 1,
The adhesive layer 2 formed on the circuit board 1 is coated with a conductive coating film 3 for conductive paths and a conductive coating film 4 for soldering by heating and pressurizing the adhesive layer 2 formed on the circuit board 1 (see FIG. 2) by applying heat and pressure using means such as a plate 7 or a heat roll. is transferred to form an electric circuit (see Figure 3).

As is clear from this FIG. 3, conductive coating film 3 for conductive path
An electric circuit can be formed on which a conductive coating film 4 for soldering is laminated.

The support film 5 on which such a conductive coating film 4 for soldering is laminated is not fundamentally limited in the present invention, and has good adhesion to the conductive coating film 4 for soldering at room temperature, Immediately after heating and pressurizing, it easily peels off from the conductive coating film 4 for soldering, and it is effective to use a synthetic resin film that is heat resistant or smooth and is not attacked by the solvent contained in the conductive coating film. Can be used.

Specific examples of the support film 5 include plastic films such as polyester films, polyimide films, and polypropylene films, and aluminum foil. In particular, when the electrical circuit to be transferred is normally soldered, polyimide film or aluminum foil, which have good heat resistance, are preferred.

・: When transferring the conductive coating film 3 for solder and the conductive coating film 4 for conductive paths to the adhesive layer 2 by heating and applying pressure, 80 to
It is preferable to transfer at a temperature of 300° C. and a pressure of 5 to 10 kg/cI11. If the transfer temperature is lower than 80° C., there is a possibility that the conductive coating film 3 for solder and the conductive coating film 4 for conductive paths may not be transferred to the circuit pattern-shaped adhesive layer 2 formed on the circuit board 1. If the temperature is higher than 300° C., there is a possibility that the circuit board 1 may be warped, thermally contracted, or thermally deteriorated.

Furthermore, if the transfer pressure is lower than 5 Kg/cJ, there is a risk that the conductive coating film 4 will not be transferred well;
This is because if it is larger than l, there is a risk that the circuit pattern will collapse.

Example 1 A so-called paper-phenol circuit board made of paper coated with phenolic resin was coated with an adhesive having the following composition-1 (50 poise).
A circuit pattern with a line width of 0.5 ms was screen printed with a thickness of 10 μm. Next, this adhesive layer is heated to
0% semi-cured state.

Composition 1 Epoxy adhesive DER331 (manufactured by Dow) 100 parts by weight Benzyldimethylamine (BDMA) 1 part by weight 1 part by weight phthalic anhydride 60 parts by weight Next,
A circuit transfer foil was prepared in which a conductive coating film for solder having the following composition 2 and a conductive coating film for conducting paths having the following composition 3 were laminated on a silicone-treated release film to a thickness of 5 μm and 17 μm, respectively. The conductive coating film was transferred to the adhesive layer to form an electric circuit under the conditions of , 130° C., and 8 kg/crl.

Composition 2 Acrylic resin 100 parts by weight Methyl isobutyl ketone 150 parts by weight Copper particles
800 parts by weight Composition 3 Acrylic resin 100 parts by weight Methyl isobutyl ketone 180 parts by weight Silver-coated copper particles 850 parts by weight (average particle size 2 μm) Dispersant 0.3 parts by weight Antioxidant 0.5 parts by weight Produced in this way Measuring the conductivity of an electric circuit, the surface resistance is Q, 2Ω/mouth (resistivity 4 x 10-3Ω・cIi)
It showed good conductivity.

Further, the above two-layer conductive coating film was applied to the above adhesive layer at 10×
After manufacturing 10 samples formed in a grid pattern and pasting cellophane tape on them, the cellophane tape was peeled off in the vertical direction, and how many of the grid-shaped coating film of 10XIO was peeled off was measured. An eye peel test was performed. As a result, no coating film was peeled off, indicating that the film had good peel strength.

Furthermore, when electrical components were connected by soldering to the electrical circuit formed as described above, the soldering was successful.

〔Effect of the invention〕

As explained above, the highly conductive electric circuit according to the present invention has the advantage of having good conductivity and being able to be soldered.

Further, according to the method for forming a highly conductive electric circuit according to the present invention, an electric circuit can be formed on the substrate without problems with adhesion to the circuit board, and therefore a highly conductive circuit can be formed. Soldering has the advantage that possible electrical circuits can be easily formed.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view of an example of a highly conductive electric circuit according to the present invention, and FIGS. 2 and 3 are cross-sectional views for explaining an example of a method for manufacturing a highly conductive electric circuit according to the present invention. DESCRIPTION OF SYMBOLS 1... Circuit board, 2... Adhesive layer, 3... Conductive coating film for conductive path, 4... Conductive coating film for solder, 5
...Support film, 6 ...Circuit transfer foil. Applicant's agent Tadashi Amemiya Pencil case Figure 1 Figure 2 Figure 3 Procedural amendment (written July 29, 1986)

Claims (2)

[Claims] (1) On the adhesive layer formed in the circuit pattern shape on the circuit board, 500 to 500 parts of conductive particles are added to 100 parts by weight of resin.
500 to 2 parts by weight of conductive particles per 100 parts by weight of the conductive coating film and resin for conductive paths that are basically obtained by adding 1000 parts by weight.
1. A highly conductive electric circuit comprising an electric circuit in which a basic conductive coating film for solder is sequentially laminated by adding 0.000 parts by weight. (2) Add 500 to 2000 parts by weight of conductive particles to 100 parts by weight of resin on the support film to basically form the
500 to 100 parts of conductive particles are added to 100 parts by weight of a conductive coating film and resin for solder that exhibits easy peelability immediately after heating and pressurizing.
A circuit transfer foil in which conductive coating films for conductive paths are sequentially laminated with 0 parts by weight added is brought into contact with a circuit board on which an adhesive layer has been formed in a circuit pattern, and heated and pressed to form a layer on the circuit board. A method for producing a highly conductive electric circuit, which comprises transferring the conductive coating film for conduction and the conductive coating film for soldering onto an adhesive layer to form an electric circuit.