JPS62183592A - Flexible printed circuit substrate - 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] LfL First February 3Ji The present invention relates to flexible printed circuit boards.

More specifically, (A) (1) an ethylene copolymer having at least ethylene and at least one unit selected from the group consisting of a carboxylic acid unit, a dicarboxylic acid unit, an anhydride unit thereof, and a halfester unit thereof; ) A crosslinked product of an ethylene copolymer mixture having at least ethylene units and at least one unit selected from the group consisting of 7 mino units and glycidyl units, or a crosslinked product having a thermal conductivity of 1 x 1 O-3 cat/°C
・At least a resin layer with a thickness of 3 to 4000 microns filled with at most 70% by volume of an inorganic filler having an electrical resistance of 101θΩ or more and an electrical resistance of 101θΩ or more and a conductive metal layer (CB) is laminated. The purpose of this invention is to provide a flexible printed circuit board that is not only flexible and has good heat resistance, but also has excellent repeated bending properties.

Modern electronic devices are rapidly becoming smaller, lighter, thinner, and more densely packaged. In particular, printed wiring boards began to be commercialized for consumer equipment such as radios, and are now being used in industrial equipment such as telephones and computers, supported by mass production and high reliability.

Flexible printed circuit boards were initially used as a substitute for electric wires and cables, but their flexibility not only allows for high-density three-dimensional mounting in narrow spaces, but also allows them to withstand repeated bending, making them ideal for electronic devices. Its use is expanding as a composite component that provides wiring, cable, and connector functions for moving parts.

Currently, the materials used as three-dimensional wiring materials in devices such as cameras, electric desktop calculators, telephones, and printers are:
A wiring pattern is formed using a flexible copper-clad board in which electrolytic copper foil of 35 microns is adhered to both or one side of a polyimide or polyester film with a thickness of about 25 microns. A wiring pattern in which through-hole plating is applied, and both sides and the outer layer are coated with a coverlay is also used.

Polyimide or polyester resin films are generally used as base materials for current flexible printed circuit boards, but boyester films not only have poor solder heat resistance, but also cannot be used for adhesion to conductive metal layers such as copper foil. The epoxy adhesives currently available have a high water absorption rate and a large thermal expansion coefficient at 20°C to 250°C, so they lack through-hole connection reliability. In addition, when manufacturing 170
In '0', curing is sometimes performed by steam press, and when multi-layered, not only the adhesiveness between resins decreases, but also the flexibility tends to decrease.

On the other hand, polyimide film is soldered at the normal soldering temperature (26
Polyimide resin has the advantage of being able to easily perform solder connections at temperatures above 0°C), but in addition to being hygroscopic, polyimide resin has poor surface activity, making it extremely difficult to bond with metal foil. There are drawbacks. To solve this problem of adhesion, the general method is to apply a chemical treatment using caustic soda, a chromic acid mixture, aluminum hydroxide, etc. to the surface of the film, and then bond it with an adhesive. It is. However, even if these methods are used for adhesion, it is not possible to obtain a printed circuit board with sufficient adhesion, and the chemical resistance and heat resistance are poor. There are disadvantages such as occurrence.

In addition, thermosetting adhesives with excellent heat resistance (for example,
In the method of bonding with metal foil using epoxy resin,
Polyimide film coated with adhesive must be layered with metal foil and cured using heat and pressure in a press for 1 to 20 hours, which poses problems in terms of productivity, mass production, and cost. Furthermore, due to its high hygroscopicity, it is necessary to dehydrate it under heat and reduced pressure before the soldering process.

From the above, the present invention does not have these drawbacks (problems) and not only has excellent flexibility by a simple method, but also has good heat resistance and repeated bendability. The object of the present invention is to obtain a flexible printed circuit board with excellent properties.

According to the fortune telling and the present invention, these problems can be solved by (A) (1
) r Consisting of at least ethylene and at least one type of unit selected from the group consisting of carboxylic acid units, dicarboxylic acid units, their anhydride units, and Hafester units, and the content of ethylene units is 30 to 99.5% by weight
[hereinafter referred to as "ethylene copolymer (A)"] 1 to 99% by weight and (2)
"Contains at least ethylene units and at least one type of unit selected from the group consisting of amino units and glycidyl units, and has an ethylene unit content of 30 to 98.
5% by weight of an ethylene-based copolymer" [hereinafter referred to as "ethylene-based copolymer (B)"] 99 to 1% by weight of a crosslinked mixture, or the crosslinked product has a thermal conductivity of 1
0-3 cal/”O・sec, and electrical resistance is 1
A flexible printed circuit board comprising a resin layer having a thickness of 3 to 4000 microns filled with at most 70% by volume of an inorganic filler of 0.010 Ω·C11 or more, and (B) a conductive metal layer.

It can be solved by The present invention will be explained in detail below.

(A) Ethylene copolymer (A) The ethylene copolymer (A) used in the present invention contains at least ethylene units and a group consisting of carboxylic acid units, dicarboxylic acid units, anhydride units thereof, and halfester units thereof. It is an ethylene copolymer containing 30 to 89.5% by weight of the ethylene units.

This ethylene copolymer (A) contains at least the second component (
A) Copolymers that can be obtained by copolymerizing the following heptamers, multi-component copolymers of these and other heptamers, and acids in these copolymers. Examples include those obtained by hydrolyzing and/or alcohol modification of anhydride groups.

Representative examples of such monomers include unsaturated monocarboxylic acids with at most 25 carbon atoms such as acrylic acid, methacrylic acid, and ethacrylic acid, as well as maleic anhydride, tetrahydrophthalic anhydride, maleopimaric anhydride,
-methylcyclohexane-4-ene-1,2-fihydrocarboxylic acid and bicyclo(2,2,1)-hebuta-5-
4 carbon atoms such as ene-2,3-dicarboxylic anhydride
-50 unsaturated dicarboxylic acid anhydrides.

Other monomers include unsaturated carbon atoms having at most 30 carbon atoms (preferably 10 or less) such as methyl (meth)acrylate, ethyl (meth)acrylate, hydroxymethyl (meth)acrylate and diethyl fumarate. Mention may be made of carboxylic acid esters and vinyl esters having at most 30 carbon atoms, such as vinyl acetate and vinyl propionate.

Among the above ethylene copolymers (A), copolymers of ethylene and unsaturated dicarboxylic anhydrides or multicomponent copolymers of these and unsaturated dicarboxylic esters and/or vinyl esters are hydrolyzed and The dicarboxylic anhydride units of these copolymers can be converted into dicarboxylic acid units or Hafester units by/or modification with alcohol. In the present invention, an ethylene copolymer (A) obtained by replacing part or all of the unsaturated dicarboxylic anhydride units of the copolymer or multicomponent copolymer with dicarboxylic acid units or halfester units is also preferred. It can be used with

To carry out the hydrolysis, the ethylene copolymer (A
) in the presence of a catalyst (e.g. tertiary amino) in an organic solvent (e.g. toluene) that dissolves the copolymer.
It can be obtained by reacting with water at a temperature of ~100°C for 0.5 to 10 hours (preferably 2 to 8 hours, preferably 3 to 8 hours), followed by neutralization with an acid.

To carry out the alcohol modification, the ethylene copolymer (A) can be obtained by the solution method or crosslink method described below.

The solution method is similar to the case of hydrolysis, in which the reaction is carried out in an organic solvent in the presence or absence of the above-mentioned catalyst (the reaction is slow in its absence).
2 minutes to 5 hours at the reflux temperature of the alcohol used in
Preferably from 2 minutes to 2 hours, preferably from 15 minutes to 1 hour.
time).

On the other hand, in the cross-wire method, tertiary amino and Generally from 0.1 to dicarboxylic acid units in the copolymer.
3.0 times the mole (preferably 1.0 to 2.0 times the mole) of saturated alcohol at a temperature above the melting point of the ethylene copolymer (A) but below the boiling point of the alcohol used,
This is a method in which the reaction is carried out while kneading for several minutes to several tens of minutes (preferably 10 to 30 minutes) using a kneading machine such as a Banbury Mixer 1 extruder that is commonly used in the fields of rubber and synthetic resins. .

The saturated alcohol used in the above modification with alcohol is a linear or branched saturated alcohol having 1 to 12 carbon atoms, and includes methyl alcohol, ethyl alcohol, and -butyl alcohol.

In the case of the above hydrolysis and in the case of modification with alcohol, the conversion rate to dicarboxylic acid and the halfesterization rate are always 0.5 to 100%, and 10.0 to 100%.
Too% is desirable.

The ethylene units in this ethylene copolymer (A) are 30
-99.5% by weight, preferably 30-99.0% by weight, particularly preferably 35-99.0% by weight. Also,
The proportion of carboxylic acid units, their anhydride units and halfester units in the copolymer is 0.1 to 70% by weight in total, preferably 0.5 to 70% by weight, particularly 0.5% by weight. ~60% by weight is preferred.

If an ethylene-based polymer in which the proportion of carboxylic acid units, its anhydride units, and halfester units in this ethylene-based copolymer (A) is 0.1% by weight is used, the ethylene-based copolymer described below When heating and crosslinking the composite (B), not only is the crosslinking incomplete, but also the adhesion between the metal plate and the metal layer described later is poor. On the other hand, 70
Although the characteristics of the present invention can be achieved even if the amount exceeds 70% by weight, it is not necessary from the viewpoint of production and economy.

In addition, when using a multicomponent copolymer containing the unsaturated carboxylic acid ester and/or vinyl ester, the total amount thereof is usually at most 70% by weight, and 6% by weight.
It is preferably 0% by weight or less. If an ethylene copolymer with a copolymerization ratio of unsaturated dicarboxylic acid ester and/or vinyl ester exceeds 70% by weight is used, the softening point of the copolymer will be high and the fluidity will be low at temperatures below 150°C. Not only is this undesirable because of the damage it causes, but it is also undesirable from an economic point of view.

(B) Ethylene copolymer (B) In addition, the ethylene copolymer (B) used in the present invention (
B) consists of at least ethylene units and "at least one type of unit selected from the group consisting of amino units and glycidyl units" [hereinafter referred to as "second component (B)"], and the ethylene units are 30 to 99. It is an ethylene copolymer containing 5% by weight.

This ethylene copolymer (B) is a copolymer obtained by copolymerizing at least ethylene with the following monomers to constitute the second component (B), and a copolymer of these and other monomers. Examples include multicomponent copolymers.

This monomer includes glycidyl alkyl (meth)acrylates represented by the following general formulas [Formula (1) and Formula (II)] (the alkyl group usually has 1 to 25 carbon atoms) and 2 to 25 carbon atoms. α-amino and primary or secondary aminoalkyl (meth)acrylates (alkyl group usually has 1 to 25 carbon atoms).

(Here, R1 is H or methyl group R2 has 1 to 1 carbon atoms.
(2 linear or branched alkyl groups, R3 being vinyl, allyl or methacrylic) Representative examples of this monomer of formula (I) include butene tricarboxylic acid monoglycidyl ester, glycidyl meth Mention may be made of acrylate, glycidyl acrylate, glycidyl methacrylate and itaconic acid glycidyl ester.

Further, examples of the amino unit include allyl amino and aminoethyl (meth)acrylate. Furthermore, representative examples of the hexamer represented by formula (II) include vinyl glycidyl ether, allyl glycidyl ether, and methallyl glycidyl ether.

Moreover, examples of other monomers include the unsaturated carboxylic acid esters and vinyl esters.

The ethylene unit in this ethylene copolymer (B) is 30
-89.5% by weight, preferably 30-99.0% by weight, particularly preferably 35-99.0% by weight. Further, the proportion of amino units and glycidyl units in the copolymer is 0.1 to 70% by weight for the same reason as in the case of the ethylene copolymer (A), and is 0.5 to 70% by weight. is preferred, particularly 0.5 to 60% by weight. Furthermore, when using a multicomponent copolymer containing the unsaturated carboxylic acid ester and/or vinyl ester,
For the same reason as in the case of the ethylene copolymer (A), the total amount thereof is generally at most 70% by weight,
Particularly desirable is 60% by weight or less.

Melt index of the ethylene copolymer (A) and ethylene copolymer (B) (JLJ K-721
(Measured under condition 4 according to 1, hereinafter referred to as "wings, ■") is generally o,oot to tooog/to minutes, preferably 0.05 to 500 g/10 minutes, particularly 0. 1 to 500 g for 710 minutes is suitable. M, 1
．． When these ethylene-based copolymers having a weight ratio of less than 0.01 g/10 minutes are used, it is not only difficult to mix these copolymers uniformly, but also the moldability is poor.

Among these ethylene copolymers, when produced by copolymerization method, the amount is usually 500 to 2500 kg/c.
ethylene and the second component (A) or second component CB) or these and other components in the presence of a fast chain transfer agent (e.g. an organic peroxide) at a temperature of 120 to 260 °C under high pressure of rn' They can be obtained by copolymerizing them, and their production methods are well known. Furthermore, the method of producing the ethylene copolymer (A) by hydrolysis and/or modification with alcohol is also a well-known method.

(C) Production of mixture (1) Mixing ratio In producing the mixture of the present invention, ethylene copolymer (A) and ethylene copolymer (B
) Ethylene copolymer (A) in the total amount (total)
The mixing ratio of the ethylene copolymer (B) is 1 to 89% by weight [that is, the mixing ratio of the ethylene copolymer (B) is 99 to 1% by weight], and the mixing ratio is 5 to 8% by weight.
5% by weight is desirable, and 10 to 80% by weight is particularly preferred. Ethylene copolymer (A) in the total amount of ethylene copolymer (A) and ethylene copolymer (B)
Even if the mixing ratio is less than 1% by weight or more than 98% by weight, the crosslinking of the mixture by the method described later will be insufficient, and for example, the adhesion with the conductive metal layer described later will be poor.

(2) Mixing method This mixture can be produced by uniformly mixing the ethylene copolymer (A) and the ethylene copolymer (B). The mixing method may be tri-blending using a mixer such as a Henschel mixer, which is commonly used in the field of olefin polymers, or melt-kneading using a mixer such as a Banbury, extruder, or roll mill. can give. At this time, a more uniform mixture can be obtained by triblending in advance and melt-kneading the resulting mixture. When melt-kneading, it is necessary that the ethylene copolymer (A) and the ethylene copolymer (B) do not substantially undergo a crosslinking reaction (
If the resulting mixture is crosslinked, it will not only deteriorate the moldability when molding the resulting mixture as described below, but also cause a decrease in the shape of the intended molded product and the heat resistance when crosslinking the molded product. unfavorable for the sake of becoming). Therefore, the melt-kneading temperature is preferably room temperature (20°C) to 150°C, and preferably 140°C or lower, although it depends on the type and viscosity of the ethylene polymer used.

As a guideline for this "substantially no crosslinking", "residual aroma with a diameter of 0.1 micron or more after extraction treatment in boiling toluene for 3 hours" (hereinafter referred to as "extraction residual aroma") is generally 15% by weight. It is preferably at most 10% by weight, most preferably at most 5% by weight.

In producing this mixture, in order to further improve heat dissipation (thermal conductivity) and insulation,
Moreover, by filling the inorganic filler with high thermal conductivity, the effects of the present invention can be further exhibited.

(3) Inorganic filler The thermal conductivity of the inorganic filler is lXl0'cal/''
O・cmφ seconds or more, and the electrical resistance value is 1010Ω
・Any substance with 01 or higher is acceptable, but representative examples include beryllium oxide, boron nitrogen, and magnesium oxide (
magnesia), aminium oxide (alumina), silicon carbide and glass beads. Furthermore, the particle size of the inorganic filler powder is preferably 100 microns or less, particularly preferably 0.1 to 20 microns. If the particle size is less than 0.1 micron,
It is difficult to uniformly disperse it in the resin composition.

On the other hand, if it exceeds 100 microns, the thickness of the resin layer becomes thick and the adhesive strength also decreases, which is not desirable.

The blending ratio of this inorganic filler is at most 70% by volume. If the thickness of this insulating layer is thin (for example, 20 microns or less), the thermal conductivity will improve even if it is not filled (mixed) with an inorganic filler, so there is no need to add it. is limited to applications with low voltage resistance. Generally, the thicker the insulating layer, the better the insulation, but the lower the thermal conductivity, so inorganic fillers are more effective. For these reasons, when the thickness of the insulating layer (resin layer) is in the range of 3 to 30 microns, the blending ratio of the inorganic filler is preferably 50% by volume or less. In addition, when the thickness is in the range of 30 to 4000 microns, 20 to 7
0% by volume is desirable. If the blending ratio of the inorganic filler in this resin layer exceeds 70% by volume, the thermal conductivity of the resin layer will improve, but not only will the adhesion with the conductive metal layer described later decrease, but also the bending This is not preferable because the resin layer (insulating layer) may be destroyed during drawing, resulting in cracking.

(4) Production of thin-walled products To produce thin-walled products from the mixture obtained as described above, the T-Guy film method and inflation method, which are commonly used in the field of thermoplastic resins, are widely used to produce films. It can be obtained by extruding it into a film or sheet using a conventional extruder. At this time, if extrusion is carried out at a high temperature, the ethylene copolymer (A) and the ethylene copolymer (B
) is partially or completely crosslinked and small gel-like particles are generated, making it impossible to obtain a uniformly thin product.

For these reasons, the extrusion temperature is usually 250°C or lower. In particular, it is preferable to carry out the process in the same temperature range as in the case of the above-mentioned melt crosstalk.

In any of the above cases, after producing the thin-walled article, a good thin-walled article can be obtained by rapidly cooling it in a water-cooling roll or a water bath to prevent adhesion between the thin-walled articles or between the thin-walled articles and a take-up roll or the like. The thickness of the thin-walled material thus obtained is between 3 microns and 4000 microns,
5 to 3000 microns are preferred, with 10 to 500 microns particularly preferred.

It is preferable that the thin-walled product obtained in this manner is not crosslinked. That is, the extracted residual aroma is preferably 15% by weight or less, preferably 10% by weight or less, and particularly preferably 5% by weight or less, as described above.

(D) Conductive Metal Layer Methods for obtaining the conductive metal layer of the present invention include a method using a metal foil, a method of vapor depositing metal, a method of electroless plating, and an electroless plating method and an electrolytic plating method as described below. One method is to use them together.

(1) Types of metals Metals include metals such as aluminum, gold, silver, iron, copper, nickel, and platinum, and alloys containing these as main components (50% by weight or more) (for example, stainless steel)
can be given.

(2) Foil The thickness of this metal foil is usually 5 to 500 microns, and 1
0 to 300 microns is preferred, especially 15
~100 microns is preferred. Among the metals, electrolytic copper foil with a thickness of 15 to 50 microns is preferably used.

(3) Vapor deposition As a method for vapor depositing the metal, commonly used vacuum heating vapor deposition such as resistance heating, electron beam heating, induction heating, or thermal radiation heating, or sputtering can be applied. Particularly for fine circuits, platinum and gold are often used, and when forming a circuit by etching after forming a thin film, copper, aluminum, and alloys containing these as main components are preferably used.

The thickness of the deposited conductive thin film can be freely selected depending on the conditions of the equipment used, but is usually from 100 Angstroms to 100 microns, preferably from 100 Angstroms to 20 microns.

Furthermore, copper, nickel,
It is also possible to electroplate a metal such as gold to protect the surface and prevent corrosion, or to apply solder on the conductive path through a solder bath.

A so-called full additive method is also possible in which a circuit is formed by vapor deposition on the inner surface of the through-hole of the metal or alloy plate described above by the vapor deposition carried out in the present invention.

In addition, the conductive metal layer can be manufactured by using an electroless plating method or a combination of an electroless plating method and an electrolytic plating method, which are described in detail in Japanese Patent Application No. 60-9999.

(E) Flexible printed circuit board and method for manufacturing the same The flexible printed circuit board used in the present invention may be composed of the thin material obtained as described above and a conductive metal layer, but it may also be composed of the thin material obtained as described above and a conductive metal layer, but it may also be composed of the thin material obtained as described above and the conductive metal layer. It may also consist of

(1) Other substances Other substances include metal or alloy foil of the conductive metal layer, glass fiber cloth or nonwoven fabric, aramid fiber nonwoven fabric, and heat-resistant thermoplastic resin such as polyamide-imide, polyimide, and polyester. The following films can be mentioned. The thickness of the metal or alloy foil is usually from 5 microns to less than 100 microns, especially from 10 microns to 1
Preferably, the diameter is less than 0.00 microns. Also, the thickness of the glass or aramid fibrous or non-woven fabric is from 5 microns to 2II1 m, especially from 20 microns to 0.
．． 5mm is preferable. Furthermore, the thickness of the film of heat-resistant thermoplastic resin is 3 microns to 1.0 mm, preferably 10 microns to 200 microns.

(2) Manufacture of flexible printed circuit board The flexible printed circuit board of the present invention is produced by subjecting the above-mentioned thin-walled material to heat and pressure treatment as described below, and applying the above-mentioned "vapor deposition, electroless plating or The conductive metal layer may be provided by any method of combining electrolytic plating method and electrolytic plating method [hereinafter referred to as "Method (A)"]. The plate may also be subjected to heat and pressure treatment. Alternatively, at least one other substance may be placed on one or both sides of the thin-walled object, and these materials may be heated and pressurized, and a conductive metal layer may be provided on one side of the resulting crosslinked object by method (A). Place a metal foil on one side of an object and another substance on the other side, or place a metal foil and another substance on one side of a thin object (with the metal foil on the surface) and a metal plate on the other side, and heat and pressurize. It may be processed.

(3) Heat/pressure treatment The thin-walled product obtained as described above exhibits the same behavior as a normal thin-walled product because crosslinking has hardly progressed. It is important to heat and pressurize in the range of ~400°C. Heating temperature is 1
10-20 minutes in the range of 00-160℃, teo-24
By heating and pressurizing for 0.5 to 10 minutes in the range of 0℃ and 0.1 to 5 minutes in the range of 240 to 400℃, a crosslinking reaction (condensation reaction) occurs within the resin, improving adhesiveness and heat resistance. performance is significantly improved. The pressurization conditions are generally 0.1Kg/cm'' (gauge pressure) or higher, and 1
~100 Kg/c is desirable, especially 2-20
Kg/cm' is preferred.

Furthermore, in order to obtain uniform adhesion, a method of applying pressure with a slight load under vacuum and reduced pressure is also used.

Since the thin-walled article obtained by the present invention exhibits thermocompression adhesion (adhesiveness) at a temperature of 100° C. or higher, the effects of the present invention are further enhanced by bonding the metal layer and other substances simultaneously with the crosslinking treatment. That is, ethylene copolymer (A
) and the ethylene copolymer (B) exhibits thermoplasticity at a temperature of 250°C or lower, but when the mixture is heated and pressurized to 100°C or higher, it undergoes a crosslinking reaction and exhibits adhesive properties at the same time. .

When air is involved between a metal foil or other material and a thin object, it is necessary to use a hot press, hot roll, etc. to bond the thin material. A product with sufficient adhesive properties can be obtained even if the heating temperature is 300°C or lower, but if heat resistance is required, the heating temperature should be as high as possible (usually 200 to 300°C).
It is preferable to press-bond the material.

The extracted residual aroma of the thin-walled product heated and pressurized in this manner is usually at least 80%, preferably 70% or more, and particularly preferably 75% or less.

A typical flexible printed circuit board of the present invention will be briefly explained with reference to the drawings.

1-1 to 1-4, and 2-1 and 2-2 are partially enlarged cross-sectional views of typical flexible printed circuit boards. FIG. 1-1 is a partially enlarged sectional view of a laminated resin layer (thin material) 2 and conductive metal layer 1 according to the present invention. Moreover, FIG. 1-2 is a partially enlarged sectional view when a conductive metal layer l and a film 3 of heat-resistant thermoplastic resin such as polyester or polyimide are laminated with a resin layer 2 of the present invention interposed therebetween. 1-3 are similarly enlarged partial cross-sectional views of a case where a conductive metal layer 1 and a metal foil 4 are laminated with the resin layer 2 of the present invention interposed therebetween. Furthermore, FIG. 1-4 shows a case where the resin layer 2 of the present invention is present on both sides of the non-woven cloth 5 made of glass or aramid fibers, and a conductive metal layer l is laminated on either layer of the resin layer 2. FIG.

FIGS. 2-1 and 2-2 are partially enlarged sectional views when both surface layers are made of conductive metal. In FIG. 2-1, the core layer is a film 3 made of the heat-resistant thermoplastic resin,
It is a partially enlarged cross-sectional view when the resin layer 2 of the present invention exists as an intermediate layer on both sides of this film, and the conductive metal layer 1 is laminated as a surface layer on each other side of this intermediate layer. In addition, in FIG. 2-2, the resin layer 2 of the present invention is present as an intermediate layer on both sides of the nonwoven fabric 5 (as a core layer), and the other surfaces of each of the intermediate layers are shown in FIG. FIG. 2 is a partially enlarged cross-sectional view of a case in which a conductive metal layer 1 is laminated thereon.

The present invention will now be explained in more detail with reference to Examples.

In addition, in the examples and comparative examples, the peel strength is JIS
In accordance with C-13481, 3111 m of the conductive metal layer (copper foil, etc.) was left, the remainder was removed by etching, and the conductive metal layer was peeled off at 80 degrees (tensile speed 50+nm).
/min). In addition, the heat resistance test was conducted using lead/tin = 90710 (
It was evaluated by floating it for 20 seconds in a solder bath (weight ratio). The evaluation is shown in Table 1 as follows.

0: No change in the original form X: Peeling, cracking, between layers with base insulating material and between copper circuit
Deformations such as cracking and separation were observed. The mixtures of ethylene copolymers (A) and ethylene copolymers (B) used in Examples and Comparative Examples are shown below.

Ethylene copolymer (A) and ethylene copolymer (B)
As a mixture with M, 1. Ethylene-acrylic acid copolymer (density 0.!115
4g/crrr, acrylic acid copolymerization ratio 20% by weight,
rEAAJ) and ethylene-methyl methacrylate-glycidyl methacrylate terpolymer (copolymerization ratio of methyl methacrylate 18.8% by weight, copolymerization ratio of glycidyl methacrylate 12.7% by weight,
(hereinafter referred to as rGMAJ) [mixing ratio: 30
: 70 (weight ratio), hereinafter referred to as "mixture (I)"], 200 g 710 minutes of ethylene-
Methacrylic acid copolymer (density 0.950 g/cm''
, methacrylic acid copolymerization ratio 25% by weight) and the GMA
(mixture ratio 50:50 (weight ratio),
(hereinafter referred to as "mixture (■)"), M, 1. is 212
g/10 minutes of ethylene-ethyl acrylate-maleic anhydride terpolymer (ethyl acrylate copolymerization ratio 30.7% by weight, maleic anhydride copolymerization ratio 1
．． 7% by weight) and the above-mentioned GMA [mixing ratio 70
A terpolymer of ethylene-methyl methacrylate-maleic anhydride (copolymerization of methyl methacrylate) having a weight ratio of 105 g/10 min. Proportion 20.
5% by weight, copolymerization ratio of maleic anhydride 3.1% by weight
) and a terpolymer of ethylene-methyl methacrylate-glycidyl methacrylate (copolymerization ratio of methyl methacrylate: 18.8% by weight, copolymerization ratio of glycidyl methacrylate: 8.8% by weight) [Mixing ratio: 5
0:50 (weight ratio), hereinafter referred to as "mixture (IV)" was used. These mixtures were prepared by mixing each copolymer or terpolymer or these copolymers using a Henschel mixer. Produced by triblending for 5 minutes.

Mixture (I) to IV) obtained as described above
and a mixture of these and FAA and GMA respectively in an extruder equipped with a T-die (diameter 40mm, die width
3Qc+s, rotational speed 85 revolutions/min) under the conditions of the cylinder temperature shown in Table 1, and the thickness shown in Table 2 was molded. The extracted residual aroma of the obtained film was measured.

In both cases it was 0%.

(Margin below) Table 1 Examples 1-10, Comparative Examples 1-3 The top surface of each film thus obtained had a thickness of 35 mm.
Micron electrolytic copper foil, stacked with various sheets, foils or nonwoven fabrics with the thickness shown in Table 2 on the bottom surface, and heated at 300℃ for 1
20Kg/cm' each using 0 minute heat press machine
(gauge pressure) to produce a copper-clad substrate.

The obtained board was subjected to UL, 79B (printed wiring board)7.
Etching (ammonium persulfate etching) was performed on the test pattern shown in FIG.

The obtained board was subjected to a solder heat resistance test and a copper foil peeling test. The results obtained are shown in Table 2. A film manufactured by Ontaisha was used as the polyester film, and a film manufactured by Toshisha (trade name: Kapton) was used as the polyimide film.

(Margin below) In addition, Example 5 is a flexible printed circuit board whose partially enlarged sectional view is shown in FIGS. 1-4, and the thickness of each resin layer 2 in this drawing is 10 microns (the The thickness is 80 microns). Further, Example 6 is a flexible printed circuit board whose partially enlarged cross-sectional view is shown in FIGS. 60 microns).

Example 11 Instead of the resin layer which was a crosslinked product of mixture (1) used in Example 1, 60 parts by volume of a crosslinked product of mixture CI) and 4
0 parts by volume of low soda alumina powder (A1203 content 89.8% by weight, true density 3.91 g/cm
A copper foil board was manufactured by laminating electrolytic copper foil in the same manner as in Example 1, except that a copper foil with an average particle size of 0.6 microns was used.The peel strength was 2.8 kg/am. A heat resistance test was conducted, but the original shape remained and no deformation could be observed.

From the results of the above examples and comparative examples, it is clear that the flexible printed circuit board of the present invention not only has excellent heat resistance, but also has high adhesive strength with the conductive circuit part, so it can be used for high density, that is, flexible printed circuit boards with thin circuits. This shows that it is possible to manufacture printed circuit boards, and Surf Ace
It is obvious that it can be used extensively in the future as a substrate for mounts and the like.

[11go] The flexible printed wiring board obtained by the present invention exhibits the following effects (characteristics) including its manufacturing process.

(1) Since no thermosetting resin adhesive such as epoxy resin is used, the adhesion process is not only omitted, but also
There is no complication (such as drying) associated with the process.

(2) Excellent electrical properties (for example, insulation, withstand voltage, and dielectric loss tangent performance).

(3) It has good heat resistance and can not only withstand temperatures of 250°C or higher, but also can be used to bond metals such as copper foil without using the adhesives mentioned above by applying pressure at temperatures of 100°C or higher. Good adhesion to foils or plates can be achieved.

(4) It has excellent flexibility.

(5) In particular, the flexible printed circuit board of the present invention is characterized by the fact that the crosslinking process is performed at a relatively high temperature (200°C or higher) as described below, compared to the case where conventionally used polyimide films and polyester films are used alone. Not only does it have excellent dimensional stability, but it also has good adhesion even at high temperatures, has good adhesion, and has very few residual voids.

As described above, the printed circuit board of the present invention not only has good electrical properties such as insulation resistance and dielectric constant, but also has good dimensional stability, heat resistance, chemical resistance, moisture resistance, etc., and is also flexible. The bending durability of the substrate exhibits flexibility that has not been previously available.

The flexible printed circuit board of the present invention can be widely used as a flexible circuit board since it exhibits the above effects.

Specifically, the following can be mentioned.

(1) Printed circuit boards for internal wiring of home appliances such as washing machines, refrigerators, microwave ovens, television receivers, video cameras, cassette recorders with radios, and speaker units.

(2) Printed circuit boards for wiring automobile parts (e.g., instrument panels, lights, wipers, doors); (3) OA equipment (e.g., word processors, printers, wet or dry copying machines, facsimiles,
Computers, desktop calculators), printed circuit boards for internal wiring of cameras, telephone exchanges, telephones, fire alarms, watches, etc., surface mount printed circuit boards, etc.

[Brief explanation of drawings]

FIG. 1-1 is a partially enlarged sectional view of a flexible printed circuit board comprising a resin layer 2 and a conductive metal layer 1 according to the present invention. Also, Figures 1-2 to 1-4 and 2-1
2 and 2-2 are partially enlarged cross-sectional views of a flexible printed circuit board comprising a resin layer 2, a conductive metal layer 1, and other substances according to the present invention. 1... Conductive metal layer 2... Resin layer 3 of the present invention... Heat resistant thermoplastic resin film 4...
...metal foil

Claims (1)

[Scope of Claims] (A) (1) Consists of at least ethylene and at least one unit selected from the group consisting of carboxylic acid units, dicarboxylic acid units, anhydride units thereof, and half ester units, and contains ethylene units. 1 to 99% by weight of an ethylene copolymer in an amount of 30 to 99.5% by weight; and (2) at least ethylene units and at least one unit selected from the group consisting of amino units and glycidyl units; Ethylene unit content is 30-9
99-1% by weight of ethylene-based copolymer which is 9.5% by weight
A crosslinked product of the mixture or a thermal conductivity of 1
A resin layer with a thickness of 3 to 4000 microns filled with at most 70% by volume of an inorganic filler with an electrical resistance of 10^-^3 cal/℃・sec or more and an electrical resistance of 10^1^0 Ω・cm or more. and (B) a flexible printed circuit board formed by laminating at least a conductive metal layer.