JPH0444287A - Flexible printed board - Google Patents

Abstract

PURPOSE:To obtain excellent adhesive properties, mechanical characteristics and heat resistance by laminating a layer of crosslinked compound of composition made of phthalate compound and special two types of ethylene copolymers I, II and a metal foil. CONSTITUTION:Phthalate compound includes diarylorthophthalate, diarylisophthalate, etc. The ratio of composition occupying in the composition is 1 - 99 wt.%. On the other hand, ethylene copolymer I is copolymer of ethylene and unsaturated carboxylic acid, and polyaddition copolymer of them and unsaturated carboxylic acid ester. Further, ethylene copolymer II is ethylene unsaturated monomer containing ethylene and epoxy group, or copolymer of it and unsaturated carboxylic acid ester or vinyl ester. The ratio of carboxyl group in the copolymer I or epoxy group of the copolymer I to one mole of anhydride group is 0.1 - 20 moles. They are kneaded in melted state to manufacture further uniform mixture. When a metal foil and composition are thermally press-bonded by the so-called dry laminating method, it is necessary to substantially crosslink the composition or a thin compound.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a flexible printed circuit board with excellent heat resistance, adhesiveness, and mechanical properties (particularly toughness and rigidity). More specifically, a layer of a crosslinked composition of a phthalate compound and two specific ethylene polymers and a metal foil are laminated, and the layer has heat resistance, adhesion and mechanical properties (especially toughness, This invention relates to a flexible printed circuit board with excellent rigidity.

[Conventional technology]

Flexible printed circuit boards have the advantage of being lightweight, thin, and flexible, allowing for three-dimensional mounting.
It is used in electronic equipment, industrial equipment, and computer memory.

Conventionally, the insulating base material for flexible printed circuit boards is
Polyimide resin (PI), polyamide resin (PA)
, polyethylene terephthalate resin (PETP), and other films are known.

Furthermore, flexible printed circuit boards made of glass cloth or glass nonwoven fabric impregnated with epoxy resin are also well known.

Further, (A) an ethylene copolymer of at least ethylene and an α,β-unsaturated dicarboxylic acid and/or an anhydride thereof; and (B) an ethylene copolymer of at least ethylene and an ethylenically unsaturated monomer containing an epoxy group. A flexible printed circuit board in which a layer of a crosslinked copolymer composition and at least a metal foil is laminated has also been proposed (JP-A-62-11289 and JP-A-82-18).
No. 3592 and Japanese Patent Application No. 1983-201578).

[Problem to be solved by the invention]

Among the resins mentioned above, PI and PA have high water absorption, have poor dimensional stability, and are expensive. On the other hand, P
ETP has poor heat resistance, and has the drawback of being significantly degraded in solder heat resistance, which poses a practical problem.

Moreover, the epoxy resin impregnated with glass cloth has difficulty in flexibility, and in the MIT type folding test measured according to JIS P8115, it breaks in Figures 2 to 3, which is a practical problem.

Furthermore, when using a crosslinked composition of the above two types of ethylene copolymers, although the heat resistance is sufficient, there is a problem with mechanical strength (especially rigidity), making it unusable. .

From the above, the present invention does not have these drawbacks (problems), that is, it not only has excellent adhesive properties, but also has good mechanical properties (especially toughness and rigidity), and has excellent heat resistance. The purpose of this invention is to obtain an excellent flexible printed circuit board.

[Means and effects for solving the problems] According to the present invention, these problems are solved by: (A) a phthalate compound having at least two reactive allyl groups in one molecule or a polymer thereof; ) Copolymers of ethylene and α, β-unsaturated dicarboxylic acids and/or their anhydrides, or these and unsaturated carboxylic esters [hereinafter referred to as “ethylene copolymers (I)”] and (C) A composition consisting of an ethylenically unsaturated monomer containing ethylene and an epoxy group, or a copolymer of these with an unsaturated carboxylic acid ester and/or vinyl ester [hereinafter referred to as [ethylene copolymer (■)]] The composition ratio of the phthalate compound and/or its polymer in the composition is 1 to 99%.
% by weight, and the ratio of epoxy groups in the ethylene copolymer (II) to 1 mole of carboxyl groups and/or their anhydrides in the ethylene copolymer (I) is 0.
The problem can be solved by a flexible printed circuit board formed by laminating a substantially crosslinked layer of a resin material of 1 to 20 mol % and a metal foil. The present invention will be explained in detail below.

(A) Phthalate compounds and polymers thereof Among the phthalate compounds and polymers thereof used in the present invention, phthalate compounds include diallyl orthophthalate (DAP), diallyl isophthalate (DA I
P) and diallyl terephthalate (DATP).

In addition, the polymer includes a homopolymer obtained by polymerizing only one type of these phthalate compounds, and a copolymer obtained by copolymerizing at least two types of these phthalate compounds. It is.

All of these polymers can be produced by either a solution polymerization method or a bulk polymerization method. Incidentally, as the polymerization catalyst, a radical generator described below is preferably used.

The polymer is substantially liquid at room temperature, and its molecular weight is usually 30,000 or less, particularly 3.000 to 2.
A value of 0.000 is preferred.

(B) Ethylene copolymer (I) In addition, the ethylene copolymer (I) used in the present invention
I) is a copolymer of ethylene and "α,β-unsaturated dicarboxylic acid and/or its anhydride" [hereinafter referred to as "unsaturated dicarboxylic acid component"], and these (i.e.
It is a multi-component copolymer of ethylene, an unsaturated dicarboxylic acid component) and an unsaturated carboxylic acid ester.

Among the unsaturated dicarboxylic acid components, the α,β-unsaturated dicarboxylic acid usually has at most 20 carbon atoms, and preferably 4 to 16 carbon atoms. Typical examples of the dicarboxylic acids include maleic acid, fumaric acid, itaconic acid, citraconic acid, and 3,6-endomethylene-2,3,4,6-
Examples include titrahydrosis-phthalic acid.

Among the unsaturated dicarboxylic acid components of the present invention, the α, β-
Anhydrides of unsaturated dicarboxylic acids are preferred, with maleic anhydride being particularly preferred.

Additionally, the number of carbon atoms in unsaturated carboxylic acid esters is generally 4.
~40 pieces, preferably 4 to 30 pieces, and particularly preferably 4 to 20 pieces.

Representative examples of suitable unsaturated carboxylic acid esters include methyl (meth)acrylate, ethyl (meth)acrylate, butyl acrylate, and 2-methylhexyl acrylate, with methyl methacrylate being most preferred.

The copolymerization ratio of the unsaturated dicarboxylic acid component of the ethylene copolymer (I) of the present invention is usually 0.1 to 20 mol%,
The content is preferably 0.1 to 15 mol%, particularly 0.1 to 10 mol%. If an ethylene copolymer (I) with a copolymerization ratio of unsaturated dicarboxylic acid component of less than 0.1 mol % is used, the crosslinking density with the ethylene copolymer (If) described later will be low, resulting in a poor composition. The heat resistance of the product becomes insufficient.

On the other hand, if an ethylene copolymer (I) exceeding 20 mol% is used, it will be difficult to produce the polymer and stable production will be difficult, and even if it is obtained, acid anhydride Absorption of moisture from the air by chemical substances increases,
This is undesirable because foaming occurs when the composition is manufactured by kneading or the like, and when the resulting product is molded. Also,
The copolymerization ratio of the unsaturated carboxylic acid ester is generally at most 50 mol%, preferably 45 mol% or less,
Particularly suitable is 40 mol% or less. If the ethylene copolymer (I) in which the copolymerization ratio of unsaturated carboxylic acid ester exceeds 50 mol % is used, the characteristics of the present invention can be expressed, but it is not preferable in terms of production and economy.

The melt flow index of the ethylene copolymer (I) (according to JIS K7210, the conditions in Table 1 are 4)
Measured at rM, 1. J] is generally 0.5 to 500 g/10 minutes, preferably 1.0 to 500 g/10 minutes, especially 5
．． 0 to 400 g/10 minutes is suitable.

(C) Ethylene copolymer (II) Furthermore, the ethylene copolymer (II) used in the present invention is an ethylenically unsaturated monomer containing ethylene and an epoxy group, or a combination of these and the unsaturated carboxylic acid ester. and/or a copolymer with vinyl ester.

The general formula of a typical example of the ethylenically unsaturated monomer containing an epoxy group, which is a comonomer component of the ethylene copolymer (I [)], is represented by the following formula [formula (I) and formula (II)]: 0-CH2-CCH2 (II) Representative examples of the unsaturated monomer include glycidyl (meth)crylate, allyl glycidyl ether, and methacryl glycidyl ether. Further, as a representative example of the vinyl ester which is a comonomer component, it is generally preferable that the number of carbon atoms is at most 20, particularly 4 to 18 carbon atoms.
preferably. Suitable vinyl esters include vinyl acetate, vinyl propionate, and vinyl butyrate, with vinyl acetate being most suitable.

The copolymerization ratio of the ethylenically unsaturated monomer containing an epoxy group in the ethylene copolymer (If) of the present invention is usually 0.
．． The amount is 2 to 20 mol%, preferably 0.2 to 15 mol%, and particularly preferably 0.5 to 15 mol%. If the copolymerization ratio of the epoxy group-containing ethylenically unsaturated monomer in the copolymer is less than 0.2 mol%, the crosslinking density with the above-mentioned ethylene copolymer (I) will be low, resulting in a poor composition. The heat resistance of the product becomes insufficient. On the other hand, if it exceeds 20 mol %, although the characteristics of the present invention are exhibited, it is difficult to produce the copolymer and there are economical problems. In addition, the copolymerization ratio of unsaturated carboxylic acid ester and vinyl ester is generally at most 50 mol% as their total amount, and 45
It is preferably mol% or less, particularly 40 mol% or less. When the copolymerization ratio of unsaturated carboxylic acid ester and vinyl ester exceeds 50 mol% in total, production becomes difficult.

M and I of the ethylene copolymer (II) are usually 0.5 to 0.0 for the same reason as the above-mentioned ethylene copolymer (I).
50 [1 g/10 minutes, J, 0 to 500 g/10 min is desirable, and 5.0 to 400 g/10 min is particularly preferred.

In producing the resin composition of the present invention, a radical initiator described below may be further blended in order to increase the crosslinking density and improve the heat resistance and mechanical properties of the resulting composition.

(D) Radical initiator The radical initiator is generally a radical polymerization initiator,
Furthermore, it is widely used as a crosslinking agent for rubbers and polymers, and organic peroxides are preferably used. Among these, those with a half-life of 1 minute of 120°C or more are preferred, and those with a half-life of HO to 200°C are particularly preferred. Representative examples of preferred organic peroxides include diacyl peroxides such as benzoyl peroxide, ketone peroxides such as 1,1-bis-tertiary-butylperoxy-3,3,5-trimethylcyclohexane, and dicumyl. Dialkyl peroxides such as peroxide, hydroperoxides such as 2,5-dimethylhexane-2,5-hydroperoxide and 2,5-dimethyl-2,5-
Polyesters such as dibenzoyl peroxyhexane are used.

(E) Composition ratio In the composition of the present invention, the composition ratio of the phthalate compound and/or its polymer in the composition is 1 to 9.
9% by weight, preferably 2 to 98% by weight, particularly preferably 5 to 95% by weight. The composition ratio of the phthalate compound and/or its polymer in the composition is 1
If the amount is less than % by weight, a composition with sufficient rigidity cannot be obtained. On the other hand, if it exceeds 99% by weight, a composition with satisfactory adhesiveness and flexibility cannot be obtained.

Further, the ratio of epoxy groups in the ethylene copolymer (U) to 1 mole of carboxyl groups and/or its anhydride groups in the ethylene copolymer (I) is 0.1 to 20 moles, and 0.2 to 15 moles. The amount is preferably mol, particularly 0.5 to 2 mol. Crosslinking of the composition obtained even if the ratio of the epoxy groups of the ethylene copolymer (II) to 1 mole of carboxyl groups and/or its anhydride groups of the ethylene copolymer (II) is less than the lower limit or exceeds the upper limit. A composition with low density and sufficient heat resistance cannot be obtained.

(F) Production of Composition To produce the composition of the present invention, a phthalate compound and/or a polymer thereof, an ethylene copolymer (I), an ethylene copolymer, or a radical initiator is combined with the phthalate compound and/or its polymer. Just mix it evenly. At this time, some of the composition components are mixed in advance [for example, ethylene copolymer (I) and ethylene copolymer (II) are mixed]
, the remaining composition components may be mixed into this mixture.

The mixing method for producing the composition of the present invention may be tri-blending using a mixer such as a Henschel mixer, which is commonly used in the field of polyolefin resins, a Banbury mixer, a kneader 5 single-screw mixer, etc. Ethylene copolymer (I), ethylene copolymer (I
I) and the phthalate compound and/or its polymer can be mixed at a temperature at which both are melted. Furthermore, by using a static mixer or the like at the tip of the extruder, a more homogeneous mixture can be produced. Furthermore, a more homogeneous mixture can be produced by triblending in advance and kneading the resulting mixture in a molten state.

In addition, when crosslinking in a molten state, it is necessary to conduct the crosslinking under conditions in which each component is not substantially crosslinked. If crosslinking occurs during kneading, it will not be possible to obtain a uniform composition, which will not only impair moldability when molding the composition, but also cause crosslinking to occur in the shape of the desired molded product and the molded product. This is not preferable because it lowers the heat resistance etc. Therefore, when mixing in a molten state, it is necessary to mix at 25°C (room temperature), depending on the viscosity of each component.
It is preferable to carry out at a temperature range of 150°C to 150°C,
A temperature of 25°C to 140°C is particularly suitable.

Further, if the total viscosity of each component differs greatly, it is difficult to obtain a uniform composition. Therefore, it is necessary to select a material whose viscosity ratio is as close to 1 as possible.

Furthermore, additives such as antioxidants, ultraviolet absorbers, antistatic agents, electrical property improvers, flame retardants, processability improvers, pigments, talc, mica, calcium carbonate, barium sulfate, silicon An appropriate amount of an inorganic filler such as calcium acid may also be blended.

(G) Metal foil The metal foil used in the present invention may be any metal foil that can be a conductor, such as copper (including electrolytic copper) foil, aluminum or aluminum-based alloy foil, stainless steel foil, etc. The thickness of the metal foil is generally 5 to 200 mm (preferably 5 to 100 mm).

()l) Flexible printed circuit board and method for manufacturing the same The flexible printed circuit board of the present invention may be produced by press-molding the metal foil and the composition or a thin material thereof, or may be formed by forming a thin material in advance and bonding it under heat and pressure. . moreover,
The metal foil and the composition may be heat-pressed by a so-called dry lamination method.

It is necessary that the thin-walled material be essentially non-crosslinked.

As a guideline for non-crosslinking, the "xylene insoluble matter after 8 hours in boiling xylene" (hereinafter referred to as "extraction residue") is usually less than 20% (preferably less than 15%, preferably less than 1%).
0% or less).

Manufacturing the flexible printed circuit boards of the present invention requires that the composition or thin-walled material be substantially crosslinked.

Common crosslinking methods include heating methods and electron beam irradiation methods.

When producing by the heating method, the heating temperature varies depending on the type and composition ratio of the ethylene copolymer (I) used, the ethylene copolymer (II) and the phthalate compound, and whether or not a radical initiator is used. is 100
10 to 20 minutes in the range of ~160℃, 160℃ to 24
In the range of 0°C, the time is generally 0.5 to 10 minutes, and in the range of I0°C, it is generally 0.1 to 5 minutes. may be temporarily bonded (usually at 120 to 250° C.) and then heated in the above temperature range to bond and crosslink.

The extraction residue of the thin-walled material crosslinked in this way is at least 70%, preferably 75% or more, especially 80%.
% or more is suitable.

The thickness of the thin material in the flexible printed circuit board is usually 10 to 250 m (preferably 10 to 200 m) from the viewpoint of handling the resulting board.

[Examples and comparative examples]

Hereinafter, the present invention will be explained in more detail with reference to Examples.

In addition, in the examples and comparative examples, the heat resistance is 300°C.
Sample (thickness 100m, 2.5X2.
5c+++) was placed thereon, and the deformation after 3 minutes was observed with the naked eye. Moreover, the adhesiveness was shown by the T-peel strength (JIS K6654) of the resulting flexible printed circuit board.

The physical properties, manufacturing method, etc. of the ethylene copolymer (I) and ethylene copolymer (II) used in the Examples and Comparative Examples are shown below.

[(^) Ethylene copolymer (I)]

The ethylene copolymer (I) was obtained by copolymerizing ethylene, maleic anhydride, and methyl methacrylate using high-pressure low-density polyethylene manufacturing equipment, and the copolymerization ratio of maleic anhydride was 3.0. mole%
and the copolymerization ratio of methyl methacrylate is 37.0
mol %, and M, 1. of ethylene-maleic anhydride-methyl methacrylate terpolymer (hereinafter referred to as rP E (A) J) having a ratio of 2.5 g/10 min, maleic anhydride obtained by copolymerizing in the same manner. The copolymerization ratio is 0.8 mol%, the copolymerization ratio of methyl methacrylate is 2.5 mol%, and M, I,
Ethylene-maleic anhydride-methyl methacrylate terpolymer [hereinafter referred to as r P
E (B)J] and the copolymerization ratio of acrylic acid produced by copolymerizing ethylene and acrylic acid in the same manner is 3.4 mol%, and M, I,
An ethylene-acrylic acid copolymer C (hereinafter referred to as "rPE") having a weight ratio of 8.2 g/10 minutes was used.

[(B) Ethylene copolymer (■)]

In addition, as the ethylene copolymer (II), the copolymerization ratio of ethylene and glycidyl methacrylate or glycidyl methacrylate obtained by copolymerizing these and vinyl acetate using high-pressure low density polyethylene production equipment is 2. .5 mol%, and M, 1.
Ethylene-glycidyl methacrylate copolymer whose
and the copolymerization ratio of glycidyl methacrylate is 2.
3 mol%, the copolymerization ratio of vinyl acetate is 1.9 mol%, and M, I is 6.8 g/lo min [hereinafter referred to as rPE (2) J] was used.

[(C) Phthalate compound]

Further, as a phthalate compound, a polymer substance of diallyl phthalate (monomer content: 3.5% by weight, hereinafter referred to as rDAPJ) having a viscosity of 90 cps at 20° C. was used.

Examples 1 to 10, Comparative Examples 1 to 7 Ethylene copolymer (I) and ethylene copolymer (I) whose types and amounts are shown in Table 1
I), a phthalate compound (DAP) whose amount is shown in Table 1, and 2.0 parts by weight of dicumyl peroxide (as a radical initiator) were triblended for 5 minutes using a Henschel mixer. Each of the obtained mixtures was melt-kneaded using a Brabender at 100"c at 40 rpm for 10 minutes to produce a composition. Note that the ethylene copolymer (
Table 1 shows the ratio of carboxyl groups or acid anhydride groups in the ethylene copolymer (I) to 1 mole of epoxy 1X in If).

Using a press machine, the obtained composition was coated with electrolytic copper (thickness: 35 mm).
6) 200℃l: 100kg/cj at OL'
(gauge pressure) to create a flexible printed circuit board with a crosslinked thickness of 1 (I0-), and measured heat resistance, adhesion, tensile strength at break, and RFII. Furthermore, the extraction residue was measured.The results are shown in Table 2.

Table (Part 1) Table (Part 2) The above results, especially from Table 2, show that even when the flexible printed circuit board shown in the comparative example has a strong mechanical strength of 1, the adhesion and heat resistance (I) It is clear that the deviation is inferior and impractical.

〔Effect of the invention〕

The flexible printed circuit board of the present invention exhibits the following effects.

(I) Excellent heat resistance.

(2) Good adhesion to metals.

(3) Excellent mechanical strength (particularly toughness and rigidity).

Claims (1)

[Scope of Claims] (A) A phthalate compound having at least two reactive allyl groups in one molecule and/or a polymer thereof; (B) Ethylene and an α,β-unsaturated dicarboxylic acid and/or a polymer thereof;
or their anhydrides, or copolymers of these with unsaturated carboxylic esters (I) and (C) ethylenically unsaturated monomers containing ethylene and epoxy groups, or these with unsaturated carboxylic esters and/or vinyl It is a composition consisting of a copolymer (II) with an ester, and the composition ratio of the phthalate compound and/or its polymer is 1 to 99%.
% by weight, and the copolymer (I) per mole of carboxyl group and/or its anhydride in the copolymer (I).
II) A flexible printed circuit board comprising a substantially crosslinked layer of a resin composition in which the ratio of epoxy groups in II) is 0.1 to 20 moles and a metal foil.