JPS62218423A - Flame-retarding flexible circuit board - Google Patents

Abstract

PURPOSE:To obtain the titled board being excellent in adhesiveness, soldering heat resistance, chemical resistance, etc., having uniform stable flame retardancy and being capable of being produced by a simplified process, by bonding a flame-retarding plastic film to a metal foil with a specified flame-retarding adhesive. CONSTITUTION:A flame-retarding polyester resin (a) comprising an acid component comprising 20-50mol% P-containing acid component of the formula (wherein R is a 1-6C alkylene, a 6-12C arylene or R1 is a 1-6C alkyl or a 6-12C aryl) and a P-free acid component such as isophthalic acid or adipic acid and a glycol component (e.g., ethylene glycol) is mixed with an epoxy resin (b) comprising 30-80wt% halogen-containing epoxy resin and a halogen- free epoxy resin or the like and a curing agent (c) such as an acid anhydride to obtain a flame-retarding adhesive (B). A solution of component B in an organic solvent is applied to the surface of a flame-retarding plastic film (A) (e.g., polyimide film) by, for example, rolling and dried. A metal foil (C) (e.g., copper foil) is bonded to the film.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a flame-retardant flexible circuit board.

[Prior Art] Flame-retardant flexible circuit boards include those in which a halogen-containing compound and a flame retardant-free (e.g., 5b203, 80(OH)3) are blended in the adhesive layer (e.g., 5B203, 80(OH)3).
3039) is well known.

[Problems to be Solved by the Invention] However, when a halogen-containing compound or an inorganic flame retardant is added, although flame retardancy is imparted, on the other hand, the adhesion to metal foils and substrates, soldering heat resistance, chemical resistance, etc. performance may deteriorate. Further, since advanced technology is required to uniformly disperse the inorganic flame retardant in the adhesive layer, non-uniformity in dispersion is likely to occur.

Therefore, they have the disadvantage of varying flame retardancy.

The present invention improves these problems and provides a flexible printed circuit board that has uniform and stable flame retardancy without deteriorating the physical properties required for flexible printed circuit boards, such as adhesiveness, soldering heat resistance, and chemical resistance. The purpose is to provide circuit boards.

Means for Solving Problem U] The present invention provides a flame-retardant flexible circuit board formed by laminating a flame-retardant plastic film and a metal foil with a flame-retardant adhesive, in which the flame-retardant adhesive has a chain shape. In the molecule, the formula (wherein R is an alkylene group having 1 to 6 carbon atoms or 6 carbon atoms)
-12 arylene groups, R1 is an alkyl group having 1 to 6 carbon atoms or an aryl group having 6 to 12 carbon atoms) in an amount of 20 to 50 mol% of the total acid components in the polyester. The present invention relates to a flame-retardant flexible circuit board characterized by comprising a polyester resin (A), an epoxy resin (B), and a curing agent (C).

The flame-retardant plastic film in the present invention includes:
Examples include polyimide, polyamideimide, Teflon, polyphenylene sulfide, and general flame retardant films coated or coated with a flame retardant, but polyimide is particularly preferred from the standpoint of heat resistance.

Copper foil, aluminum foil, and the like are known as metal foils, and copper foil is particularly preferred.

In the flame-retardant adhesive of the present invention, the flame-retardant polyester resin is mainly composed of an acid component containing phosphorus, an acid component not containing phosphorus, and a gelcol component.

The acid component containing phosphorus needs to be present in an amount of 20 to 50 mol % of the total acid component in the polyester. If the phosphorus-containing acid component is less than 20 mol%, desired flame retardancy may not be obtained.

Moreover, when it exceeds 50 mol%, there is a drawback that it is difficult to obtain a polymer due to low reactivity. More preferably 25~
It is 45 mol%, more preferably 30 to 40 mol%.

In addition, its structure is expressed in a chain molecule by the formula % ((wherein R is an alkylene group having 1 to 6 carbon atoms or an arylene group having 6 to 12 carbon atoms, and R1 is an arylene group having 1 to 6 carbon atoms. It is an alkyl group or an aryl group having 6 to 12 carbon atoms).Specifically, it is a phosphorus compound that can be condensed well during polyester polymerization, and carboxyphosphinic acid and its cyclic anhydride are examples thereof.

As carboxyphosphinic acid, 2-carboxy-ethyl-methyl-phosphinic acid Ho-P-CH2-CH2-COOH "Hj 2-carboxy-ethyl-ethyl-phosphinic acid↑ HO-P-CH coco-H2-C0OH 2H5 2 -carboxy-ethyl-phenyl-phosphinic acid↑ and the like.

Further, as the cyclic anhydride, 2-methyl-2,5-dioxo-1-oxa-2-phosphorane CH+-P
CH2 C 2-ethyl-2,5-dioxo-1-oxa-2-phosphorane ↑ OCH2 2-phenyl-2,5-dioxo-1-oxa-phosphorane. From the viewpoint of reactivity, cyclic anhydrides are preferred.

Examples of acid components that do not contain phosphorus include terephthalic acid, isophthalic acid, naphthalene-2,6-dicarboxylic acid,
These include sebacic acid, adipic acid, maleic acid, fumaric acid, trimesic acid, trimellitic acid, and pyromellitic acid. Among these, terephthalic acid, isophthalic acid, sebacic acid, and adipic acid are preferred.

Glycol components include nyrelene glycol, diethylene glycol, triethylene glycol, polyethylene glycol, propylene glycol, polypropylene glycol, neopentyl glycol, trimethylene glycol, tetramethylene glycol, polytetramethylene glycol, bisphenol to ethylene oxide adduct, and bisphenol A. -Propylene oxide adducts, etc. Among them, ethylene glycol and neopentyl glycol are preferred.

To give further specific examples, the acid components include 30 to 50 mol% of isophthalic acid, 10 to 30 mol% of adipic acid, 2-
A flame-retardant polyester resin consisting of 30 to 50 mol% of methyl-2,5-dioxo-2-phosphorane and 100 mol% of ethylene glycol, and as acid components, 10 to 30 mol% of terephthalic acid and 10. to 30 mol% of isophthalic acid. %
, cepatic acid 10-30 mol%, 2-methyl-2,5-
30 to 50 mol% of dioxo-2-phosphorane, 20 to 60 mol% of ethylene glycol as a glycol component,
A flame-retardant polyester resin containing 20 to 60 mol% of neopentyl glycol is preferably used. Preferably, these resins are soluble in common organic solvents such as acetone, methyl ethyl ketone, chloroform, benzene, trichloroethylene, and carbon tetrachloride. Also,
It is preferable that the glass transition temperature is between 110°C and 70°C.

Examples of the epoxy resin used in the present invention include epoxy resins that do not contain halogen or epoxy resins that contain halogen, and these may be used alone or in combination.

The halogen-free epoxy resin used in the present invention may be any epoxy resin as long as it has two or more epoxy groups in one molecule, but suitable examples include novolac type epoxy resin, dimer acid There are type epoxy resins, polyglycol type epoxy resins, etc.

The halogen-containing epoxy resin used in the present invention includes:
Any material may be used as long as it has an epoxy group and a halogen atom in one molecule, but suitable examples include bisphenol-type brominated epoxy resin, novolac-type brominated epoxy resin, and ether-type brominated epoxy resin. It will be done. Specifically, "Epicote 1050" manufactured by Shell Chemical Co., Ltd. and "DER54" manufactured by Dow Chemical Co., Ltd.
2″, “BREN-S” manufactured by Nippon Koyaku Co., Ltd.
"and so on.

If it is desired to further improve flame retardancy, it is effective to use a halogen-containing epoxy resin as the epoxy resin, or to use a combination of a halogen-containing epoxy resin and a halogen-free epoxy resin.

In this case, it is preferable to use 30 to sowt% of the halogen-containing epoxy resin out of all the epoxy resins. When the content of the halogen-containing epoxy resin exceeds 80 wt%, the adhesive strength tends to decrease. Moreover, if it is less than 30 wt%, the effect of improving flame retardance may not be achieved.

Examples of the curing agent used in the present invention include known epoxy resin curing agents such as amines, acid anhydrides, and imidazoles, but acid anhydrides are preferred from the viewpoint of heat resistance.

The amounts of the above-mentioned components of the adhesive composition according to the present invention are not particularly limited, but they are preferably used in the following proportions.

That is, for 100 parts of flame-retardant polyester (parts represent parts by weight), 10 to 10 parts of epoxy resin is
It is recommended to mix 200 parts, more preferably 20 to 10 parts.
It is 0 copies. If the amount of epoxy resin is too small, the adhesive strength may decrease, and if it is too large, the flame retardance may decrease. The curing agent is 1 to 20 parts, preferably 3 to 10 parts.

If there is too little curing agent, the epoxy resin will not harden and the adhesive strength will tend to decrease. If the amount is too high, curing may progress too much and adhesive strength may decrease. Further, other components may be added without reducing adhesive strength and flame retardant properties. Examples include organic resins such as acrylic resins and acrylonitrile-butadiene rubber, 5b203, Aff (OH
) 3 different inorganic particles are produced.

Next, a method for manufacturing a flame-retardant flexible circuit board of the present invention will be explained. First, a method for producing a flame-retardant adhesive will be explained.

First, a phosphorus-free acid and a glycol are reacted to form an ester. Next, predetermined amounts of bosphinic acid and a polymerization catalyst are added and polymerized to obtain a flame-retardant polyester resin. A predetermined amount of organic solvent is added to this to dissolve the resin. Subsequently, predetermined amounts of epoxy resin and curing agent are added and dissolved to obtain a flame-retardant adhesive composition. Next, a flame-retardant flexible circuit board is manufactured using this adhesive. That is, it is manufactured by applying a flame-retardant adhesive onto a flame-retardant film using a roll method, drying it, and then laminating it with metal foil.

The thus obtained flame-retardant flexible circuit board of the present invention can be used as a material for a flexible wiring board manufactured through a photolithography process.

[Method for Measuring Characteristics and Evaluating Effects] Methods for measuring characteristic values and evaluating effects of the present invention are as follows.

The force required to peel off the copper foil in the 90' direction from the surface of the substrate at a speed of 50 mm/min was measured.

Soldering heat resistance: The quality of the appearance after floating the sample in a solder bath at 300'C for 30 seconds was judged.

Solvent resistance: A 20 mm square sample was immersed in methylene chloride for 15 minutes at room temperature, and then the penetration distance of methylene chloride was measured.

Flame retardancy: A flame test was conducted in accordance with the UI-94 standard. The UL-94 standard defines flame retardancy as V-O, V-1, V-2,
It is ranked into four categories: HB, with V-〇 having the best flame retardancy. Next, V-1. The order is V-2 and HB.

[Example] Example 1 83 g of isophthalic acid, 409 g of adipic acid, 86 g of ethylene glycol. ag was placed in a three-hole flask, heated to 200° C. with stirring, and dehydrated for about 4 hours to effect esterification. Next, 40.2 g of 2-methyl-2,5-dioxo-1-oxa-2-phosphorane and 5b203147I
rI! j was added, and while further heating, the mixture was gradually evacuated to bring the internal temperature to 290° C. and the pressure to 0.1 n+mHO. Polymerization was completed after about 3 hours of reaction. To 100 parts of this polyester, 150 parts of methyl ethyl ketone was added and dissolved. In addition, 30 parts of "BRFN-3" (brominated epoxy resin) [Nissui Kayaku Co., Ltd.] and 5 parts of "Epicote 152" (epoxy resin) [manufactured by Shell Chemical Co., Ltd.]
0 parts and 4.0 parts of phthalic anhydride (hardening agent) were added and stirred thoroughly. The adhesive has a concentration of 55°1wt% and a viscosity of 3.5.
[PS/25°C].

Next, this adhesive solution was applied onto a polyimide film having a thickness of 25 μm so that the coating thickness after drying was 15 to 40 μm. Thereafter, it was heated and dried at 80'C for 2 minutes.

Next, a copper foil with a thickness of 35 μm was laminated on top of it, and
Roll lamination was performed at C12k'j/Cm at a speed of 1 m/min, and then cured in a hot air oven at 150'C for 5 hours to obtain a flexible circuit board. Characteristic values are shown in the table.

Example 2 Terephthalic acid 51. Isophthal IQ 30y, Cepatine 1
56.8g, 37.2g of ethylene glycol, and 42y of neopentyl glycol were placed in a Mitsuro flask. After that, the same operation as in Example 1 was performed to obtain a flame-retardant polyester resin. For 100 parts of this polyester resin, 20
0 parts of dimethylformamide was added to dissolve well.

Zarani "DER542" (brominated epoxy resin) [
1350 copies of Dow Chemikaf and ``Epicor i~871''
(Epoxy resin) [manufactured by Shell Chemical Co., Ltd.] 40 parts and 4.0 parts of phthalic anhydride were added and thoroughly dissolved. The adhesive is
The concentration was 49.2 wt% and the viscosity was 2.8 [PS/25°C]. Using this, a flexible circuit board was obtained in the same manner as in Example 1. Characteristic values are shown in the table.

Comparative Example 1 Terephthal 1116', 2! J, ethylene glycol 8
6. Put three El in a flask and add 200 ml while stirring.
The temperature was raised to 0.degree. C., and a dehydration reaction was carried out for about 4 hours to effect esterification.

147 mg of Sb203 was added, and the internal temperature was raised to 290°C and the pressure to 0.1n.
+mt (g). Polymerization is completed after about 3 hours of reaction.

To 100 parts of this polyester, 150 parts of methyl ethyl ketone was added and dissolved. Further” D E
120 parts of R542'', 12 parts of ``Epikote 152'''
0 parts and 4.0 parts of phthalic anhydride were added and dissolved. This adhesive has a concentration of 69.6 wt% and a viscosity of 3.2 [PS/
25°C]. Characteristic values are shown in the table. Since the polyester does not contain phosphinic acid, it is not flame retardant and contains too much brominated epoxy, resulting in poor adhesive strength.

[Effects of the Invention] The present invention relates to a flame-retardant flexible circuit board, and has the following excellent effects.

(1) It was possible to satisfy various characteristics required for a flexible circuit board and to provide a high degree of flame retardancy.

(2) Since no inorganic flame retardant is used in the adhesive layer, the process can be simplified and excellent properties can be obtained.

Claims (3)

[Claims] (1) In a flame-retardant flexible circuit board formed by laminating a flame-retardant plastic film and a metal foil with a flame-retardant adhesive, the flame-retardant adhesive has a formula ▲ mathematical formula, chemical formula, There are tables, etc. ▼ (In the formula, R is an alkylene group with 1 to 6 carbon atoms or 6 carbon atoms.
~12 arylene group, R_1 is an alkyl group having 1 to 6 carbon atoms or an aryl group having 6 to 12 carbon atoms), out of the total acid components in the polyester, 20 to 50
1. A flame-retardant flexible circuit board comprising a flame-retardant polyester resin (A) having a mol% content, an epoxy resin (B), and a curing agent (C). (2) The flame-retardant flexible circuit board according to claim 1, wherein the epoxy resin (B) is a halogen-containing epoxy resin. (3) The flame-retardant flexible circuit board according to claim 1, wherein the epoxy resin (B) is a halogen-containing epoxy resin and a halogen-free epoxy resin.