JPH04171787A - Nonflammbable flexible metal foil-clad laminate board - Google Patents

Abstract

PURPOSE:To improve dimensional stability, solder heat resistance, solvent resistance, and electrical characteristics by impregnating unwoven fabric including aromatic polyimide fibers as a chief ingredient with a specific resin composition, and laminating a metal foil on one surface of the unwoven fabric and thereafter curing the same. CONSTITUTION:A resin composition containing a reactive nonflemmable agent is impregnated with unwoven fabric mainly comprising aromatic polyimide fibers, nonflammable agent containing epoxy acrylate, crosslinking monomer, an ethylenic unsaturated group capable of radical polymerization. A metal foil is laminated at least on one surface of the impregnated unwoven fabric and thereafter cured.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a flexible metal foil-clad laminate for use in flexible printed wiring boards.

In recent years, as electronic devices have become smaller, demand for flexible printed wiring boards has increased. In the field of flexible printed wiring boards that involve mounting, flame retardancy is required in addition to solder heat resistance and dimensional stability. Wiring boards based on aromatic polyimide films are heat resistant and flame retardant, and are used in large quantities in this field, but problems have arisen in dimensional stability as high-density packaging increases. It's also expensive. Although polyester film base wiring boards are inexpensive, they are flammable and cannot be used to mount components with solder (which causes large shrinkage when soldered).

Recently, flexible laminates based on aromatic polyamide (aramid) fiber nonwoven fabric impregnated with cross-linked alkylene terephthalate resin, diallyl phthalate resin, etc. have been used as relatively inexpensive wiring boards for mounting. However, there is a drawback that solvent resistance decreases when a required amount of additive flame retardant is added to make flame retardant.

Therefore, the present invention aims to create a flame retardant material that is excellent in dimensional stability, soldering heat resistance, solvent resistance, electrical properties, etc., and has excellent cost performance. To provide a flexible metal foil laminate.

RULE 1ヱI ``Children's Work Friend Your Few Means'' The present invention is characterized by the following: (a) urethane acrylate, (b) halogen-containing epoxy acrylate-1, (c) a crosslinking monomer, (d) a halokene-containing reactive flame retardant having a radically polymerizable ethylenically unsaturated group, and a metal foil is laminated on at least one side of the impregnated nonwoven fabric, and then cured. Flame-retardant flexible metal foil cladding 1) Laminated board.

By using a resin composition containing the above components (a) to d) as 7 trisox, a flexible laminate can be obtained that simultaneously satisfies flammability, flexibility, and solvent resistance.

The urethane acrylate used in the present invention is produced by the addition reaction of a terminal hydroxyl polymer, a polyisocyanate, and a monohydroxyalkyl acrylate or methacrylate, and is substantially It is preferable to have an average molecular weight of 2,000 or more, with no residual isocyanyl((-)5), and an acroyloxy or methacroyloxy group at both ends.

Urethane acrylates having an average molecular weight of less than 2000 are not preferred because they cannot impart sufficient flexibility to the sheet-like substrate. The hydroxyl-terminated polymers herein include hydroxyl-terminated polyesters, hydroxyl-terminated polyethers, and hydroxyl-terminated polybutadienes. Mixtures thereof can also be used. The terminal hydroxyl polyester is a saturated polybasic acid such as phthalic anhydride, isophthalic acid, adipic acid, succinic acid, and dimer acid, or its anhydride, and ethylene glycol, diethylene glycol, propylene glycol, dipropylene glycol, 1,4-butanediol, Those produced from polyhydric alcohols such as 1.6-hexanediol by conventional synthetic methods can be used. Lactone esters obtained by polymerizing ε-caprolactone using glycols as an initiator can also be used as the terminal hydroxy polyester. As the terminal hydroxy polyether, polyethylene glycol, polypropylene glycol, polyethylene propylene glycol, Bolite I/ramethylene glycol, etc. can be used. As the hydroxyalkyl (meth)acrylate I, hydroxyalkyl (meth)acrylate, droxypropyl (ivy)acrylate 1, etc. are used. Poly 1' Socia-1- contains polymethyl xylylene diisocyanate, phenylene diisocyanate 1-. 1 ~ Lylene diisocyanate 1 ~
, isophorone diisocyanate, etc. can be used.

The urethane acrylate used here can be one synthesized by a known synthesis method using these raw materials. The amount of urethane acrylate in the resin composition is 1
It is 0 to 50% by weight, preferably 20 to 40% by weight.

If it is less than 10% by weight, it is not preferable because sufficient flexibility cannot be imparted.

Moreover, if it is more than 50% by weight, it is not preferable because heat resistance and solvent resistance deteriorate.

The halogen-containing epoxy acrylate resin used in the present invention is preferably one obtained by ring-opening addition reaction of acrylic acid or methacrylic acid to the epoxy group of a halogenated bisphenol-based epoxy resin such as tetrabromohisphenol A. . The blending amount in the resin composition is 5 to 30% by weight, preferably 10 to 20% by weight. If it is less than 5% by weight, the adhesion to metal foil at high temperatures and heat resistance will deteriorate, which is not preferable. Moreover, if it exceeds 30%, the flexibility of the sheet deteriorates, which is not preferable.

The crosslinking monomers used in the present invention include - styrene is used for boat fishing, α-methylstyrene, vinyltoluene, p-methylstyrene, chlorostyrene, bromostyrene, divinylbenzene C3-CIO alkyl methacrylate, Co- Co.

Monomers such as alkyl acrylates, hydroxyalkyl acrylates, hydroxyalkyl methacrylates, diallyl phthalates, triallyl cyanurates, and mixtures thereof with styrene can also be used. The blending amount of the crosslinking monomer is 20 to 40% by weight in the resin composition. If it is less than 20% by weight, the viscosity of the resin composition will increase, causing problems in impregnability, which is not preferable. Also, 40% by weight
The above is not preferable because it impairs the flexibility of the sheet.

The reactive flame retardant used in the present invention is an organic halide having a polymerizable ethylenically unsaturated bond in the molecule. These are copolymerized with other components in the resin composition,
It becomes part of the resin skeleton.

Examples include acrylates or methacrylates of halogenated phenols such as tribromophenol, diacrylates or dimethacrylates of halogenated bisphenols such as tetrabromobisphenol A, chlorostyrene, bromostyrene, and the like. Other classes of reactive flame retardants include dicyclopentadiene (
Examples include products obtained by adding bromine to acrylate (DCPD) or methacrylate. In this case, the double bond of the DCPD ring is more reactive than the double bond of (meth)acrylic acid, so bromine can be preferentially and selectively added to the double bond of the DCPD ring, which is preferable. .

The halogen in halogen-containing epoxy acrylates and halogen-containing reactive flame retardants is generally bromine, and the resin composition is prepared using bromine as the halogen provided by these components at least 10% by weight of the entire resin composition, preferably 10 to 10% by weight of the total resin composition. It should contain 25% by weight.

The resin composition may contain an inorganic flame retardant such as antimony dioxide, molybdenum dioxide, zinc borate, and alumina permanent, if necessary.

The resin composition of the present invention can be cured (crosslinked) using a general-purpose organic peroxide. An example of a preferred organic peroxide is 1,1-bis(L) as a peroxyketal.
Di-butyl peroxide is used as dialkyl peroxides, t-butyl peroxide is used as peroxy esters, etc. Examples include oxybenzoate. These are used in an amount of about 0.5 to 2.0 parts by weight based on the resin composition.

In the present invention, the aromatic polyamide fiber nonwoven fabric usually has a thickness of 30 to 200 μm and an apparent density of 0.3 to 0.0 μm.
7 g/cTll, preferably 0.4-0.6 g/
CII! are used. As the aromatic polyamide, polyparaphenylene terephthalamide or
Examples include polymetaphenylene isophthalamide. A material having a high content of para-aromatic polyamide such as polyparaphenylene terephthalamide is preferable from the viewpoint of dimensional stability and heat resistance.

It is preferable that a nonwoven fabric containing aromatic polyamide fibers as a main component is subjected to a surface treatment in advance, and among these, it is most preferable to use a surface treatment with a wholly aromatic amide-imide resin. This treatment has the effect of further improving soldering heat resistance. As these wholly aromatic amide-imide resins, a methylpyrrolidone solution of wholly aromatic polyamide-imide, which is generally used as a face for copper wires, can be used. That is, a polymer of trimellitic anhydride or its halide, pyromellitic anhydride, aromatic dibasic acid halide, etc. and aromatic diamine or diisocyanate,
A polymer having an amide group bond and an imide bond in the polymer is used.

As for the metal foil, electrolytic steel foil, rolled copper foil, electrolytic aluminum foil, etc. are preferable.

The flexible laminate of the present invention is preferably manufactured by a continuous lamination method.

FIG. 1 is a process explanatory diagram showing a typical embodiment of the present invention.

The long nonwoven fabric unwound from the reel 1 is passed through a dryer 2 and dried as required. Excessive moisture contained in the nonwoven fabric reduces the soldering heat resistance required of the metal-clad laminate, and often causes blistering during soldering, which is undesirable. Furthermore, when heated to harden the resin, voids may be generated due to the generation of water vapor. It is desirable that the nonwoven fabric stored in the atmosphere be dried under drying conditions of about 110° C. for 10 minutes.

After drying, the nonwoven fabric is continuously and quantitatively impregnated with a radical curing resin liquid by a resin impregnation coater 3. Further, in order to achieve good impregnation and impregnation rate, it is preferable to appropriately select the viscosity of the resin liquid and the apparent density of the heat-resistant nonwoven fabric. Generally, the lower the viscosity of the resin liquid, the higher the impregnating property. The viscosity can be lowered by increasing the proportion of liquid monomer in the resin liquid and lowering the molecular weight of the radical-curing resin, but lowering the viscosity more than necessary will impede the heat resistance, mechanical strength, and flexibility of the resulting product and is not desirable. do not have. Using a heat-resistant nonwoven fabric with a low density also improves impregnation, but the required amount -I
The decrease in the density of - impedes the product's n, mechanical properties, and qualitative processability according to the XI method. In case of unexploded BI agriculture, 25° of resin liquid
Favorable results are obtained when the viscosity of C is 0.5-30 voices and the density of the heat-resistant nonwoven fabric is 0.3-0.7 g/era. More preferably, the viscosity of the resin liquid is 2 to 2.
0 poise, and the density of the heat-resistant nonwoven fabric is 0.4 to 0.6.
g/c++f. In addition, the impregnation method may be a method such as dipping the nonwoven fabric in a resin liquid, but in order to ensure a good impregnated state in the present invention, which requires time to remove air bubbles etc. and is aimed at a continuous manufacturing method, It is preferable to impregnate the resin liquid from one side of the heat-resistant nonwoven fabric. The amount of resin to be impregnated is preferably slightly in excess of the amount required for the substrate, and is preferably 1.03 to 1.5 times the required amount, more preferably 1.
．． Impregnate with 05 to 1.3 times the amount of resin. By adjusting the amount of resin in this way, the amount of excess resin protruding out during lamination in step 6 can be minimized, making it possible to laminate without trapping air bubbles in the resin, and also reducing the need for recycling because there is less excess resin. The equipment can be simplified since there is no need for The metal foil and the film-like air barrier or two metal foils unwound from the reels 4 and 5 are laminated onto the resin-impregnated nonwoven fabric by a laminating roll 6.

The uncured laminate 10 is sequentially introduced into the curing furnace 7.

The heating furnace 7 is preferably heated to 70'C to 150''C. Curing conditions vary depending on the amount and type of catalyst used, and the type and amount are determined by taking into account the pot life and curing characteristics of the resin liquid. Next, the hardened N plate 11 is continuously taken up by a take-up machine 8 and wound up by a product take-up machine 9. If the reel 4 is a film-like air barrier, the take-up machine It is peeled off from the product at step 8 and wound up by a winding machine 12. Although curing may be completed at this stage, it is also possible to harden it to a state where it can be wound up and then perform after-curing for an appropriate period of time.

When manufacturing a thin sheet-like base material, one or more sets of two parallel wooden rolls 13 that can maintain a constant clearance are installed in the curing furnace, and the sheet-like base material is conveyed through this gap to make the sheet-like base material thicker. Accuracy can be improved. It is important to install this roll just before the resin in the curing furnace becomes slag and loses its fluidity completely. In this case, the thickness is substantially determined by this clearance, and it is preferable that this clearance is narrower than the clearance of the lamirol 6 by 5 to 30 μm.

The film-like air barrier of the present invention is preferably a film having two surface smoothness properties, such as polyester film, polyimide film, cellophane film, release-treated film thereof, silicone release paper, etc.

This will be explained in more detail below with reference to Examples.

Example 1 A terminal hydroxy polyester with a hydroxyl value of 55.5 was obtained by a conventional synthesis method from ethylene glycol and adipic acid, and after adding styrene to this to make a solution with a styrene content of 30%, tetramethyl xylylene diisocyanate was prepared. and hydroxyethyl acrylate were reacted in a conventional manner to obtain a solution (A) of urethane acrylate with no remaining NGO groups and a styrene content of 30%. The average molecular weight of this urethane acrylate was 2,600.

Next, epoxy acrylate obtained by ring-opening addition of methacrylic acid to the terminal epoxy ring of tetrabromobisphenol A epoxy resin is added to styrene. The mixture was dissolved to obtain a resin solution (B) having a styrene content of 50%.

Mix 28 parts by weight of the resin solution (A), 52 parts by weight of the resin solution (B), and 20 parts by weight of the reactive flame retardant (tribromophenol meccrylate), and add to the par;
1 part by weight of the resin composition (urethane acrylate 1
9.6% by weight, 26% by weight epoxy acrylate, 34.4% by weight styrene, 20% by weight reactive flame retardant)
, rose aromatic polyamide fiber nonwoven fabric (basis weight 25g
/m), then laminated with a 35 μm thick copper foil and cured to obtain a 110 μm thick flexible copper clad laminate 1.

Example 2 40 parts by weight of the resin solution (A) of Example 1 and the resin solution (B)
) and 020 parts by weight of a reactive flame retardant,
Using a resin composition to which 1 part by weight of Perhexa 3M was added, a flexible copper-clad laminate 2 was prepared in the same manner as in Example 1.
I got it.

Example 3 55 parts by weight of the resin solution (A) of Example 1 and the resin solution (B)
) 21 parts by weight of reactive flame retardant ■24v24 parts by weight,
A flexible copper-clad laminate 3 was prepared in the same manner as in Example 1 using a resin composition in which 1 part by weight of Perhexa 3M was added.
I got it.

Example 4 35 parts by weight of the resin solution (A) of Example 1 and the resin solution (B)
) and 35 parts by weight of a reactive flame retardant ■ (Daiichi E5, manufactured by Kogyo Seiyaku Co., Ltd. GX6170), and using a resin composition in which 1 part by weight of Perhexa 3M was added, Example 1 and A flexible copper-clad laminate 4 was obtained in the same manner.

Example 5 The nonwoven fabric used in Example 1 was previously surface-treated with amide-imide resin (manufactured by Hitachi Chemical Co., Ltd., trade name HI-405-30) so that the amount of adhesion was 3 g/rrr. A laminate 5 was obtained in the same manner as in Example 1.

Comparative Example 40 parts by weight of the resin solution (A) of Example 1 and the resin solution (B)
) 40 parts by weight, and a flame retardant without radically polymerizable ethylenically unsaturated groups ■ (5R900 manufactured by Dai-Kogyo Seiyaku) 2
A flexible copper-clad laminate 6 was obtained in the same manner as in Example 1 using a resin composition in which 0 parts by weight of Perhexa 3M were mixed and 1 part by weight of Perhexa 3M was added thereto.

Flame retardancy, solder heat resistance, folding strength, and door resistance of the flexible laminates obtained in Examples 1 to 4 and Comparative Examples 6 All of the flexible copper-clad laminates of Recleaning Examples 1 to 4 had excellent flame retardancy. , soldering heat resistance, bending strength, and solvent resistance (triclene resistance). On the other hand, the laminate of the comparative example in which no reactive flame retardant was used had good flame retardancy, soldering heat resistance, and folding strength, but had a problem with solvent resistance. In particular, when immersed in Triclean, the surface of the substrate disappeared and the surface became rough.

(Margin below) g ■ Eight-

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram of the process of manufacturing a flexible laminate according to the present invention. 1, nonwoven fabric 2, dryer 3, coke for resin impregnation 4, film air barrier or metal foil 5, metal foil or film air barrier 6, lamination 1-roll 7, curing furnace 8, take-up machine 9, Product winder 10, uncured laminate 11, cured laminate 12, film air barrier winder 13, thickness control roll

Claims (4)

[Claims] (1) A nonwoven fabric mainly composed of aromatic polyamide fibers containing (a) urethane acrylate, (b) halogen-containing epoxy acrylate, (c) a crosslinking monomer, and (d) ethylenically unsaturated groups capable of radical polymerization. A flame-retardant flexible metal foil-clad laminate is obtained by impregnating a resin composition containing a halogen-containing reactive flame retardant, laminating metal foil on at least one side of the impregnated nonwoven fabric, and then curing the impregnated nonwoven fabric. (2) The resin composition includes: (a) urethane acrylate 10-50% by weight, (b) halogen-containing epoxy acrylate 5-30% by weight, (c) crosslinking monomer 20-40% by weight, (d) halogen-containing 1. A flame-retardant flexible metal foil-clad laminate according to item 1, comprising 10 to 40% by weight of a reactive flame retardant. (3) The flame-retardant flexible metal foil-clad laminate according to item 1 or 2, wherein the resin composition contains bromine as a halogen in an amount of 10 to 25% based on the weight of the resin composition. (4) The flame-retardant flexible metal foil-clad laminate of Items 1 to 3, which is a nonwoven fabric whose main component is aromatic polyamide fiber and whose surface is previously treated with a wholly aromatic amide-imide resin.