JPH07119087B2 - Manufacturing method of flexible double-sided metal-clad laminate - Google Patents

Description

The present invention relates to a method for producing a flexible double-sided metal-clad laminate having good heat resistance.

[Conventional technology]

As a method of manufacturing a flexible metal-clad laminate, a metal foil and a polyimide film are made of acrylic, epoxy,
Method of laminating with rubber adhesive, method of heat-pressing by sandwiching thermoplastic polyimide film with copper foil and polyimide film, coating of polyamic acid varnish on substrate surface, heating to volatilize solvent and imidization reaction There is known a method in which a polyimide resin layer is formed by heating, and the adherends are superposed and heated and pressed.

[Problems to be Solved by the Invention]

The method of laminating the metal foil and the polyimide film with an acrylic, epoxy, or rubber adhesive does not take advantage of the high heat resistance of the polyimide film because a material with low heat resistance is used for the adhesive layer. There was a problem with the peel strength at high temperatures. Further, when a thermoplastic polyimide film is used as the adhesive layer, the adhesive polyimide film must be produced from a polyamic acid or a polyimide varnish by a method such as casting, which poses a problem in terms of cost and economy. It was Furthermore, the method of applying the polyamic acid varnish to the surface of the base material and heating and then stacking the adherends together is such that the dehydration of imidization that occurs during heating may cause pinholes in the adhesive layer. There is a problem that internal stress is likely to remain in the substrate due to shrinkage.

The present invention provides a method for producing a flexible double-sided metal-clad laminate which is excellent in heat resistance, particularly peel strength at high temperature, and has little residual internal stress.

[Means for Solving the Problems]

The present invention is characterized in that a polyimide varnish is applied to both sides of a flexible core material, dried, and then metal foils are laminated on both sides and heated and pressed.

A film or metal foil is used as the core material, and these require high heat resistance and high strength. For this reason, it is desirable to use a polyimide film as the film. If necessary, the polyimide film can be treated with a coupling material. As the metal foil, there are iron foil, aluminum foil, copper foil, and the like, and the same metal foil is used on both sides.

The polyimide varnish is preferably one that forms an uncured adhesive layer by applying the polyimide varnish to a core material and drying the core material, and further causes a thermosetting reaction when the adhesive layer is heated and pressed. It has superior heat resistance and chemical resistance as compared with adhesive layers that exhibit thermoplasticity.

The polyimide varnish is preferably formed by dissolving a polyimide resin and a polymerizable compound having an imide ring in an organic solvent. By containing the polymerizable compound, this not only exhibits thermosetting property, but also improves the fluidity of the uncured adhesive layer and improves the adhesive property with the metal foil. It can be said that the thermosetting adhesive layer is made of an imide resin.

The polyimide resin is 3,3 ′, 4,4′-benzophenone tetracarboxylic dianhydride, 3,3 ′, 4,4′-biphenyl tetracarboxylic dianhydride, 3,3 ′, 4. , 4'-Diphenyloxytetracarboxylic dianhydride, 2,2'-bis (3,4-
Dicarboxyphenyl) hexafluoropropane dianhydride, 2,2-bis [4- (3,4-dicarboxyphenoxy)
Phenyl] hexafluoropropane dianhydride, 4,4'-
Bis (3,4-dicarboxyphenoxy) diphenyl sulfide dianhydride, ethylene bis trimellitate dianhydride, bisphenol A bis trimellitate dianhydride, biphenyl bis trimellitate dianhydride, pyromellitic acid Acid dianhydrides such as dianhydride and 4,4′-diaminodiphenylmethane, 4,4′-diaminodiphenyl ether, 4,4′-
A product obtained by reacting a diamine such as diaminodiphenyl sulfone or 3,3'-diaminodiphenyl sulfone, which has completed imidization and is soluble in an organic solvent, is used. It As the above-mentioned diamine, diamines represented by the following general formula (I) and diamines represented by the general formula (II) can be used in addition to those already exemplified.

General formula (I) (However, in the general formula (I), X is isopropylidene,
Hexafluoroisopropylidene, O, S, SO ₂ , CH ₂ , CF ₂ and
At least one group selected from the group consisting of CO, n is
It is 2 or more. ) General formula (II) (However, in the general formula (II), m is 0 or an integer of 1 to 4.) Examples of the compound represented by the general formula (I) include 1,3-bis (4-aminophenoxy) benzene, 1, 3-bis (3-
Aminophenoxy) benzene, bis [4- (4-aminophenoxy) phenyl] sulfone, bis [4- (3-aminophenoxy) phenyl] ketone, 2,2-bis [4-
(4-Aminophenoxy) phenyl] propane, 2,2-
Bis [4- (3-aminophenoxy) phenyl] propane, bis [4- (3-aminophenoxy) phenyl] methane, bis [4- (4-aminophenoxy) phenyl]
Examples include difluoromethane, bis [4- (3-aminophenoxy) phenyl sulfide, and 2,2-bis [4- (3-aminophenoxy) phenyl] hexafluoropropane.

Examples of the compound represented by the general formula (II) include metaphenylenediamine, paraphenylenediamine, 2,4-diaminotoluene, 2,5-diaminotoluene, 2,6-diaminotoluene and 2,3-dimethylparaphenylene. Diamine, 2,5-
Dimethylparaphenylenediamine, 2,6-dimethylparaphenylenediamine, 3,4-dimethylmetaphenylenediamine, 2,3,5-trimethylparaphenylenediamine,
There are 2,3,4-trimethyl metaphenylenediamine, 2,3,6-trimethyl metaphenylenediamine, diaminodiurene and the like.

Examples of the polyimide include 3,3 ', 4,4'-benzophenonetetracarboxylic dianhydride and the diamine represented by the general formula (I) in an amount of 50 to 100 mol% (preferably 55 to 90 mol%) and Those obtained by reacting a diamine consisting of 0 to 50 mol% (preferably 10 to 45 mol%) of the diamine represented by the general formula (II) are preferable.

Polyimide resin is manufactured by reacting the reaction components in an organic solvent (particularly a polar solvent) to form a polyamic acid varnish, then adding a ring-closing agent and a ring-closing catalyst while keeping the liquid temperature at 10 ° C or lower, and then imidizing this solution. Is dropped into water or methanol or ethanol to form a solid polyimide, which is then dried to obtain a powder. At this time, the polar solvent used is N-methylpyrrolidone,
N, N-dimethylacetamide, N, N-dimethylformamide, dimethyl sulfoxide and the like are preferable. The ring-closing agent used for imidization includes acetic anhydride, dicyclohexylcarbodiimide and the like, and the ring-closing catalyst is preferably pyridine, N, N-dimethylaniline, triethylamine and the like.

Besides this method, a one-step method in which the reaction components are heated in a solvent to directly imidize, a method using a corresponding diisocyanate instead of the diamine, and the like can be used. When the polyimide resin is obtained by co-condensing the reaction components, it may be a random polymer or a block polymer.

The above-mentioned polymerizable compound having an imide ring preferably has a functional group reactive with the amino group and / or the carboxyl group of the polyimide resin. In addition, those in which the imide ring is changed to an isoimide group also include the above-mentioned polymerizable compound. Examples of such products include vinyl groups at the end of the molecule,
Those having an ethyl group, an allyl group, a methacrylic group, an acryl group, an alkenyl group, a norbornene structure, and a maleic acid structure are preferable.

Examples of the polymerizable compound include those represented by the general formula (III) However, in the formula, R and R'are CH ₂ = CH-, CH≡C-, CH ₂ =
CH-CH _2- , CH ₂ = CH-COO-, Etc., and R and R'may be the same or different. Ar
₁ is (Here, X'is O, CO, SO ₂ , CH ₂ , And so on, and Ar ₂ is (Here, X ″ is the same as X ′, and k is 1 to 6
When there are a plurality of Ar ₂ , they may be the same or different, and l represents 0 or an integer of 1 to 100. In the general formula (III), 1 is particularly preferably 0 or an integer of 1 to 20 for improving molding.

Specific examples of the compound represented by the general formula (III) include: as well as (However, p and q represent an average degree of polymerization and are about 1.)
Are commercially available as Thermite MC-600 and Thermite FA-700 (trade name of National Starch and Chemical Co.).

Also, (Where r is the average degree of polymerization) is the thermite IP-
600 (r = 1), Thermite IP-603 (r = 3), Thermite IP-615 (r = 15) and Thermite IP-630 (r = 3)
0) [All of these are commercially available as National Starch and Chemical Co., Ltd.].

As the polymerizable compound, polymaleimide can be used in addition to the compound represented by the general formula (III).

Specific examples of the polymaleimide that can be used in the present invention include N, N '-(4,4'-diphenylmethane) bismaleimide, N, N'-(4,4'-diphenyloxy) bismaleimide, N, N '. -P-phenylene bismaleimide, N, N'-
m-phenylene bismaleimide, N, N'-2,4-tolylene bismaleimide, N, N'-2,6-tolylene bismaleimide, N, N'-ethylene bismaleimide, N, N'-hexa Methylene bismaleimide, (However, h is an integer of 1 to 10.) and polymaleimide represented by the structural formula, and these may be used alone or in combination of two or more kinds.

The polyimide varnish applied to the core material is synthesized by dissolving 50 to 99% by weight of the above-mentioned polyimide resin and 1 to 50% by weight of the polymerizable compound in a polar solvent. Particularly, the proportion of the polyimide resin is preferably 80 to 95% by weight. As the polar solvent, N, N-dimethylacetamide, N, N-dimethylformamide, N-methylpyrrolidone, dimethylsulfoxide and the like are preferable. The solid content concentration in the polyimide varnish is preferably 10 to 50% by weight, and particularly preferably 15 to 20% by weight. The viscosity of the varnish is preferably 50 to 1000 poise, more preferably 100 to 800 poise.

This polyimide varnish is applied thinly on both sides of a core material such as a film or a metal foil with a coating machine such as a blade coater, knife coater, rod coater or squeeze coater. Next, the solvent is removed by continuously heating and drying. The drying temperature at this time is preferably 80 to 250 ° C, more preferably 100 to 230 ° C. It is also possible to set the drying temperature stepwise and perform the drying at different temperatures. The thickness of the obtained adhesive layer is preferably 5 to 50 μm. Next, copper foils are laminated on both sides and heated and pressed in a batch or continuous manner. At this time, it is preferable that the heating temperature is 200 to 300 ° C. and the pressurization is 5 to 50 kg / cm ² . It is also possible to increase the heating temperature stepwise from the low temperature.

Example 1 1,3− in 10 flasks equipped with a stirrer and a N ₂ gas replacement device
Bis (4-aminophenoxy) benzene 409.2g and 2,5-
Dimethyl-para-phenylenediamine (190.4 g) and N, N-dimethylformamide (5031.6 g) were added and dissolved while flowing N ₂ guns. After cooling the solution temperature to 35 ℃, 3,3 ', 4,
4'-bezophenone tetracarboxylic dianhydride (BTDA) 9
01.6 g was added over 50 minutes so that the liquid temperature did not exceed 10 ° C. After this, stirring was continued for 3 hours. At this stage, make sure that the viscosity is over 1000 poise. 1677.2 g of N, N-dimethylformamide was added to make the resin solid content 20% by weight. Then, the obtained solution was cooled to 0 ° C. or lower, and 553 g of pyridine and acetic anhydride were added so that the temperature of the solution did not exceed 5 ° C.
4 g was added and the mixture was continuously stirred for 2 hours. The solution containing the obtained polyimide was poured into 5 times the amount of water to solidify the polyimide linearly, and then pulverized. The crushed polyimide was put in acetone and stirred for 2 hours, and then the powdered polyimide was separated by filtration. The separated polyimide was immersed again in acetone and left for one day. Then, the polyimide separated by filtration was dried at 130 ° C. for 4 hours to obtain 1780 g of powdery polyimide.

A polyimide varnish was produced by dissolving 1400 g of the above powdery polyimide and 140 g of N, N '-(4,4'-diphenylmethane) bismaleimide in 5600 g of N, N'-dimethylformamide and then filtering.

Approximately 140 μm of the above polyimide varnish using a coating machine on both sides of a polyimide film (Kapton 100H, made by Dyupon).
It was applied thickly. After heating in a continuous curing oven at 100 ℃, 200
The heat treatment was carried out through a continuous curing furnace at ℃. The thickness of the formed adhesive layer was 25 μm. Then, copper foil was laminated on both sides of this film and pressed at 275 ° C. and 50 kg / cm ² for 30 minutes. The obtained double-sided copper-clad laminate has good adhesion, has a peel strength of 2.7 kgf / cm at room temperature, and has a peel strength of 1.4 kgf / cm at high temperature (150 ° C), which is the current acrylic adhesive. The value was 2.4 times better than that using the agent.

Example 2 An aluminum foil was used instead of the polyimide film of Example 1, but a double-sided copper-clad laminate excellent in peel strength at high temperature was obtained as in Example 1.

Example 3 Instead of 1,3-bis (4-aminophenoxy) benzene and 2,5 dimethylparaphenylenediamine as amines, 604.8 g of bis [4- (3-aminophenoxy) phenyl] sulfone (m-APPS) and 4- A double-sided copper-clad laminate was obtained in the same manner as in Example 1 except that the polyimide varnish produced in the same manner as in Example 1 was used except that 170.8 g of methyl-1,3-diaminobenzene was used. The peel strength of this laminate at room temperature is 3.1 kgf / cm, and the peel strength at 150 ° C is
It was 1.6 kgf / cm, which was 2.6 times that of the one using an acrylic adhesive, which was excellent.

Example 4 BTDA32.2g, m-APPS 21.6g and 2,4-diaminotoluene 6.1
g into a four-necked flask equipped with a stirrer, a thermometer, a nitrogen gas introduction tube, and a cooling tube, and m-cresol 539 g, toluene 1
08 g was added, and the mixture was heated and stirred while flowing nitrogen gas. 150
Resin content 17.8% by weight, viscosity 15 after reacting at ~ 160 ℃ for 16 hours
A solution containing poise polyimide was obtained. This solution was poured into acetone, reprecipitated, pulverized, washed and dried to obtain a polyimide powder. Reduced viscosity of polyimide powder [concentration 0.1 g / dl, solvent N, N-dimethylformamide (DM
F), temperature 30.0 ° C] was 0.72 dl / g. 100 g of the obtained polyimide powder and N, N '-(4,4'-diphenylmethane)
10 g of bismaleimide was dissolved in 400 g of N, N-dimethylformamide to obtain a polyimide varnish.

Using this varnish, a double-sided copper clad laminate was obtained in the same manner as in Example 1. Peel strength at room temperature is 2.8kgf / cm, 150 ℃
The peel strength was 1.5 kgf / cm.

Comparative Example 1 A polyimide varnish was obtained in the same manner as in Example 1 except that bismaleimide was not added, and a double-sided copper clad laminate was obtained in the same manner as in Example 1 using this varnish. The peel strength of this laminate at room temperature was as weak as 0.5 kgf / cm.

Comparative Example 2 A polyimide varnish was obtained in the same manner as in Example 3 except that bismaleimide was not added, and a double-sided copper clad laminate was obtained in the same manner as in Example 1 using this varnish. The peel strength of this laminate at room temperature was as weak as 0.6 kgf / cm.

〔The invention's effect〕

Since the flexible double-sided metal-clad laminate of the present invention uses an imide resin for the adhesive layer, it is excellent in heat resistance, especially in peel strength at high temperatures. Further, since the adhesive layer uses a coating method of polyimide varnish, it is more economical than the conventional method using a polyimide film for adhesion.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Takehiko Ishibashi 2772, Kajiku, Yuki-shi, Ibaraki Prefecture 2 Minami Yuki Plant, Hitachi Chemical Co., Ltd. (72) Inventor Yasuo Miyadera 48, Wadai, Tsukuba, Ibaraki (72) Inventor, Haruki Yokono, Industrial Building Co., Ltd. Tsukuba R & D Lab. 1772, Kagoku, Yuki City, Ibaraki Prefecture 2 72, Minami-Yuki Plant, Hitachi Chemical Co., Ltd. (56) Reference JP-A-55-18426 (JP, A) JP-A-61-22937 (JP, A) JP-A-62-104840 (JP, A) JP-A-62-30122 (JP, A)

Claims (5)

[Claims] 1. A flexible core material is provided on both sides with (a) 3,3 ′, 4,4′-benzophenonetetracarboxylic acid as an acid dianhydride; (Wherein, X is at least one group selected from the group consisting of isopropylidene, hexafluoroisopropylidene, O, CH ₂ , CF ₂ and CO, and n is 2 or more); 50 to 100 mol%, and general formula (II) (Wherein, m is 0 or an integer of 1 to 4); a polyimide resin obtained by reacting with a compound; 0 to 50 mol%; and (b) an imide ring-containing polymerizable compound. Compound; (b) a polymerizable compound having an imide ring; is applied to a polyimide varnish obtained by dissolving the compound in an organic solvent, and after drying, a metal foil is laminated on both sides and heated and pressed, which is flexible both sides Manufacturing method of metal-clad laminate. 2. The amount of the polyimide resin is 50 to 99% by weight, and the amount of the polymerizable compound having an imide ring is 1 to 50% by weight.
The method for producing a flexible double-sided metal-clad laminate according to claim 1, wherein 3. The polymerizable compound having an imide ring is one having a vinyl group, an ethynyl group, an allyl group, a methacryl group, an acryl group, an alkenyl group, a norbornene structure or a maleic acid structure at the terminal of the molecule. 2. The method for producing a flexible double-sided metal-clad laminate according to any one of 2 above. 4. The method for producing a flexible double-sided metal-clad laminate according to claim 1, wherein the polymerizable compound having an imide ring is polymaleimide. 5. The method for producing a flexible double-sided metal-clad laminate according to claim 1, wherein the core material is a polyimide film or a metal foil.