JPH01157844A - Laminated member and its manufacture - Google Patents

Abstract

PURPOSE:To obtain a laminated member having superior stability in size, resistance to medicines and stability to moisture by co-biaxially stretching biaxially- stretching film of polyallylenesulfid, and bismaleimide resin adhesive layer. CONSTITUTION:At least on one surface of a biaxially-stretching film (A) made of polyallylenesulifed (PAS), an adhesive layer (B) made of bismaleimide resin is laminated, which is then co-biaxially stretched. After the PAS is melted and extruded to be a sheet at temperatures 280 deg.C-320 deg.C, the sheet of the PAS is maintained at temperatures not more than 110 deg.C. Bismaleimide resin having the melting temperature of 90 deg.C-120 deg.C is applied at least on one surface of the PAS sheet while the resin is being melted. Then, the laminated member is biaxially stretched not less than four times by the area ratio. Accordingly, the PAS sheet is strongly coupled to the adhesive layer, so that the laminated member having superior resistance to heat, moisture bending, etc., can be effectively obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a laminate suitable for internal wiring of small electronic devices, particularly a base film or coverlay film for a flexible printed wiring board, and a flexible printed wiring board. Regarding the plate, in more detail, dimensional stability using a biaxially stretched film of polyarylene sulfide,
The present invention relates to a laminate having excellent chemical resistance and humidity stability, and a method for producing the same.

BACKGROUND ART Flexible printed circuit boards (abbreviated as FPC) are usually made of 25 to 2
It has a laminated structure in which metal foil such as copper foil (electrolytic copper foil or rolled copper foil) of about 18 to 35 μm is bonded to a 50 μm polymer film. Using this laminate, a circuit board is made through circuit forming processes such as lithography, etching, coverlay, and soldering.

FPCs equipped with electronic components such as ICs are required to have usage characteristics such as heat resistance, moisture resistance, bending resistance, nonflammability, and copper foil peel strength under each usage environment condition. and,
Most of these usage characteristics depend on the properties of the polymer film used as the raw material.

By the way, currently, the main material for polymer films for FPC is polyimide, which has excellent heat resistance, and polyester (abbreviated as PET) is used in the field of non-heat resistant applications, but these resins each have different It has its drawbacks.

Although polyimide film has excellent heat resistance, it is expensive, is sensitive to strong alkalis such as the sodium hydroxide aqueous solution used in the FPC manufacturing process, and is highly hygroscopic, causing dimensional changes due to changes in humidity. There are drawbacks such as. Furthermore, polyimide films have poor adhesion and peeling of the copper foil becomes a problem.

The adhesion between the copper foil and the base film or coverlay film is determined by soldering (for example, 260'C/several tens of seconds).
Thermal stress peeling and peeling of the copper foil due to repeated bending under FPC usage conditions are a problem, and are the most important point in FPC manufacturing.

Although PET has good adhesive properties, the resin itself has low heat resistance (continuous use temperature is about 130° C.), and is mainly used for FPCs that do not require flow soldering. recently,
Heat-resistant PET (crystallized PET) is being considered for application to FPCs, but its heat resistance at a soldering temperature of 260°C is 20 seconds or less, which is considerably lower than polyimide's 60 seconds. There's a problem.

F using polyarylene sulfide (abbreviated as PAS)
Regarding PC, an example using a polyphenylene sulfide (abbreviated as pps) film is disclosed in Japanese Patent Publication No. 61-53880 (Japanese Unexamined Patent Publication No. 55-36945). In this method, PPS is biaxially stretched to an area ratio of 3 times or more, and then heat-set at a temperature of 230°C to 280°C. Copper foil is adhered to the film base material using an adhesive, and the solder heat resistance is improved. The FPC has a bending resistance of 10,000 times or more at 260°C/60 seconds.

According to this method, it is possible to take advantage of the excellent electrical properties, dimensional stability, and low moisture absorption properties of PPS itself. Since a modified epoxy solution or a polyamide-imide solution is used, the adhesive technology is the same as when using conventional polyimide films.6 Ordinary thermosetting adhesives contain many polar groups,
A problem arises in that the electrical properties of the FPC deteriorate due to this polar group.

A method of improving the surface tension by subjecting PPS films to corona discharge treatment has been reported (February 1988).
(April 27th, Proceedings of the 12th Plastic Film Research Group, Japan Society of Polymer Science, page 45), this treatment increases the surface tension to more than 58dV n / cm, so it is possible to use adhesives for PET. It is said.

A technique using polyimide or its precursor as an adhesive for PPS is known. According to JP-A No. 59-58032, an amic acid type polyimide oligomer solution with terminal acetylene capping is applied to bond the PPS molded body,
After drying at 50 to 150°C for 10 minutes to 1 hour and removing the solvent, it is heated and cured at 100 to 280°C for 100 to 24 hours. This method is suitable for applying adhesive to a part of a molded object with a complex shape, but since it generates a large amount of volatile matter during drying and heat curing, it is difficult to apply adhesive to polymer films such as FPC. It is difficult to apply this method to devices in which copper foil is pasted on one or both sides with an adhesive.

Furthermore, JP-A-57-121052 discloses that a PPS sheet extruded from a T-die or circular die is heat-treated to a fixed length, then subjected to corona treatment, and then the sheet is coated with polyamide such as timer acid as the main component. A conventional solution-type adhesive is applied, and electrolytic copper foil (35 μm thick) is applied on top of it.
Although a technique for laminating two layers together has been disclosed, it is still beyond the scope of conventional adhesive technology.

Problems to be Solved by the Invention 'The present inventors have developed a PP material that has excellent electrical properties, dimensional stability, and low moisture absorption.
PAS films such as S film are applied to laminates such as flexible printed wiring boards, and in that case, the adhesion between the PAS film and metals such as copper foil is improved, and the heat resistance, moisture resistance, and resistance of the FPC composite are improved. We conducted extensive research to improve flexibility. As a result, by using bismaleimide resin as an adhesive and co-biaxially stretching this bismaleimide resin with a PAS sheet to obtain a biaxially stretched PAS film having a bismaleimide resin layer, the PAS film and the bismaleimide resin layer It was discovered that good adhesion was developed between the two, and therefore the adhesion between the PAS film and the metal base material was improved through the bismaleimide resin layer, making it excellent as an FPC or coverlay film.

The present invention was completed based on these findings.

Means to solve problems That is, the gist of the present invention is as follows.

(1) A laminate having an adhesive layer (Bl) made of bismaleimide resin on at least one side of a biaxially stretched film (A) made of polyarylene sulfide, comprising a biaxially stretched polyarylene sulfide film (Al and bismaleimide resin). A laminate characterized in that the adhesive layer [B) and the adhesive layer [B] are co-biaxially stretched.

(2) Polyarylene sulfide at 280°C to 320°C
After melting and extruding it into a sheet, at least one side of the sheet maintained at a temperature of 110°C or less has a melting temperature of 90°C to
A method for producing a laminate, comprising applying a bismaleimide resin at 120° C. in a molten state, and then biaxially stretching the resin to an area ratio of 4 times or more.

(3) Biaxially stretched film made of polyarylene sulfide (A), adhesive layer made of bismaleimide resin (B)
and a laminate formed by laminating a metal base material (C),
A laminate characterized in that a polyarylene sulfide biaxially stretched film (A) and a bismaleimide resin adhesive layer (B) are co-biaxially stretched.

(4) Polyarylene sulfide at 280°C to 320°C
After melting and extruding it into a sheet, at least one side of the sheet maintained at a temperature of 110°C or less has a melting temperature of 90°C to
Bismaleimide resin at 120°C is applied in a molten state, then biaxially stretched to an area ratio of 4 times or more, and then a metal base material is laminated on the bismaleimide resin layer and heated at 240°C to 200°C.
A method for manufacturing laminates characterized by bonding by heat and pressure bonding at 80°C.

Further, according to the present invention, when a metal foil is used as the metal substrate (C1), the metal foil is attached to at least one side of the polyarylene sulfide biaxially stretched film (A) via the bismaleimide resin adhesive layer (B). F with laminated configuration
A PC will be provided.

Furthermore, the laminate of the present invention consisting of a biaxially stretched PAS film (Al and a bismaleimide resin adhesive layer (B)) can be used not only for lamination with metal substrates, but also as a cover layer for flexible printed wiring boards. Useful as a film.

The present invention is characterized in that strong adhesiveness is developed between the PAS film and the bismaleimide resin by co-biaxially stretching the bismaleimide resin applied to a PAS melt-extruded sheet.

Conventionally, it has not been known that an adhesive interface between different types of polymers can be formed by a co-biaxial stretching method. For crystalline polymers, especially non-polar polymers such as PAS, it is difficult for other polymers to form molecular entanglements in the dense crystalline parts of the film after stretching and orientation alone, resulting in poor adhesion. The formation of an interface for this purpose had to rely on roughening the film surface by mechanical means such as sandblasting and the resulting anchoring effect. However, according to the above co-biaxial stretching method, a strong bond is formed between the adhesive layer made of bismaleimide resin and the PAS film.

Hereinafter, the constituent elements of the present invention will be explained in detail.

(Left below) (Polyarylene sulfide (PAS)) PAS used in the present invention has a melt viscosity of 1,000 voices (310
C. and a shear rate of 200 sec-1) or higher, preferably a substantially linear high molecular weight material with 2,500 to 100,000 voids. here,
Substantially linear high molecular weight PAS is not a polymer obtained by thickening (curing) by oxidative crosslinking,
A polymer obtained essentially only from difunctional monomers.

Evaluation of such substantially linear high molecular weight PAS is as follows:
For example, in the measurement of melt viscosity at 310°C, the dependence on shear rate is small, so in the relational expression S=αD' between shear rate (S) and shear stress (D),
The criterion for determination is that the nondiaethonian coefficient (n) is close to 1. Here, n and α are constants.

Substantially linear high molecular weight PAS means that the value of n is 1≦n<2 when calculated at a shear rate of around 200 sec-1.
It refers to something that is within the range of degree.

This is because if the melt viscosity is less than 1,000 voices, the film forming properties will be poor and it will be difficult to stably obtain a biaxially stretched film.

Such a substantially linear high molecular weight PAS can be produced by any known method.

For example, as described in JP-A No. 61-7332, an alkali metal sulfide and a dihaloaromatic compound are subjected to a specific two-step reaction in the presence of water in an organic amide solvent such as N-methylpyrrolidone. It can be suitably obtained by a warm polymerization method.

Among PAS, poly p-phenylene sulfide or poly p-phenylene sulfide copolymer containing m-phenylene sulfide as a minor component is preferred.

The PAS used in the present invention includes antioxidants, heat stabilizers,
Various additives such as a lubricant, a crystal nucleating agent, an ultraviolet absorber, and a coloring agent can be added. Further, other polymers may be blended in small amounts within a range that does not impede the purpose of the present invention.

(Bismaleimide resin) The bismaleimide resin used as the adhesive resin in the present invention can be obtained by reacting polyamino bismaleimide resin (abbreviated as PABM resin) with bismaleimide and diamine or by reacting bismaleimide with bisisocyanate. It is a bismaleimide triazine resin (abbreviated as BT resin).

Both are applied to PAS in the form of a heat-meltable prepolymer, and then proceeded with a curing reaction at a higher temperature to finally form an insoluble, infusible three-dimensional structure, forming an adhesive layer with excellent heat resistance.

The reason why bismaleimide resin is used as the adhesive layer in the present invention is that it is possible to synthesize a prepolymer with a melting temperature range of 90°C to 120°C that is relatively easy to process, and that the curing reaction is similar to metals such as copper foil. The curing reaction proceeds at a temperature of 240°C to 280°C, which is suitable for adhesion of PAS films, and more importantly, the curing reaction is an addition reaction and no volatile substances are generated during the curing process, so it is suitable for bonding large areas such as copper foil. It is suitable for bonding metals.

In the case of BT resin having a triazine ring, it has the effect of preventing deterioration of insulation properties due to migration of copper ions generated from copper foil, and is the most suitable adhesive for long-term reliability of FPC.

B1 Minobismaleimide The PAEMI resin used in the present invention is a thermoplastic polyimide obtained by an addition condensation reaction of bismaleimide and diamine (Nouvelles
resins bismaleimides 5a
nssolvent pour composites
avancesthermostables,,
20es Journey Europenes
des Composites-PARIS).

PABMI resin is commercially available (trade name "Kelimide") and is a thermoplastic resin with a softening temperature of 95°C to 110°C, but it can be heated to about 250°C and hardened to achieve a heat resistance class of 180°C to 250°C (250°C). ,000 hours) and nonflammable (A
STM-D653) heat-resistant polymer.

Bismaleimide/triazine 2 The BT resin used in the present invention has two main components: bismaleimide (B component) and triazine resin (T component), and has an imide group in the molecule with high heat resistance. It is a general term for polymerizable thermosetting polyimide resins, and those with various degrees of polymerization are commercially available.

This BT resin can be obtained by reaction of bismaleimide and bisisocyanate.

(Metal base material) The metal base material used in the present invention is not particularly limited, but metal foils such as copper foil, aluminum foil, iron foil, and nickel foil are preferable for use as a laminate FPC.

Copper foil for printed wiring boards is commonly used with a thickness of 18 to 70 μm, but copper foil for FPCs has a thickness of 18 to 35 μm.
Electrolytic copper foil or rolled copper foil is preferred. Aluminum foil has good etching properties. Iron foil has the problem of rust, but recently iron foil with a thickness of about 5 microns has been developed, and its flexible properties are attracting attention. Although nickel foil has the disadvantage of being prone to cracking, it has good corrosion resistance and is useful as printed circuit boards for aerospace and the like.

(Laminated structure of laminate) The laminate of the present invention includes a laminate consisting of a biaxially stretched PAS film (A) and a bismaleimide resin adhesive layer (B),
The biaxially stretched PAS film (A)-t is roughly divided into a laminate consisting of a bismaleimide resin adhesive layer (B) and a metal base material (C).

The former is mainly used as a base film or coverlay film for FPC, and the latter is mainly used as FPC. A base film for FPC is used as an FPC by laminating it with a metal base material such as metal foil. Therefore, the laminate structure of the laminate of the present invention will be explained by taking coverlay films for FPCg and UFPC as examples.

The laminated structure of the FPC of the present invention is one in which a metal base material such as copper foil is laminated on one side of a biaxially stretched PAS film via a bismaleimide resin adhesive layer. Taking copper foil as an example of a metal base material, the following two types of laminated structures are basic.

■Copper foil (conductor)/bismaleimide resin (heat-resistant adhesive layer)
/PAS (heat-resistant base material) ■Copper foil (conductor)/bismaleimide resin (heat-resistant adhesive layer)
/PAS (heat-resistant base material)/bismaleimide resin (heat-resistant adhesive layer)/copper foil (conductor) A maleimide resin adhesive layer is formed.

The coverlay film for FPC of the present invention can be used as a coverlay film for various FPCs on which a circuit pattern is formed using ordinary copper foil, but for FPCs whose base film is a biaxially stretched film having the bismaleimide resin adhesive layer. It is particularly effective when applied to , since it can provide high resistance to bending and repeated bending. ? In other words, by creating a structure in which the circuit part is sandwiched between a base film and a coverlay film, and both films are PAS films with the same physical properties, the circuit part is protected, and the circuit part is sandwiched between two PAS films. Since it is located in the center, uneven stress can be prevented or minimized, resulting in improved bending and folding resistance.

Therefore, the following two types of laminated structures are typical when applied to the FPC coverlay film PC of the present invention.

■Coverlay film (PAS/bismaleimide resin)
/FPC [copper foil (conductor)/bismaleimide resin (heat-resistant adhesive layer)/PAS (heat-resistant base material)] or other base film (heat-resistant base material) ■Coverlay film/double-sided FPC [copper foil (conductor) )/bismaleimide resin (heat-resistant adhesive layer)/PAS/bismaleimide resin (heat-resistant adhesive layer)/copper foil (conductor)]/coverlay film (hereinafter referred to as blank space) (method for producing laminate) laminate of the present invention The manufacturing method includes a step of applying a bismaleimide resin in a molten state to at least one side of a PAS sheet melt-extruded from a T-die and then co-biaxially stretching to obtain a biaxially stretched PAS film having a bismaleimide resin layer. In order to obtain a metal-clad laminate such as FPC, a step of hot-pressing a metal base material such as metal foil onto the bismaleimide resin layer and thermosetting it is added.

As described above, the method for producing the laminate of the present invention essentially includes a co-biaxial stretching method in which both the PAS and the bismaleimide resin are biaxially stretched simultaneously. That is, the co-biaxial stretching method in the present invention is a method of biaxially stretching an unstretched PAS sheet coated with a bismaleimide resin.

That is, the method for manufacturing a laminate of the present invention includes the following steps.

■PAS at 280℃~320℃, preferably 300℃~
A process of extruding into a sheet from a T-die at 310°C.

■ The sheet is heated to 110°C or less, preferably 90°C to 110°C.
The process of maintaining the temperature at ℃.

■ At least one side of the sheet has a melting temperature of 90°C to 120°C.
℃ process of applying bismaleimide resin in molten state.

■The process of biaxially stretching a PAS sheet coated with bismaleimide resin to more than four times the area ratio.

A biaxially stretched PAS film having a bismaleimide resin layer can be obtained through the steps (1) to (2) above.

This film can be suitably used as a base film for a metal-clad laminate such as an FPC, or as a coverlay film for an FPC.

In order to manufacture a metal clad laminate such as FPC, the following steps are added in addition to the above steps.

■The process of bonding and laminating a metal base material such as copper foil on the bismaleimide resin layer of a laminated film.

■The process of heat-pressing at 240°C to 280°C to harden the bismaleimide resin.

In the production method of the present invention, PAS is usually 280°C to
Melt extrusion into a sheet through a T-die at a temperature range of 320°C, preferably 300°C to 310°C, then 110°C
Hereinafter, bismaleimide resin is applied in a molten state to one or both sides of the sheet, which is preferably maintained at a temperature in the range of 90°C to 110°C.

The temperature of the PAS sheet is 110℃ or less, preferably 90℃
The reason why the temperature is maintained at 110° C. is that this temperature range is suitable for biaxial stretching, and the viscosity of the bismaleimide resin is within a suitable range for uniformly coating the resin in a molten state.

The co-biaxial stretching method may be either sequential biaxial stretching or simultaneous biaxial stretching, and the stretching temperature is usually 90°C to 110°C. If the stretching ratio is 2 to 4 times in both length and width, and if the area ratio is 4 times or more, but the zero area ratio is less than 4 times, the film will have poor bending resistance, which is not preferable.

Adhesion to metal substrates such as copper foil is performed by heat-pressing the metal substrate to the bismaleimide resin layer of the biaxially stretched film.As for copper foil for FPC, copper foil for printed circuit boards is used during manufacturing. Preferably, one surface is roughened. The temperature conditions at this stage are preferably in the range of 90° C. to 100° C., where the bismaleimide resin is in a molten state, and close contact with the copper foil is achieved by applying pressure with a roll or the like. Continuing to raise the temperature to 240°C to 280°C,
By gradually three-dimensionally curing the bismaleimide resin layer, the formation of the heat-resistant adhesive layer is completed, and a laminate in which each layer is integrated, that is, a flexible printed wiring board can be obtained. Further, under this temperature condition, the biaxially stretched PAS film is simultaneously heat-set.

When using a biaxially oriented PAS film having a bismaleimide resin layer as a coverlay film for FPC, adhesion between the coverlay film and FPC can be achieved by connecting the bismaleimide resin layer of the coverlay film to the copper foil layer of the FPC. The temperature conditions are as follows:
90°C to 100°C, where the bismaleimide resin is in a molten state
A range of 1 is preferable, and close contact with the FPC can be achieved by pressurizing and holding with a roll or the like. Continue to increase the temperature to 24
When the temperature rises from 0°C to 280°C, the bismaleimide resin layer gradually hardens in three dimensions, completing the formation of a heat-resistant adhesive layer, resulting in a laminate in which each layer is integrated, that is, an FPC protected by a coverlay film. can be obtained. Further, under this temperature condition, the biaxially stretched PAS film is simultaneously heat-set.

When the laminate of the present invention is used as an FPC or a cover coverlay film for FPC, the thickness of each layer is such that PAS is 10
-125 um, preferably 20-50 um, 1 bismaleimide resin layer is 3-30 um, preferably 5-10 um,
The copper foil has a thickness of 5 to 70 μm, preferably 18 to 35 μm.

A typical FPC is composed of PAS (33um)/bismaleimide resin layer (6μm)/copper foil (18μm).

In order to form a circuit using the FPC of the present invention, a circuit pattern is formed on one or both sides of the film base through the steps of resist coating, exposure, resist peeling, and etching using a conventional method. Since PAS, which has extremely low water absorption, is used as the material, intermediate drying steps and the like can be largely omitted. In particular, the F of the layer structure of copper foil/bismaleimide resin/PAS film
Since one side of the PC is made of a PAS film, a wide area is protected from chemicals during the process.

After the circuit is formed, the FPC is loaded with electronic components and begins the process later on. During this process, the surface of the metal foil such as copper foil, that is, the side that is in contact with the highly heat-resistant bismaleimide resin layer, receives heat from the solder bath. As a result, the PAS film surface, which has relatively low heat resistance, becomes a heat dissipation surface, so that the soldering heat resistance of the FPC as a whole is improved.

Function: According to the co-biaxial stretching method of the present invention, a strong adhesive effect that cannot be obtained when a bismaleimide resin is applied to a biaxially stretched PAS film can be obtained. Although the details of the mechanism by which such an adhesive effect is obtained by the co-biaxial stretching method are not clear, for example, the following phenomenon occurs and an adhesive interface is formed between the PAS film and the bismaleimide resin layer. It can be assumed that this is due to the following.

■Stable polymer radicals (phenyl radicals or phenyl-
S radical) extracts hydrogen from the molecular chain of the bismaleimide resin and forms a chemical bond at the interface through a radical coupling process.

(2) Under co-biaxial stretching conditions, PAS and bismaleimide resin form molecular chain entanglement (IPN), and as a result, a PAS-bismaleimide resin composite film without interfacial peeling is obtained.

In addition, according to the co-biaxial stretching method, when the polymer chains are pulled out from the amorphous part or spherulite during the stretching process, they form entanglements with other polymer chains coexisting at the interface and are simply heated. It is thought that an interfacial layer was formed that could not be obtained by simply melting, and as a result, heat-resistant adhesion became possible.

In order to form an IPN, it is generally said that compatibility between two types of polymers is required. In the co-biaxial stretching method of the present invention, the interface of the JPN is formed while forcibly moving the polymer chains. In such a case, it is unclear whether thermodynamic compatibility is necessarily required between the two resins. Polyimide with a general structure is compatible with PAS, and for example, Japanese Patent Application Laid-Open No. 53-10651 shows that the two form a polymer alloy and become a material with excellent processability. In this case, it can be assumed that compatibility at the interface is maintained to some extent, considering that no peeling occurs between the two types of polymers.

(Margins below) Examples The present invention will be specifically described below with reference to Examples, but the present invention is not limited to these Examples.

Example 1 PPS resin manufactured by Kureha Chemical Industry ■ (melt viscosity 3.000 voids; measured at 310°C and shear rate 200 sec-')
was extruded into a sheet with an average thickness of 300 microns from a T-Guy with a width of 200 mm at a resin temperature of 310°C, and the surface temperature was reduced to 1.
The temperature is stabilized by passing it in an S-shape between two metal rolls that are controlled to have a temperature of 00°C.
T-resin (trade name: rBT-21704) heated and melted at 100°C is applied to one side of the sheet via an auxiliary roll, and then uniformized using the next two rolls.

With the internal temperature of the continuous biaxial stretching machine controlled at 100°C, the sheet was fed with the BT resin coated side facing up, and the longitudinal magnification was 3.
Continuous stretching was carried out at a film speed of 6 m/sec at a transverse magnification of 3 times.

At the exit of the drawing machine, the roughened surface of an electrolytic copper foil with a thickness of 18 μm was applied to the BT resin surface, pressed tightly with two rolls, and cut into sheets. 240℃
The material is heat-pressed and hardened in a controlled hardening furnace.
A flexible printed circuit board material with a width of 375 mm was created.

The main characteristic values of this FPC were as follows.

Average thickness 57±4μm (copper foil 18μm) Copper foil peel strength 1.8Kg/l 0mm (normal state) (1
80” square) 1.6Kg/10mm (Solder 260℃
After 10 seconds) Soldering heat resistance 〉260℃×30 seconds (J I 5-C-6481) Dimensional change rate -0,12% (MD) -〇, OS% (TD) (IPC-TM-650) Breaking resistance Characteristics 50 times (MD) (25℃) 40 times (TD) MIT method R = 0.38mm 500g conductor width 1.5
mm Surface resistance normal 1.5X10" (J I 5-C-6481) Moisture absorption 1.0X10" Dielectric constant Normal 3.5 (IMHz) (JIS-C-6481) Moisture absorption 3.7 (IMHz) Dissipation factor normal 7x l O-' (IMHz) (J I 5-
C-6481) Moisture absorption 8X 10-' (IMHz) Water absorption 0.3% Gravimetric method (JIS-C-96/23/751 Flame retardancy UL94V-0 Example 2 Same PPS resin and temperature conditions as Example 1 In,
Polyamino bismaleimide resin manufactured by Nippon Polyimide Co., Ltd. (
The same amount of Kerimide R' 601J (trade name) was applied at 100°C, stretched in the same manner and copper foil pasted, and then heat-pressed and hardened in a curing furnace whose center was controlled at 250°C. I did it.

The characteristic values of the obtained FPC were as follows.

Average thickness 57±6μm (copper foil 18μm) Copper foil peel strength 1.9Kg/10mm (normal) (18
0° angle) 1.5Kg/10mm (Solder 260℃ 1
After 0 seconds) Other characteristic values were almost the same as those of Example 1 within the range of measurement accuracy.

Comparative Example 1 Biaxially stretched PPS manufactured under the same manufacturing conditions as Example 1 but omitting the application of BT resin and the pasting of copper foil.
The film was coated with BT resin at 100°C, then 1
An 8 μm electrolytic copper foil was attached and heat-pressed at 240° C. for 40 minutes.

The obtained FPC was significantly curled and lacked flatness compared to that of Example 1.

The copper foil peel strength of the obtained FPC was as follows.

Copper foil peel strength 1.4 Kg/10mm Normal state (1.8Kg/10mm for Example 1) 0, 6 K17
10mm After soldering (Example 1 is 1.6K
g/10+u+) In Comparative Example 1, there was no effect of the adhesive interface formed by the co-biaxial stretching method, so the copper foil peel strength decreased significantly, especially after soldering.

Example 3 Using the same PPS resin and manufacturing conditions as Example 1, the width was 20 mm.
It is extruded into a sheet with an average thickness of 100 microns from a 0mm T-tie and stabilized by passing it in an S-shape between two metal rolls whose surface temperature is controlled to 100℃.
Next, BT resin manufactured by Mitsubishi Gas Chemical (trade name: rBT-21)
70J) heated and melted at 100° C. is coated on one side of the sheet to an average thickness of 60 μm via an auxiliary roll, and is made uniform with the next two rolls.

With the internal temperature of the continuous biaxial stretching machine controlled at 100°C, the sheet was fed with the BT resin coated side facing up, and the longitudinal magnification was 2.
．． Continuous stretching is carried out at a film speed of 6 m/sec, with a lateral magnification of 5 times and a lateral magnification of 2.5 times.

In this way, a coverlay film for FPC with a width of 375 mm was obtained.

On the other hand, after forming a circuit pattern on the FPC material prepared by the method of Example 1 by a conventional method, the above-mentioned coverlay film was superimposed on the surface of the copper foil, which was subjected to adhesive base treatment by a conventional method, and heated at 240 to 260°C. It was heat-pressed and cured.

The main characteristic values of the obtained coverlay film laminated FPC were as follows.

Coverleaf 25±4μm Average thickness of ilm Coverleaf 1.7Kg/10mm (normal state) Ilm and copper foil 1.2Kg/10mm Peel strength (after soldering at 260℃ for 10 seconds) (180
° angle) Soldering heat resistance >260°C x 30 seconds (JIS-C-6481) No peeling or swelling of the coverlay film was observed after soldering.

Example 4 Using the same PPS resin and temperature conditions as in Example 3, the same amount of polyamino bismaleimide resin (trade name "Kelimide R'601J") manufactured by Nippon Polyimide Co., Ltd. was applied at 100°C and stretched in the same manner. The resulting coverlay film was laminated at 250°C, heat-pressed, and cured to form an FPC.
The characteristic values of the FPC (PAS base material, copper foil 18 μm) were as follows.

Coverleaf 24±6μm Average of ilm (Average thickness of adhesive layer 9μm) Thickness Coverleaf 1.6Kg/10mm (Normal state) Ilm and copper foil 1.2Kg/10mm Peel strength (After soldering at 260℃ for 10 seconds) ( 180
(° angle) After coverlaying, I rarely saw any curls or twists in the FPC.

Comparative Example 2 A biaxially stretched PPs film produced under the production conditions of Example 3 but omitting the application of ET resin was coated with 10% BT resin.
A coverlay film was prepared by coating at 0°C. This coverlay film was prepared in the same manner as in Example 3 at a temperature of 240 to 26C.
)”C was laminated and heated and pressed, and the FPC obtained was obtained in Example 3.
Compared to the previous one, the curl was remarkable and the flatness was lacking.

The copper foil peel strength of the obtained FPC was as follows.

Peel strength of coverlay film and copper foil 1, 4 Kg/l 0mm Normal state (1.8Kg/10mm for Example 3) 0, 6
Kg/l 0mm After soldering (Example 3 is
1.6 Kg 710 mm) In Comparative Example 2, there was no effect of the adhesive interface formed by the co-biaxial stretching method, so the copper foil peel strength decreased significantly, especially after soldering.

Effects of the Invention The novel co-biaxial stretching method of the present invention creates a strong bond between the PAS film and the bismaleimide resin layer that is the adhesive layer, resulting in a laminate with excellent heat resistance, moisture resistance, and bending resistance. ,
In particular, a laminate suitable for FPCl and FPC coverlay films can be efficiently obtained. Further, by protecting with the coverlay film of the present invention, the circuit made of metal foil is protected and fixed, and an FPC with improved corrosion resistance, water resistance, bending resistance, etc. can be manufactured.

Claims (6)

[Claims] (1) A laminate having an adhesive layer (B) made of bismaleimide resin on at least one side of a biaxially stretched film (A) made of polyarylene sulfide, the biaxially stretched film (A) made of polyarylene sulfide and A laminate characterized in that the maleimide resin adhesive layer (B) is co-biaxially stretched. (2) The laminate according to claim 1, wherein the laminate is a base film or a coverlay film for a flexible printed wiring board. (3) Polyarylene sulfide at 280°C to 320°C
After melting and extruding it into a sheet, at least one side of the sheet maintained at a temperature of 110°C or less has a melting temperature of 90°C to
A method for producing a laminate, comprising applying a bismaleimide resin at 120° C. in a molten state, and then biaxially stretching the resin to an area ratio of 4 times or more. (4) Biaxially stretched film made of polyarylene sulfide (A), adhesive layer made of bismaleimide resin (B)
and a laminate formed by laminating a metal base material (C),
A laminate characterized in that a polyarylene sulfide biaxially stretched film (A) and a bismaleimide resin adhesive layer (B) are co-biaxially stretched. (5) The metal base material (C) is a metal foil, and the laminate is a polyarylene sulfide biaxially stretched film (
On at least one side of A), a bismaleimide resin adhesive layer (
The laminate according to claim 4, which is a flexible printed wiring board on which metal foil is laminated via B). (6) Polyarylene sulfide at 280°C to 320°C
After melting and extruding it into a sheet, at least one side of the sheet maintained at a temperature of 110°C or less has a melting temperature of 90°C to
Bismaleimide resin at 120°C is applied in a molten state, then biaxially stretched to an area ratio of 4 times or more, and then a metal base material is laminated on the bismaleimide resin layer and heated at 240°C to 200°C.
A method for producing a laminate, characterized in that bonding is carried out by heat compression bonding at 80°C.