JP2008189711A - Laminating film - Google Patents

Abstract

[PROBLEMS] To laminate easily on a material having a low coefficient of thermal expansion such as a metal foil or a thermosetting polyimide resin without causing warpage, and has excellent heat resistance, electrical characteristics and mechanical strength inherent to polyimide. In addition, the present invention provides a film for lamination excellent in various properties such as dimensional stability and heat resistance.
A lamination film obtained by biaxially stretching a thermoplastic polyimide resin film, wherein the film has a thermal expansion in either the MD direction (film longitudinal direction) or the TD direction (film width direction). The rate α _{20-200 is} also in the range of 5 × 10 ⁻⁶ to 30 × 10 ⁻⁶ / K. In a preferred embodiment, the laminating film is obtained by biaxially stretching a film obtained by melt-extrusion of a thermoplastic polyimide resin, and preferably the MD direction and the TD direction. The difference in coefficient of thermal expansion α _20-200 is within 20 × 10 ⁻⁶ / K.
[Selection figure] None

Description

  The present invention relates to a laminating film comprising a biaxially stretched thermoplastic polyimide resin film and having a specific coefficient of thermal expansion.

  Aromatic polyimides are widely used in various industrial fields such as the electric / electronic industry, aircraft industry, and nuclear power industry because of their excellent heat resistance, mechanical properties, chemical properties, and environmental resistance properties. In particular, in the electronics industry, a flexible printed wiring board as a three-layer substrate bonded to copper foil using an adhesive such as an epoxy resin, or tape automated bonding (TAB) that can be said to be a kind of flexible printed wiring board. ) Although widely used in the manufacture of products, there is a problem that the use of an adhesive increases the dielectric constant and decreases the heat resistance.

In recent years, thermoplastic polyimide resins that can be melt-molded, such as extrusion molding and injection molding, and have excellent cost performance have been developed, and various stretched films have been proposed (patents). References 1-4).
JP-A-5-154909 (Claims) JP-A-5-169526 (Claims) Japanese Patent Laid-Open No. 7-178804 (Claims) Japanese Patent Laid-Open No. 7-246652 (Claims)

According to the research of the present inventors, by the development of a film of a thermoplastic polyimide resin that can be melt-molded, it can be bonded to various substrates by a simple laminating method using heat melting property without using an adhesive. It has been found that the problems associated with the use of the adhesive can be solved.
However, when a thermoplastic polyimide resin film is used, because it is thermoplastic, it has a higher coefficient of thermal expansion than conventional thermosetting polyimide resins, and if it is laminated with a metal foil or the like having a low coefficient of thermal expansion, warping tends to occur. There's a problem.

That is, since the thermal expansion coefficient of the thermoplastic polyimide resin is as large as 40 × 10 ^{−6 to} 60 × 10 ⁻⁶ / K, when it is laminated with a metal foil of about 20 × 10 ⁻⁶ / K, it is dimensioned when cooled to room temperature. Differences cause warping and, if severe, curl.
As described above, various types of stretched films of thermoplastic polyimide resin have been proposed in the past, but the aim is mainly on the dimensional stability and heat resistance of the stretched film itself. None of the problems of warping in laminating to a material having a low coefficient of thermal expansion such as a conductive polyimide resin have been studied.

  Therefore, the main object of the present invention is to laminate on a material having a low coefficient of thermal expansion such as a metal foil or a thermosetting polyimide resin, and can be easily laminated without causing warpage. An object of the present invention is to provide a film for lamination excellent in various characteristics such as dimensional stability and heat resistance in addition to electrical characteristics and mechanical strength.

In order to achieve the above object, according to the present invention, a film for lamination obtained by biaxially stretching a thermoplastic polyimide resin film, the film being in the MD direction (film longitudinal direction) and the TD direction. Any thermal expansion coefficient α _{20-200 in the} (film width direction) is in the range of 5 × 10 ⁻⁶ to 30 × 10 ⁻⁶ / K.

In a preferred embodiment, the laminating film is obtained by biaxially stretching a film obtained by melt extrusion molding a thermoplastic polyimide resin, preferably in the MD direction (film longitudinal direction). And the TD direction (film width direction) _have a difference in coefficient of thermal expansion α _20-200 within 20 × 10 ⁻⁶ / K. More preferably, the laminating film preferably has a glass transition temperature Tg of 10 to 80 ° C. higher than the glass transition temperature Tg of the thermoplastic polyimide resin film before stretching. In addition, the glass transition temperature Tg as used in this specification means the glass transition temperature measured according to the method described in "5.17.1 TMA method" of JISC6481: 1996 by thermomechanical analysis (TMA). .

In another preferred embodiment, the thermoplastic polyimide resin is a crystalline thermoplastic polyimide resin, or alternatively, a crystalline thermoplastic polyimide resin and another thermoplastic resin having a melting point of 280 ° C to 350 ° C. Consists of a mixture. Further, the thermoplastic polyimide resin has a glass transition temperature (Tg) of 180 to 280 ° C., or a shear in the range of 50 to 500 [sec ⁻¹ ] at an extrusion temperature 30 ° C. higher than the melting point of the resin. It is preferable that the melt viscosity measured by the speed is 5 × 10 ¹ to 1 × 10 ⁴ [Pa · S]. Here, the melt viscosity [Pa · S] of the thermoplastic polyimide resin is a value measured using a Shimadzu flow tester CFT-500 in accordance with JIS K-7199, but is not limited thereto. Any value that can be measured under the same conditions may be used.

  In a more specific preferred embodiment, the crystalline thermoplastic polyimide resin is a thermoplastic polyimide resin having a repeating structural unit of the general formula (1) described later, preferably a repeating structural unit of the formula (6) described later. . More preferably, the thermoplastic polyimide resin has repeating structural units of formula (6) and formula (7) described later, the number of moles m of the structural unit of formula (6) and the number of moles of the structural unit of formula (7). The ratio n / m is a thermoplastic polyimide resin contained in a ratio of 4 to 9. Moreover, in another suitable aspect, it is a thermoplastic polyimide resin which has a repeating structural unit of Formula (6) and Formula (8) which will be described later, and a repeating structural unit represented by Formula (6) which will be described later. A thermoplastic polyimide resin having a molar ratio with the repeating structural unit represented by the formula (8) in the range of 1: 0 to 0.75: 0.25.

The film for lamination of the present invention is obtained by biaxially stretching a thermoplastic polyimide resin film, and has a coefficient of thermal expansion α _20-200 in the MD direction (film longitudinal direction) and TD direction (film width direction). (Hereinafter simply referred to as the coefficient of thermal expansion) is adjusted so as to be within the range of 5 × 10 ⁻⁶ to 30 × 10 ⁻⁶ / K (hereinafter referred to as ppm / K). There is little or little difference in thermal expansion coefficient from the material to be laminated such as thermosetting polyimide resin, it can effectively prevent warpage occurring during lamination, has excellent adhesive strength, and polyimide In addition to the inherently excellent heat resistance, electrical characteristics, and mechanical strength, a laminate excellent in various characteristics such as dimensional stability and heat resistance can be provided. In particular, the laminating film comprises a biaxially stretched thermoplastic polyimide resin film obtained by further biaxially stretching a thermoplastic polyimide resin film obtained by melt extrusion molding a crystalline thermoplastic polyimide resin. In this case, a high-purity biaxially stretched thermoplastic polyimide resin film free from impurities such as monomer residues and residual solvents can be produced. In addition, a biaxially stretched thermoplastic polyimide resin film having a difference in thermal expansion coefficient between the MD direction and the TD direction within 20 ppm / K can be easily produced, and more uniform lamination is possible without causing warpage. It becomes. Furthermore, by biaxially stretching the thermoplastic polyimide resin film, the glass transition temperature Tg can be 10 to 80 ° C. higher than the glass transition temperature Tg of the unstretched thermoplastic polyimide resin film. improves.

  Furthermore, according to a preferred aspect of the present invention, the film for lamination is a crystalline thermoplastic polyimide resin, particularly a thermoplastic polyimide resin having a repeating structural unit of the formula (6) described later, more preferably a formula ( 6) Since the film of the thermoplastic polyimide resin containing the repeating structural unit of the formula (7) is biaxially stretched, the thermoplastic polyimide resin before stretching is used by utilizing the thermoplasticity of these polyimide resins. Physical state of softening and solidification by heating and pressing at a glass transition temperature Tg or higher, preferably a glass transition temperature Tg or higher and a melting point or lower, preferably 300 to 380 ° C., of a biaxially stretched thermoplastic polyimide resin film It can be easily stacked using the change. In particular, in the case of a mixture of a crystalline thermoplastic polyimide resin and another thermoplastic resin that is molten at the lamination processing temperature, preferably another thermoplastic resin having a melting point of 280 to 350 ° C., the adhesive strength at the time of lamination Can be further improved.

The film for laminating of the present invention is obtained by biaxially stretching a thermoplastic polyimide resin film, and there is little or little difference in thermal expansion coefficient from a material to be laminated such as metal foil and thermosetting polyimide resin. Thus, the thermal expansion coefficient in both the MD direction (film longitudinal direction) and the TD direction (film width direction) is adjusted to be in the range of 5 to 30 ppm / K.
As described above, when laminated on a metal foil or the like using a thermoplastic polyimide resin film, it has a higher thermal expansion coefficient than conventional thermosetting polyimide resins because it is thermoplastic. When they are laminated to each other, a dimensional difference is produced when they are cooled to room temperature, resulting in warping. In severe cases, curling occurs, and it is difficult to produce a laminate having excellent dimensional stability.
As a result of further research on such a phenomenon, the inventors of the present invention, when biaxially stretching a crystalline thermoplastic polyimide resin film, adjusting its temperature, stretching speed, and stretching ratio, its thermal expansion. The rate can be reduced to about 20 ppm / K equivalent to copper foil or thermosetting polyimide resin film or the vicinity thereof, and the glass transition temperature Tg can be increased by biaxial stretching. It has been found that the rigidity is maintained even at a temperature of 300 ° C. or higher, and the present invention has been completed.

That is, by biaxially stretching the thermoplastic polyimide resin film, the thermoplastic polyimide resin is molecularly oriented isotropically in the plane direction of the film, and the coefficient of thermal expansion is reduced. By adjusting the stretching ratio, particularly the stretching temperature, it can be adjusted so as to be reduced to a thermal expansion coefficient equivalent to that of the copper foil or thermosetting polyimide resin film.
In addition, by heating while restricting shrinkage after biaxial stretching to fix the molecular orientation (heat setting), the original thermal expansion coefficient can be obtained even in the temperature range exceeding the glass transition temperature Tg of the thermoplastic polyimide resin before stretching. Without returning to the above, in the temperature range of the glass transition temperature Tg or more and the melting point or less, the heat bonding can be performed while maintaining the reduced coefficient of thermal expansion. Further, the residual stress of the film generated during extrusion molding is also removed, and the film has excellent dimensional stability without causing a dimensional change even after being heated and cooled to a temperature capable of bonding. Thus, it is possible to laminate with good dimensional accuracy and dimensional stability without causing warp or the like when laminating to a metal foil or a conductor circuit.

  Further, it is possible to increase the glass transition temperature by biaxially stretching the thermoplastic polyimide resin film. For example, the thermoplastic polyimide resin film having a glass transition temperature Tg of 258 ° C. is biaxially stretched. The temperature rises to 305 ° C. By biaxially stretching the thermoplastic polyimide resin film, the glass transition temperature can be improved by 10 to 80 ° C., and the rigidity is maintained even at a temperature of 300 ° C. or higher. As a result, the softening of the film does not start even at a temperature exceeding the glass transition temperature Tg before stretching. For example, when used for a printed wiring board, the solder heat resistance during solder reflow is also improved.

The glass transition temperature can be measured by a TMA test that measures the coefficient of thermal expansion. Hereinafter, description will be given with reference to the accompanying drawings.
FIG. 1 is a schematic diagram showing TMA curves of an unstretched thermoplastic polyimide resin film and a stretched thermoplastic polyimide resin film. As apparent from FIG. 1, the glass transition temperature Tg is improved by biaxially stretching the thermoplastic polyimide resin film. The glass transition temperature Tg is an intersection of a tangent line with a slowly increasing thermal expansion coefficient and a tangent line with a rapidly rising line segment.

Next, biaxial stretching of the thermoplastic polyimide resin film will be described.
The stretching step can be either simultaneous biaxial stretching or sequential biaxial stretching, and the stretching temperature is preferably in the range of 250 to 275 ° C. If the stretching temperature is too low, the stretching stress is strong and stretching is not possible, or the film is torn or unevenly stretched during the stretching process. On the other hand, if the stretching temperature is too high, the molecular orientation is small and the effect of reducing the thermal expansion coefficient due to stretching does not appear.
The stretching ratio is preferably in the range of 2.5 to 5 times. If the draw ratio is too low, the molecular orientation is insufficient and the coefficient of thermal expansion does not decrease, or wrinkles occur in the film during heat setting. On the other hand, when the draw ratio is too high, problems such as breakage of the film during stretching occur.

The stretching speed is preferably in the range of 100 to 1000% / min. When the stretching speed is low, the molecular orientation is small and the coefficient of thermal expansion does not decrease. On the other hand, there is an upper limit to the stretching speed due to the limitations of the stretching equipment.
Next, as the heat setting conditions, the heating temperature is 280 to 380 ° C., preferably 290 to 330 ° C., the limited shrinkage is 2 to 20%, preferably 4 to 10%, and the time is within the range of 1 to 5000 minutes. Can be set arbitrarily. When the heat setting temperature is too low, a large dimensional change occurs when the stretched film is reheated. On the other hand, when the heat setting temperature is higher than the melting point, the molecular orientation formed by stretching is canceled.

  As a biaxial stretching method, a conventionally known method such as a method of stretching using a plurality of roll groups, a method of stretching using a tenter, a stretching method by rolling using a roll, a tubular stretching method, or the like may be used. it can. Stretching methods using tenters that are often used in industry include sequential stretching in which the machine direction and the orthogonal direction are stretched in two stages, respectively, and simultaneous stretching in which the machine direction and the orthogonal direction are simultaneously stretched. Biaxial stretching may be performed by this method.

  In the case of sequential biaxial stretching, first, a thermoplastic polyimide resin film to be stretched is preheated at 250 to 275 ° C., and is stretched 2 to 5 times in one direction while being uniformly heated to a predetermined temperature. Next, the film is stretched 2 to 5 times in one direction in a direction perpendicular to the stretching direction in a temperature range of 250 to 275 ° C. Next, the film is heat-set under tension in a temperature range of 280 to 380 ° C. In heat setting, the film is contracted after stretching, but the film is cooled while being gradually contracted to 2 to 20% while maintaining a tension state in which the contraction is restricted.

  In the case of simultaneous biaxial stretching, the thermoplastic polyimide resin film to be stretched is preheated at 250 to 275 ° C., and is heated to a predetermined temperature uniformly, and simultaneously 2 to 5 times in two directions perpendicular to each other. Stretch. Next, the film is heat-set under tension in a temperature range of 280 to 380 ° C. In heat setting, the film is contracted after stretching, but the film is cooled while being gradually contracted to 2 to 20% while maintaining a tension state in which the contraction is restricted.

  By biaxially stretching the thermoplastic polyimide resin film as described above, the thermal expansion coefficient in both the MD direction and the TD direction is in the range of 5 to 30 ppm / K, preferably 10 to 25 ppm / K. A biaxially stretched thermoplastic polyimide resin film having a difference in thermal expansion coefficient between the MD direction and the TD direction within 20 ppm / K can be produced, and the warp generated when laminating with a metal foil or the like is effectively prevented. Can be prevented. Furthermore, by biaxially stretching the thermoplastic polyimide resin film, the glass transition temperature Tg can be 10 to 80 ° C. higher than the glass transition temperature Tg of the unstretched thermoplastic polyimide resin film. improves. In addition, it can maintain a low coefficient of thermal expansion even when subjected to a thermal history below the melting point, while maintaining good dimensional stability and necessary adhesive strength, while selecting appropriate lamination conditions, There is no resin flow out.

The biaxially stretched thermoplastic polyimide resin film obtained as described above is not in a state where it is completely melted in a material to be heated such as a copper foil, a conductor circuit layer, a polyimide film, etc. Lamination can be easily carried out by heating and pressing at a glass transition temperature Tg or higher of the plastic polyimide resin, preferably at or above the glass transition temperature Tg of the biaxially stretched thermoplastic polyimide resin film, and below the melting point, preferably 300 to 380 ° C. can do. The higher the laminating pressure, the lower the laminating temperature can be. However, generally, when the laminating pressure is too high, the resulting laminate tends to change dimensions, so the range of 5-50 kgf / cm ² is appropriate. It is.

The following points are mentioned as characteristics of the production of a flexible laminate by such a laminating method.
(1) Rather than laminating by imidization reaction or resin curing reaction of polyamic acid, lamination is performed utilizing the physical state change of softening and solidification by heating press using the thermoplasticity of polyimide resin. Lamination by imidization reaction causes voids due to gas generation and warpage of the laminate, but these problems do not occur because the thermoplasticity of the biaxially stretched thermoplastic polyimide resin film is used.
(2) A felt-like cushioning material having heat resistance between a pressure plate arranged in contact with the material to be heated and a pressure plate of the press machine, preferably an aromatic polyamide or polybenzoxazole, during heating press By interposing the felt-shaped cushion material, a laminate having a smooth and uniform thickness can be obtained even in a large area.
(3) Since the biaxially stretched thermoplastic polyimide resin film that has already been formed is simply heat-pressed, the process is simple. Further, the substrate on which the circuit is formed can be further laminated. Further, by stacking a plurality of layers, multilayer stacking can be performed in one step.
(4) A laminate having the inherent heat resistance, electrical characteristics, and mechanical strength of polyimide can be obtained without using an adhesive having poor heat resistance. Accordingly, it is possible to produce an all polyimide laminate. Moreover, in the lamination of the metal foil or conductor layer and the thermoplastic polyimide resin film, a circuit board having high adhesive strength can be obtained.

As the thermoplastic polyimide resin film before biaxial stretching, a thermoplastic polyimide resin film obtained by melt extrusion molding of a thermoplastic polyimide resin, or a thermoplastic polyimide resin film obtained by a conventional casting method Any of them can be used, but the following advantages are obtained particularly in the case of a thermoplastic polyimide resin film obtained by melt extrusion molding a thermoplastic polyimide resin.
(1) A polyimide resin film can be formed by a T-die extrusion method excellent in mass productivity.
(2) Since the imidization reaction has already been completed in the resin pellet production stage, it is not necessary to carry out an imidization reaction during film formation, and a high-purity thermoplastic polyimide resin free from impurities such as monomer residues and residual solvents. A film can be used.
(3) Since the purity of the thermoplastic polyimide resin film is high, it is excellent in migration resistance.

As a material of the thermoplastic polyimide resin film used in the present invention, what is called a thermoplastic polyimide resin or a polyetherimide resin as described later can be used, and these are used alone or in combination of two or more. May be used. In the present specification, the term “thermoplastic polyimide resin” should be understood to include thermoplastic polyimide resin and polyetherimide resin, and the term “thermoplastic polyimide resin film” refers to thermoplastic ( It means a polyimide resin film having thermoreversibility of curing and softening. The logarithmic viscosity of the thermoplastic polyimide resin used in the present invention is not particularly limited, but it is generally about 0.35 to 1.30 dl / g, preferably about 0.40 to 1.00 dl / g. When the logarithmic viscosity is lower than the above range, the resin has a low molecular weight and is inferior in characteristics. On the other hand, when the logarithmic viscosity is too high, the resin has a too high molecular weight, resulting in difficulty in fluidity during extrusion. Therefore, it is not preferable. The logarithmic viscosity of the thermoplastic polyimide resin is the same as that obtained by dissolving the sample in a mixed solvent of 9 parts by volume of phenol and 1 part by volume of p-chlorophenol (concentration 0.5 g / dl) and the viscosity of the mixed solvent, respectively. It is a value measured at 30 ° C. using a formula viscometer and calculated by the following mathematical formula (1).

[Wherein, t is the drop time (sec) of the solution, t ₀ is the drop time (sec) of the mixed solvent, and C is the solution concentration (g / dl). ]

Examples of the thermoplastic polyimide resin include those having a repeating structural unit represented by the following general formula (1).
In the general formula (1), X is a direct bond, —SO ₂ —, —CO—, —C (CH ₃ ) ₂ —, —C (CF ₃ ) ₂ — or —S—, and R ¹ , R ² , R ³ and R ⁴ each independently represent a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, an alkoxy group, a halogenated alkyl group, a halogenated alkoxy group, or a halogen atom, and Y represents the following formula (2) A group selected from the group consisting of:

  The thermoplastic polyimide resin having the repeating structural unit represented by the above general formula (1) is an organic material using an ether diamine of the following general formula (3) and a tetracarboxylic dianhydride of the following general formula (4) as raw materials. It can be produced by reacting in the presence or absence of a solvent and imidating the resulting polyamic acid chemically or thermally. These specific manufacturing methods can utilize the conditions of a known polyimide manufacturing method.

In the general formula (3), R ¹ , R ² , R ³ and R ⁴ each have the same meaning as the symbol in the formula (1).

In the said General formula (4), Y shows the same meaning as the symbol in the said General formula (1).

Specific examples of R ¹ , R ² , R ³ , and R ^{4 in} the general formula (1) and general formula (3) include alkyl groups such as hydrogen atom, methyl group, and ethyl group, methoxy group, ethoxy group, and the like. And a halogenated alkyl group such as a fluoromethyl group and a trifluoromethyl group, a halogenated alkoxy group such as a fluoromethoxy group, and a halogen atom such as a chlorine atom and a fluorine atom. Preferably, it is a hydrogen atom. X in the formula is a direct bond, —SO ₂ —, —CO—, —C (CH ₃ ) ₂ —, —C (CF ₃ ) ₂ — or —S—, preferably a direct bond, — _{SO 2 -, - CO -,} - C (CH 3) 2 - a.
Moreover, in the said General formula (1) and General formula (4), Y is what is represented by the said Formula (2), Preferably it is what uses the pyromellitic dianhydride as an acid dianhydride. is there.

A more preferable thermoplastic polyimide resin is a thermoplastic polyimide resin having a repeating structural unit represented by the following formula (5).

In addition, the thermoplastic polyimide resin which has a repeating structural unit represented by the said Formula (5) can be purchased as Mitsui Chemicals, Inc. make: brand name "Aurum".

  Moreover, the thermoplastic polyimide resin which has a repeating structural unit of following formula (6) and Formula (7) is also mentioned as a preferable specific example.

  In the above formulas (6) and (7), m and n mean the molar ratio of each structural unit (not necessarily a block polymer), and m / n is 4-9, more preferably 5-9, More preferably, the number is in the range of 6-9.

  The thermoplastic polyimide resin having the repeating structural unit of the formula (6) and the formula (7) is reacted in the presence or absence of an organic solvent using the corresponding ether diamine and tetracarboxylic dianhydride as raw materials. The resulting polyamic acid can be produced by imidizing chemically or thermally. These specific manufacturing methods can utilize the conditions of a known polyimide manufacturing method.

In the present invention, instead of the thermoplastic polyimide resin having the repeating structural unit represented by the general formula (1) or in combination with the resin, the heat having the repeating structural unit represented by the following formula (8). It is also preferable to use a plastic polyimide resin. Further, it is also preferable to use a copolymer of a monomer having a structural unit represented by the formula (6) and a monomer having a structural unit represented by the following formula (8). In this case, the copolymer represented by the formula (6) is used. As for the molar ratio of the repeating structural unit represented by the following formula (8), a ratio of 1: 0 to 0.75: 0.25 is appropriate.

  The thermoplastic polyimide resin having the repeating structural unit of the above formula (8) was obtained by reacting each of the corresponding ether diamine and tetracarboxylic dianhydride as raw materials in the presence or absence of an organic solvent. Polyamic acid can be produced by chemically or thermally imidizing. These specific manufacturing methods can utilize the conditions of a known polyimide manufacturing method.

Examples of the polyetherimide resin include those having a repeating structural unit represented by the following general formula (9).

In the general formula (9), D is a trivalent aromatic group, and E and Z are both divalent residues.

  The polyetherimide resin having the repeating structural unit of the general formula (9) was obtained by reacting the corresponding ether diamine and tetracarboxylic dianhydride as raw materials in the presence or absence of an organic solvent. Polyamic acid can be produced by chemically or thermally imidizing. These specific manufacturing methods can utilize the conditions of a known polyimide manufacturing method.

  Specific examples of the polyetherimide resin include polyetherimide resins having at least one repeating structural unit selected from repeating structural units represented by the following general formulas (10) to (12).

In the general formulas (10) to (12), the symbol E is a divalent aromatic residue such as a group represented by the following formula.

The polyetherimide resin that is particularly preferably used is a polyetherimide resin having a repeating structural unit represented by the following formula (13).
The polyetherimide resin having a repeating structural unit represented by the above formula (13) can be purchased as ULTEM (registered trademark) manufactured by GE.

  The diamine or tetracarboxylic dianhydride used as the raw material for the thermoplastic polyimide resin as described above can be used alone or in combination, and contains other copolymerization components as long as the object of the present invention is not impaired. Can do. Further, a plurality of polyimide resins obtained from different monomers may be arbitrarily polymer blended as long as the object of the present invention is not impaired.

  Other resins may be added to the thermoplastic polyimide resin used in the present invention. For example, polyamide resin, preferably wholly aromatic polyamide resin, polyamideimide resin, polyarylate resin, polyether nitrile resin, polyphenylene sulfide resin, polyether sulfone resin, polyether ether ketone resin, liquid crystal polymer, etc. May be included as long as it does not harm. In particular, in the case of a mixture of a crystalline thermoplastic polyimide resin and another thermoplastic resin that is molten at the lamination processing temperature, preferably another thermoplastic resin having a melting point of 280 to 350 ° C., the adhesive strength at the time of lamination Can be further improved.

  The thermoplastic polyimide resin film of the present invention is further provided with additives such as a colorant, a release agent, various stabilizers, a plasticizer, a lubricant, various inorganic fillers, oils and the like within the range in which the object of the present invention can be achieved. You may make it contain.

The melt viscosity that can be formed into a film by extrusion molding is 5 × 10 ¹ to 1 × 10 ⁴ [Pa · S], preferably 4 × 10 ² to 3 × 10 ³ [Pa · S]. When the melt viscosity is less than 5 × 10 ¹ [Pa · S], drawdown after discharging from the die is remarkable, and film production becomes impossible. On the other hand, when the melt viscosity exceeds 1 × 10 ⁴ [Pa · S], the load applied to the extrusion screw at the time of melting is large, or the discharge from the die becomes difficult, and the production of the film becomes impossible.

Next, the manufacturing process of a thermoplastic polyimide resin film will be described.
The polyimide resin film of the present invention can be produced by molding by a melt extrusion molding method. For example, polyimide resin pellets or powder and optionally other resins and additives are dry-mixed by a Henschel mixer, a ribbon blender, or the like, and then melted, kneaded and extruded by a twin-screw kneading extruder. The extruded strand is cooled in water and cut to obtain a pellet of the mixture. Next, after removing the adsorbed moisture by heating and drying the obtained pellets, it is heated and melted with a single screw or twin screw extruder, and discharged from a T die provided at the tip of the extruder into a flat film shape, A polyimide resin film is obtained by contacting or pressure bonding with a cooling roll to cool and solidify. Moreover, the method of extruding a pellet or powder directly, without kneading | mixing may be used.
The thickness of the thermoplastic polyimide resin film is not particularly limited, and is usually 10 μm to 1 mm, preferably 20 μm to 400 μm.

The polyimide resin film generally used is obtained by performing a dehydration condensation reaction after casting a solution containing polyamic acid on a roll or a base film. Therefore, the monomer and solvent at the time of the polymerization reaction remain, which is accompanied by a decrease in electrical characteristics and transparency.
On the other hand, for the thermoplastic polyimide resin film, a pellet manufacturing process by kneading extrusion is once required before performing T-die extrusion. The monomer residue and solvent remaining in the polyimide resin after the polymerization reaction and dehydration condensation reaction process are removed by melt-kneading during the pellet manufacturing process, so that the electrical properties and mechanical strength inherent to the polyimide resin material itself are fully exhibited. In addition, a highly transparent thermoplastic polyimide resin film can be obtained.

  When the biaxially stretched thermoplastic polyimide resin film of the present invention obtained by further stretching the thermoplastic polyimide resin film produced as described above is subjected to thermocompression bonding with a copper foil, a conductor layer, or a normal polyimide resin film It is possible to further increase the adhesive strength by performing a modification treatment on the film surface. As surface modification treatment, general surface treatments such as corona discharge treatment, plasma treatment, ozone treatment, excimer laser treatment, and alkali treatment are possible. From the viewpoint of cost and treatment effect, corona discharge treatment, plasma Treatment is preferred.

Next, several embodiments in which the film for lamination of the present invention is applied to a flexible laminated substrate will be described with reference to the drawings.
First, FIGS. 2 and 3 show two structures of a flexible double-sided copper-clad laminate.
The flexible double-sided copper-clad laminate shown in FIG. 2 has the biaxially stretched thermoplastic polyimide resin film 1 superimposed on the treated side of a copper foil 2 having at least one surface roughened or adhesively treated. It is obtained by superposing the treatment side of the copper foil 2 having at least one surface roughened or adhesively treated on the opposite surface of the plastic polyimide resin film 1 and heating and pressing.

  On the other hand, in the flexible double-sided copper-clad laminate shown in FIG. 3, the biaxially stretched thermoplastic polyimide resin film 1 is superimposed on both sides of the polyimide resin film 3 which has been subjected to no treatment or adhesion treatment on both sides, and further on the outside. It is obtained by stacking the processing side of the copper foil 2 having at least one surface roughened or adhesively processed inward and heating and pressing.

  Next, FIG. 4 shows an embodiment in which a biaxially stretched thermoplastic polyimide resin film is used as a bonding sheet for circuit embedding. In this multilayer flexible laminate, the biaxially stretched thermoplastic polyimide resin film is formed between the double-sided flexible substrates in which the conductor circuit layers 4 are formed on both sides of the polyimide resin film 3 and no treatment or adhesion treatment is performed on both sides. It is obtained by sandwiching 1 and heating and pressing.

  Finally, FIG. 5 shows an embodiment in which a biaxially stretched thermoplastic polyimide resin film is used as an interlayer insulating material for circuit embedding. In this multilayer flexible laminate, conductor circuit layers 4 are formed on both sides of a polyimide resin film 3, and the biaxially stretched thermoplastic polyimide resin film 1 is disposed outside a double-sided flexible substrate that has been subjected to no treatment or adhesion treatment on both sides. Are obtained by stacking them so that the treated side of the copper foil 2 on which at least one surface is roughened or adhesively treated is inside, and heating and pressing.

Moreover, the following application examples are also possible for the lamination film of the present invention.
(1) It can be used as a coverlay film for various flexible substrates and planar heating elements.
(2) It can be laminated with a metal foil such as copper, stainless steel, aluminum and nickel, and can be preferably used as a laminated material with a copper foil. In addition, interlayer connection can be simultaneously performed by penetrating an insulating layer (biaxially stretched thermoplastic polyimide resin film) on the surface of the metal foil using a metal paste or metal bump.
(3) Batch multilayer lamination is possible, and lamination can be performed in one step.
(4) Sequential lamination is possible. For example, sequential lamination is possible by sequentially using biaxially stretched thermoplastic polyimide resin films having different Tg. In addition, after laminating with a biaxially stretched thermoplastic polyimide resin film having a high Tg first, a biaxially stretched thermoplastic polyimide resin film having a low Tg is sequentially laminated, but the number of times of lamination is limited. Is possible.

  EXAMPLES The present invention will be specifically described below with reference to examples and the like, but the present invention is not limited to these examples. The present invention can be carried out in various modifications, changes and modifications based on the knowledge of those skilled in the art without departing from the spirit of the present invention.

Example 1
Thermoplastic polyimide having the chemical structural formula (6) (Aurum (registered trademark) PD450C manufactured by Mitsui Chemicals, Inc .; Tg 250 [° C.], melting point 388 [° C.], melting measured at a shear rate of 500 sec ⁻¹ The pelletized resin material having a viscosity of 500 [Pa · S] is dried to remove adsorbed moisture, and then heated and melted with a single screw extruder, and a flat film is formed from a T die provided at the tip of the extruder. The film was discharged in a shape and brought into contact with a cooling roll to be cooled and solidified to obtain a thermoplastic polyimide resin (hereinafter abbreviated as TPI) film (A).
The obtained thermoplastic polyimide resin film (A) was heated to 260 ° C., and a three-fold stretching operation was performed in two directions perpendicular to each other. The obtained stretched film was heat-set under tension at 300 ° C. to obtain the intended biaxially stretched thermoplastic polyimide resin film (A-3). In addition, "-3" of the sign (A-3) is attached so that it can be easily understood that the stretching is 3 times (hereinafter the same).

Example 2
Thermoplastic polyimide having a chemical structural formula of the above formulas (6) and (7) in a ratio of 9: 1 (Aurum (registered trademark) PD500A manufactured by Mitsui Chemicals, Inc .; Tg258 [° C], melting point 380 [° C] The thermoplastic polyimide was prepared in the same manner as in the film production process shown in Example 1, except that a pelletized resin material having a melt viscosity of 700 [Pa · S] measured at a shear rate of 500 sec ⁻¹ was used. A resin film (B) was obtained.
The obtained thermoplastic polyimide resin film (B) was heated to 260 ° C., and a three-fold stretching operation was performed in two directions perpendicular to each other. The obtained stretched film was heat-set under tension at 300 ° C. to obtain the intended biaxially stretched thermoplastic polyimide resin film (B-3).

Example 3
Thermoplastic polyimide (Aurum (registered trademark) PD450C manufactured by Mitsui Chemicals, Inc.) having the chemical structural formula (6) and polyether ether ketone resin (Victrex Thermoplasticity is the same as the film manufacturing process shown in Example 1 except that a resin material pelletized from an 80:20 blend with a product name “450P” manufactured by MC Co., Ltd. is used. A polyimide resin film (C) was obtained.
The obtained thermoplastic polyimide resin film (C) was heated to 260 ° C., and a three-fold stretching operation was performed in two directions perpendicular to each other. The obtained stretched film was heat-set under tension at 300 ° C. to obtain the intended biaxially stretched thermoplastic polyimide resin film (C-3).

Example 4
The both sides of the biaxially stretched thermoplastic polyimide resin film (A-3) produced according to Example 1 were subjected to corona discharge treatment to obtain the desired biaxially stretched thermoplastic polyimide resin film (D-3). In addition, the corona discharge process to the film surface was performed on the conditions of the watt density of 120 W / m < ² > per minute using the corona treatment apparatus by Sakai Kogyo Co., Ltd.

Comparative Example 1
In Example 1, a biaxially stretched thermoplastic polyimide resin film (A-2) was produced in the same manner as in Example 1 except that it was stretched twice.

Comparative Example 2
Using the pelletized resin material of thermoplastic polyimide (Aurum (registered trademark) PD450C manufactured by Mitsui Chemicals, Inc.) whose chemical structural formula is the above formula (6), similar to the film manufacturing process shown in Example 1 Through the operation, a thermoplastic polyimide resin film (A) was obtained.
The obtained thermoplastic polyimide resin film (A) was heated to 280 ° C., and a three-fold stretching operation was performed in two directions perpendicular to each other. The obtained stretched film was heat-set under tension at 310 ° C. to obtain a biaxially stretched thermoplastic polyimide resin film (E-3).

Comparative Example 3
Using the pelletized resin material of thermoplastic polyimide (Aurum (registered trademark) PD450C manufactured by Mitsui Chemicals, Inc.) whose chemical structural formula is the above formula (6), similar to the film manufacturing process shown in Example 1 Through the operation, a thermoplastic polyimide resin film (A) was obtained.
The obtained thermoplastic polyimide resin film (A) was heated to 260 ° C., and an operation of stretching three times in only one direction was performed. The obtained stretched film was heat-set under tension at 300 ° C. to obtain a uniaxially stretched thermoplastic polyimide resin film (F-3).

Table 1 summarizes the thermal expansion coefficient α _20-200 and the glass transition temperatures (Tg) before and after stretching of the stretched thermoplastic polyimide resin films obtained in Examples 1 to 4 and Comparative Examples 1 to 3. Moreover, the data of an unstretched thermoplastic polyimide resin film (A) are also shown for reference. In addition, about the thermal expansion coefficient, it measured with the following method using the linear expansion coefficient (CTE) from the point of the two-dimensional shape of a film. The glass transition temperature (Tg) was determined by the following measurement method by thermomechanical analysis (TMA).

<Linear expansion coefficient (CTE)>
Using a thermomechanical measuring device TMA-60 manufactured by Shimadzu Corporation, the coefficient of thermal expansion up to 20 to 200 ° C. was measured at a heating rate of 5 ° C./min under a tensile load of 2 × 23 mm and a test piece of 5 gf.

<Tg by TMA measurement method>
In accordance with the method described in “5.17.1 TMA method” of JIS C 6481: 1996, using a thermomechanical measuring device TMA-60 manufactured by Shimadzu Corporation, a tensile load of 2 × 23 mm and a test piece of 5 gf Below, the glass transition temperature Tg was measured under the condition of a heating rate of 5 ° C./min.

As shown in Table 1 above, in the case of the biaxially stretched thermoplastic polyimide resin film (A-2), the coefficient of thermal expansion could not be sufficiently reduced even when biaxially stretched because the stretch ratio was low. On the other hand, in the case of the biaxially stretched thermoplastic polyimide resin film (E-3), since the stretching temperature was as high as 280 ° C., the molecular orientation was small, and the effect of reducing the thermal expansion coefficient due to stretching was not exhibited. Further, in the case of the uniaxially stretched thermoplastic polyimide resin film (F-3), the thermal expansion coefficient in the MD direction was 30 ppm / K or less, but the thermal expansion coefficient in the TD direction was not reduced and was 60 ppm / K. .

Application example 1
A 12.5 μm biaxially stretched thermoplastic polyimide resin film (A-3) obtained in Example 1 was overlaid with a 18 μm thick copper (hereinafter sometimes abbreviated as Cu) foil. This was sandwiched between stainless steel plates (hereinafter referred to as SUS plates) through a 100 μm thick polytetrafluoroethylene resin (hereinafter referred to as PTFE) film as a release film from both sides. Furthermore, Fujiron STM made by Fujiko Co., Ltd. was overlapped on both sides of the SUS plate as a felt cushion material made of polybenzoxazole, and set in a vacuum high-temperature press machine made by Kitagawa Seiki Co., Ltd. Thereafter, the pressure was reduced to 1.0 kPa, the temperature was increased to 360 ° C. at a temperature increase rate of 5 ° C./min at a pressure of 10 kgf / cm ² , and then the pressure was increased to a secondary molding pressure of 25 kgf / cm ² . The state was maintained for 10 minutes. Then, it cooled slowly to room temperature and obtained the flexible single-sided copper clad laminated board of the layer structure of TPI / Cu.

Application example 2
The same procedure as in Application Example 1 was conducted except that the biaxially stretched thermoplastic polyimide resin film (A-3) of Application Example 1 was changed to the biaxially stretched thermoplastic polyimide resin film (B-3) obtained in Example 2. Thus, a flexible single-sided copper-clad laminate having a target TPI / Cu layer structure was obtained.

Application example 3
The same procedure as in Application Example 1 was performed except that the biaxially stretched thermoplastic polyimide resin film (A-3) of Application Example 1 was changed to the biaxially stretched thermoplastic polyimide resin film (C-3) obtained in Example 3. Thus, a flexible single-sided copper-clad laminate having a target TPI / Cu layer structure was obtained.

Table 2 summarizes various properties evaluated using the flexible single-sided copper-clad laminates obtained in Application Examples 1 to 3.
The evaluation methods of adhesive strength, warpage after adhesion, and solder reflow resistance shown in Table 2 are as follows, and the same applies to Examples described later.

(1) Adhesive strength The peel strength of the obtained flexible copper-clad laminate was measured in accordance with JIS C 6481 and the peel strength (N / mm) was measured. The judgment criteria are as follows.
○:> 0.8 N / mm
Δ: 0.4 to 0.8 N / mm
×: <0.4 N / mm

(2) Warpage after bonding After completion of pressing, it was visually determined whether or not the obtained flexible copper-clad laminate had warpage. The judgment criteria are as follows.
○: No warping ×: Warping

(3) Resistance to solder reflow After the obtained flexible copper clad laminate was passed through a reflow furnace having a maximum temperature of 260 ° C., it was visually determined whether or not there was swelling or warping. The judgment criteria are as follows.
○: No swelling or warping △: Slight swelling or warping ×: Swelling or curling

Application example 4
Except not using the cushion material of the application example 1, it carried out similarly to the application example 1, and obtained the flexible single-sided copper clad laminated board of the layer structure of the target TPI / Cu. As a result, since no cushion material was used, high surface smoothness could not be obtained.

Application example 5
Except that the biaxially stretched thermoplastic polyimide resin film (A-3) in Application Example 1 is changed to a biaxially stretched thermoplastic polyimide resin film (D-3), the same TPI / Cu as the target TPI / Cu is performed. A flexible single-sided copper-clad laminate having a layer structure of was obtained.

Comparative application example 1
Except that the biaxially stretched thermoplastic polyimide resin film (A-3) of Application Example 1 was changed to a biaxially stretched thermoplastic polyimide resin film (A-2), the same procedure as in Application Example 1 was performed, and the layer structure of TPI / Cu. A flexible single-sided copper-clad laminate was obtained. Since the linear expansion coefficient of the resin film was large, warping occurred after bonding with the copper foil.

Comparative application example 2
Except that the biaxially stretched thermoplastic polyimide resin film (A-3) of Application Example 1 was changed to a biaxially stretched thermoplastic polyimide resin film (E-3), the same procedure as in Application Example 1 was performed, and the layer structure of TPI / Cu. A flexible single-sided copper-clad laminate was obtained. Since the linear expansion coefficient of the resin film was large, warping occurred after bonding with the copper foil.
Table 3 summarizes various characteristics evaluated using the flexible single-sided copper-clad laminates obtained in Application Examples 4 and 5 and Comparative Application Examples 1 and 2.

Application example 6
A copper foil having a thickness of 18 μm was stacked on both sides of a 12.5 μm biaxially stretched thermoplastic polyimide resin film (A-3), and sandwiched between SUS plates through a PTFE film having a thickness of 100 μm as a release film. Furthermore, Fujiron STM was overlapped on both sides of the SUS plate as a felt cushion material made of polybenzoxazole and set in a vacuum high-temperature press machine manufactured by Kitagawa Seiki Co., Ltd. Thereafter, reduced to 1.0 kPa, After initial pressure 10 kgf / cm heated to 360 ° C. at a heating 5 ° C. / min at a ^second pressure, raising the pressure to a forming pressure of 25 kgf / cm ^2, 10 minutes That state was maintained. Then, it cooled slowly to room temperature and obtained the flexible double-sided copper clad laminated board of the layer structure of Cu / TPI / Cu.

Application example 7
The same Cu / TPI was performed as in Application Example 6 except that the biaxially stretched thermoplastic polyimide resin film (A-3) of Application Example 6 was changed to a biaxially stretched thermoplastic polyimide resin film (B-3). A flexible double-sided copper-clad laminate having a layer structure of / Cu was obtained.

Application example 8
The same Cu / TPI was performed as in Application Example 6 except that the biaxially stretched thermoplastic polyimide resin film (A-3) of Application Example 6 was changed to a biaxially stretched thermoplastic polyimide resin film (C-3). A flexible double-sided copper-clad laminate having a layer structure of / Cu was obtained.

Table 4 summarizes various properties evaluated using the flexible double-sided copper-clad laminates obtained in Application Examples 6-8.

Application example 9
50 μm Kapton EN (Polyimide resin film manufactured by Du Pont); this polyimide resin is a linear polymer that does not have thermoplasticity (thermoreversibility between curing and softening) and cannot be extruded by itself. Therefore, this commercially available polyimide resin (hereinafter referred to as PI) film is obtained by performing a dehydration condensation reaction after casting a solution containing polyamic acid as a precursor on a roll or a flat surface. ), A biaxially stretched thermoplastic polyimide resin film (A-3) having a thickness of 12.5 μm and a copper foil having a thickness of 18 μm were stacked. This is sandwiched between SUS plates via a PTFE film with a thickness of 100 μm as a release film from both sides, and FUJIRON STM is superimposed on both sides of the SUS plate as felt cushion material made of polybenzoxazole. ) Made in a vacuum high-temperature press machine. Thereafter, reduced to 1.0 kPa, After initial pressure 10 kgf / cm heated to 360 ° C. at a heating 5 ° C. / min at a ^second pressure, raising the pressure to a forming pressure of 25 kgf / cm ^2, 10 minutes That state was maintained. Then, it cooled slowly to room temperature and obtained the flexible double-sided copper clad laminated board of the layer structure of Cu / TPI / PI / TPI / Cu.

Application Example 10
The same Cu / TPI was performed as in Application Example 9 except that the biaxially stretched thermoplastic polyimide resin film (A-3) of Application Example 9 was changed to a biaxially stretched thermoplastic polyimide resin film (B-3). A flexible double-sided copper-clad laminate having a layer structure of / PI / TPI / Cu was obtained.

Application Example 11
The same Cu / TPI was performed as in Application Example 9 except that the biaxially stretched thermoplastic polyimide resin film (A-3) of Application Example 9 was changed to a biaxially stretched thermoplastic polyimide resin film (C-3). A flexible double-sided copper-clad laminate having a layer structure of / PI / TPI / Cu was obtained.

Table 5 summarizes various properties evaluated using the flexible double-sided copper-clad laminates obtained in Application Examples 9-11.

Application Example 12
A two-layer flexible polyimide double-sided board having a conductor circuit was laminated on both sides of a 12.5 μm biaxially stretched thermoplastic polyimide resin film (A-3). This is sandwiched between SUS plates via a 100 μm thick PTFE film as a release film from both sides, and Fujiron STM is stacked as a cushioning material on both sides of the SUS plate, and a vacuum high-temperature press machine manufactured by Kitagawa Seiki Co., Ltd. Set. Thereafter, reduced to 1.0 kPa, After initial pressure 10 kgf / cm heated to 360 ° C. at a heating 5 ° C. / min at a ^second pressure, raising the pressure to a forming pressure of 25 kgf / cm ^2, 10 minutes That state was maintained. After that, the multilayer flexible double-sided copper-clad laminated substrate having a layer configuration of conductor circuit / PI / conductor circuit / TPI / conductor circuit / PI / conductor circuit in which the conductor circuit is embedded in a thermoplastic polyimide resin film is slowly cooled to room temperature. Obtained.

Application Example 13
Except that the biaxially stretched thermoplastic polyimide resin film (A-3) of Application Example 12 is changed to a biaxially stretched thermoplastic polyimide resin film (B-3), the same conductor circuit / A multilayer flexible double-sided copper-clad laminate having a layer configuration of PI / conductor circuit / TPI / conductor circuit / PI / conductor circuit was obtained.

Application Example 14
Except that the biaxially stretched thermoplastic polyimide resin film (A-3) of Application Example 12 is changed to a biaxially stretched thermoplastic polyimide resin film (C-3), the same conductor circuit / A multilayer flexible double-sided copper-clad laminate having a layer configuration of PI / conductor circuit / TPI / conductor circuit / PI / conductor circuit was obtained.

The various characteristics evaluated using the multilayer flexible double-sided copper-clad laminate obtained in the application examples 12 to 14 are summarized in Table 6.

Application Example 15
A 12.5 μm biaxially stretched thermoplastic polyimide resin film (A-3) and an 18 μm copper foil were respectively overlapped on both sides of a two-layer flexible polyimide double-sided board having conductor circuits formed on both sides. This is sandwiched between SUS plates via a PTFE film with a thickness of 100 μm as a release film from both sides, and Fujiron STM is stacked as a cushioning material on both sides of the SUS plate. A vacuum high-temperature press machine manufactured by Kitagawa Seiki Co., Ltd. Set. Thereafter, the pressure is reduced to 10 kgf / cm ² , the initial pressure is 1.0 MPa, the temperature is increased to 360 ° C. at a temperature increase of 5 ° C./min, and the pressure is increased to a secondary molding pressure of 25 kgf / cm ^{2 for} 10 minutes. That state was maintained. Then, it cooled slowly to room temperature, and obtained the multilayer flexible double-sided copper clad laminated board of the layer structure of Cu / TPI / conductor circuit / PI / conductor circuit / TPI / Cu where the conductor circuit was embedded in the thermoplastic polyimide resin film. .

Application Example 16
The same Cu / TPI was performed as in Application Example 15 except that the biaxially stretched thermoplastic polyimide resin film (A-3) of Application Example 15 was changed to a biaxially stretched thermoplastic polyimide resin film (B-3). A multilayer flexible double-sided copper-clad laminate having a layer structure of / conductor circuit / PI / conductor circuit / TPI / Cu was obtained.

Application Example 17
The same Cu / TPI was performed as in Application Example 15 except that the biaxially stretched thermoplastic polyimide resin film (A-3) of Application Example 15 was changed to a biaxially stretched thermoplastic polyimide resin film (C-3). A multilayer flexible double-sided copper-clad laminate having a layer structure of / conductor circuit / PI / conductor circuit / TPI / Cu was obtained.

Table 7 summarizes various properties evaluated using the multilayer flexible double-sided copper clad laminates obtained in Application Examples 15 to 17.

Comparative application example 3
An unstretched thermoplastic polyimide resin film (A) having a thickness of 25 μm was used, and a copper foil having a thickness of 18 μm was stacked on one surface. This is sandwiched between SUS plates via a PTFE film with a thickness of 100 μm as a release film from both sides, and FUJIRON STM is superimposed on both sides of the SUS plate as felt cushion material made of polybenzoxazole. ) Made in a vacuum high-temperature press machine. Thereafter, reduced to 1.0 kPa, After initial pressure 10 kgf / cm heated to 360 ° C. at a heating 5 ° C. / min at a ^second pressure, raising the pressure to a forming pressure of 25 kgf / cm ^2, 10 minutes That state was maintained. Then, it cooled slowly to room temperature and obtained the flexible single-sided copper clad laminated board of the layer structure of unstretched TPI / Cu. In the obtained flexible single-sided copper-clad laminate, the unstretched thermoplastic polyimide resin film used had a large coefficient of linear expansion, so that significant warping (curl) occurred after adhesion to the copper foil.

Comparative application example 4
A uniaxially stretched TPI / Cu layer was applied in the same manner as in Applied Example 1 except that the biaxially stretched thermoplastic polyimide resin film (A-3) of Application Example 1 was changed to a uniaxially stretched thermoplastic polyimide resin film (F-3). A flexible single-sided copper-clad laminate with a configuration was obtained. In the obtained flexible single-sided copper-clad laminate, the linear expansion coefficient in the MD direction (film longitudinal direction) of the stretched thermoplastic polyimide resin film (E-3) is a value close to that of the copper foil, but in the TD direction ( Due to the large linear expansion coefficient (in the film width direction), significant warpage (curl) occurred after adhesion to the copper foil.

Comparative application example 5
A flexible single-sided copper-clad laminate having a TPI / Cu layer structure was manufactured in the same manner as in Application Example 1 except that the press temperature of Application Example 1 was changed to 240 ° C. As a result, because of the press at a temperature lower than the Tg of the biaxially stretched thermoplastic polyimide resin film, the biaxially stretched thermoplastic polyimide resin film did not start to soften and could not be bonded.

Various characteristics evaluated using the flexible single-sided copper-clad laminate obtained in Comparative Application Examples 3 to 5 are summarized in Table 8.

  The laminating film of the present invention can be used particularly advantageously as an adhesive layer (resin insulating layer) of a flexible wiring board, but besides this, a light reflector for automobiles, a laminate for airplane partition materials, a fuel cell Separators, solar cell flexible substrates, semiconductor and OA equipment, such as transfer rolls and TAB spacers for copying machines, heat resistant coating materials for piping, heat resistant sheets for observation windows, heat resistant coating films for heaters, motor insulating films, engineering adhesives Widely used in various fields such as electrical material coating, insulation material, name plate heat-resistant protective film, sensor component coating material, organic EL, inorganic EL, diodes and other adhesives and insulation materials, membrane switches, heat- and flame-proof sheets Can be used.

It is a schematic diagram which shows the TMA curve of a thermoplastic polyimide resin unstretched film and a biaxially stretched thermoplastic polyimide resin film. It is a schematic fragmentary sectional view which shows an example of the structure of the flexible double-sided copper clad laminated board to which the biaxially stretched thermoplastic polyimide resin film which concerns on this invention is applied. It is a schematic fragmentary sectional view which shows the other example of the structure of the flexible double-sided copper clad laminated board to which the biaxially stretched thermoplastic polyimide resin film which concerns on this invention is applied. It is a general | schematic fragmentary sectional view which shows an example of the structure of the multilayer flexible laminated board to which the biaxially stretched thermoplastic polyimide resin film which concerns on this invention is applied. It is a general | schematic fragmentary sectional view which shows the other example of the structure of the multilayer flexible laminated board to which the biaxially stretched thermoplastic polyimide resin film which concerns on this invention is applied.

Explanation of symbols

1 Biaxially stretched thermoplastic polyimide resin film 2 Copper foil 3 Polyimide resin film 4 Conductor circuit layer

Claims (7)

It is a film for lamination obtained by biaxially stretching a thermoplastic polyimide resin film, and the film has a thermal expansion coefficient α _{20− in} any of the MD direction (film longitudinal direction) and the TD direction (film width direction). laminating film, characterized in that in the ₂₀₀ also within the scope of ^{5 × 10 -6 ~30 × 10 -6} / K.   The film for laminating according to claim 1, wherein the film for laminating is obtained by biaxially stretching a film obtained by melt extrusion molding a thermoplastic polyimide resin. The difference in thermal expansion coefficient α _20-200 between the MD direction (film longitudinal direction) and the TD direction (film width direction) of the laminating film is within 20 × 10 ⁻⁶ / K. The film for lamination according to 1 or 2.   The film for lamination is a thermoplastic polyimide having a glass transition temperature Tg measured by thermomechanical analysis (TMA) according to the method described in “5.17.1 TMA method” of JIS C 6481: 1996 before stretching. The film for lamination according to any one of claims 1 to 3, wherein the film is higher by 10 to 80 ° C than the glass transition temperature Tg of the resin film.   The film for lamination according to any one of claims 1 to 4, wherein the thermoplastic polyimide resin comprises a mixture of a crystalline thermoplastic polyimide resin and a thermoplastic resin having a melting point of 280 to 350 ° C. The said crystalline thermoplastic polyimide resin is a crystalline thermoplastic polyimide resin containing the repeating structural unit of following formula (6), The film for lamination | stacking of Claim 5 characterized by the above-mentioned.
The film for lamination according to claim 5, wherein the crystalline thermoplastic polyimide resin is a crystalline thermoplastic polyimide resin having repeating structural units represented by the following formulas (6) and (7).


(In the formula, m and n represent the molar ratio of each structural unit, and m / n = 4 to 9).