JPH0693537B2 - Method for producing double-sided conductor polyimide laminate - Google Patents

Description

TECHNICAL FIELD The present invention relates to a double-sided conductor polyimide laminate excellent in heat resistance, mechanical properties or electrical properties, and is particularly suitable as a through-hole connection type double-sided flexible circuit board. The present invention relates to a method for producing a double-sided conductor polyimide laminate having excellent circuit processability and excellent practical properties as a circuit board.

[Conventional technology]

In recent years, there has been an increasing demand for miniaturization and weight reduction of electronic components and electronic devices using the same, and accordingly, wiring materials have tended to be simplified and densified. Is no exception.

A flexible printed circuit board is a flexible printed circuit board, and contributes greatly to downsizing and weight reduction of electric devices and electronic devices. Regarding this flexible printed circuit board, one having a single-sided structure having a conductor layer only on one side and one having a double-sided through-hole structure having conductor layers on both sides of the insulator layer are put into practical use. However, in particular, the double-sided through-hole structure allows circuits to be formed on both sides of the substrate, and has been widely adopted in recent years for high-density mounting.

However, in the case of such a double-sided through-hole structure, a flexible printed circuit board having a single-sided structure is formed by sticking a conductor copper foil or the like on both sides of the base film, which is an insulator layer, via an adhesive. Generally, there is a problem that the flexibility is low as compared with.

Further, since it has an adhesive layer substantially, there is a problem that the characteristics as a circuit board are deteriorated, and particularly the excellent heat resistance and flame retardancy of the polyimide base film are impaired. Another problem with the adhesive layer is that the processability of the circuit deteriorates. Specifically, the occurrence of resin smear due to drilling during through hole processing,
There are problems such as a decrease in adhesion in conductor through-hole plating and a large dimensional change rate during etching.

On the other hand, as the density of ICs and the miniaturization and density of printed wirings increase, heat generation increases, and it may be necessary to bond good thermal conductors. There is also a method of integrating the wiring with the housing in order to make it more compact.
Further, there are cases where wirings having different electric capacities are required, or wiring materials capable of withstanding higher temperatures are required.

In order to solve such a problem, the present inventors have previously
A method for manufacturing a flexible printed circuit board in which an insulating material is laminated on a conductor without an adhesive is proposed (Japanese Patent Laid-Open No. 63-
84,188).

[Problems to be Solved by the Invention]

The present inventors have developed a technique for manufacturing a flexible printed circuit board by laminating an insulating material on a conductor without interposing an adhesive, which has been previously proposed, and conductive on both sides of a polyimide resin layer without interposing an adhesive. The present invention has been achieved by further researching a method for laminating a metal layer.

Therefore, an object of the present invention is to provide a method for producing a double-sided conductor polyimide-based laminate by laminating conductive metal layers on both sides of a polyimide-based resin layer without interposing an adhesive.

Another object of the present invention is to provide a double-sided conductor polyimide laminate having excellent circuit processability in forming a through-hole connection type double-sided flexible circuit board, and having excellent heat resistance and flexibility as a circuit board. It is to provide a method of manufacturing a body.

[Means for Solving the Problems]

That is, the present invention provides a conductive metal foil (M ₁ ) on the at least one low thermal expansion polyimide precursor resin layer that can be converted into a low thermal expansion polyimide resin, further on the thermoplastic polyimide resin. Providing a convertible at least one thermoplastic polyimide precursor resin layer and then heat treating to produce a single sided conductor laminate having at least one low thermal expansion polyimide based resin layer and at least one thermoplastic polyimide based resin layer. In the first step, a conductive metal foil (M ₂ ) is laminated on the thermoplastic polyimide resin layer of the one-sided conductor laminate under heat and pressure, and at least one low thermal expansion polyimide resin layer and at least one heat A second step of forming a double-sided laminate in which conductive metal layers are laminated on both sides of a polyimide-based resin layer made of a plastic polyimide-based resin layer. It is the method for producing the double-sided conductor polyimide laminate, wherein, also, the present invention is a conductive metal foil (M ₁₎ at least one convertible to a thermoplastic polyimide resin on the thermoplastic polyimide precursor resin A layer is provided, and at least one low thermal expansion polyimide precursor resin layer that can be converted into a low thermal expansion polyimide resin is provided thereon, and at least one thermoplastic polyimide that can be converted into a thermoplastic polyimide resin is further provided thereon. Providing a precursor resin layer, and then heat-treating at least one thermoplastic polyimide resin layer, at least one low thermal expansion polyimide resin layer and at least one thermoplastic polyimide resin layer of at least three layers of polyimide resin The first step of producing a single-sided conductor laminate having a layer, and the heating of the single-sided conductor laminate under heat and pressure Plastic polyimide resin layer on the conductive metal foil (M ₂₎ were laminated, comprising at least one low-thermoplastic polyimide resin layer, at least one low thermal expansion polyimide resin layer and at least one thermoplastic polyimide resin layer A method for producing a double-sided conductor polyimide laminate, comprising a second step of forming a double-sided laminate in which conductive metal layers are laminated on both sides of at least three polyimide resin layers.

The polyimide-based resin here is a general term for resins having an imide ring structure, and examples thereof include polyimide, polyamide-imide, and polyester-imide. And, as the polyimide, there are various ones such as those having low thermal expansion as described in JP-A-63-84,188 and thermoplastic ones that melt or soften when heated, but in the present invention, A thermoplastic material having a low thermal expansion coefficient is preferable. When such a resin is difficult to obtain, a laminate of both can be used. Further, as a low thermal expansion polyimide resin, its linear expansion coefficient is 30 × 10 ^-6 (1 /
K) or less is preferable, and one having excellent performance in heat resistance and flexibility of the film is preferable.

Here, the coefficient of linear expansion is determined by using a sample in which the imidization reaction has been sufficiently completed, using a thermomechanical analyzer (TMA) to raise the temperature to 250 ° C., and then cooling at a rate of 10 ° C./min.
This is an average linear expansion coefficient obtained in the range of 100 ° C.

Specific examples of the low thermal expansion polyimide-based resin having such properties include the polyamide-imide resin as described in JP-A-63-84,188 and the following general formula (I). (However, in the formula, R _{1 to} R ₄ represent a lower alkyl group, a lower alkoxy group, a halogen group or hydrogen), and there is a polyimide resin having a unit structure.

Further, the thermoplastic polyimide resin used in the present invention may have any structure as long as its glass transition point is 350 ° C. or less, but preferably its interface when pressure-bonded under heat and pressure. Adhesive strength is sufficient. The term "thermoplastic polyimide resin" as used herein does not necessarily exhibit sufficient fluidity in a normal state above the glass transition point, and includes those which can be bonded by pressure.

Specific examples of the thermoplastic polyimide resin having such properties include the following general formula (II) (Wherein Ar ₁ is a divalent aromatic group having a carbon number of 12 or more),
General formula (III) (However, in the formula, Ar ₂ is a divalent aromatic group having a carbon number of 12 or more).

Here, specific examples of the divalent aromatic group Ar ₁ Ar ₂ include, for example, And the like, and preferably Is.

The polyimide precursor solution or polyimide solution used in the present invention, a curing agent such as a known acid anhydride-based or amine-based curing agent, a silane coupling agent, a titanate coupling agent, an adhesion imparting agent such as an epoxy compound, Various additives such as a flexibility-imparting agent such as rubber and a catalyst may be added.

Next, the method for producing the double-sided conductor type polyimide laminate of the present invention will be described in detail.

The manufacturing method of the present invention is basically a method of applying a polyimide resin solution or a polyimide precursor solution that can be converted to a polyimide resin to a conductive metal foil (M ₁ ) and then heat-treating the single-sided conductor laminate. In the first step of manufacturing the single-sided conductor laminate, a conductive metal foil (M ₂ ) is laminated on the resin layer of this single-sided conductor laminate under heat and pressure, and a conductive metal layer is laminated on both sides of the polyimide resin layer. And a second step of forming a laminated body.

The single-sided conductor laminate manufactured in the first step is a polyimide resin laminated on the conductive metal foil (M ₁ ),
Including at least one thermoplastic polyimide resin layer,
Alternatively, in addition to this, it is preferable that at least one low thermal expansion polyimide-based resin layer is included, and the thermoplastic polyimide-based resin layer is further laminated on the outermost surface layer. Here, when the low thermal expansion polyimide-based resin layer is not included, warpage or curl of the single-sided conductor laminate obtained in the first step becomes large, and workability in the next second step is significantly reduced. Further, if the outermost surface layer does not include the thermoplastic polyimide resin layer, the adhesive force by thermocompression bonding with the conductive metal foil cannot be sufficiently exhibited in the second step, which is not preferable.

At that time, the ratio of the thickness t _{1 of} the low thermal expansion polyimide-based resin layer to the thickness t ₂ of the thermoplastic polyimide-based resin layer (t ₁ / t ₂ )
Is in the range of 2 to 100, preferably 5 to 20. If this thickness ratio (t ₁ / t ₂ ) is smaller than 2, the coefficient of thermal expansion of the entire polyimide resin layer becomes too high compared to that of the metal foil, and the single-sided conductor laminate obtained in this first step The warp and curl of the sheet become large, and the workability in the next second step is significantly reduced. Also, if the thickness t _{2 of the} thermoplastic polyimide resin layer is too small and the thickness ratio (t ₁ / t ₂ ) becomes too large to exceed 100, the adhesive force by thermocompression bonding in the second step will be fully exerted. There may be cases where it is not done.

The application of these plural polyimide resins on the conductive metal foil (M ₁ ) can be performed in the form of the resin solution,
It is preferably carried out in the form of its precursor solution. At that time, in order to impart sufficient adhesive force between the respective polyimide-based resin layers in the laminate, after batch or sequential coating of a plurality of precursor solutions or after desolvation treatment at an imide ring closure temperature or less,
It is desirable to carry out the heat conversion of the precursor into polyimide all at once. If another polyimide-based precursor solution is applied onto the layer that has been completely converted to polyimide, and heat treatment is performed to cause imide ring closure, the adhesive force between the polyimide-based resin layers may not be fully exerted. It causes the deterioration of the quality of the double-sided laminate.

The method for coating the polyimide resin solution or its precursor solution on the conductive metal foil (M ₁ ) may be any method, for example, knife coater, die coater, roll coater, curtain coater, etc. Can be carried out by a known method, and a die coater or a knife coater is particularly suitable for thick coating. A roll coater is suitable for applying a thin coating of 50 μm or less in the resin solution state. Among them, the reverse type roll coater capable of controlling the coating thickness by the rotation speed ratio of the three rolls and the gap is an advantageous method for coating a thin film. Further, there is a multi-layer die method as a simple method for simultaneously coating two or more kinds of resin solutions. There are various types of multi-layer dies, but the multi-manifold type multi-layer dies are superior in terms of accuracy of thickness accuracy and wide tolerance of thickness ratio.

The polymer concentration of the polyimide-based precursor solution used for coating is usually 5 to 30% by weight, though it depends on the degree of polymerization of the polymer.
It is preferably 10 to 20% by weight. When the polymer concentration is lower than 5% by weight, a sufficient film thickness cannot be obtained by one coating, and when it is higher than 30% by weight, the solution viscosity becomes too high and the coating becomes difficult.

The polyamic acid solution applied to the conductive metal foil with a uniform thickness is then subjected to heat treatment to remove the solvent and further undergo imide ring closure. In this case, when the heat treatment is rapidly performed at a high temperature, a skin layer is formed on the resin surface, the solvent is hard to evaporate, or foaming occurs. Therefore, it is desirable to perform the heat treatment while gradually increasing from a low temperature to a high temperature. .

The final heat treatment temperature at this time is usually 300 to 400 ° C.
The thermal decomposition of the polyimide gradually begins to occur at 400 ° C or higher, and at 300 ° C or lower, the polyimide coating is not sufficiently oriented on the conductive metal foil, and a single-sided conductor laminate having good flatness cannot be obtained. . The total thickness of the polyimide resin layer thus formed is usually 10 to 150 μm.

In the second step, the conductive metal foil (M ₂ ) is superposed on the resin layer of the single-sided conductor polyimide laminate obtained as described above, and is pressure-bonded under heat and pressure to be laminated. As a method of hot pressing at this time, a normal hydropress, a vacuum type hydropress, an autoclave pressure type vacuum press, a continuous type heat laminator, or the like can be used. Among them, the vacuum hydropress can obtain a sufficient pressing pressure, can easily remove the residual volatile components, and can also use the conductive metal foil (M ₁ ,
It is the most preferable hot pressing method because it can prevent the oxidation of M ₂ ).

The hot pressing temperature at this time is not particularly limited, but is preferably not less than the glass transition of the thermoplastic polyimide resin used. As for the hot pressing pressure, depending on the type of equipment used to press, 1~500kg / cm ^2, and preferably is 5 to 50 kg / cm ² suitable.

When hot-pressing with hydropress, stacking sheet-like single-area layered body and conductive metal foil (M ₂ ) in many layers,
At the same time, it is also possible to obtain a plurality of double-sided conductor polyimide laminates by one heat pressing, by pressing and laminating under heat and pressure with a hot press.

In addition to the manufacturing method of the present invention as described above, as a method for manufacturing a double-sided conductor polyimide laminate having no adhesive layer, corona discharge treatment, plasma treatment, etc. on the polyimide-based resin layer of the adhesiveless single-sided conductor polyimide laminate It is also possible to apply a method in which the resin layer and the conductive metal foil are attached to each other to improve the adhesiveness of the resin surface, thereby forming a double-sided conductor type laminate.

The double-sided conductor polyimide laminate of the present invention has a conductive metal layer as a conductor on both sides of a polyimide resin layer as an insulator, but as the metal constituting the conductive metal layer, copper, aluminum, Examples thereof include iron, silver, palladium, nickel, chromium, molybdenum, tungsten, zinc and alloys thereof, and copper is preferable. Further, for the conductive metal foil used here, siding, nickel plating, copper-zinc alloy plating, or aluminum alcoholate, aluminum chelate, silane coupling agent or the like on its surface for the purpose of improving the adhesive strength. You may perform a mechanical or mechanical surface treatment.

〔Example〕

Hereinafter, the present invention will be specifically described based on Examples and Comparative Examples.

In the following examples and comparative examples, the coefficient of thermal expansion,
The curl and adhesive strength of the single-sided copper-clad product and the solder heat resistance were measured by the following methods.

That is, the coefficient of thermal expansion was 250 using a thermomechanical analyzer (TMA100) manufactured by Seiko Denshi Kogyo.
After the temperature was raised to 0 ° C, it was cooled at a rate of 10 ° C / min, and the average linear expansion coefficient between 240 ° C and 100 ° C was calculated and obtained.

As the curl of the one-sided copper-clad product, the radius of curvature of the copper-clad product having a size of 100 mm × 100 mm after heat treatment and imidization was measured.

Adhesive strength of the one-sided copper-clad product conforms to JIS C 5016: 7.1, uses a pattern with a conductor width of 3 mm, and puts the copper foil in the direction of 180 ° to 50 mm /
It was determined as a value when peeled at a speed of minutes.

As for solder heat resistance, according to the method of JIS C 5016, 26
Gradually raise the solder bath temperature from 0 ℃ to 10 ℃ at a maximum of 400
It was measured up to ° C.

Further, the following abbreviations are used in the examples and comparative examples.

PMDA: Pyromellitic dianhydride BTDA: 3,3 ', 4,4'-Benzophenone tetracarboxylic acid anhydride BPDA: 3,3', 4,4'-Biphenyl tetracarboxylic acid anhydride DPSDA: 3,3 ', 4 , 4'-Diphenylsulfone tetracarboxylic acid anhydride DDE: 4,4'-diaminodiphenyl ether PPD: p-phenylenediamine DDS: 3,3'-diaminodiphenylsulfone MABA: 2'-methoxy-4,4'-diaminobenz Anilide BAPP: 2,2-bis [4- (aminophenoxy) phenyl]
Propane DABP: 3,3′-diaminobenzophenone BAPB: 1,3- [bis (3-aminophenoxy)] benzene Synthesis Example 1: Synthesis of low thermal expansion polyimide N, N-dimethylacetamide while passing nitrogen through a glass reactor Charge 2,532g, then with stirring 0.5 mol DDE.
And 0.5 mol of MABA were charged and then completely dissolved. This solution was cooled to 10 ° C, 1 mol of PMDA was added little by little so that the reaction solution was kept at a temperature of 30 ° C or less, and after the addition was completed, the mixture was stirred at room temperature for 2 hours to complete the polymerization reaction. Let

The polymer concentration of the obtained polyimide precursor solution and the apparent viscosity at 25 ° C. were measured by a B-type viscometer. The results are shown in Table 1.

Synthesis Examples 2 to 5 Using various diamines and acid anhydrides, a low thermal expansion polyimide precursor solution was synthesized in the same manner as in Synthesis Example 1. The diamine and acid anhydride used in each synthesis example, the polymer concentration of the obtained polymer solution, and the B-type viscometer
Table 1 shows the apparent viscosity at ° C.

Synthesis Example 6: Synthesis of thermoplastic polyimide A thermoplastic polyimide precursor solution was prepared in the same manner as in Synthesis Example 1 except that 1 mol of DDS was used as the diamine component and 1 mol of BTDA was used as the acid anhydride component. did.

The polymer concentration of the obtained polyimide precursor solution and the apparent viscosity at 25 ° C. were measured by a B-type viscometer. The results are shown in Table 1.

Synthesis Examples 7 to 10 Using various diamines and acid anhydrides, a thermoplastic polyimide precursor solution was obtained in the same manner as in Synthesis Example 6. Table 1 shows the diamine and acid anhydride used in each synthesis example, the polymer concentration of the obtained polymer solution and the apparent viscosity at 25 ° C. measured by a B-type viscometer.

Synthesis Example 11 A polyimide precursor solution was prepared in the same manner as in Synthesis Example 1 except that 1 mol of DDE was used as the diamine component and 1 mol of BTDA was used as the acid anhydride component. 25 by the polymer concentration of the obtained polyimide precursor solution and a B-type viscometer
Apparent viscosity was measured at ° C. The results are shown in Table 1.

Synthesis Example 12 A polyimide precursor solution was prepared in the same manner as in Synthesis Example 1 except that 1 mol of BAPP was used as the diamine component and 1 mol of PMDA was used as the acid anhydride. 25 by the polymer concentration of the obtained polyimide precursor solution and a B-type viscometer
Apparent viscosity was measured at ° C. The results are shown in Table 1.

Synthesis Example 13 A polyimide precursor solution was prepared in the same manner as in Synthesis Example 1 except that 1 mol of DDE was used as the diamine component and 1 mol of PMDA was used as the acid anhydride. 25 by the polymer concentration of the obtained polyimide precursor solution and a B-type viscometer
Apparent viscosity was measured at ° C. The results are shown in Table 1.

Example 1 A 35 μm roll-shaped electrolytic copper foil (manufactured by Nikko Gould Co., Ltd.) was uniformly coated with a low thermal expansion polyimide precursor solution prepared in Synthesis Example 2 to a thickness of 215 μm on a roughened surface using a die coater. Then, the solvent was removed by continuous treatment in a hot air drying oven at 120 ° C. Next, the thermoplastic polyimide precursor solution prepared in Synthesis Example 6 was uniformly coated on the low thermal expansion polyimide precursor layer using a reverse roll coater to a thickness of 12 μm, and then in a hot air drying oven for 30 minutes. Then, the temperature was raised from 120 ° C. to 360 ° C. and heat treatment was performed to imidize to obtain a single-sided copper-clad product a with a polyimide resin layer having a thickness of 25 μm and good flatness without warping or curling. The peel strength between the copper foil layer of this single-sided copper-clad product a and the polyimide resin layer is 180 °
C-5016) was measured to be 0.4 kg / cm, and the thermal expansion coefficient of the film after etching was 23.5 × 10 ^-6 (1 / ° C).

Example 2 A 35 μm rolled electrolytic copper foil (manufactured by Nikko Gould Co., Ltd.) was uniformly coated with a thickness of 28 μm on the roughened surface of the polyimide precursor solution prepared in Synthesis Example 11 using a reverse roll coater. The solvent was removed by continuous treatment in a hot air drying oven at 120 ° C. Next, a low-heat-expansion polyimide precursor solution prepared in Synthesis Example 1 was uniformly applied to a layer of 215 μm using a die coater so as to be laminated thereon, and then continuously treated in a hot air drying oven at 120 ° C. Then the solvent was removed. Next, after further applying the thermoplastic polyimide precursor solution prepared in Synthesis Example 6 on the low thermal expansion polyimide precursor layer using a reverse roll coater to a thickness of 12 μm, from 120 ° C. in a hot air drying oven. It was heat-treated to 360 ° C. for 30 minutes for imidization to obtain a single-sided copper-clad product b having a polyimide resin layer thickness of 25 μm and good flatness without warpage or curling. The 180 ° peel strength (JIS C-5016) between the copper foil layer and the polyimide resin layer of this single-sided copper-clad product b was measured to be 1.8 kg / cm.
And the coefficient of thermal expansion of the film after etching is 21.0 ×
It was 10 ^-6 (1 / ° C).

Example 3 A 35 μm rolled electrolytic copper foil (manufactured by Nikko Gould Co., Ltd.) was uniformly coated with a polyimide precursor solution prepared in Synthesis Example 11 on a roughened surface to a thickness of 28 μm using a reverse roll coater. The solvent was removed by continuous treatment in a hot air drying oven at 120 ° C. Next, the low thermal expansion polyimide precursor solution prepared in Synthesis Example 3 and the thermoplastic polyimide precursor solution prepared in Synthesis Example 6 were uniformly extruded in two layers from a multi-manifold type multilayer die so as to be laminated thereon. I worked. The coating thickness of each of the low thermal expansion polyimide precursor solution and the thermoplastic polyimide precursor solution at this time was 196
μm and 24 μm. After coating, the product was heat-treated in a hot-air drying oven for 30 minutes from 120 ° C to 360 ° C to imidize to obtain a single-sided copper-clad product c with a polyimide resin layer thickness of 27 μm and good flatness without warping or curling. . 180 ° peeling strength between the copper foil layer and the polyimide resin layer of this single-sided copper clad product (JIS C
-5016) was 1.7 kg / cm, and the thermal expansion coefficient of the film after etching was 24.0 × 10 ^-6 (1 / ° C).

Examples 4 to 7 Various polyimide resins from the first layer to the third layer were coated in the same manner as in Example 2 and heat-treated to obtain corresponding single-sided copper-clad products d to g. Table 2 shows the coating conditions in each case and the characteristics of the obtained single-sided copper-clad products d to g.

Comparative Example 1 A 35 μm rolled electrolytic copper foil (manufactured by Nikko Gould Co., Ltd.) was uniformly coated with a thickness of 233 μm on the roughened surface of the polyimide precursor solution prepared in Synthesis Example 13 using a die coater.
A single-sided copper-clad product h having a polyimide resin layer thickness of 25 μm was obtained by heat-treating from 120 ° C. to 360 ° C. for 30 minutes in a hot air drying oven to imidize. The obtained single-sided copper-clad product h had a remarkable curl (curl radius of curvature of 5 mm), and the thermal expansion coefficient of the film after etching was as large as 34.5 × 10 ⁻⁶ (1 / ° C.). Also,
180 ° peel strength between copper foil layer and polyimide resin layer (JIS
C-5016) was 0.4 kg / cm.

Comparative Examples 2 to 4 Various polyimide resins from the first female to the third layer were applied by the same method as in Example 2 and heat-treated to obtain corresponding single-sided copper-clad products i to k. Table 2 shows the coating conditions in each case and the characteristics of the obtained single-sided copper-clad products i to k.

Comparative Example 5 35 μm rolled electrolytic copper foil (manufactured by Nikko Gould Co., Ltd.) was uniformly coated with 28 μm thick on the roughened surface using the reverse roll coater with the polyimide precursor solution prepared in Synthesis Example 11. The solvent was removed by continuous treatment in a hot air drying oven at 120 ° C. Next, using a die coater so as to be laminated thereon, the low-thermal-expansion polyimide precursor solution prepared in Synthesis Example 1 was uniformly applied to a thickness of 215 μm, and then heated at 120 ° C. for 30 minutes in a hot air drying oven. It was heat-treated to 360 ° C and imidized. Next, the thermoplastic polyimide precursor solution prepared in Synthesis Example 6 was applied uniformly to a thickness of 12 μm using a reverse roll coaster so as to be further laminated thereon, and then 120 minutes in a hot air drying oven for 120 minutes. A single-sided copper-clad product 1 having a polyimide resin layer thickness of 25 μm was obtained by heat treatment from ℃ to 360 ° C. for imidization. The 180 ° peel strength (JIS C-5016) of the copper foil layer and the polyimide resin layer of this single-sided copper-clad product 1 was measured to be 1.8 kg / cm, and the thermal expansion coefficient of the film after etching was 21.0. It was × 10 ^-6 (1 / ° C).

Example 8 The resin surface of the 500 × 500 mm cut sheet of the single-sided copper clad product a prepared in Example 1 and the 35 μm electrolytic same foil roughened surface of the same size were superposed so as to be in contact with each other, and then the vacuum hot press machine was used. Was used for hot pressing under conditions of a surface pressure of 100 kg / cm ² , 330 ° C. and 10 minutes to obtain a double-sided copper-clad product. The 180 ° peel strength of this double-sided copper-clad product at the thermocompression bonding surface is 1.4 kg / cm, 400 ° C, 1
No abnormality was found even after immersion in solder for a minute. The shrinkage rate of the polyimide film after etching at 250 ° C. for 30 minutes was 0.07%.

Examples 9 to 17 The single-sided copper-clad products b to g prepared in Examples 2 to 7 were thermocompression-bonded to a conductive metal foil to obtain corresponding double-sided copper-clad products. Table 3 shows the hot press conditions and the properties of the obtained double-sided copper-clad product.

Comparative Example 6 The resin surface of the 500 × 500 mm cut sheet of the single-sided copper-clad product h prepared in Comparative Example 1 and the 35 μm electrolytic copper foil roughened surface having the same dimensions were superposed so as to be in contact with each other, and then the vacuum hot press machine was used. Was subjected to heat pressing under the conditions of a surface pressure of 100 kg / cm ² , 330 ° C. for 10 minutes, but thermocompression bonding of the resin surface was not observed.

Comparative Examples 7 to 9 Using the single-sided copper-clad products i to k prepared in Comparative Examples 2 to 4, thermocompression bonding with a conductive metal foil was tried. The results are shown in Table 3.

Comparative Example 10 The resin surface of the 500 × 500 mm cut sheet of the single-sided copper-clad product 1 prepared in Comparative Example 5 and the 35 μm electrolytic copper foil roughened surface having the same dimensions were superposed so as to be in contact with each other, and then the vacuum hot press machine was used. Was used for hot pressing under conditions of a surface pressure of 100 kg / cm ² , 330 ° C., and 10 minutes to obtain a double-sided copper-clad product. The 180 ° peel strength of this double-sided copper-clad product at the thermocompression bonding surface is 0.5 kg / cm, 350 ° C, 1
Swelling occurred due to the immersion of solder for a minute.

EFFECTS OF THE INVENTION According to the present invention, a conductive metal layer can be laminated on both sides of a polyimide resin layer without an adhesive, and a through-hole connection type double-sided flexible having excellent heat resistance and flexibility. A double-sided conductor polyimide laminate suitable for a circuit board can be manufactured.

Claims (4)

[Claims] 1. A conductive metal foil (M ₁ ) is provided with at least one low thermal expansion polyimide precursor resin layer that can be converted into a low thermal expansion polyimide resin, and is further converted into a thermoplastic polyimide resin layer. Providing at least one possible thermoplastic polyimide precursor resin layer, followed by heat treatment to produce a single-sided conductor laminate having at least one low thermal expansion polyimide resin layer and at least one thermoplastic polyimide resin layer And a conductive metal foil (M ₂ ) is laminated on the thermoplastic polyimide resin layer of the one-sided conductor laminate under heat and pressure, and at least one low thermal expansion polyimide resin layer and at least one thermoplastic polyimide And a second step of forming a double-sided laminate in which a conductive metal layer is laminated on both surfaces of a polyimide resin layer made of a system resin layer. Method for producing a double-sided conductor polyimide laminate to. 2. A conductive metal foil (M ₁ ) is provided with at least one thermoplastic polyimide precursor resin layer that can be converted into a thermoplastic polyimide resin, and a low thermal expansion polyimide resin can be converted onto the thermoplastic polyimide precursor resin layer. Providing at least one low thermal expansion polyimide precursor resin layer, further provided at least one thermoplastic polyimide precursor resin layer convertible to a thermoplastic polyimide resin, then heat treated at least one thermoplastic polyimide System resin layer, the first step of producing a single-sided conductor laminate having at least three polyimide resin layers consisting of at least one low thermal expansion polyimide resin layer and at least one thermoplastic polyimide resin layer, and heating thermoplastic polyimide resin layer on the conductive metal foil of the single-sided conductor laminate under pressure (M ₂₎ are stacked, less the One thermoplastic polyimide resin layer,
Second step to form a double-sided laminate in which conductive metal layers are laminated on both surfaces of at least three polyimide resin layers consisting of at least one low thermal expansion polyimide resin layer and at least one thermoplastic polyimide resin layer A method for producing a double-sided conductor polyimide laminate, comprising: 3. The method for producing a double-sided conductor polyimide laminate according to claim 1, wherein the coefficient of linear expansion of the low thermal expansion polyimide resin is 30 × 10 ⁻⁶ (1 / K) or less. 4. A ratio of the thickness t _{1 of the} low thermal expansion polyimide resin layer to the thickness t ₂ of the thermoplastic polyimide resin layer (t ₁ /
t ₂ ) is in the range of 2-100.
Or a method for producing the double-sided conductor polyimide laminate according to 2.