JP2013544674A - Thick film polyimide metal-clad laminate - Google Patents

Abstract

  The present invention relates to a thick film polyimide metal-clad laminate, and relates to a thick film polyimide metal-clad laminate for producing a product having excellent process stability and dimensional stability. More specifically, the present invention relates to a polyimide laminate and a thick layer polyimide metal-clad laminate in which a metal foil is laminated on one or both sides of the polyimide laminate, and the polyimide laminate is IPC-TM- The elongation measured by the 650 (2.4.19) method is 30% or less, the tensile strength is 3 GPa or more, and the linear thermal expansion coefficient (CTE) measured at 100 to 250 ° C. is 5 to 30 ppm / The present invention relates to a thick film polyimide metal-clad laminate including a polyimide film at 0 ° C. and a thermoplastic polyimide layer on one or both sides thereof.

Description

  The present invention relates to a thick film polyimide metal-clad laminate, and relates to a physical property range of a polyimide film for producing a product excellent in process stability and dimensional stability.

  A flexible metal clad laminate used in the manufacture of a flexible printed circuit board is a laminate of a conductive metal foil and an insulating resin. Since it is possible to bend in a narrow space, its use is increasing as electronic devices become smaller and lighter. Such a flexible metal-clad laminate is usually manufactured in a two-layer structure and a three-layer structure.

  A product having a three-layer structure is manufactured by bonding a polyimide film and a metal foil using an epoxy adhesive or a urethane adhesive. In this case, the heat resistance and flame retardancy are reduced due to the presence of the adhesive layer, and the dimensional change in the etching process and the heat treatment process is large, which often hinders the printed circuit board manufacturing process. In order to eliminate the above-mentioned drawbacks, a flexible metal-clad laminate having a two-layer structure that does not use an adhesive has been developed and used. Examples of a method for producing a flexible metal-clad laminate having a two-layer structure excellent in heat resistance include a casting method and a laminating method. The cast method is a method for producing a flexible metal-clad laminate by applying a polyamic acid on a conductive metal foil and then forming a polyimide on the conductive metal foil through a curing process. After introducing a thermoplastic polyimide layer into the outermost layer, a double-sided metal-clad laminate may be produced by laminating with a conductive metal foil. The laminating method is a method for producing a single-sided metal-clad laminate or a double-sided metal-clad laminate by forming a thermoplastic polyimide layer on one or both sides of a polyimide film and then laminating with a metal foil.

  On the other hand, when manufacturing a metal-clad laminate of a thick polyimide layer using a casting method, appearance defects such as foaming may occur at the surface or at the interface between polyimide layers, and the polyimide precursor polyamic acid The degree of cure is reduced, the mechanical strength and chemical resistance are reduced, and it is difficult to remove the solvent present in the film, resulting in a problem that the dimensional stability is lowered.

  In order to eliminate such drawbacks, a method of manufacturing a thick film polyimide metal-clad laminate having a thick polyimide layer using a laminating method can be used. When the present inventors manufacture a two-layer flexible copper foil laminate by the laminating method, the appearance defect of the product (wrinkles, diagonal lines, vertical stripes, etc.) occurs during the laminating process, and the dimensional stability decreases. As a result of diligent research to solve such problems, the present invention has been completed.

  The objective of this invention is providing the physical property of the polyimide film requested | required in order to manufacture the product which has a favorable external appearance and physical property, when manufacturing a thick film polyimide metal-clad laminate using a lamination method.

  The present invention relates to a thick-film polyimide metal-clad laminate, and the physical properties of the polyimide film used as the core layer are specified in producing a thick-film polyimide metal-clad laminate with a thick polyimide laminate using a laminating method. When it is within the range, it has been found that a product excellent in process stability and dimensional stability can be produced, and the present invention has been completed.

  The thick-film polyimide metal-clad laminate according to the present invention can be manufactured by a laminating process, improves appearance defects (wrinkles, diagonal lines, vertical stripes, etc.) of the product during the laminating process, and has excellent dimensional stability.

Specifically, the present invention is a polyimide layered product and a thick layer polyimide metal-clad laminate in which a metal foil is laminated on one or both sides by a laminating method,
The polyimide laminate has an elongation measured by the IPC-TM-650 (2.4.19) method of 30% or less, a tensile elastic modulus of 3 GPa or more, and a line measured at 100 to 250 ° C. The present invention relates to a polyimide film having a coefficient of thermal expansion (CTE) of 5 to 30 ppm / ° C. and a thick film polyimide metal-clad laminate including a thermoplastic polyimide layer on one or both sides thereof.

  In particular, by limiting the physical property range of the polyimide film, a problem in appearance that occurs during the laminating process was improved, and a method for improving the dimensional stability of the polyimide metal-clad laminate was found, and the present invention was completed.

  That is, the physical properties of the polyimide film were measured by the IPC-TM-650 (2.4.19) method with an elongation of 30% or less, a tensile modulus of 3 GPa or more, and measured at 100 to 250 ° C. The linear thermal expansion coefficient is (CTE) 5-30 ppm / ° C., and when the above range is satisfied, a metal-clad laminate can be manufactured by a laminating process, and the metal has extremely excellent dimensional stability. The present inventors have found that a stretch laminate can be produced and completed the present invention.

  In the present invention, the polyimide film can be laminated with a metal foil by a laminating step when the elongation is 30% or less, more specifically 25% or less, more preferably 5 to 30%. . When it exceeds 30%, undulation occurs, and vertical defects such as vertical stripes and wrinkles appear in the product after lamination, and a product having a good appearance cannot be manufactured.

  The polyimide film preferably has a tensile modulus of 3 GPa or more, more specifically 4 GPa or more, more preferably 4 to 8 GPa. If it is less than 3 GPa, it is soft and has a high elongation rate, so there is a high possibility that an appearance defect will occur as described above.

  When the polyimide film has a coefficient of linear thermal expansion (CTE) measured at 100 to 250 ° C. in the range of 5 to 30 ppm / ° C., more preferably 10 to 25 ppm / ° C., a metal having excellent dimensional stability. A tension laminate can be produced. If it exceeds 30 ppm / ° C. or less than 5 ppm / ° C., the dimensional change rate of the product may increase because of a large CTE difference with metal foil, particularly copper foil.

  The polyimide film preferably has a thickness of 25 μm or more, more specifically 25 to 150 μm, since a thick film polyimide metal-clad laminate can be produced.

  In the present invention, the polyimide metal-clad laminate is manufactured by coating a thermoplastic polyamic acid resin on one or both sides of a polyimide film used as a core layer, followed by drying and heat treatment. In the present invention, the laminating step is to manufacture the polyimide laminate and the conductive metal foil by high temperature lamination, and includes all forms in which the conductive metal foil exists on one or both sides of the polyimide laminate. .

  Here, examples of the conductive metal foil include a copper foil, a stainless steel foil, an aluminum foil, a nickel foil, or two or more alloy foils, and the type thereof is not limited as long as the object to be achieved by the present invention is satisfied. Moreover, although the thickness of electroconductive metal foil is not restrict | limited, since it is advantageous in a process that it is 9-70 micrometers, it is preferable.

  The polyimide film used as the core layer can be subjected to surface treatment, for example, corona treatment, plasma treatment, etc. in order to improve the adhesive strength with the thermoplastic polyimide layer. As long as it is satisfied, the method is not limited. The surface treatment method may be used to increase the roughness of the surface layer of the polyimide film or to change the chemical structure.

  The method for producing the thermoplastic polyimide resin layer used in the present invention is not particularly limited. In the present invention, after a polyamic acid resin solution, which is a precursor of a thermoplastic polyimide resin, is applied to one or both sides of a polyimide film used as a core layer, a new thermoplastic polyimide is formed on the polyimide film through drying and heat treatment. A resin layer is formed. Examples of the method for applying the polyamic acid resin solution include knife coating, roll coating, die coating, curtain coating, and the like, and the present invention is intended to achieve. As long as the purpose is satisfied, the method is not limited.

  In this invention, after apply | coating the polyamic acid resin solution which is a polyimide precursor, this can be converted into a polyimide resin by a thermal conversion process or a chemical conversion process. Although any method may be applied as the heat treatment method, after forming a gel film by applying and drying a semi-cured polyimide resin or polyimide precursor resin, this may be placed in a drying furnace for a predetermined time, Generally, heat treatment is performed by moving the inside of the drying furnace continuously for a predetermined time. The heat treatment temperature is usually 300 ° C. or higher, and more preferably, a high temperature treatment of 300 to 500 ° C. is performed. As a heat treatment method, a known heating method can be applied as long as the object of the present invention is satisfied.

The thermoplastic polyimide and thermoplastic polyamic acid used in the present invention have a glass transition temperature (T _g ) of 180 ° C. or higher, more preferably 200 to 300 ° C. after complete imidization, and have thermoplastic properties. A thermoplastic polyimide resin or polyamic acid resin may be used, and the type is not particularly limited.

  Moreover, it is preferable that the thickness after the final curing of the thermoplastic polyimide layer is 3 to 20 μm because a stable adhesive force with the metal foil can be secured and there are advantages in the manufacturing process.

In the present invention, the temperature in the laminating step is not particularly limited, but it is preferably heated to a temperature equal to or higher than the glass transition temperature of the thermoplastic polyimide resin. When the heating temperature of the thermoplastic polyimide resin is not sufficient, sufficient fluidity necessary for pressure bonding with the metal foil cannot be ensured, and thus stable adhesive force cannot be ensured. The heating temperature at the time of pressure bonding is usually preferably 30 to 200 ° C. higher than the glass transition temperature (T _g ) of the thermoplastic polyimide resin. Moreover, about the lamination pressure, 50-200 kgf / cm is suitable as linear pressure. When the pressure is high, there is an advantage that the laminating temperature can be lowered. Therefore, it is advantageous to work at a pressure as high as possible.

  Other features and aspects will become apparent from the following detailed description, drawings, and claims.

  The present invention provides a polyimide used as a core layer for producing a product having excellent process stability and dimensional stability in producing a thick film metal-clad laminate having a thick polyimide layer using a laminating method. Propose the physical properties of the film. As a result, it is possible to minimize the process problems that may occur when manufacturing a thick film metal-clad laminate using a laminate method, and to manufacture a thick film metal-clad laminate having excellent physical properties. it can.

  Hereinafter, although an example is given and explained for the concrete explanation of the present invention, the present invention is not limited to the following example.

1. Appearance Evaluation In the process of producing the metal-clad laminate according to the present invention, the phenomenon appearing in the process or the appearance of the metal-clad laminate after production was visually confirmed. The undulation is a phenomenon in which the film is wavy when the film is in contact with the high-temperature roll in all stages of the laminator roll. When waviness occurs, the copper foil may be wrinkled after being laminated with the metal foil depending on the degree of the waviness. If undulation occurs, the evaluation is made according to the following criteria depending on the degree of swell.

  ○ means that a large swell occurred and wrinkled after passing through the laminator roll, and △ means that a swell occurred weakly and no wrinkle occurred after passing through the laminator roll. , X means having good process stability with no undulation. When wrinkles occurred on the appearance of the product after the lamination was completed, the level was judged as ◯, Δ, or X depending on the degree.

  The physical properties mentioned in the present invention follow the following measuring methods.

2. Mechanical properties Physical properties were measured according to the measuring method of IPC-TM-650, 2.4.19. After producing specimens for measuring the tensile strength and the elongation, the tensile strength and the elongation were measured using UTM (Universal Testing Machine). This calculated the tensile modulus.

3. Measurement of linear thermal expansion coefficient (CTE, Coefficient of Thermal Linear Expansion) The linear thermal expansion coefficient is the value of the thermal expansion value measured while increasing the temperature to 400 ° C. at a rate of 5 ° C./minute using TMA (Thermal Mechanical Analyzer). Among these, it calculated | required by the average value of the value from 100 degreeC to 250 degreeC.

4). Dimensional change after etching and heat treatment IPC-TM-650, Method B of 2.2.4 was followed. After the dough was cut into square specimens each having MD and TD of 275 × 255 mm, holes for position recognition were made at the four vertices and stored in a constant temperature and humidity chamber at 23 ° C. and 50% RH for 24 hours. After measuring the distance between the holes three times, an average value was obtained. Next, the metal foil was etched and stored in a constant temperature and humidity chamber at 23 ° C. and 50% RH for 24 hours, and then the distance between the holes was measured again. The dimensional change rate was determined after calculating the etching rate of the values measured in this way in the MD direction and the TD direction and etching. After the measurement, heat treatment was performed again at 150 ° C. for 30 minutes, and after storing for 24 hours in a constant temperature and humidity chamber at 23 ° C. and 50% RH, the distance between the holes was measured again. Compared with the distance between each hole of the cloth | dough measured previously, the dimensional change rate after the heat processing to MD direction and TD direction was calculated.

Abbreviations used in the following production examples are as follows.
-DMAc: N, N-dimethylacetamide (N, N-dimethylacetamide)
-BPDA: 3,3 ', 4,4'-biphenyltetracarboxylic dianhydride (3,3', 4,4'-biphenyltetracarboxylic acid dianhydride)
-BTDA: 3,3 ', 4,4'-benzophenone tetracarboxylic dianhydride (3,3,4,4-benzophenonetetracarboxylic dianhydride)
-PDA: para-phenylenediamine (p-phenylenediamine)
-ODA: 4,4'-diaminodiphenyl ether (4,4'-diaminodiphenylether)
-TPER: 1,3-bis (4-aminophenoxy) benzene (1,3-bis (4-aminophenoxy) benzene)

[Production Example 1]
The diamine of TPER 119.06 g and PDA 14.68 g was completely dissolved by stirring under nitrogen atmosphere in 2006 g of DMAc solution, and then 95.88 g of BPDA and 70 g of BTDA were added in three portions as dianhydrides. Next, the solution was stirred for about 24 hours to produce a polyamic acid solution. The polyamic acid solution thus produced was cast into a film having a thickness of 20 μm, and then heated to 350 ° C. for 60 minutes and maintained for 30 minutes to be cured. The measured glass transition temperature was 223 ° C.

[Production Example 2]
To 2425 g of DMAc solution, 49.7 g of TPER and 102.1 g of ODA were completely dissolved by stirring under a nitrogen atmosphere, and then 200 g of BPDA was added in three portions as a dianhydride. Next, the solution was stirred for about 24 hours to produce a polyamic acid solution. The polyamic acid solution thus produced was cast into a film having a thickness of 20 μm, and then heated to 350 ° C. for 60 minutes and maintained for 30 minutes to be cured. The measured glass transition temperature was 236 ° C.

[Production Example 3]
To 2112 g of DMAc solution, 90.7 g of TPER and 33.55 g of PDA were completely dissolved by stirring under a nitrogen atmosphere, and then 91.3 g of BPDA and 100 g of BTDA were added in three portions as a dianhydride. Next, the solution was stirred for about 24 hours to produce a polyamic acid solution. The polyamic acid solution thus produced was cast into a film having a thickness of 20 μm, and then heated to 350 ° C. for 60 minutes and maintained for 30 minutes to be cured. The measured glass transition temperature was 252 ° C.

  Table 1 shows the mechanical properties and thickness of the polyimide film used in the present invention, and the CTE value in the MD / TD direction.

[Example 1]
After applying the polyamic acid solution produced in Production Example 2 to both sides of the 38 μm-thick polyimide film (A) that has been subjected to the plasma treatment so that the thickness of one side after final curing is 6 μm, Drying with hot air in a drying furnace produced a polyamic acid precursor film on the polyimide film.

  The film thus produced was imidized by heat treatment for 9 minutes while raising the temperature from 150 ° C. to 395 ° C. at a rate of 20 ° C./min in a nitrogen atmosphere to form a thermoplastic polyimide layer.

  Next, an electrolytic copper foil having a thickness of 12 μm was pressure-bonded to both surfaces of the film at a pressure of 100 kgf / cm using a high-temperature laminator roll to produce a double-sided metal-clad laminate.

[Example 2]
A double-sided metal-clad laminate was manufactured by the same process as in Example 1 except that a rolled copper foil having a thickness of 18 μm was used.

[Example 3]
A double-sided metal-clad laminate was produced by the same process as in Example 1 except that a rolled copper foil having a thickness of 18 μm was used and the polyamic acid solution produced in Production Example 1 was used.

[Example 4]
A metal-clad laminate was manufactured by the same process as Example 1 except that a polyimide film (B) having different physical properties from the polyimide film used in Example 1 was used and an electrolytic copper foil having a thickness of 18 μm was used. .

[Example 5]
A metal-clad laminate was produced in the same manner as in Example 4 except that a rolled copper foil having a thickness of 12 μm was used and the polyamic acid solution produced in Production Example 3 was used.

[Example 6]
A metal-clad laminate was produced by the same process as Example 1 except that a polyimide film (C) having different physical properties from the polyimide film used in Example 1 was used.

[Example 7]
A double-sided metal-clad laminate was manufactured by the same process as Example 1 except that a polyimide film (D) having different physical properties from the polyimide film used in Example 1 was used.

[Example 8]
After applying the polyamic acid solution produced in Production Example 1 on both sides of the polyimide film (E) having a thickness of 50 μm that has been subjected to plasma treatment so that the thickness of one side after final curing is 3 μm, Drying with hot air in a drying furnace produced a polyamic acid precursor film on the polyimide film.

  The film thus produced was imidized by heat treatment for 9 minutes while raising the temperature from 150 ° C. to 395 ° C. at a rate of 20 ° C./min in a nitrogen atmosphere to form a thermoplastic polyimide layer.

  Next, using a high-temperature laminating roll, an electrolytic copper foil having a thickness of 35 μm was pressure-bonded to both surfaces of the film at a pressure of 100 kgf / cm to produce a double-sided metal-clad laminate.

[Example 9]
A double-sided metal-clad laminate was manufactured by the same process as Example 8 except that an electrolytic copper foil having a thickness of 12 μm was used.

[Example 10]
A double-sided metal-clad laminate was manufactured by the same process as Example 8 except that a rolled copper foil having a thickness of 18 μm was used.

[Comparative Example 1]
A metal-clad laminate was manufactured by the same process as in Example 8, except that a polyimide film (F) having a thickness of 50 μm different from that in Example 8 was used and a rolled copper foil having a thickness of 35 μm was used. .

[Comparative Example 2]
A metal-clad laminate was produced by the same process as in Example 8, except that a polyimide film (G) having a thickness of 50 μm different from that in Example 8 was used and a rolled copper foil having a thickness of 12 μm was used. .

  Table 2 shows problems in appearance that appear when a thick film polyimide copper foil laminate is manufactured using the polyimide film shown in Table 1, and the results of dimensional changes after product manufacture.

  As can be seen from Table 2, the physical property range of the present invention, that is, the elongation is 30% or less, the tensile modulus is 3 GPa or more, and the linear thermal expansion coefficient (CTE) measured at 100 to 250 ° C. When manufacturing a metal-clad laminated body using the polyimide film which is 5-30 ppm / degreeC, it confirmed that metal foil could be laminated | stacked by the laminating method. Further, it was found that when the tensile elastic modulus is 4 GPa or more and the elongation is as low as 25% or less, the process stability is further improved and the dimensional stability is excellent.

  However, as can be seen from Comparative Example 1 and Comparative Example 2, when the elongation and tensile modulus and linear thermal expansion coefficient are out of the scope of the present invention, undulation occurs, vertical stripes and wrinkles occur in the product after lamination, etc. It was found that a defect in appearance occurred and the laminating process could not be applied.

  Therefore, in order to produce a metal-clad laminate excellent in process stability and dimensional stability, the mechanical properties of the polyimide film used for the core layer, in particular, the elongation, tensile modulus and CTE value are suitable. It has been found that it must have a range.

Claims (10)

A thick film (thick layer) polyimide metal-clad laminate in which a metal foil is laminated on one or both sides of a polyimide laminate by a laminating method,
The polyimide laminate had an elongation measured by the IPC-TM-650 (2.4.19) method of 30% or less, a tensile modulus of 3 GPa or more, and was measured at 100 to 250 ° C. A thick film polyimide metal-clad laminate comprising a polyimide film having a coefficient of linear thermal expansion (CTE) of 5 to 30 ppm / ° C and a thermoplastic polyimide layer on one or both sides thereof.   2. The thick film polyimide metal tension according to claim 1, wherein the polyimide film has an elongation of 25% or less, a tensile elastic modulus of 4 GPa or more, and a linear thermal expansion coefficient (CTE) of 10 to 25 ppm / ° C. 3. Laminated body.   The thick polyimide metal-clad laminate according to claim 1, wherein the polyimide film has a thickness of 25 to 150 μm.   2. The thick film polyimide metal-clad laminate according to claim 1, wherein the metal foil is selected from copper foil, stainless steel foil, aluminum foil, nickel foil, or two or more alloy foils.   2. The thick polyimide metal-clad laminate according to claim 1, wherein the thermoplastic polyimide layer is formed by applying and drying a polyamic acid resin solution to form a gel film, and then placing it in a drying furnace or performing heat treatment. body.   The thick film polyimide metal-clad laminate according to claim 5, wherein the thermoplastic polyimide layer has a glass transition temperature of 180 to 300C.   The thick film polyimide metal-clad laminate according to claim 5, wherein a thickness of the thermoplastic polyimide layer after final curing is 3 to 20 µm.   The thick film polyimide metal-clad laminate according to claim 1, wherein the thermocompression bonding in the laminating step is performed at a temperature equal to or higher than a glass transition temperature of a thermoplastic polyimide resin.   The thick film polyimide metal-clad laminate according to claim 8, wherein the thermocompression bonding is performed at a temperature 30 to 200 ° C. higher than a glass transition temperature of a thermoplastic polyimide resin.   The thick film polyimide metal-clad laminate according to claim 8, wherein the thermocompression bonding is performed at 50 to 200 kgf / cm.