JP4941407B2 - Copper-clad laminate and method for producing copper-clad laminate - Google Patents

Description

  The present invention relates to a copper clad laminate in which a plurality of polyimide resin layers are formed on a copper foil and a method for producing the same. More specifically, after the polyimide resin layer is treated with superheated steam, The present invention relates to a copper clad laminate having the same polyimide resin layer and a method for producing the same.

A printed wiring board obtained by processing a laminated board made of an insulating material and a conductive material is used for an electric / electronic circuit of an electronic device. Printed wiring boards can be broadly classified into plate-shaped rigid printed wiring boards and flexible printed wiring boards with great flexibility.
There are a three-layer flexible substrate and a two-layer flexible substrate as flexible substrates used as the material of the flexible printed wiring board. The three-layer flexible substrate is obtained by bonding a base film such as polyimide and a copper foil using an adhesive such as an epoxy resin, an acrylic resin, or a polyester resin. On the other hand, the two-layer flexible substrate is obtained by providing a heat-resistant insulating layer directly on a copper foil without using an adhesive. There are the following three methods for obtaining a flexible substrate without using an adhesive such as epoxy resin, acrylic resin or polyester resin.
(1) Cast method. A polyimide-based heat-resistant resin solution is applied to a metal foil such as copper foil, dried, and heat-treated if necessary.
(2) Laminating method. A thermoplastic heat-resistant resin layer is provided on at least one side of a heat-resistant film such as a polyimide film, and the thermoplastic resin layer and a metal foil such as a copper foil are bonded to each other.
(3) Plating method. A heat-resistant film such as a polyimide film is plated with copper.
A method of applying a polyimide-based heat-resistant resin solution to a metal foil such as a copper foil, drying it, and subjecting it to a heat treatment if necessary is called a casting method. Since the flexible wiring board obtained by the casting method has excellent dimensional stability, it is a material corresponding to the recent increase in density and fine pitch of printed wiring boards.
As the drying method used for drying the solvent of the heat-resistant resin solution during the production of the cast method flexible substrate, hot air drying, hot roll contact drying, infrared heating drying, far infrared heating drying, or the like is used. Examples of the heat resistant resin used at this time include a polyimide precursor resin, a solvent-soluble polyimide resin, and a polyamideimide resin. As these solvents, N-methyl-2-pyrrolidone, N, N-dimethylacetamide, γ-butyrolactone, phenol, cresol and the like are used, but these solvents have a high boiling point and thus have poor drying properties. In particular, amide solvents such as N-methyl-2-pyrrolidone and N, N-dimethylacetamide have low vapor pressure due to intermolecular hydrogen bonding, and the diffusion of the solvent is poor due to the high glass transition temperature of the heat-resistant resin. Yes, it tends to remain in the coating film. Residual solvent causes a decrease in heat resistance and a decrease in dimensional stability. If the drying temperature or heat treatment temperature is too high in order not to leave the solvent, the discoloration or characteristic change of the copper foil, the adhesive strength is reduced due to the deterioration of the resin, or the mechanical characteristics are deteriorated. Drying and heat treatment are performed over time in order to avoid adverse effects caused by an increase in drying and heat treatment temperature and prevent the solvent from remaining. Therefore, there is a problem in productivity.
Further, in the casting method, as the thickness of the polyimide resin layer increases, the influence of internal stress generated by volume shrinkage due to solvent drying becomes more prominent. Even with the same resin, it may be necessary to apply, dry, and heat-treat several times.
In the cast method flexible substrate, it becomes difficult to satisfy the requirements such as adhesiveness to the copper foil, dimensional stability in the circuit plate, no curling and twisting, and various heat resistances with a single polyimide resin. A combination of resins excellent in properties such as adhesion to copper foil, a low thermal expansion coefficient, and solvent drying properties has been made. However, when a plurality of resins are used, the adhesion between the resins is often poor, and there is a problem that delamination tends to occur.
Patent Documents 1 and 2 propose providing a plurality of polyimide resin layers on a copper foil by a casting method.
Recently, superheated steam has attracted attention as a heating heat source. Superheated steam refers to steam that has been heated by further heating saturated steam at normal pressure. Since superheated steam has a radiant heat energy significantly higher than that of normal steam at a temperature of 150 ° C. or higher, the substance can be heated in a short time. Superheated steam is used for cooking food, washing resin products and metal products, sterilizing food containers, or treating soil. The use of superheated steam as a heating heat source is not very popular except for cooking food.
However, when superheated steam is compared with general heated air, it has the following characteristics.
(1) Since the heat capacity is larger than that of heated air, rapid heating is possible.
(2) Since it has a constant-pressure specific heat about twice that of heated air, it has excellent heating capacity.
(3) Since it has latent heat energy, its enthalpy is larger than that of heated air.
(4) Although heat transfer by air is limited to convection heat transfer, superheated steam has a high heat efficiency because of the combined heat transfer action from convection heat transfer, radiant heat transfer, and condensation heat transfer.
It is known in Patent Documents 3 to 8 to dry superheated steam as a heating heat source. Patent Documents 3 to 7 propose a method of drying moisture of wet paper mainly composed of cellulose fibers with superheated steam. Patent Document 8 proposes application of superheated steam to a polyolefin film, a polyamide film, a coating film on a polyester film, or a wet cellophane film. Non-Patent Document 1 shows characteristics and utilization examples of superheated steam.
Japanese Patent No. 2909844 Japanese Patent No. 3034838 Japanese Patent No. 2907265 Japanese Patent No. 2907266 Japanese Patent No. 3007542 Japanese Patent Publication No. 2003-41495 Japanese Patent Publication No. 2005-15924 Japanese Patent Publication No. 2007-276283 Superheated steam technology assembly NTS Corporation (issued in 2005)

  The subject of this invention is providing the copper clad laminated board excellent in adhesiveness and heat resistance durability, and providing the method of manufacturing this copper clad laminated board efficiently.

  The inventors of the present invention have arrived at the present invention as a result of intensive studies on a method for producing a cast laminate. That is, in the present invention, a plurality of polyimide resin layers are formed on a copper foil, and the plurality of polyimide resin layers are formed on a polyimide resin layer treated with superheated steam. It is a laminated board. Moreover, when forming a plurality of polyimide resin layers on a copper foil, another or the same polyimide resin layer is formed on a polyimide resin layer treated with superheated steam. It is a manufacturing method.

  By this invention, the copper clad laminated board excellent in adhesiveness and heat-resistant durability can be produced efficiently.

Examples of the polyimide resin used in the present invention include a polyimide precursor resin, a solvent-soluble polyimide resin, and a polyamideimide resin. The polyimide resin can be polymerized by a usual method. For example, a method of obtaining a polyimide precursor solution by reacting tetracarboxylic dianhydride and diamine in a solution at low temperature, and a method of obtaining a solvent-soluble polyimide solution by reacting tetracarboxylic dianhydride and diamine in a high temperature solution. There are a method using isocyanate as a raw material and a method using acid chloride as a raw material.
The raw materials used for the polyimide precursor resin and the solvent-soluble polyimide resin include the following. Examples of acid components include pyromellitic acid, benzophenone-3,3 ', 4,4'-tetracarboxylic acid, biphenyl-3,3', 4,4'-tetracarboxylic acid, diphenylsulfone-3,3 ', 4, 4'-tetracarboxylic acid, diphenyl ether-3,3 ', 4,4'-tetracarboxylic acid, naphthalene-2,3,6,7-tetracarboxylic acid, naphthalene-1,2,4,5-tetracarboxylic acid , Monoanhydrides, dianhydrides, esterified products such as naphthalene-1,4,5,8-tetracarboxylic acid, hydrogenated pyromellitic acid, hydrogenated biphenyl-3,3 ', 4,4'-tetracarboxylic acid Etc. can be used alone or as a mixture of two or more. Examples of the amine component include p-phenylenediamine, m-phenylenediamine, 3,4′-diaminodiphenyl ether, 4,4′-diaminodiphenyl ether, 4,4′-diaminodiphenyl sulfone, 3,3′-diaminodiphenyl sulfone, 3,4'-diaminobiphenyl, 3,3-diaminobiphenyl, 3,3'-diaminobenzanilide, 4,4'-diaminobenzanilide, 4,4'-diaminobenzophenone, 3,3'-diaminobenzophenone, 3 , 4'-diaminobenzophenone, 2,6-tolylenediamine, 2,4-tolylenediamine, 4,4'-diaminodiphenyl sulfide, 3,3'-diaminodiphenyl sulfide, 4,4'-diaminodiphenylpropane, 3,3'-diaminodiphenylpropane, 4,4'-diaminodiphenylhexafluoropropane, 3,3'-diaminodiphenylhexafluoropropane, 4,4'-diaminodiphenylmeta 3,3'-diaminodiphenylmethane, 4,4'-diaminodiphenylhexafluoroisopropylidene, p-xylenediamine, m-xylenediamine, 1,4-naphthalenediamine, 1,5-naphthalenediamine, 2,6- Naphthalenediamine, 2,7-naphthalenediamine, o-tolidine, 2,2'-bis (4-aminophenyl) propane, 2,2'-bis (4-aminophenyl) hexafluoropropane, 1,3-bis ( 3-aminophenoxy) benzene, 1,3-bis (4-aminophenoxy) benzene, 1,4-bis (4-aminophenoxy) benzene, 2,2-bis [4- (4-aminophenoxy) phenyl] propane Bis [4- (4-aminophenoxy) phenyl] sulfone, bis [4- (3-aminophenoxy) phenyl] propane, bis [4- (3-aminophenoxy) phenyl] sulfone, bis [4- (3- Aminophenoxy) phenyl] hexafuro Propane, 4,4′-bis (4-aminophenoxy) biphenyl, 4,4′-bis (3-aminophenoxy) biphenyl, 2,2-bis [4- (4-aminophenoxy) phenyl] hexafluoropropane, One or a mixture of two or more of cyclohexyl-1,4-diamine, isophoronediamine, hydrogenated 4,4′-diaminodiphenylmethane, or the corresponding diisocyanate compounds can be used. In addition, a resin separately polymerized by a combination of these acid component and amine component can be mixed and used.
Raw materials used for polyamideimide resins include trimellitic anhydride, diphenyl ether-3,3 ', 4'-tricarboxylic acid anhydride, diphenylsulfone-3,3', 4'-tricarboxylic acid anhydride, benzophenone as acid components Tricarboxylic acid anhydrides such as -3,3 ′, 4′-tricarboxylic acid anhydride, naphthalene-1,2,4-tricarboxylic acid anhydride, and hydrogenated trimellitic acid anhydride may be used alone or as a mixture. In addition to tricarboxylic acid anhydrides, tetracarboxylic acids mentioned in the polyimide resin, their anhydrides, dicarboxylic acids and the like can also be used in combination. Examples of the amine component include diamines mentioned for polyimide resins, or diisocyanates alone or as a mixture. In addition, a resin separately polymerized by a combination of these acid component and amine component can be mixed and used.
Examples of the solvent for the polyimide resin solution used in the present invention include N-methyl-2-pyrrolidone, N, N-dimethylformamide, N, N-dimethylacetamide, 1,3-dimethyl-2-imidazolidinone, and tetramethylurea. , Sulfolane, dimethyl sulfoxide, γ-butyrolactone, cyclohexanone, and cyclopentanone. Of these, N-methyl-2-pyrrolidone and N, N-dimethylacetamide are preferred. Further, a solvent such as toluene, xylene, diglyme, tetrahydrofuran, methyl ethyl ketone, etc. may be added as long as the solubility is not inhibited.
A copper foil is used as the metal foil used in the present invention. The copper foil to be used may be either an electrolytic copper foil or a rolled copper foil. Further, the copper foil may be surface-treated with an oxidation treatment, an alloy treatment, a silane coupling agent or a titanium coupling agent. The thickness of the copper foil is not particularly limited, but a 1 mm sheet can be used from an ultrathin copper foil with a carrier of 1 μm.
In the present invention, other resins and various additives may be blended or reacted for the purpose of improving various properties of the copper clad laminate such as mechanical properties, electrical properties, slipperiness, and flame retardancy. Examples of the lubricant include silica, talc, and silicone compounds. Examples of the flame retardant include phosphorus-containing compounds, triazine compounds, aluminum hydroxide, and magnesium hydroxide. Also included are stabilizers such as antioxidants and UV absorbers, plating activators, and organic and inorganic fillers. Moreover, you may mix | blend other resins, such as hardening | curing agents, such as an isocyanate compound, an epoxy resin, and a phenol resin, a polyester resin, a polyurethane resin, and a polyamide resin.
The manufacturing method of the copper clad laminated board of this invention is demonstrated. After heat-treating the polyimide resin with superheated steam, another or the same polyimide resin layer is provided on the treated resin surface. Due to the heat treatment with superheated steam, partial decomposition occurs in the surface layer of the polyimide resin, the surface activity is increased, and the adhesion can be improved even with polyimide resins having different compositions.
In the present invention, it is desirable to apply a polyimide resin solution to a copper foil and perform primary drying, followed by further drying and heat treatment at a higher temperature. By adjusting the residual solvent ratio in the coating layer after primary drying to a range of 5 to 35%, preferably 15 to 30%, the influence of volume shrinkage due to the evaporation of the solvent can be reduced, and the peel strength and curl can be reduced. It is effective in improving. The primary drying conditions are preferably 60 to 150 ° C. and 1 to 10 minutes. Superheated steam may be used during the primary drying. After the primary drying, a secondary heat treatment is performed. When the polyimide resin is a polyimide precursor resin, the residual solvent is removed and the imidization reaction is performed by heat treatment. When the polyimide resin is a solvent-soluble polyimide resin or polyamideimide resin, the solvent is removed by heating. Heat treatment with superheated steam is desirable during the secondary heat treatment. The treatment with superheated steam may be used in combination with hot air drying or infrared or far infrared drying. The temperature of the superheated steam used is 200 to 400 ° C, preferably 250 to 350 ° C. The heat treatment time varies depending on the resin used, but is preferably 10 seconds or longer and 10 minutes or shorter. At the time of the secondary heat treatment, the temperature becomes 200 ° C. or higher, which may cause discoloration of the copper foil or changes in physical properties. If necessary, it is necessary to lower the oxygen concentration. When copper foil is used, it is desirable to reduce the oxygen concentration to 5% or less, preferably 0.5% or less.
A copper-clad laminate may be produced by a laminating method using a polyimide film having a thermoplastic polyimide resin provided on the surface, and the polyimide film surface may be heat-treated with superheated steam.
Applying another or the same polyimide resin solution to the surface treated with superheated steam, or laminating a polyimide film with a thermoplastic polyimide resin on the surface, the second polyimide resin Provide a layer. Similarly, the third polyimide resin layer is provided after the second polyimide resin layer is treated with superheated steam.
When the resin thickness of the final resin layer opposite to the copper foil exceeds 20 μm, batch processing using a vacuum dryer is desirable because the resin is less deteriorated.
A combination of a plurality of polyimide resins is determined according to required characteristics. For example, in a copper clad laminate for COF (Chip on Film), a resin that is in contact with the copper foil is a resin that has a glass transition temperature of 350 ° C. or higher and good adhesion to the copper foil in order to withstand inner lead bonding. For the resin layer opposite to the foil, a resin having a low coefficient of thermal expansion is desirable because of curl reduction.

In order to describe the present invention in more detail, examples are given below, but the present invention is not limited to the examples. In addition, the measured value described in the Example is measured by the following method.
Dimensional change rate: Using a copper clad laminate having a width of 10 mm and a length of 200 mm, the dimensional change rate before and after etching and the dimensional change rate after further processing the etched product in a hot air oven at 200 ° C. for 30 minutes were obtained. .
Solder heat resistance: The copper foil of the copper foil laminate was etched by a subtractive method to create a circuit pattern having a width of 1 mm. After humidity conditioning at 40 ° C. and 65% RH for 24 hours and flux washing, the sample was immersed in a jet solder bath at 320 ° C. for 20 seconds and visually observed for peeling and swelling. The thing in which abnormality was not seen was set as (circle), and the thing in which peeling and the swelling were seen were set as x.
Adhesive force: The above-mentioned sample on which a circuit pattern having a width of 1 mm was measured was measured at a pulling speed of 50 mm / min, a measurement temperature of 20 ° C., and a peeling angle of 90 degrees.
Heat resistance durability: The adhesion strength of the sample prepared with the circuit pattern having a width of 1 mm was measured after being left in a drier adjusted to 150 ° C. for 10 days.

Synthesis example 1
In a reaction vessel, 96 g of trimellitic anhydride, 81 g of 3,3 ′, 4,4′-benzophenonetetracarboxylic dianhydride, 74 g of 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride, 1,5 -210 g of naphthalene diisocyanate, 0.5 g of triethyldiamine and 2.7 kg of N-methyl-2-pyrrolidone were added, the temperature was raised to 150 ° C. over 1 hour, and further reacted at 150 ° C. for 5 hours. The obtained polyamidoimide resin had a logarithmic viscosity of 1.8 and a glass transition temperature of 365 ° C.

Synthesis example 2
In a reaction vessel, 154 g of trimellitic anhydride, 3,3 ′, 4,4′-benzophenonetetracarboxylic dianhydride 32 g, 29 g of 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride, 3,3 Add 264 g of '-dimethyl-4,4'-biphenyl diisocyanate, 0.5 g of triethyldiamine and 2.7 kg of N-methyl-2-pyrrolidone, raise the temperature to 150 ° C. over 1 hour, and further react at 150 ° C. for 5 hours. I let you. The obtained polyamideimide resin had a logarithmic viscosity of 1.6 and a glass transition temperature of 285 ° C.

Synthesis example 3
850 g of N, N-dimethylacetamide, 42.4 g of 4,4′-diamino-2,2′-dimethylbiphenyl and 87.6 g of 1,3-bis (4-aminophenoxy) benzene were put into a reaction vessel and stirred. Dissolved. Next, 29.4 g of 2,3,3 ', 4'-biphenyltetracarboxylic dianhydride, 117.6 g of 3,3', 4,4'-biphenyltetracarboxylic dianhydride was added and stirred at room temperature for 5 hours. Subsequently, a polyimide precursor was obtained.

<Example 1>
The polyamideimide solution prepared in Synthesis Example 1 was applied to a copper foil (35 μm electrolytic copper foil manufactured by Mitsui Metal Mining Co., Ltd.) using an applicator so that the thickness after drying was 10 μm, and heated at 100 ° C. for 5 minutes with hot air Primary dried. Further, a steam superheater (“DHF Super-Hi 10” manufactured by Daiichi High Frequency Industrial Co., Ltd.) was used as a superheated steam generator, and drying and heat treatment were performed in a drying / heat treatment furnace supplying superheated steam at 10 kg / hour. The polyamideimide solution obtained in Synthesis Example 2 was applied to the resin surface of the obtained single-sided copper clad laminate so that the thickness after drying was 30 μm, and was primarily dried with hot air at 100 ° C. for 5 minutes. Furthermore, it vacuum-dried at 260 degreeC and the reduced pressure of 1 mmHg for 10 hours. As evaluation of the obtained copper-clad laminate, dimensional stability, solder heat resistance, adhesive strength, and heat resistance durability were measured. The results are shown in Table-1.

<Example 2>
After both sides of Kaneka's polyimide (PI) film “Apical AH 12.5 μm” were plasma-treated, the polyamideimide solution prepared in Synthesis Example 2 was applied to both sides so that the thickness after drying was 5 μm, at 340 ° C. Dry with hot air for 10 minutes. The plate was hot-pressed for 5 minutes at 380 ° C. under a pressure of 5 kg / cm ² with a configuration of release paper / polyamideimide double-sided coated PI film / copper foil (35 μm electrolytic copper foil manufactured by Mitsui Kinzoku Mine Co., Ltd.). After removing the release paper and treating the resin surface of the obtained copper clad laminate with superheated steam, the polyamideimide solution obtained in Synthesis Example 2 was applied so that the thickness after drying was 25 μm as in Example 1. And primary drying with hot air at 100 ° C. for 5 minutes. Further, a copper clad laminate was obtained by vacuum drying in the same manner as in Example 1. The evaluation results of the obtained copper-clad laminate are shown in Table-1.

<Example 3>
The polyamideimide solution prepared in Synthesis Example 1 was applied to a copper foil (35 μm electrolytic copper foil manufactured by Mitsui Metal Mining Co., Ltd.) using an applicator so that the thickness after drying was 10 μm, and heated at 100 ° C. for 5 minutes with hot air Primary dried. Further, a steam superheater (“DHF Super-Hi 10” manufactured by Daiichi High Frequency Industrial Co., Ltd.) was used as a superheated steam generator, and drying and heat treatment were performed in a drying / heat treatment furnace supplying superheated steam at 10 kg / hour. The polyimide precursor solution obtained in Synthesis Example 3 was applied to the resin surface of the obtained copper-clad laminate so that the thickness after drying was 30 μm, and was primarily dried at 100 ° C. for 5 minutes. Further, heat treatment was performed from 100 ° C. to 350 ° C. at a rate of temperature increase of 10 ° C./min for 25 minutes. Subsequently, hot air drying was performed at 350 ° C. for 20 minutes. The evaluation results of the obtained copper-clad laminate are shown in Table-1.

<Comparative Example 1>
The polyamideimide solution prepared in Synthesis Example 1 was applied to a copper foil (35 μm electrolytic copper foil manufactured by Mitsui Metal Mining Co., Ltd.) using an applicator so that the thickness after drying was 10 μm, and was primarily dried at 100 ° C. for 5 minutes. . Only hot air drying was performed as the secondary heat treatment. The polyamideimide solution obtained in Synthesis Example 2 was applied to the resin surface of the obtained copper-clad laminate so that the thickness after drying was 30 μm, and was primarily dried with hot air at 100 ° C. for 5 minutes. Furthermore, it vacuum-dried at 260 degreeC and the reduced pressure of 1 mmHg for 10 hours. As evaluation of the obtained copper-clad laminate, dimensional stability, solder heat resistance, adhesive strength, and heat resistance durability were measured. The results are shown in Table-1.

<Comparative Example 2>
Similar to Example 2, the polyamideimide layer prepared in Synthesis Example 1 was provided on both sides of the PI film, and after obtaining a single-area layered body, the resin surface was not subjected to superheated steam treatment, as in Example 1. The polyamideimide solution obtained in Synthesis Example 2 was applied so that the thickness after drying was 25 μm, and was primarily dried with hot air at 100 ° C. for 5 minutes. Further, a copper clad laminate was obtained by vacuum drying in the same manner as in Example 1. The evaluation results of the obtained copper-clad laminate are shown in Table-1.

<Comparative Example 3>
The polyamide-imide solution prepared in Synthesis Example 1 was applied to a copper foil (35 μm electrolytic copper foil manufactured by Mitsui Metal Mining Co., Ltd.) using an applicator so that the thickness after drying was 10 μm, and further heated at 100 ° C. for 5 minutes. Then, secondary drying was performed. Furthermore, the polyimide precursor solution obtained in Synthesis Example 3 was applied to the resin surface of the obtained copper-clad laminate so that the thickness after drying was 30 μm, and was primarily dried at 100 ° C. for 5 minutes. Further, heat treatment was performed from 100 ° C. to 350 ° C. at a rate of temperature increase of 10 ° C./min for 25 minutes. Subsequently, hot air drying was performed at 350 ° C. for 20 minutes. The evaluation results of the obtained copper-clad laminate are shown in Table-1.

  The present invention relates to a simple method for producing a copper-clad laminate in which a plurality of polyimide resin layers are provided on a copper foil. By using this production method, productivity can be improved, and adhesion and heat resistance can be improved. A copper-clad laminate having excellent durability can be provided.

Claims (2)

  A copper-clad laminate, wherein a plurality of polyimide resin layers are formed on a copper foil, and the plurality of polyimide resin layers are formed on a polyimide resin layer treated with superheated steam.   When forming a plurality of polyimide resin layers on a copper foil, another or the same polyimide resin layer is formed on the polyimide resin layer treated with superheated steam, .