JP2001342270A - Method for producing heat-resistant bonding sheet and copper-clad laminated board produced by using heat- resistant bonding sheet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a heat-resistant bonding sheet and a copper-clad laminated board having sufficiently high mechanical strength and excellent soldering heat- resistance, adhesivity, dimensional stability, low dielectric constant and high productivity. SOLUTION: A composition composed of (A) a polyamic acid as a precursor of a thermoplastic polyimide, (B) a dehydrating agent and (C) a catalyst is applied to at least one surface of a base film composed of a heat-resistant resin and the component A is imidated. A heat-resistant bonding sheet can be produced by this method in a short time to improve the productivity compared with a thermal imidation method without using a dehydrating agent. High bonding strength can be attained between the base film and the thermoplastic polyimide and the produced sheet has excellent heat-resistance and soldering heat-resistance. The heat-resistant bonding sheet can be used especially for the production of a flexible copper-clad laminated sheet.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a bonding sheet having a thermoplastic polyimide layer on at least one surface of a base film and a copper-clad laminate comprising the same, and more particularly to a heat resistance excellent in heat resistance, adhesion and dimensional characteristics. The present invention relates to a bonding sheet and a copper-clad laminate comprising the same.

[0002]

2. Description of the Related Art In recent years, higher performance and higher functionality of electronic devices have been developed.
The miniaturization is rapidly progressing, and there is an increasing demand for miniaturization and weight reduction of electronic components used in electronic devices. Along with this, the heat resistance, mechanical strength,
Various physical properties such as electrical characteristics are further required, and the semiconductor element packaging method and the wiring board on which they are mounted have higher densities,
High-performance and high-performance products have been required. Flexible printed wiring board (hereinafter referred to as FPC)
In regard to, thin wire processing, multilayer formation, etc. are being performed, component mounting FPCs that directly mount components on the FPC, double-sided FPCs with circuits formed on both sides, multiple FPCs are laminated, and layers are connected by wiring Multilayer FPCs and the like have emerged.

In general, an FPC has a structure in which a circuit pattern is formed on a flexible and thin base film and a cover layer is provided on the surface thereof. In order to obtain the above-mentioned FPC, an insulating adhesive used as a material thereof is used. It is necessary to improve the performance of agents and insulating organic films. Specifically, it has high heat resistance and mechanical strength, and is excellent in workability, adhesiveness, low hygroscopicity, electrical characteristics, and dimensional stability.

At present, a film made of a polyimide resin having excellent characteristics is widely used as an insulating organic film of FPC. An epoxy resin or an acrylic resin that is excellent in low-temperature workability and workability is used as the insulating adhesive. However, it has been found that these adhesives are not particularly satisfactory in heat resistance. More specifically, when exposed to a temperature of 150 ° C. or more for a long time, these adhesives are deteriorated, which affects various characteristics. Furthermore, when using these adhesives, the adhesive is applied on a base film, dried, and then adhered to a conductor layer (generally, copper foil is used). Have to be heat-treated.

[0005] In particular, with the expanding use of FPCs, there is an urgent need to solve the problem of heat resistance. In order to solve this problem, a two-layer FPC having no adhesive layer, an FPC using a polyimide resin having excellent melt fluidity, and the like have been proposed. As for the two-layer FPC having no adhesive layer, a method of forming a conductor layer directly on an insulating film and a method of forming an insulating layer directly on a conductor layer are general. In the method of forming a conductor layer directly on an insulating layer, a method is used in which a thin layer of a conductor is formed by vapor deposition or sputtering, and then a thick layer of the conductor is formed by plating. There are problems that holes are easily generated and it is difficult to obtain a sufficient adhesive force between the insulating layer and the conductor layer.

On the other hand, in a method of forming an insulating layer directly on a conductor layer, a method of casting and drying a solution of a polyimide copolymer or a polyamic acid copolymer on the conductor layer and drying the same is used. In addition, the conductor layer is likely to be corroded by various solvents. In addition, when producing a double-sided plate, there is a problem that a complicated process of attaching two single-sided plates and then abutting these single-sided plates is required.

[0007] Further, with respect to FPC using a polyimide resin having excellent melt fluidity, Japanese Patent Application Laid-Open No. 2138789/1990,
A bonding sheet having a thermoplastic polyimide layer on at least one surface of a base film made of a heat-resistant resin proposed in JP-A-5179224 or JP-A-5112768 is used, but excellent adhesiveness, dimensional stability, soldering heat resistance and the like are obtained. It was difficult to realize.

[0008]

As described above, the FPC having excellent heat resistance has problems in any form, but in consideration of productivity and characteristics, a base film made of a heat-resistant resin is required. It is considered that a method of bonding a copper foil and a bonding sheet obtained by laminating a thermoplastic polyimide on the substrate is most advantageous. Therefore, in order to solve the above-mentioned problems relating to this case, in a method of manufacturing a heat-resistant bonding sheet, a heat-drying process in a short time is performed, and the adhesiveness, dimensional characteristics, solder heat resistance, and further, low water absorption and low dielectric properties are obtained. It is an object of the present invention to provide a method for producing a heat-resistant bonding sheet suitable for FPC and the like, which can exhibit the various physical properties described above.

[0009]

SUMMARY OF THE INVENTION The present invention provides the following method for producing a heat-resistant bonding sheet and a copper-clad laminate using the heat-resistant bonding sheet obtained by the method. To achieve. 1) A composition containing (A) a polyamic acid which is a precursor of a thermoplastic polyimide, (B) a dehydrating agent, and (C) a catalyst,
A method for producing a heat-resistant bonding sheet, wherein the component (A) is imidized after being applied to at least one surface of a base film made of a heat-resistant resin. 2) The component (A) has a general formula (Formula 31)

[0010]

Embedded image (In the formula, k is an integer of 1 or more, m and n are each an integer of 0 or more where m + n is 1 or more. Ar1, X, and Y are divalent organic groups, and Ar2 is a tetravalent organic group. The method for producing a heat-resistant bonding sheet according to (1), wherein the bonding sheet has a chemical structure of amic acid represented by (2). 3) Ar1 in the general formula (Formula 31) is represented by the following formula (Formula 32)
~

[0011]

Embedded image

[0012]

Embedded image

[0013]

Embedded image Wherein Ar2 in the general formula (Chemical Formula 31) is selected from the following formulas (Chemical Formula 35) to (Chemical Formula 41)

[0014]

Embedded image

[0015]

Embedded image

[0016]

Embedded image

[0017]

Embedded image

[0018]

Embedded image

[0019]

Embedded image

[0020]

Embedded image The method for producing a heat-resistant bonding sheet according to 2), wherein the method is selected from the group of tetravalent organic groups shown in (1). 4) X and Y in the general formula (Formula 31) are represented by the following formula (Formula 4)
2)-(Chemical Formula 60)

[0021]

Embedded image

[0022]

Embedded image

[0023]

Embedded image

[0024]

Embedded image

[0025]

Embedded image

[0026]

Embedded image

[0027]

Embedded image

[0028]

Embedded image

[0029]

Embedded image

[0030]

Embedded image

[0031]

Embedded image

[0032]

Embedded image

[0033]

Embedded image

[0034]

Embedded image

[0035]

Embedded image

[0036]

Embedded image

[0037]

Embedded image

[0038]

Embedded image

[0039]

Embedded image (2) The method for producing a heat-resistant bonding sheet according to (2) or (3), which is at least one selected from the group of divalent organic groups shown in (1). 5) The method for producing a heat-resistant bonding sheet according to any one of 1) to 4), wherein the base film of the heat-resistant bonding sheet is a non-thermoplastic polyimide film. 6) A copper-clad laminate characterized in that a copper foil is disposed on at least one surface of a heat-resistant bonding sheet obtained by the method for manufacturing a heat-resistant bonding sheet described in 1) to 5).

[0040]

Embodiments of the present invention will be described below. First, a method for preparing the polyamic acid (A) for obtaining the thermoplastic polyimide of the present invention will be described.

The component (A) can be obtained by reacting an acid dianhydride with a diamine in an organic solvent. According to the present invention, first, in an atmosphere of an inert gas such as argon or nitrogen, Formula (Formula 61)

[0042]

Embedded image (In the formula, A represents a tetravalent organic group.) At least one acid dianhydride is dissolved or diffused in an organic solvent. The solution has the general formula

[0043]

Embedded image (In the formula, B represents a divalent organic group.) At least one kind of diamine is added to obtain a solution of a polyamic acid which is a precursor of a thermoplastic polyimide. In this reaction, contrary to the above addition procedure, a diamine solution may be prepared first, and a solid acid dianhydride or an organic solvent solution of acid dianhydride may be added to the solution. The reaction temperature at this time is preferably from 10C to 0C. The reaction time is preferably 30 minutes to 3 hours. By this reaction, a polyamic acid solution which is a precursor of the thermoplastic polyimide is prepared.

Examples of the organic solvent used in the synthesis reaction of the polyamic acid include sulfoxide solvents such as dimethyl sulfoxide and diethyl sulfoxide, formamide solvents such as N, N dimethylformamide and N, N diethylformamide, and N, N dimethyl Acetamide solvents such as acetamide and N, N diethylacetamide; pyrrolidone solvents such as N-methyl-2-pyrrolidone; phenol solvents such as phenol, o-, m- or p-cresol, xinol, halogenated phenol and catechol. Or hexamethylphosphoramide, γ-butyrolactone and the like. These may be used alone, or a mixed solvent of two or more kinds may be used. Further, a mixed solvent composed of these polar solvents and a non-solvent of polyamic acid can also be used. Examples of the non-solvent for the polyamic acid include acetone, methanol, ethanol, isopropanol, benzene, and methyl cellosolve.

Although the molecular weight of the polyamic acid copolymer and the obtained polyimide copolymer is not particularly limited, the number average molecular weight is 50,000 or more from the viewpoint of maintaining the strength as a heat-resistant adhesive. Further, it is preferably at least 80,000, particularly preferably at least 100,000. The molecular weight of the polyamic acid copolymer (solution) as the adhesive can be measured by GPC (gel permeation chromatography).

The component (A) has the general formula (Chemical Formula 63) from the viewpoint that the water absorption of the obtained polyimide is reduced and the heat resistance of the heat-resistant bonding sheet obtained by the method of the present invention is improved.

[0047]

Embedded image (In the formula, k is an integer of 1 or more, m and n are each an integer of 0 or more where m + n is 1 or more. Ar1, X, and Y are divalent organic groups, and Ar2 is a tetravalent organic group. ) Is preferable.

Further, Ar in the general formula (Formula 63)
1 is the following formula (Formula 64) to (Formula 67)

[0049]

Embedded image

[0050]

Embedded image

[0051]

Embedded image Wherein Ar2 in the general formula (Chemical Formula 63) is selected from the following formulas (Chemical Formulas 67 to 73):

[0052]

Embedded image

[0053]

Embedded image

[0054]

Embedded image

[0055]

Embedded image

[0056]

Embedded image

[0057]

Embedded image

[0058]

Embedded image It is preferably at least one selected from the group of tetravalent organic groups shown in the following.

X and Y in the above general formula (Formula 63)
The following formulas (Formula 74) to (Formula 92)

[0060]

Embedded image

[0061]

Embedded image

[0062]

Embedded image

[0063]

Embedded image

[0064]

Embedded image

[0065]

Embedded image

[0066]

Embedded image

[0067]

Embedded image

[0068]

Embedded image

[0069]

Embedded image

[0070]

Embedded image

[0071]

Embedded image

[0072]

Embedded image

[0073]

Embedded image

[0074]

Embedded image

[0075]

Embedded image

[0076]

Embedded image

[0077]

Embedded image

[0078]

Embedded image It is preferable that the compound is at least one selected from the group of divalent organic groups shown in the above. Among them, (Chemical Formula 90) is particularly preferable in that it can balance the adhesive strength with the copper foil and the solder heat resistance. .

The dehydrating agent (B) used in the present invention is not particularly restricted but includes, for example, aliphatic acid anhydrides such as acetic anhydride and aromatic acid anhydrides such as phthalic anhydride.

Examples of the catalyst (C) include aliphatic tertiary amines such as triethylamine, aromatic tertiary amines such as dimethylaniline, and heterocyclic tertiary amines such as pyridine and isoquinoline. Can be

In the method for producing a heat-resistant bonding sheet of the present invention, a stoichiometric or more dehydrating agent (B) component and a catalyst (C) component are added to a solution containing the component (A), and the solution is coated on a base film. Thereafter, imidization and solvent removal are performed by a heat drying treatment to obtain a bonding sheet having a desired configuration. According to this method, the heat-drying time can be shortened, and a heat-resistant bonding sheet exhibiting sufficient physical properties such as solder heat resistance and adhesiveness can be obtained. The coating thickness at this time is preferably 5 to 30 μm.

Heat drying is carried out for the purpose of removing the solvent and dehydrating and cyclizing the polyamic acid. The conditions are preferably such that the organic solvent is first evaporated at a temperature of 200 ° C. or lower within 5 minutes. Subsequently, this is dried by heating to imidize it. The heating temperature for imidization is 200
C. to 300.degree. C. is preferred. In this chemical dehydration method, by using a dehydrating agent and a catalyst, imidization can be performed in a shorter time than in the case of thermal dehydration.

In the method for producing a heat-resistant bonding sheet of the present invention, the base film is formed from the viewpoint that the heat resistance of the heat-resistant bonding sheet obtained by the method of the present invention and the copper-clad laminate using the same are improved. The base film is preferably made of a non-thermoplastic polyimide.

Although the embodiment of the heat-resistant bonding sheet according to the present invention has been described above, the present invention is not limited to this, and the present invention is based on the knowledge of those skilled in the art without departing from the scope of the present invention. , Various improvements,
The present invention can be implemented in a form in which changes and modifications are made. The present invention will be described more specifically with reference to the above examples, but the present invention is not limited to these examples.
The copper-clad laminate of the present invention can be obtained by arranging a copper foil on at least one surface of the heat-resistant bonding sheet by a pressing method or a laminating method.

[0085]

Example 1 The whole system was cooled with ice water and purged with nitrogen.
123.1 g of 2,2′-bis [4- (4-aminophenoxy) phenyl] propane (hereinafter, referred to as BAPP) and 716.2 g of dimethylformamide (hereinafter, referred to as DMF) are placed in a 000 ml three-neck separable flask. It was charged and stirred for 15 minutes. Then, 3,3 ', 4,4'
-Benzophenonetetracarboxylic dianhydride (hereinafter referred to as B
A solution obtained by dissolving 33.8 g of TDA in 20 g of DMF was charged. Subsequently, 76.0 g of 3,3 ′, 4,4′-ethylene glycol dibenzoate tetracarboxylic dianhydride (hereinafter referred to as TMEG) was added to 20 g of DMF.
Was added and stirred for 30 minutes. After stirring for 30 minutes, a solution obtained by dissolving 4.1 g of TMEG in 36.9 g of DMF was gradually added while paying attention to the viscosity of the solution in the flask.
A polyamic acid solution having a C (solid content) of 23% was obtained.

The polyamic acid solution 80 obtained by the above operation
g of acetic anhydride while cooling and stirring.
A mixed solution of 5.2 g of isoquinoline and 4.7 g of DMF was added. The solution after the addition is applied to both sides of a polyimide film (Apical 12.5 NPI; manufactured by Kaneka Corporation)
After applying a polyamic acid so that the final one-sided thickness of the thermoplastic polyimide layer is 6 μm, 2 minutes at 150 ° C.
The solvent was removed and imidization was performed by heating at 20 ° C. for 1 minute to obtain a bonding sheet. A rolled copper foil having a thickness of 18 μm is laminated on the thermoplastic polyimide surface of the obtained bonding sheet, and a polyimide film having a thickness of 25 μm is disposed thereon as a release film. A double belt press (DBP)
To obtain a copper-clad laminate. The lamination temperature was 280 ° C., the pressure was 70 kgf / cm, and the lamination time was about 5 minutes.

The obtained copper-clad laminate was subjected to JIS C
Measure adhesive strength (kgf / cm) according to 6481 (measurement equipment: SHIMADZU AUTOGRAPH S-
100-C), and the solder heat resistance was measured. Table 1 shows the results.
Shown in Solder heat resistance after normal condition adjustment (20 ° C, 60% R
H, after adjusting for 24 hours, immersion at 300 ° C. for 1 minute), after moisture absorption (40 ° C., 90% RH, after adjusting for 96 hours, 280 ° C. 1
(Soaked for 0 seconds). Table 1 shows the results.

[0088]

Example 2 The whole system was cooled with ice water and replaced with nitrogen.
123.1 g of 2,2'-bis [4- (4-aminophenoxy) phenyl] propane (hereinafter referred to as BAPP) and 719.7 g of dimethylformamide (hereinafter referred to as DMF) are placed in a 000 ml three-neck separable flask. It was charged and stirred for 15 minutes. Then, 3,3 ', 4,4'
-Benzophenonetetracarboxylic dianhydride (hereinafter referred to as B
A solution obtained by dissolving 48.3 g (referred to as TDA) in 20 g of DMF was charged. Subsequently, 59.0 g of 3,3 ′, 4,4′-ethylene glycol dibenzoate tetracarboxylic dianhydride (hereinafter referred to as TMEG) was added to 20 g of DMF.
Was added and stirred for 30 minutes. After stirring for 30 minutes, a solution in which 2.6 g of TMEG was dissolved in 23.4 g of DMF was gradually added while paying attention to the viscosity of the solution in the flask.
A polyamic acid solution having a C (solid content) of 23% was obtained.

As in Example 1, after adding a dehydrating agent and a catalyst, application and drying were performed on a base film to obtain a bonding sheet. The subsequent copper-clad laminate (hereinafter CCL)
Production and measurement of physical properties were performed in the same manner as in Example 1. Table 1 shows the results.

[0090]

Example 3 The whole system was cooled with ice water and purged with nitrogen.
123.1 g of 2,2'-bis [4- (4-aminophenoxy) phenyl] propane (hereinafter referred to as BAPP) and 658.4 g of dimethylformamide (hereinafter referred to as DMF) are placed in a 000 ml three-neck separable flask. It was charged and stirred for 15 minutes. Then, 3,3 ', 4,4'
-Biphenyltetracarboxylic dianhydride (hereinafter referred to as BPD
A solution obtained by diffusing 79.4 g of A) into 20 g of DMF was charged. Subsequently, a solution in which 10.0 g of 3,3 ′, 4,4′-ethylene glycol dibenzoate tetracarboxylic dianhydride (hereinafter, referred to as TMEG) was dissolved in 20 g of DMF was added, and the mixture was stirred for 30 minutes. After stirring for 30 minutes, an additional 2.3 g of TMEG was added to 20.7 g of DM
F. The solution dissolved in F was gradually added while paying attention to the viscosity of the solution in the flask.
A polyamic acid solution having a solid content of 23% was obtained.

As in Example 1, after adding a dehydrating agent and a catalyst, coating and drying were performed on a base film to obtain a bonding sheet. Subsequent production of CCL and measurement of physical properties were performed in the same manner as in Example 1. Table 1 shows the results.

[0092]

Comparative Example 1 A polyamic acid was polymerized in the same manner as in Example 1, and then a polyimide film (Apical 12.5NPI; manufactured by Kaneka Chemical Industry Co., Ltd.) without adding a dehydrating agent and a catalyst.
On both sides, the final thickness of one side of the thermoplastic polyimide layer is 6μ
m and heated at 150 ° C. for 2 minutes and at 220 ° C. for 1 minute to remove the solvent and imidize to obtain a bonding sheet. Subsequent production of CCL and measurement of physical properties were performed in the same manner as in Example 1. Table 1 shows the results.

[0093]

Comparative Example 2 Polyamide acid was polymerized in the same manner as in Example 2, and then a polyimide film (Apical 12.5NPI; manufactured by Kaneka Chemical Industry Co., Ltd.) without adding a dehydrating agent and a catalyst.
On both sides, the final thickness of one side of the thermoplastic polyimide layer is 6μ
m and heated at 150 ° C. for 2 minutes and at 220 ° C. for 1 minute to remove the solvent and imidize to obtain a bonding sheet. Subsequent production of CCL and measurement of physical properties were performed in the same manner as in Example 1. Table 1 shows the results.

[0094]

Comparative Example 3 Polyamide acid was polymerized in the same manner as in Example 3, and then a polyimide film (Apical 12.5NPI; manufactured by Kaneka Corporation) without adding a dehydrating agent and a catalyst.
On both sides, the final thickness of one side of the thermoplastic polyimide layer is 6μ
m and heated at 150 ° C. for 2 minutes and at 220 ° C. for 1 minute to remove the solvent and imidize to obtain a bonding sheet. Subsequent production of CCL and measurement of physical properties were performed in the same manner as in Example 1. Table 1 shows the results.

[0095]

[Table 1]

[0096]

As described above, the bonding sheet according to the present invention has excellent heat resistance, excellent peel strength at the interface between the base film and the thermoplastic polyimide and between the thermoplastic polyimide and the copper foil, the dimensional characteristics, and the thermal imide. Since the desired physical properties can be obtained in a shorter time than in the case where the chemical conversion is performed, the productivity is excellent. The bonding sheet according to the present invention is suitable for use in new high-density packaging materials such as FPC and rigid-flex board materials, COF and LOC packages, and MCM.
Other uses are not particularly limited.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) H05K 1/03 610 H05K 1/03 610P // C08L 79/08 C08L 79/08 F term (reference) 4F006 AA39 AB38 BA01 BA04 CA08 DA04 EA05 4F100 AB17C AB33C AK01B AK49A AK49B AL05A BA02 BA03 BA07 BA10B BA10C BA13 BA15 CA30A EH112 EH462 EJ012 GB43 JB16A JG05 JJ03B JL02 JL04 JL11 4J04 GA03 GA05 GA02 CD03 GA05 GA02 HC07 HC21 HC22 JA09 KA14 LA06 LA08 LA09 MA02 NA20 4J043 PA04 PA09 QB15 QB26 QB31 RA34 SA06 SA42 SA43 SA44 SA54 SA71 UA121 UA122 UA131 UA132 UA141 UA151 UB011 UB021 UB022 UB061 UB121 X01 UB141 XB 321 ZA02 ZA12 ZB02 ZB50

Claims (6)

[Claims] After applying a composition containing (A) a polyamic acid which is a precursor of a thermoplastic polyimide, (B) a dehydrating agent, and (C) a catalyst to at least one surface of a base film made of a heat-resistant resin. A method for producing a heat-resistant bonding sheet, wherein the component (A) is imidized. 2. The method according to claim 1, wherein the component (A) is represented by the general formula (1). (In the formula, k is an integer of 1 or more, m and n are each an integer of 0 or more where m + n is 1 or more. Ar1, X, Y
Represents a divalent organic group, and Ar2 represents a tetravalent organic group. The method for producing a heat-resistant bonding sheet according to claim 1, wherein the method has a chemical structure of an amic acid represented by: 3. Ar1 in the above general formula (Chem. 1) is represented by the following formulas (Chem. 2) to (Chem. 4). Embedded image Embedded image Wherein Ar2 in the general formula (Chemical Formula 1) is selected from the group of divalent organic groups shown below: Embedded image Embedded image Embedded image Embedded image Embedded image Embedded image 3. The method for producing a heat-resistant bonding sheet according to claim 2, wherein the heat-resistant bonding sheet is selected from the group of tetravalent organic groups shown in 3). 4. X and Y in the general formula (Chem. 1) are represented by the following formulas (Chem. 12) to (Chem. 30). Embedded image Embedded image Embedded image Embedded image Embedded image Embedded image Embedded image Embedded image Embedded image Embedded image Embedded image Embedded image Embedded image Embedded image Embedded image Embedded image Embedded image Embedded image The method for producing a heat-resistant bonding sheet according to claim 2 or 3, wherein the method is at least one selected from the group of divalent organic groups shown in (1). 5. The method according to claim 1, wherein a base film of the heat-resistant bonding sheet is a non-thermoplastic polyimide film. 6. A copper-clad laminate comprising a heat-resistant bonding sheet obtained by the method for producing a heat-resistant bonding sheet according to claim 1 and a copper foil disposed on at least one surface of the bonding sheet.