JPH0812914A - Polyimide ink - Google Patents

Abstract

PURPOSE:To obtain a polyimide ink which forms a film excellent in heat resistance, flexibility, adhesiveness, etc., by incorporating a polyimide resin obtd. by reacting terminal maleimide groups of a specific polyimide with a diamine compd. into an ink. CONSTITUTION:Maleimide groups of a polyimide of the formula (wherein n is 1-10) are reacted with a diamine compd. to produce a polyimide resin. An alicyclic diamine [e.g. 4,4'-bis(cyclohexylamine) or 4,4'-methylene-bis(cyclohexylamine)] is suitable as the diamine compd., and it is used pref. in an amt. of 0.3-1 mol based on 1mol of the polyimide. The resulting resin as the main component, a filler (e.g. a fine silica powder) surface-treated with a silane coupling agent, a defoaming agent, etc., are compounded to give a polyimide ink, which is suitable for a cover coat, etc., of a flexible printed circuit board.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thermosetting polyimide ink which can be cured at a low temperature and gives a film having excellent flexibility, which is a protective film for a flexible printed circuit board or a copper clad board for TAB, It is useful as an adhesive.

[0002]

2. Description of the Related Art In recent years, printed wiring boards have been used more and more with the development of electronic equipment, and the demand for flexible printed wiring boards, one of them, has increased. The organic material used therein is required to have excellent flexibility as well as heat resistance and insulation.

A polyimide coverlay film is used as a coating base material for circuit protection of a flexible printed circuit board. This is a polyimide film coated with adhesive on one side.Before coating, punch out only the terminal connection part with a mold, then align this by hand, then crimp at high temperature with a hot plate press. are doing.
However, there is a problem that the die cost is high and the dimensional accuracy of punching and the accuracy of alignment must be improved as the mounting density increases. Further, even if the physical properties of the film itself are improved, the physical properties of the material may be reduced as a whole depending on the adhesive used.

On the other hand, a method of forming an insulating protective film on a printed wiring board by a printing method has been developed.
However, the coverlay ink agent currently used is an improved version of the solder resist that has been conventionally used for rigid substrates, and it has poor flexibility and also has the problem that it is not always sufficient in heat resistance and electrical characteristics. . Polyamic acid solutions and polyimide solutions in which ether bonds, siloxane bonds, etc. are introduced into the polyimide skeleton have been developed in order to give polyimides with excellent heat resistance flexibility. Since high temperature is required, there has been a serious problem that the electrical reliability of the circuit is feared due to the progress of oxidation of the copper foil forming the circuit. Furthermore, in order to use the polyamic acid solution and the polyimide solution in the printing ink, a filler and an additive are usually required, and a solvent is also used, but the filler and the additive that have been conventionally used are There are also problems that sufficient performance cannot be exhibited due to the polarity of the solvent that dissolves the resin, and that these materials are altered due to the high processing temperature.

[0005]

The present invention has been made to solve the above-mentioned drawbacks of the prior art, and is a polyimide ink curable at a low temperature, and is excellent in flexibility and heat resistance. The purpose was to provide a coated film.

[0006]

Means for Solving the Problems The inventors of the present invention have conducted extensive studies to solve the above problems, and as a result, a compound represented by the general formula (I)
(In the formula, n represents an integer of 1 to 10.) An ink composition containing a polyimide resin obtained by reacting a polyimide and a diamine, particularly an alicyclic diamine as a main component forms a coating film at a low temperature, Moreover, it was found that the coating film has excellent physical properties such as heat resistance and flexibility, and further, the mutual relationship with the filler added for practical use is sufficient as an ink composition, and the present invention was further studied. Came to.

The polyimide of the general formula (I) used in the present invention has excellent flexibility and heat resistance because it has a spiroacetal ring in its skeleton. However, in applications such as coating base materials for flexible printed wiring boards, it is necessary to satisfy various physical properties as a film such as high flexibility, adhesiveness, heat resistance, etc. in terms of the purpose of use or process, and it is necessary to use a polymer. It is essential to be. Generally, the polyimide of the general formula (I) can be radically polymerized by heating in the presence of peroxide to form a polymer.
High temperature above ℃ is required. Therefore, in order to obtain a polymer at a low temperature, in the present invention, it becomes possible to form a polymer having excellent physical properties by subjecting a terminal maleimide group to a diamine, particularly an alicyclic diamine.

The alicyclic diamines particularly used in the present invention include 4,4'-bis (cyclohexylamine) and 4,4 '.
-Methylenebis (cyclohexylamine), 4,4'-
Ethylenebis (cyclohexylamine), 4,4'-propylenebis (cyclohexylamine), 4,4'-tetramethylenebis (cyclohexylamine), 4,4 '
-Bis (aminocyclohexyl) ether, 4,4'-
Bis (aminocyclohexyl) sulfide, 4,4'-
Examples of the bis (aminocyclohexyl) ketone and isophoronediamine include aliphatic amines such as trimethylenediamine, tetramethylenediamine, hexamethylenediamine, and 2,11-dodecanediamine, and aromatic amines such as 4,4′-. Diaminodiphenylmethane, 3,
3'-diaminodiphenylmethane, 4,4'-diaminodiphenyl ether, 4,4'-diaminodiphenyl sulfone, 4,4'-diaminodiphenyl sulfide,
3,3′-dimethyl-4,4′-diaminodiphenylmethane, 3,3′-dimethyl-4,4′-diaminodiphenyl, 1,3-bis (4-aminophenoxy) benzene, 2,2-bis (4 -Aminophenoxyphenyl) propane, orthophenylenediamine, metaphenylenediamine, paraphenylenediamine, benzidine and the like can be used.

The advantages of using an alicyclic diamine as the diamine are, firstly, that the addition reaction proceeds easily and secondly that the obtained polymer can be cured at a low temperature. In other words, in the addition reaction, the reactivity is greatly affected by the nucleophilicity of the diamine used, and the aliphatic diamine tends to have high reactivity, so the control of the reaction is delicate. This is because a reaction for a long time tends to be required. Further, the minimum temperature required for curing the obtained polymer is sometimes high in aromatic diamines, and alicyclic diamines are most suitable in the present invention in terms of reactivity and low temperature curing. Can say

The polyimide resin used in the present invention is obtained by reacting a polyimide of the general formula (I) having a maleimide at the terminal with a diamine in a proportion of 0.3 to 1, preferably 0.5 to 1 mol. The reaction concentration is usually 1 to
50%, preferably 2-40%. There are optimum reaction temperature and reaction time depending on the type of amine used, but it is usually 150 ° C. or less and 1 to 100 hours. Preferably, the aromatic amine is used at 100 to 150 ° C, the alicyclic amine is used at 20 to 140 ° C, and the aliphatic amine is preferably 0 to 50 ° C. The solvent used here is dimethylformamide, dimethylacetamide,
Examples thereof include N-methylpyrrolidone and dioxane.

The composition of the polyimide ink of the present invention contains the polyimide resin obtained by the above reaction as a main component. In addition to this, a filler, a defoaming agent, a coupling agent, etc. may be used if necessary. Good.

As the filler which can be used in the present invention, finely powdered products of silica and alumina are preferred, but surface-treated products can also be preferably used. The mixing ratio of the filler is 2 to 2 with respect to 100 parts of the solid polyimide resin.
0 parts by weight can be added, but preferably 5 to 15
Parts by weight. If the proportion of the filler added is too high, the flexibility and adhesion will be reduced, and if it is too low, the printability will be poor and the heat resistance will be reduced.

When a coupling agent is used for the surface treatment of the filler used in the present invention, γ-aminopropyltriethoxysilane, N-phenyl-γ-aminopropyltrimethoxysilane, N-β (aminoethyl) γ A silane-based coupling agent such as -aminopropyltrimethoxysilane is used, among which γ-aminopropyltriethoxysilane is preferable.

To use the defoaming agent in the present invention, a silicon type defoaming agent is preferable. The polyimide ink composition 100
It is preferable to add 0.1 to 5 parts by weight with respect to parts by weight, but the amount used is adjusted so as to be practical depending on the defoaming property during printing.

As a method for preparing the composition of the polyimide ink of the present invention, a method known per se can be used. For example, by adding a filler, a defoaming agent, and an additive to a polar solvent solution of a polyimide resin, which is an addition reaction product of a polyimide of the general formula (I) and an amine, and uniformly dispersing the mixture with a three-roll mill, a stirrer, a ball mill, or the like. Done. Screen printing of this ink can be performed using a 150 mesh stainless screen on a flexible printed board. The applied resin is 150 ℃
30 minutes in a hot air drying oven, and then 200-250
A cured coating can be obtained by heating at 3 ° C. for 3 minutes.

[0016]

The present invention will be described in detail below with reference to examples. However, the present invention is not limited to the following examples. [Preparation Example] Synthesis of Polyimide of General Formula (I) 3,3 ′, in a 2000 ml four-necked flask equipped with a thermometer, a stirrer, a cooler and a dry nitrogen gas inlet.
4,4'-benzophenone tetracarboxylic acid dianhydride 2
14.26 g, maleic anhydride 65.2 g, N, N'-
674.69 g of dimethylformamide was added and heated to 50 ° C. to dissolve.

Then 3,9-bis (3-aminopropyl) -2,4,8,10 tetraoxaspiro [5,5]
273.62 g undecane (this compound is known
If the manufacturing method is required, it is disclosed in JP-A-62-21239.
0) to N, N'-dimethylformamide 508.
The liquid dissolved in 15 g was added dropwise over 2 hours while maintaining the temperature of the flask at 50 to 60 ° C., and after completion of the addition, stirring was continued at the same temperature for 2 hours.

Next, nickel acetate 1
g, triethylamine 24.93 g, and acetic anhydride 2
03.65 g was added, and the mixture was stirred for 3 hours while maintaining the temperature at 60 ° C. to carry out a dehydration cyclization reaction.

After the reaction was completed, the reaction product was poured into a large amount of water to precipitate crystals. This was separated by filtration, washed with water, and dried to obtain 420 g of a white polyimide powder of the general formula (I). [Example 1] In a 200 ml four-necked flask equipped with a thermometer, a stirrer, a cooler and a dry nitrogen gas inlet, 46.6 g of the polyimide powder of Preparation Example 1 and N-methyl-2-
Pyrrolidone (100 g) was added, and the mixture was heated to 50 ° C. and dissolved.
Then 4,4'-diaminodiphenyl ether 6.0 g
22.8 g solution of N-methyl-2-pyrrolidone of was added dropwise at the same temperature. Then, the solution temperature was raised to 140 ° C., and the mixture was stirred at this temperature for 3 hours to carry out an addition reaction.

To 100 g of the above resin solution (30% concentration),
3.33 g of fine powder silica and 0.30 g of a silicone-based defoaming agent.
1 g, γ-aminopropyltriethoxysilane 0.66
g and kneaded 5 times with a three-roll mill to obtain a composition as an ink. Example 2 In a 200 ml four-necked flask equipped with a thermometer, a stirrer, a condenser and a dry nitrogen gas inlet, 46.6 g of the polyimide powder of Preparation Example 1 and N-methyl-2-
Pyrrolidone (100 g) was added, and the mixture was heated to 50 ° C. and dissolved.
Then 4,4'-diaminodicyclohexylmethane 5.
68 g of N-methyl-2-pyrrolidone 22.0 g solution was added dropwise at the same temperature. Then, stir at 50 ° C. for 10 hours,
An addition reaction was performed.

The above resin solution was added in the same ratio as in Example 1,
A composition which is an ink was obtained by the same method. [Example 3] 46.6 g of the polyimide powder of Preparation Example 1 and 100 g of N, N'-dimethylformamide were added to a 200 ml four-necked flask equipped with a thermometer, a stirrer, a cooler and a dry nitrogen gas blowing port, and added. It was heated to ℃ and dissolved. Then, after cooling to room temperature, 5.75 g of 3,9-bis (3-aminopropyl) -2,4,8,10-tetraoxaspiro [5,5] undecane was dissolved in 22.2 g of N, N'-dimethylformamide. Was dripped. Then 50
The mixture was stirred at 0 ° C for 4 hours to carry out addition reaction.

The above resin solution was added in the same ratio as in Example 1,
A composition which is an ink was obtained by the same method. Example 4 In a 200 ml four-necked flask equipped with a thermometer, a stirrer, a condenser and a dry nitrogen gas inlet, 46.6 g of the polyimide powder of Preparation Example 1 and N-methyl-2-
Pyrrolidone (100 g) was added, and the mixture was heated to 50 ° C. and dissolved.
Then 4,4'-diaminodicyclohexylmethane 5.
68 g of N-methyl-2-pyrrolidone 22.0 g solution was added dropwise at the same temperature. Then, stir at 50 ° C. for 10 hours,
An addition reaction was performed.

To 100 g of the above resin solution (30% concentration),
3.33 g of fine powder silica (10% based on solid resin),
An ink composition was obtained by adding 0.1 g of a silicone-based defoaming agent and 0.66 g of γ-aminopropyltriethoxysilane, and kneading the mixture with a triple roll 5 times. Example 5 In a 200 ml four-necked flask equipped with a thermometer, a stirrer, a condenser and a dry nitrogen gas inlet, 46.6 g of the polyimide powder of Preparation Example 1 and N-methyl-2-
Pyrrolidone (100 g) was added, and the mixture was heated to 50 ° C. and dissolved.
Then isophorone diamine 4.60 g of N-methyl-2
-Pyrrolidone 22.0 g solution was added dropwise at the same temperature. Then, it stirred at 50 degreeC for 6 hours, and performed the addition reaction.

An ink composition was obtained using the above resin solution in the same ratio and in the same manner as in Example 1. [Example 6] Resin solution (30% concentration) 1 obtained in Example 1
To 00 g, 1.58 g of fine powder silica (5% based on solid resin), 0.1 g of silicone antifoaming agent and 0.66 g of γ-aminopropyltriethoxysilane were added and kneaded 5 times with a three-roll mill. To obtain an ink composition. [Example 7] Resin solution (30% concentration) 1 obtained in Example 1
To 00 g, 5.30 g of fine powder silica (15% based on solid resin), 0.1 g of silicone antifoaming agent, and 0.66 g of γ-aminopropyltriethoxysilane were added, and the mixture was kneaded 5 times with a three-roll mill. To obtain an ink composition. [Comparative Example 1] 4,4'-Bismaleimidediphenylmethane 35.8 was placed in a 200 ml four-necked flask equipped with a thermometer, a stirrer, a condenser and a dry nitrogen gas inlet.
g, N-methyl-2-pyrrolidone 110 g was added, and the temperature was 50 ° C.
It was heated and melted. Then 4,4'-diaminodiphenylmethane 20.0 g of N-methyl-2-pyrrolidone 2
A 0.02 g solution was added dropwise at the same temperature. Then, the solution temperature was raised to 140 ° C., and the mixture was stirred at this temperature for 2 hours to carry out an addition reaction.

The above resin solution was added in the same ratio as in Example 1,
An ink composition was obtained in the same manner. [Comparative Example 2] 4,4'-Bismaleimidodiphenylmethane 35.8 was placed in a 200 ml four-necked flask equipped with a thermometer, a stirrer, a condenser and a dry nitrogen gas inlet.
g and 100 g of dionsan were added and heated to 50 ° C. to dissolve. Then, a solution of 14.73 g of 4,4'-diaminodicyclohexylmethane in 18.0 g of dioxane was added dropwise at the same temperature. Then, it stirred at 50 degreeC for 4 hours, and performed the addition reaction.

The above resin solution was added in the same ratio as in Example 1,
An ink composition was obtained in the same manner. [Comparative Example 3] 4,4'-Bismaleimidodiphenylmethane 34.0 was placed in a 200 ml four-necked flask equipped with a thermometer, a stirrer, a condenser and a dry nitrogen gas inlet.
g and 100 g of dioxane were added, and the mixture was heated to 50 ° C. and dissolved. Then, after cooling to room temperature, 3,9-bis (3-aminopropyl) -2,4,8,10 tetraoxaspiro [5,5] undecane 18.2 g of dioxane 21.8.
g solution was added dropwise. Then, the mixture was stirred at room temperature for 20 hours to carry out an addition reaction.

The resin solution was added in the same ratio as in Example 1,
An ink composition was obtained in the same manner.

Next, the ink composition thus obtained was screen-printed on the copper foil side of the flexible printed circuit board so that the thickness of the coating film after curing was about 15 μm. After that, it is dried in a hot air drying oven at 150 ° C for 30 minutes, and further 2
It heated at 00-250 degreeC for 3 minutes, and obtained the hardened film.

The characteristics of the cured film are hardness, flexibility, heat resistance,
The adhesion was evaluated. The results are shown in Table 1. For the hardness, the pencil scratch resistance test of JIS K5400 was used, and for the flexibility, the test piece was bent at 180 ° C. on a wire having a diameter of 1 mm, and thereafter cracks, cracks, and peeling were visually judged.
Regarding the heat resistance, peeling, swelling, and discoloration of the coating film when the test piece was floated in a solder bath at 300 ° C. for 10 seconds were visually judged. The adhesiveness was determined by cross-cutting in accordance with the JISK5400 cross cut test, attaching cellophane tape, and then peeling it off to count the remaining squares in 1 to 100 pieces.

[0030]

[Table 1]

[0031]

EFFECTS OF THE INVENTION The polyimide ink composition according to the present invention can be used in applications where it could not be used because high temperature is conventionally required for curing, and has sufficient film characteristics such as heat resistance, flexibility and adhesion. It is a polyimide ink composition. When used as a cover coat of a flexible printed circuit board, a highly reliable protective film can be formed by a printing method, so that the work of laminating a coverlay film is unnecessary,
Further, since an expensive mold is not required, it is extremely advantageous in terms of equipment cost and material cost.

Claims (7)

[Claims] 1. A compound represented by the following general formula (I) (In the formula, n represents an integer of 1 to 10) A polyimide ink containing a polyimide resin obtained by reacting a terminal maleimide group of a polyimide with a diamine compound. 2. The polyimide ink according to claim 1, wherein the ratio of the diamine compound is 0.3 to 1 mol per 1 mol of the polyimide. 3. The polyimide ink according to claim 1, wherein the diamine compound is an alicyclic diamine. 4. The polyimide ink according to claim 1, wherein the filler is added to the polyimide resin at a ratio of 2 to 20: 100 in terms of solid matter. 5. The amount of filler added is 5 to 15:10.
The polyimide ink according to claim 4, which has a ratio of 0. 6. The polyimide ink according to claim 4, wherein the filler is fine powder of silica or alumina. 7. The polyimide ink according to claim 4, wherein the filler is surface-treated with a silane coupling agent.