JPS5815948B2 - Insulating materials for circuit boards - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a heat-resistant material that is used to form an insulating layer of a circuit board that requires particularly bendability in a circuit board that has a structure consisting of metal foil and an insulating layer or other various structures. The present invention relates to an insulating material comprising a fiber base material and a thermosetting resin composition.

Traditionally, bendable circuit boards have been made of metal foils such as copper foil and aluminum foil, heat-resistant resins containing heterocycles such as polyimide, polyamideimide, and polyparapanic acid, polyester, and polyethylene. A structure in which a sheet or film made of a thermoplastic resin represented by the following is bonded together with an adhesive or by thermocompression bonding is known.

However, this type of substrate has drawbacks such as poor dimensional accuracy due to heat treatment and low tear strength.

On the other hand, as a circuit board with relatively good dimensional accuracy, thermosetting resin compositions such as epoxy resins and phenolic resins are applied to the same metal foil as described above, mainly from inorganic fibers such as glass cloth and glass mats. It is also known that one or more prepregs are made by impregnating and applying a semi-cured fiber base material to a semi-cured fiber base material, stacking them together, heat-pressing them, and then subjecting them to high-temperature heat treatment to completely cure them. .

Since the insulating layer of this type of board is composed of a fiber base material and a thermosetting resin, relatively good dimensional accuracy can be obtained when the board thickness is reduced, and a certain degree of flexibility can also be obtained. It will be done.

However, in a 180° bending test, the metal foil tends to break, the substrate itself tends to break, and stress concentration occurs at the interface between the base material, such as glass cloth or glass mat, and the thermosetting resin. The tear strength tends to decrease easily, which is a fatal drawback as a flexible circuit board, and there are limits to its use as a circuit board.

The inventors found that the material does not have such drawbacks, that is, it has high dimensional stability that allows the dimensional change rate to be 0.1% or less during heat treatment and etching treatment, and also has excellent flexibility. Furthermore, with the aim of obtaining a circuit board that provides good results in terms of peel strength, as a result of intensive studies, we have developed specific materials for the heat-resistant fiber base material and thermosetting resin composition used to form the insulating layer. It was discovered that the above object could be achieved by using a product, and this led to the completion of this invention.

That is, the present invention provides an insulating material composed of a heat-resistant fiber base material and a thermosetting resin composition used for forming an insulating layer of a circuit board, in which the base material is composed of inorganic fibers and organic fibers, and The above composition may include a polyester comprising an aliphatic or alicyclic dicarboxylic acid or a derivative thereof and an aliphatic polyhydric alcohol having two or more hydroxyl groups bonded to different carbon atoms, 1,2,3,4-butane Mainly composed of polyesteramide-imide or polyesterimide modified with tetracarboxylic acid (hereinafter simply referred to as BTC) or its derivative and an aliphatic polyvalent amine in which two or more amine groups are bonded to different carbon atoms. The present invention relates to an insulating material for a circuit board, characterized in that it uses an insulating material.

According to the present invention, by using a thermosetting resin composition for forming an insulating layer that is mainly composed of the above-mentioned specific polyesteramide-imide or polyesterimide, it is possible to provide a circuit with improved flexibility. A substrate can be obtained, and when such a resin composition is used, both dimensional stability and tear strength can be improved by using inorganic fibers and organic fibers together as a heat-resistant fiber base material.

In this way, in this invention, it is only when the thermosetting resin composition and the heat-resistant fiber base material are specified that all of the flexibility, dimensional stability, and tear strength can be satisfied. When epoxy resins or phenolic resins are used as the curable resin composition, the flexibility is mainly improved, and when the heat-resistant fiber base material is made only of inorganic fibers such as glass cloth or glass mat, the tear strength is improved. If a fabric consisting only of organic fibers, such as polyester nonwoven fabric, is used, the dimensional stability will be extremely impaired, and the object of the present invention cannot be achieved in either case.

Examples of aliphatic or alicyclic dicarboxylic acids or derivatives thereof used as the acid component of the polyester in the thermosetting resin composition of the present invention include oxalic acid, succinic acid, malonic acid, adipic acid, and 1,5-pentane. Dicarboxylic acid, 1,6-hexanedicarboxylic acid, azelaic acid, 1
・Aliphatic dicarboxylic acids such as 9-nonadicarboxylic acid, sepatic acid, and 1,10-decanedicarboxylic acid, alicyclic dicarboxylic acids such as tetrahydroterephthalic acid, tetrahydrophthalic acid, tetrahydroisophthalic acid, and tetrahydrofuran dicarboxylic acid, or these dicarboxylic acids One or more derivatives such as lower alkyl esters and halides of acids are used.

Among these, the most preferable ones have a carbon number of 1 to 1.
0, particularly preferably 3 to 8 linear aliphatic dicarboxylic acids or derivatives thereof.

If necessary, aromatic dicarboxylic acids such as terephthalic acid or derivatives thereof may be used together with these dicarboxylic acids, but the proportion should be small enough to not impair flexibility after high-temperature heat treatment. It is.

As the aliphatic polyhydric alcohol in which two or more hydroxyl groups are bonded to different carbon atoms and used as the alcohol component of the polyester in the thermosetting resin composition of the present invention, a wide variety of conventionally known aliphatic alcohols can be used, but particularly preferred. It is preferable to use a linear aliphatic polyhydric alcohol, particularly a dihydric alcohol, having 2 to 10 carbon atoms, most preferably 2 to 8 carbon atoms.

Specifically, ethylene glycol, propylene glycol, 1,3-butanediol, 1,4-butanediol,
1,5-bentanediol, 1,6-hexanediol, 1,7-hebutanediol.

1,8-octanediol, 1,9-nonanediol,
Examples include dihydric alcohols such as 1,10-decanediol, diethylene glycol, and triethylene glycol, and trihydric alcohols such as glycerin, trimethylolpropane, and pentaerythritol, and one or more of these alcohols may be used.

The ratio of these acid components and polyhydric alcohol components is as follows:
Generally, it is best to set the ratio such that the total amount of hydroxyl groups (equivalent) is greater than the reactive acid groups (carboxyl groups, etc.) of the acid component.
For example, the ratio of alcohol component to acid component is 1.1 to 4.
Good results are obtained when the amount is increased by 0 times, preferably 1.1 to 2.0 times (equivalent).

In this invention, a polyester having a high molecular weight sufficient to satisfy flexibility is formed by subjecting the acid component and alcohol component described above to a polycondensation reaction, generally at 130 to 200°C for 0.5 to 4 hours. Polyester generally contains unreacted hydroxyl groups as well as unreacted reactive acid groups.

BTC used to modify such polyester
or a derivative thereof, and an aliphatic polyvalent amine in which two or more amino groups are bonded to different carbon atoms, improve the heat resistance of the polyester and give better results in flexibility; If polybasic acids other than BTC are used, such as trimellitic acid or pyromellitic acid, or if aromatic polyvalent amines are used, the above effects will not only be lost, but also due to the denaturation conditions, polybasic acids and polybasic acids. Since a polyesterimide that is difficult to dissolve in general organic solvents is produced depending on the molar ratio with the amine, a composition suitable for impregnation and coating on heat-resistant fiber substrates cannot be obtained.

Derivatives of BTC include its monoanhydride, dianhydride, ester, and halide.

Furthermore, as an aliphatic polyvalent amine in which two or more amine groups are bonded to different carbon atoms, it is particularly preferable that the number of carbon atoms is 2.
~8 linear aliphatic polyvalent amines, especially diamines, are preferably used, such as ethylenediamine, propylenediamine, butanediamine, pentanediamine, hexamethylenediamine, heptamethylenediamine, octamethylenediamine, nonamethylenediamine, decamethylene One or more types of diamine, triaminopropane, etc. are used.

Furthermore, if particularly desired, an aromatic polyvalent amine such as phenylenediamine may be used together with an aliphatic polyvalent amine in an amount within a range that does not impede the effects of the present invention.

The ratio of BTC or its derivative and aliphatic polyvalent amine to the polyester is usually 0.3 to 4.0 per mole of dicarboxylic acid or its derivative, which is one of the polyester forming components.
mol, preferably 0.5 to 2.0 mol, while the aliphatic polyvalent amine is in a proportion of 0.4 to 1.4 mol, preferably 0 to 1 mol of the above-mentioned BTC or its derivative. .6
The usage ratio may be approximately 1.2 mol.

The polyester modification reaction in the thermosetting resin composition of the present invention involves adding BTC or a derivative thereof and an aliphatic polyvalent amine to the system in which the polyester has been synthesized to carry out a polycondensation reaction between the two. What is necessary is to adopt a method of sequentially reacting substances with polyester.

Of course, if necessary, it is also possible to prepare a condensation product of BTC or its derivative and a polyvalent amine outside the polyester synthesis system and react it with the polyester.

In addition, in some cases, a polyester forming component and a modifier component may be simultaneously added to the reaction system to sequentially carry out the polycondensation reaction of BTC or its derivative with a polyvalent amine, the polyester condensation reaction, and the polyester modification reaction in one step. is also possible.

In these methods, the condensation reaction of BTC or its derivative with an aliphatic polyvalent amine is generally carried out by heating at a temperature of 60 to 230°C, preferably 80 to 200°C, until no water produced by the reaction is distilled out. The reaction between the condensation product and the polyester is generally carried out at a temperature of 100°C or higher, preferably 150 to 230°C, for a period of time until the reaction product water stops distilling out, usually about 0.5 to 4 hours. Just let it happen.

The polyester modified product obtained in this way usually becomes an imide-modified polyester when BTC or its derivative is used in excess compared to the aliphatic polyvalent amine.
Furthermore, when an aliphatic polyvalent amine is used in an equivalent amount or in excess of BTC or its derivatives, it usually becomes an amide-imide modified polyester, and in both cases, free reactive acid groups or hydroxyl groups remain in the polymer. It has the property of being soluble in organic solvents.

The thermosetting resin composition used in this invention has such a polyester amide-imide or polyester imide as a main component, and optionally various optional components, such as conventionally known resins such as epoxy resins and polyester resins. , titanium-based, tin-based organic metal compounds, pigments, dyes, and inert substances such as organic and inorganic fillers can be blended.

In addition, this composition can be of a solvent-free type, but
An appropriate organic solvent may be added to improve impregnation and coating workability.

This organic solvent may be added during the polyester condensation reaction, polyester modification reaction, or the like, or may be further added as a diluent afterwards.

The organic solvents used here include ethyl cellosolve, alcohols, etc. from the viewpoint of resource conservation and pollution prevention.
Ketones are preferable, but other general-purpose solvents such as cresol and phenol, N/N-dimethylformamide,
Of course, polar solvents such as N-N-dimethylacetamide and dimethyl sulfoxide can be used.

Furthermore, the thermosetting resin composition of the present invention can be applied as a water-soluble type composition, since the raw materials of the polyesteramide-imide or polyesterimide all have the property of being dissolved in water. be.

In this case, polyesteramides having free reactive acid groups or hydroxyl groups in the molecule produced by the above-mentioned method are usually used.
It is preferable to treat the imide or polyester imide with a nitrogenous base compound to form a water-soluble salt.

Ammonia is preferred as the nitrogenous base compound, but various other primary amines, secondary amines, tertiary amines, heterocyclic compounds that act in the same way, and quaternary ammonium compounds can also be used.

Next, the heat-resistant fiber base material used in this invention is composed of inorganic fibers and organic fibers. There are cases in which a processed base material is used, and there are cases in which a processed base material such as a woven fabric or non-woven fabric made solely from inorganic fibers is used in combination with a processed base material such as a woven fabric or non-woven fabric made solely from organic fibers. .

In the latter case, two processed base materials are laminated and used,
In this case, not only a two-layer structure but also a multi-layer structure of three or more layers may be used.

In these various embodiments, the total thickness of the base material is generally 0.01 to 0.00.
The thickness is preferably about 5 mm; if it is too thin, the strength will be insufficient, and if it is too thick, the bendability will be impaired.

The most typical inorganic fiber is glass fiber, but fine asbestos and the like can also be used.

Organic fibers include various fibers such as polyamide, polyester, and rayon.

Since the ratio of inorganic fibers to organic fibers greatly affects the characteristics of the resulting circuit board, it is preferable to set the ratio appropriately depending on each material.

Generally, the proportion of organic fibers in the heat-resistant fiber base material is 15
The weight is preferably 30 to 90, preferably 30 to 90.

If the proportion of organic fibers used is too high, there is a risk of impairing dimensional stability, and if the proportion of organic fibers is too small, there is a tendency for tear strength to decrease.

The insulating material for circuit boards of the present invention essentially consists of a thermosetting resin composition of various types as described above and a heat-resistant fiber base material composed of the above-mentioned organic fibers and inorganic fibers. However, these materials are usually made into a prepreg state before making a circuit board.

When making this prepreg, the heat-resistant fiber base material is a woven fabric made by integral processing of inorganic fibers and organic fibers,
When it is made of a processed base material such as a nonwoven fabric, it may be impregnated and coated with the above-mentioned thermosetting resin composition.

On the other hand, if the heat-resistant fiber base material is composed of a processed base material such as a woven fabric or non-woven fabric made solely of inorganic fibers and a processed base material such as a woven fabric or non-woven fabric made solely of organic fibers, at least one of them The above-mentioned thermosetting resin composition may be impregnated and applied to the processed base material.

Therefore, one processed base material may be used as is without being made into a prepreg.

Of course, if necessary, one or both may be made into prepregs and then both may be bonded under heat and pressure to form a laminated prepreg.

How to make a circuit board using the insulating material of this invention.

The above-mentioned prepreg or laminated prepreg, or prepregs made of different processed base materials, or prepreg and processed base material that is not a prepreg, are superimposed on a metal foil such as copper foil or aluminum foil and bonded under heat, What is necessary is just to heat-process further at 200-250 degreeC for 1-10 hours.

Through this treatment, free reactive acid groups, hydroxyl groups, etc. contained in the polyester amide-imide or polyester imide constituting the thermosetting resin composition react in a complex manner and are completely cured, and organic fibers are added to the cured resin. Moreover, it is possible to obtain a circuit board consisting of an insulating layer and a metal layer with excellent heat resistance and in which inorganic fibers are firmly integrated.

Furthermore, not only circuit boards having a structure made of such an insulating layer and metal foil, but also other circuit boards having various structures such as a circuit board with a resistor can be produced in accordance with the above method.

The circuit board obtained in this way has very good flexibility and can withstand 180° bending, and also has good dimensional stability and reduces the rate of dimensional change during high temperature heat treatment and etching treatment. , can be suppressed to 1% or less, and also has excellent tear strength, making it possible to provide a circuit board with extremely high utility value and a wider range of uses than conventional ones.

Examples of the present invention will be described below to explain it more specifically.

Example 1 36.5 g (0.25 mol) of adipic acid and 31.5 g (0.25 mol) of adipic acid and 31.5 g (0.25 mol) of adipic acid were added to a 500 ml four-bottle flask equipped with a stirrer, a side tube, and a thermometer. Og (0.50 mol) and
A polyester condensation reaction was carried out by holding the mixture at 180° C. for 2 hours while stirring.

The amount of distilled water from the side pipe was 7.2 g.

After cooling this reaction system to 70°C, 58.5 g of BTC was added.
(0,25 mol), followed by 29.1 g (0,25 mol)
A solution prepared by diluting 25 mol) of hexamethylene diamine with 50.0.9 mol of ion-exchanged water was gradually added dropwise to carry out a polycondensation reaction between BTC and hexamethylene diamine.

The dropping time was 15 minutes, during which time the reaction system reached a maximum temperature of 105°C due to the reaction heat, and water was distilled out from the side pipe.

Thereafter, the temperature of the reaction system was raised to 200° C., and water and unreacted components remaining in the system were distilled off.

From the total amount of distilled water, it was found that the amount of reaction water in the polycondensation reaction between BTC and hexamethylene diamine was 18.0 g.

Next, the temperature was maintained for 1.5 hours to carry out a polyester modification reaction.

Distilled water during this period was 68 g.

The polyester modified product thus obtained has an acid value of 4.
0, and it was confirmed from the nuclear magnetic resonance spectrum that it was a polyester amide-imide containing an ester bond, an amide bond, and an imide bond.

After cooling the polyesteramide-imide to 130° C., 128.1 g of ethyl cellosolve was added to obtain a solution-like thermosetting resin composition.

This composition, and EP4012 (glass mat) manufactured by Nippon Vilene Co., Ltd. and HC50 manufactured by the same company as heat-resistant fiber base materials.
23N (polyamide nonwoven fabric) was used at a ratio of about 80 overlapping parts of the latter to form an insulating material for a circuit board of the present invention.

Further, among the above base materials, only the glass mat was impregnated and coated with the above thermosetting resin composition to obtain a prepreg.

The amount of impregnation coating at this time was 200 g/m2, and after the impregnation coating, ethyl cellosolve was volatilized in a hot air dryer at 150°C.

Examples 2 to 5 Four types of polyester amides were prepared under exactly the same operation and reaction conditions as in Example 1, except that polybasic acids and polyhydric alcohols were used in the amounts shown in Table 1 below as polyester forming components. - Created an imide.

The acid value of each polyesteramide-imide is as listed in the same table, and the thermosetting resin composition used in this invention is obtained by adding ethyl cellosolve in the amount listed in the same table to these polyesteramide-imides. It became a thing.

For each of the above compositions, the heat-resistant fiber base material described in Example 1 was used, and in the same manner as in Example 1, only the glass mat was impregnated and coated with the thermosetting resin composition to form a prepreg. , four types of insulating materials for circuit boards of the present invention.

Example 6 The amount of hexamethylene diamine used was 23.39 (0.2
A polyester modified product was obtained under exactly the same operation and reaction conditions as in Example 1, except that the amount was changed to 0 mol).

This modified product had an acid value of 70, and was confirmed from nuclear magnetic resonance spectroscopy to be a polyesterimide containing ester bonds and imide bonds.

After cooling this polyesterimide to 130° C., 122.3 g of ethyl cellosolve was added to obtain a thermosetting resin composition used in the present invention.

For this composition, the heat-resistant fiber base material described in Example 1 was used, and in the same manner as in Example 1, only the glass mat was impregnated and coated with the thermosetting resin composition to prepare a prepreg. It was used as an insulating material for circuit boards.

Comparative Examples 1 to 6 Heat-resistant fiber base material manufactured by Asahi Schniebel Co., Ltd. 2] 6AS3
08 (glass cloth), and each thermosetting resin composition described in Examples 1 to 6 was applied thereto at a coating amount of 200 g/m2.
It was impregnated and coated to form a prepreg, which was used as an insulating material for circuit boards, which is different from this invention.

Comparative Example 7 HC5023 manufactured by Nippon Vilene Co., Ltd. as a heat-resistant fiber base material
Using only N (polyamide nonwoven fabric), Example 1
The coating amount of the thermosetting resin composition described in 200 g/m"
This was impregnated and coated to form a prepreg, which was used as an insulating material for circuit boards different from that of the present invention.

Comparative Example 8 Into the same fourth flask as in Example 1, 58.5 g of BTC (
0.25 mol) and 50.0 g of ion-exchanged water,
A solution prepared by diluting 29.1 g (0.2 s mol) of hexamethylene diamine with 50.0 g of ion-exchanged water was gradually added dropwise to this to carry out a polycondensation reaction.

The dropping time was 15 minutes, during which time the temperature inside the system reached a maximum of 105°C due to reaction heat, and water was distilled out from the side pipe.

Thereafter, the temperature of the reaction system was raised to 200°C to distill off the water remaining in the system.

From the total amount of distilled water, it was found that the reaction water was 16.0 g.

The reaction was further maintained at the same temperature for 1.5 hours to complete the reaction.

The polycondensation product thus obtained had an acid value of 53, and was confirmed to be a polyimide from nuclear magnetic resonance spectroscopy.

After cooling this polyimide to 130° C., 69.6 g of ethyl cellosolve was added to obtain a thermosetting resin composition.

For this composition, the heat-resistant fiber base material described in Example 1 was used, and in the same manner as in Example 1, only the glass mat was impregnated and coated with the thermosetting resin composition to prepare a prepreg. It is a different insulating material for circuit boards.

The insulating materials of Examples 1 to 6 and Comparative Examples 1 to 8 described above were stacked on copper foil, thermocompression bonded at 120°C, and further heated to 200°C.
A circuit board was made by heat treatment for 4 hours.

In Examples 1 to 6 and Comparative Example 8, when overlapping the insulating material on the copper foil, a prepreg made of glass mat was brought into contact with the copper foil, and a polyamide nonwoven fabric was provided on the prepreg and bonded together by thermocompression.

The results of examining the characteristics of each of these substrates are shown in Table 2 below.

For reference, the table lists conventional epoxy resin compositions and EP40 manufactured by Nippon Vilene Co., Ltd. as a heat-resistant fiber base material.
The test results using a prepreg using only No. 2 (glass mat) are also listed as Comparative Example 9.

Moreover, the tear strength in the table was measured according to JISL-1097.

As is clear from the above table, the insulating material of the present invention provides a circuit board with excellent dimensional stability, flexibility, and tear strength.

On the other hand, those using insulating materials different from those of the present invention are inferior in any of the above characteristics.

In the above example, a glass mat is impregnated with a thermosetting resin composition as a prepreg, and this prepreg is brought into contact with a copper foil, and a polyamide nonwoven fabric is provided on top of it and bonded together by thermocompression. A mode in which a polyamide nonwoven fabric is brought into contact with a copper foil and the above-mentioned prepreg is provided thereon and bonded together by thermocompression, a mode in which the polyamide nonwoven fabric is impregnated with a thermosetting resin composition to form a prepreg, or a mode in which a prepreg is formed by impregnating the polyamide nonwoven fabric with a thermosetting resin composition, or Results similar to those in Table 2 were obtained even when various embodiments were adopted, such as a mode in which a prepreg made of one base material and a prepreg made of the other base material were bonded by heat and pressure to form a laminated prepreg before thermocompression bonding.

Claims (1)

[Scope of Claims] 1. An insulating material composed of a heat-resistant fiber base material and a thermosetting resin composition used for forming an insulating layer of a circuit board, wherein the base material is composed of inorganic fibers and organic fibers. At the same time, as the above composition, a polyester consisting of an aliphatic or alicyclic dicarboxylic acid or a derivative thereof and an aliphatic polyhydric alcohol having two or more hydroxyl groups bonded to different carbon atoms is used.・4-Butanetetracarboxylic acid, which is mainly composed of polyesteramide-imide or polyesterimide modified with a derivative thereof and an aliphatic polyvalent amine in which two or more amine groups are bonded to different carbon atoms. An insulating material for circuit boards characterized by its use. 2. The insulating material for circuit boards according to claim 1, wherein the proportion of organic fibers in the heat-resistant fiber base material is 15 to 98% by weight. 3. The heat-resistant fiber base material is made of a processed base material such as woven fabric or non-woven fabric made by integral processing of inorganic fibers and organic fibers, and the heat-resistant fiber base material is a prepreg made by impregnating this with a thermosetting resin composition. Insulating material for circuit boards according to scope 1 or 2. 4. The heat-resistant fiber base material consists of a processed base material such as a woven fabric or non-woven fabric made solely from inorganic fibers and a processed base material such as a woven fabric or non-woven fabric made solely from organic fibers, and at least one of the processed base materials The insulating material for a circuit board according to claim 1 or 2, wherein the prepreg is made of a prepreg impregnated with a thermosetting resin composition, and if necessary, both are bonded under heat and pressure to form a laminated prepreg. 5. Any one of claims 1 to 4 which specifically selects a linear aliphatic dicarboxylic acid having 3 to 8 carbon atoms or a derivative thereof from aliphatic or alicyclic dicarboxylic acids or derivatives thereof. Insulating material for circuit boards described in . 6 Claim 1 in which a linear aliphatic dihydric alcohol having 2 to 8 carbon atoms is used as the aliphatic polyhydric alcohol
The insulating material for circuit boards according to any one of items 1 to 5. 7 Claims 1 to 6 in which a linear aliphatic diamine having 2 to 8 carbon atoms is used as the aliphatic polyvalent amine
The insulating material for circuit boards according to any of paragraphs.