JP2003064158A - Epoxy resin composition for impregnating glass fiber substrate and prepreg, laminate and printed wiring board using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a nonhalogen epoxy resin composition suitable as a glass- fiber substrate printed wiring board ensuring flame retardance without causing lowering of copper foil adhesive strength and heat resistance. SOLUTION: This epoxy resin composition for impregnating the glass fiber substrate, drying the impregnated substrate and producing a prepreg is obtained from the following compounding. (90/10) to (50/50) compounding mass ratio of a trifunctional epoxy resin to a cresol novolak type epoxy resin as an epoxy resin, 0.8-1.2 mass% of phosphorus content in the resin solids and p-cresol novolak resin as a curing agent. The hydroxy group/epoxy group equivalent ratio based on the p-cresol novolak resin and epoxy resin is preferably 0.8-1.4.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a flame-retardant epoxy resin composition for impregnating a glass fiber base material. The present invention also relates to a prepreg, a laminated board or a metal foil-clad laminated board, and a printed wiring board using the epoxy resin composition.

[0002]

2. Description of the Related Art Epoxy resin printed wiring boards incorporated in electronic equipment are required to have safety such as being hard to burn and hard to spread. Therefore, a brominated epoxy resin or a brominated phenol novolac resin is used as a curing agent for the epoxy resin to impart flame retardancy.
However, if a material containing halogen such as bromine / chlorine is used at high temperature for a long time, there is a concern that the halide may be dissociated, and if the halogen-containing material is incinerated, there is a concern that harmful halide may be generated. In recent years, from the viewpoint of environmental safety, there is a shift toward the non-halogen flame retardancy. Phosphorus compounds have been attracting attention as flame retardants instead of halogen compounds. This phosphorus compound is
Almost all phosphoric acid ester type, low melting point (80-100 ° C)
Since it is a compound of, it is easily pyrolyzed at high temperatures during combustion. The carbonized film of polyphosphoric acid produced by thermal decomposition shields the resin from oxygen and heat, thereby exhibiting a flame retardant effect. Laminated boards and printed wiring boards that are non-halogenated and have flame retardancy are imparted with flame retardancy by adding a large amount of an inorganic filler such as a phosphorus compound or aluminum hydroxide.

On the other hand, in the printed wiring board and the multilayer printed wiring board, the adhesiveness between the copper foil and the insulating layer has been strongly required due to the thinning of the copper foil wiring pattern. Also,
Due to environmental issues, attention has been focused on lead-free soldering in the component mounting process, the reflow temperature becomes high, and the heat resistance of printed wiring boards and multilayer printed wiring boards is also required. It was

As mentioned above, most of phosphorus compounds have low melting points, so they are easily liberated at high temperatures as described above.
Adhesion between the copper foil and the resin and heat resistance are adversely affected, so it is not desirable to add a large amount thereof. In addition, the thermal decomposition temperature of inorganic fillers such as aluminum hydroxide is 280.
Since it is around 300 ° C, it is not desirable to add a large amount from the viewpoint of heat resistance.

Furthermore, in order to impart nonflammability and flame retardancy, bisphenol F is used as a bifunctional epoxy resin.
Type epoxy resin and bisphenol S type epoxy resin have been proposed, but since these epoxy resins have epoxy groups only at both ends of the molecular chain, the cross-linking density of the cured resin tends to be low, and heat resistance tends to decrease. is there.

[0006]

The problem to be solved by the present invention is to limit the compounding amount of a phosphorus compound for imparting flame retardancy with non-halogen, and to use bisphenol F type as an inorganic filler or a bifunctional epoxy resin. Epoxy resin composition suitable for glass fiber-based printed wiring boards that imparts flame retardancy and does not reduce the adhesive strength and heat resistance of copper foil while eliminating the compounding of epoxy resin and bisphenol S type epoxy resin as much as possible. It is to provide things. Another object of the present invention is to provide a prepreg of a glass fiber substrate to which the epoxy resin composition is applied, a laminated board or a metal foil-clad laminated board, a printed wiring board or a multilayer printed wiring board.

[0007]

In order to solve the above-mentioned problems, the epoxy resin composition for impregnating a glass fiber base material according to the present invention is characterized by having the following composition. As the epoxy resin, the compounding mass ratio of the trifunctional epoxy resin and the phenolic novolac type epoxy resin is 90/10 to 50.
/ 50, and the phosphorus content in the resin solid content is 0.8 to
The composition is 1.2% by mass and contains para-cresol novolac resin as a curing agent.

When the cured product of the above resin composition burns, the phosphorus compound thermally decomposes to form a carbonized film of polyphosphoric acid, which shields the resin from oxygen and heat, thereby exhibiting a flame retardant effect. Furthermore, the blending of para-cresol novolac resin also contributes to imparting flame retardancy, and the reason is speculated as follows. For burning high molecular compounds,
There is a mechanism of thermal transition → crosslinking → carbonization, and it is considered that the combustion reaction is proceeding radically (Kyoei Communication Co., Ltd., “Polymer”, Vol. 49, April issue (2000), p.242-).
247, written by Kunihiko Takeda). In the case of combustion of a cresol novolac resin cured product, it is presumed that the cresol novolac resin cured product is passed through a phenoxy radical or a benzyl radical. It is presumed that it becomes difficult to burn because the reaction leading to carbonization easily proceeds. By incorporating the para-cresol novolac resin, flame retardancy can be imparted for the first time while limiting the phosphorus content as described above.

The above-mentioned resin composition makes it possible to impart halogen-free flame retardancy to a laminated board or a printed wiring board made of a glass fiber base material while limiting the phosphorus content in the resin solid content to a small amount. By limiting the phosphorus content to a small amount, it is possible to secure the adhesive strength and heat resistance of the copper foil at the same time. Moreover, since the crosslink density of the resin is increased by blending a phenolic novolac type epoxy resin which is a polyfunctional epoxy resin as the epoxy resin, this also contributes to ensuring the adhesive strength and heat resistance of the copper foil.

The blending mass ratio of the trifunctional epoxy resin to the phenol novolac type epoxy resin is 90/10 to 50 because if the trifunctional epoxy resin is too large, the heat resistance is lowered and if it is too small, flame retardancy cannot be imparted. The range is / 50. Further, when the phosphorus content in the resin solid content is low, flame retardancy cannot be imparted, and when the phosphorus content is high, the copper foil adhesive strength and heat resistance are deteriorated, so the range is set to 0.8 to 1.2 mass%.

The equivalent ratio of hydroxyl group / epoxy group based on para-cresol novolac resin and epoxy resin is preferably 0.8 to 1.4. If this equivalent ratio is reduced, the amount of epoxy resin is increased and the flame retardancy is reduced. On the other hand, if this equivalent ratio increases, the heat resistance after moisture absorption will be affected by the effect of the hydroxyl groups that remain unreacted.

A sheet-shaped glass fiber base material is impregnated with the above-mentioned epoxy resin composition and dried to obtain a prepreg. The glass fiber base material is a glass fiber woven cloth or a glass fiber nonwoven cloth for electrical insulation.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION The epoxy resin composition according to the present invention is not particularly limited to the kind of phenolic novolac type epoxy resin, and cresol novolac type epoxy resin, phenol novolac type epoxy resin and the like can be appropriately selected. The phenol novolac type epoxy resin has better flame retardancy as compared with the cresol novolac type epoxy resin because it has less methyl groups. In addition, a bisphenol novolak type epoxy resin may be selected.
2-Ethyl 4-methylimidazole or the like is added as a curing accelerator.

The phosphorus compound which is a component of the resin composition is a phosphorus-based polyol, an addition type phosphoric acid ester which does not react with an epoxy resin, a reactive type phosphoric acid ester which reacts with an epoxy resin and the like. Since the reactive phosphoric acid ester reacts with the epoxy resin to prevent the crosslinking reaction between the para-cresol novolac resin which is the curing agent and the epoxy resin, the addition phosphoric acid ester is preferably selected.

Furthermore, flame retardancy can be increased by adding an inorganic compound powder such as aluminum hydroxide or magnesium hydroxide. However, care should be taken not to add a large amount. When the amount of inorganic compound powder is large,
The inorganic compound powder remains on the surface of the prepreg, and the adhesiveness at the interface between the metal foil (printed wiring) and the resin decreases. Also,
Heat resistance decreases. It does not prevent blending of an inorganic compound powder such as aluminum hydroxide or magnesium hydroxide for imparting flame retardancy as long as the amount is such that the adhesiveness and heat resistance are not deteriorated.

A prepreg is produced by impregnating a sheet-shaped glass fiber base material with the above-mentioned epoxy resin composition and drying (heating and drying). A printed wiring board is manufactured by first stacking a metal foil on the layer of the prepreg, heating and press-molding these to form a metal foil-clad laminate, and etching the metal foil into a predetermined wiring pattern. The multilayer printed wiring board is manufactured by stacking a metal foil on the printed wiring board via a prepreg and integrating them by heat and pressure molding, and etching the surface metal foil into a predetermined wiring pattern. It is also possible to increase the number of wiring layers by stacking a metal foil on the surface via a prepreg and integrating them by heat and pressure molding, and etching the metal foil on the surface into a predetermined wiring pattern. In another method, a prepreg is interposed between a plurality of printed wiring boards, a metal foil is overlaid on the surface via the prepreg, these are integrated by heat and pressure molding, and the surface metal foil is etched into a predetermined wiring pattern. To process. The laminated board and the printed wiring board may be configured by using the prepreg according to the present invention in combination with the prepreg of another resin composition. The glass fiber woven fabric base material prepreg and the glass fiber nonwoven fabric base material prepreg may be combined, or the organic fiber base material prepreg may be combined.

[0017]

EXAMPLES Examples will be described below. Although the printed wiring board is not specifically described below, its configuration and manufacturing method are as described above, and thus the description thereof is omitted. In order to confirm the flame resistance, copper foil adhesive strength, and heat resistance of the insulating layer of the printed wiring board, in the following example, for convenience, copper foil with a thickness of 18 μm is placed on both sides with four prepregs stacked and heated and pressed. A molded copper-clad laminate (0.8 mm thick) was manufactured and subjected to a test.

Examples 1 to 10 and Comparative Examples 1 to 4 As the sheet-shaped glass fiber base material, the following glass fiber base material for electrical insulation is used. It is a woven glass fiber cloth having a thickness of 180 μm, which is woven with a thread in which glass fibers having a fiber diameter of 9 μm are bundled. Weaving density is 42 yarns / 25mm length, 32 yarns / 25mm width
Is. As the epoxy resin composition which uses the glass fiber woven fabric as a base material and impregnates the base material, the epoxy resin is a trifunctional epoxy resin (“VG3101M80” manufactured by Mitsui Chemicals, Inc.)
And cresol novolac type epoxy resin (Tohto Kasei Co., Ltd.)
"YDCN704EK75"), a phosphorus compound is a phosphoric acid ester ("PX-200" manufactured by Daihachi Chemical Co., Ltd.), and a curing agent is paracresol novolac resin ("YLH-987" manufactured by Japan Epoxy Resins Co., Ltd.). A resin varnish was prepared. This resin varnish has a resin solid content of 70% by mass using methyl ethyl ketone as a solvent, and contains 0.2% by mass of 2-ethyl-4-methylimidazole as a curing accelerator in the resin solid content. Tables 1 and 2 show that the resin varnish in each example contains the trifunctional epoxy resin and the cresol novolac type epoxy resin in terms of solid content in terms of the compounding mass ratio (indicated as “3 Epo / Klenovo ratio” in the table) and the phosphate ester. Based on the phosphorus content in the resin solids (expressed as “phosphorus content” in the table), the equivalent ratio of hydroxyl group / epoxy group based on paracresol novolac resin and epoxy resin (“OH / epo equivalent ratio” in the table). ").

The above varnish was impregnated with the glass fiber woven cloth and dried at 150 ° C. for 5 minutes to obtain a prepreg. The content of the resin is 49% by mass. A copper clad laminate was manufactured using this prepreg. Molding conditions are temperature 170
It is a heat and pressure molding for 60 minutes at a temperature of 4.9 MPa.

[0020]

[Table 1]

[0021]

[Table 2]

Examples 11 to 17 Based on the compounding mass ratio of the trifunctional epoxy resin and the cresol novolac type epoxy resin in the resin varnish in terms of solid content (indicated in the table as "3 Epo / Klenovovo ratio"), phosphate ester, Phosphorus content in resin solids (expressed as "phosphorus content" in the table), equivalent ratio of hydroxyl group / epoxy group based on paracresol novolac resin and epoxy resin (in the table, "OH / epo equivalent ratio") The notation) is as shown in Table 3, and the others are the same as in Example 3 to produce a copper-clad laminate.

[0023]

[Table 3]

Comparative Example 5 As an epoxy resin composition, a trifunctional epoxy resin and a bisphenol F type epoxy resin (blending mass ratio 70/30) were used as the epoxy resin, and in addition, phosphorus content and para-cresol novolac resin as a curing agent were blended. , Hydroxyl group /
The epoxy group equivalent ratio was the same as in Example 3 to produce a copper-clad laminate.

Comparative Examples 6 to 7 A copper clad laminate was produced in the same manner as in Example 3 except that orthocresol novolac resin (Comparative Example 6) and metacresol novolac resin (Comparative Example 7) were used as the curing agent. did.

Tables 4 to 7 show the evaluation results of the flame retardancy, the peeling strength of the copper foil, and the heat resistance of the copper-clad laminates of the above examples. Each property shown in the table was evaluated as follows. For flame retardancy, the afterflame time (seconds) was measured based on the UL-94 test method. The copper foil peeling strength was measured based on JIS. Heat resistance is 250 x 250 as a sample
The mm-sized copper-clad laminate was left in a constant temperature and humidity bath at 85 ° C.-85% RH for 48 hours, then taken out, floated in a solder bath at 280 ° C., and the time until swelling on the surface was measured.

[0027]

[Table 4]

[0028]

[Table 5]

[0029]

[Table 6]

[0030]

[Table 7]

From the controls of Examples 1 to 10 and Comparative Examples 1 to 4, the phosphorus content in the resin solid content was 0.8 to 1.2% by mass.
By setting the compounding mass ratio of the trifunctional epoxy resin / cresol novolac type epoxy resin to be in the range of 90/10 to 50/50, it is found that the copper foil peeling strength and heat resistance can be secured together with the flame retardancy. . When the phosphorus content is less than 0.8% by mass, it becomes difficult to impart flame retardancy (Comparative Example 1), and when the phosphorus content exceeds 1.2% by mass, the copper foil peeling strength and heat resistance decrease (comparison). Example 2). Looking at the compounding mass ratio of trifunctional epoxy resin / cresol novolac type epoxy resin, heat resistance could not be secured when the amount of trifunctional epoxy resin increased (Comparative Example 3).
When the amount of cresol novolac type epoxy resin is increased, the polyfunctional epoxy resin component is increased and it becomes difficult to impart flame retardancy (Comparative Example 4).

From the comparison between Examples 12 to 16 and Examples 11 and 17, the hydroxyl group / epoxy group equivalent ratio was 0.8 to 1.4.
It can be seen that the flame retardancy and heat resistance can be maintained at a higher level by setting the above.

Comparative Example 5 shows that heat resistance cannot be maintained when a bifunctional epoxy resin is blended. Comparative Example 6
7 and 7 show that imparting flame retardancy is difficult even if an ortho-cresol novolac resin is blended as a curing agent or a meta-cresol novolac resin is blended, and para-cresol novolac resin is blended as a curing agent. It has been clarified for the first time that flame retardancy can be secured.

[0034]

As described above, by applying the epoxy resin composition according to the present invention, a glass which is halogen-free and has sufficient flame retardancy and which does not cause a decrease in copper foil adhesive strength and heat resistance. A fiber-based printed wiring board can be provided.

Continued front page    F-term (reference) 4F072 AA04 AA07 AB09 AB28 AB29                       AD23 AD27 AD28 AF16 AG03                       AG17 AG19 AH02 AH31 AK14                       AL09 AL13                 4F100 AA04 AB17 AB33B AG00A                       AH07 AK33A AK53A AL05A                       AL06A BA02 BA07 CA02A                       DG06A DG12A DH01A EJ82A                       GB43 JJ07 YY00A                 4J002 CC053 CD001 CD052 CD062                       EW046 FD130 FD143 FD206                       GQ01 GQ05                 4J036 AA05 AD08 AF06 AF07 AJ02                       BA02 DC40 DC41 FA12 JA07                       JA08 JA11

Claims (6)

[Claims] 1. An epoxy resin composition for impregnating a glass fiber base material, wherein a compounding mass ratio of a trifunctional epoxy resin and a phenolic novolac type epoxy resin is 90/10 to 50/50, and a resin solid content. The epoxy resin composition for impregnating a glass fiber base material, wherein the phosphorus content in the glass fiber base material is 0.8 to 1.2% by mass, and a para-cresol novolac resin is added as a curing agent. 2. A hydroxyl group / epoxy group equivalent ratio of 0.8 based on para-cresol novolac resin and epoxy resin.
It is -1.4, The epoxy resin composition for glass fiber base material impregnation of Claim 1 characterized by the above-mentioned. 3. A prepreg, which is obtained by impregnating a sheet-shaped glass fiber base material with the epoxy resin composition according to claim 1 or 2 and drying it. 4. A laminate comprising a part or all of the layers of the prepreg according to claim 3, which is formed by heating and pressing. 5. A metal foil-clad laminate having a metal foil integrated on at least one surface of the laminate according to claim 4. 6. A printed wiring board comprising an insulating layer formed by heat-pressing the layer of the prepreg according to claim 3.