JPH10180932A - Manufacture of metal-clad laminate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a metal-clad laminate, excellent in tracking resistance without spoiling the general characteristics and fire retardancy of a glass epoxy laminate and the like, by a method wherein the essential constituents are specified so as to be epoxy resin, the polycondensation product of bisphenol A and formaldehyde, a curing promoter and a high-purity aluminum hydroxide. SOLUTION: In manufacturing a metal-clad laminate for print wiring, which is employed for electric instruments, electronic instruments and the like, epoxy resin, the polycondensation product of bisphenol A and formaldehyde, a curing promoter and a high-purity aluminum hydroxide are specified so as to be essential constituents while a prepreg, obtained by impregnating the thermocuring resin, having the bromine content of 5-15wt.%, into the woven fabric of glass, is laminated on a metallic foil and is molded through hot pressing. In this case, a glass woven fabric, treated through fibrillation treatment preferably, is employed as the glass woven fabric. On the other hand, in a composite laminate, employing non-woven fabric for the inner side and glass woven fabric for the outer sides, the prepreg, obtained by impregnating the resin, is employed for at least the outermost layers of the same.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a metal-clad laminate for a printed wiring board used for electric and electronic equipment, and more particularly to a method for manufacturing a metal-clad laminate having excellent tracking resistance.

[0002]

2. Description of the Related Art As consumer electronic devices and industrial electronic devices have become smaller and more sophisticated, measuring instruments, computers, televisions,
A glass epoxy laminate is often used as a power supply substrate to which a high voltage is applied such as an air conditioner. Recently, composite laminates using a glass non-woven fabric in places other than the surface layer have begun to be used because of their low cost and excellent workability. The demand for safety such as tracking resistance and flame retardancy has become extremely large for consumer and industrial electronic devices using these laminated plates due to the enforcement of the PL method.
However, although the conventional glass epoxy laminate and composite laminate have excellent mechanical, electrical and thermal properties, their tracking resistance index is about 200 V, which is a safety problem. In order to improve the tracking resistance, a method of reducing the bromine content and adding a filler has become mainstream.

[0003]

The reduction of the bromine content, which is carried out to improve the tracking resistance, is attributable to the fact that the bromine compound exhibits flame retardancy and the resin is carbonized to form a conductive path. This is a method of reducing carbonization and preventing carbonization. The addition of the filler is a method of relatively lowering the content of the resin by adding the filler and lowering the proportion of the resin to be carbonized. However, in these methods, the method by reducing the bromine content or adding a filler inevitably reduces the general properties such as flame retardancy and heat resistance, and satisfies tracking resistance and flame retardancy. I couldn't do that.

[0004]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention has excellent tracking resistance without deteriorating general properties such as heat resistance and flame retardancy of a glass epoxy laminate or a composite laminate. To provide a metal-clad laminate. The present invention relates to (a) an epoxy resin, (b)
Polycondensate of bisphenol A and formaldehyde,
A prepreg obtained by impregnating a glass woven fabric with (c) a hardening accelerator and (d) a thermosetting resin containing high-purity aluminum hydroxide as an essential component and having a bromine content of 5 to 15 wt% is a metal foil. This is a method for producing a metal-clad laminate which is laminated and heated and pressed. Further, the metal-clad laminate is a glass woven fabric in which the glass woven fabric has been subjected to an opening treatment.

[0005]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail. The epoxy resin (a) used in the present invention may be any one having two or more epoxy groups in the molecule.
For example, bisphenol A epoxy resin, bisphenol F epoxy resin, bisphenol epoxy resin such as bisphenol S epoxy resin, phenol novolak epoxy resin, phenol novolak epoxy resin such as cresol novolak epoxy resin, alicyclic epoxy Resins, glycidylamine-type epoxy resins, and the like, and those obtained by brominating these are more preferable.
When a brominated epoxy resin is not used, tetrabromobisphenol A, tetraphenylphosphine, or the like can be added as a flame retardant. Also,
The molecular weight of these epoxy resins is not particularly limited, and several types can be used in combination.

[0006] The polycondensate of bisphenol A and formaldehyde (b), which is a curing agent for the epoxy resin used in the present invention, is not limited in molecular weight, and may contain a bisphenol A monomer. Further, a phenol resin such as a phenol novolak resin can be used in combination as long as the effects of the present invention are not impaired. The amount of the curing agent
It is preferable to mix the epoxy equivalent to the hydroxyl equivalent of the curing agent to be used so that hydroxyl equivalent / epoxy equivalent = 0.8 to 1.2. If the ratio is less than 0.8 and exceeds 1.2, the heat resistance becomes poor.

The curing accelerator (c) used in the present invention includes imidazole compounds and amines, but is not particularly limited. Examples of imidazole include 2-methylimidazole, 2-ethyl-4-methylimidazole, 2-undecylimidazole, 2-heptadecylimidazole,
-Phenylimidazole, 2-phenyl-4-methylimidazole, 1-benzyl-2-methylimidazole,
2-ethylimidazole, 2-isopropylimidazole, 1-cyanoethyl-2-methylimidazole, 1-
Cyanoethyl-2-phenylimidazole, 1-cyanoethyl-2-undecylimidazole, 1-cyanoethyl-2-isopropylimidazole, 1-cyanoethyl-2-phenylimidazole, 1-cyanoethyl-2-
Phenylimidazolium trimellitate, 1-cyanoethyl-2-ethyl-4-methylimidazole trimellitate, 1-cyanoethyl-2-undecylimidazole trimellitate, 1-cyanoethyl-2-phenylimidazole trimellitate, 1- And cyanoethyl-2-phenyl-4,5-di (cyanoethoxymethyl) imidazole. Examples of the amines include dimethylaminomethylphenol, 2,4,6-tri (dimethylaminomethyl) phenol, and tri-2-ethylhexane salt of tri (dimethylaminomethyl) phenol.
In addition, a boron trifluoride complex compound, a boron trifluoride / monoethylamine complex compound, a boron trifluoride / triethylamine complex compound, a boron trifluoride / piperidine complex compound, a trifluoride Boron / n-butyl ether complex compounds, boron trifluoride / amine complex compounds, and the like. The curing accelerator is (a) an epoxy resin and (b) a polycondensate of bisphenol A and formaldehyde in total of 100.
It is preferable to mix 0.1 to 10 parts by weight with respect to parts by weight. If the amount is less than 0.1 part by weight, the effect is poor, and if it exceeds 10 parts by weight, the storage stability of the prepreg deteriorates.

[0008] The high-purity aluminum hydroxide (d) used in the present invention is the same as the impurity Na contained in aluminum hydroxide.
₂ 0 content is well if Te the following 0.2 wt%,
There is no particular limitation on the shape. Commercially available high-purity aluminum hydroxide can be used.
This high-purity aluminum hydroxide is preferably blended in an amount of 70 to 180 parts by weight based on 100 parts by weight of the resin. If the amount is less than 70 parts by weight, the tracking resistance is inferior. If the amount exceeds 180 parts by weight, the coating workability and moldability deteriorate, and the heat resistance and peel strength decrease.

In the present invention, the bromine content, which is the content of bromine element, is 5 to 15% by weight based on the weight of the thermosetting resin. The content of the bromine element relative to the weight of the thermosetting resin is defined as an essential component (a) an epoxy resin,
(B) Content of bromine element with respect to the total amount of the polycondensate of bisphenol A and formaldehyde, and (c) the total weight of the curing accelerator and other resin blended. 5 bromine content
When the content is less than 15 wt%, the flame retardancy is significantly reduced, and when the bromine content exceeds 15 wt%, the reduction in tracking resistance is inevitable. As the bromine element, a brominated epoxy resin in which a bromine atom is introduced into an epoxy resin skeleton is preferably used. A reaction product of tetrabromobisphenol A with epichlorohydrin, a reaction product of bisphenol A type epoxy resin with tetrabromobisphenol A, and a brominated epoxy resin obtained by a reaction product of brominated phenol novolak and epichlorohydrin It can be suitably used. Further, a bromine-containing compound such as tetrabromobisphenol A can be blended as a flame retardant.

The glass woven fabric used in the present invention may be a usual glass woven fabric used in the field of laminates. In particular, spraying high-pressure water on glass woven fabric,
It is preferable to use a glass woven fabric that has been opened by being squeezed with a roll. The thermosetting resin is dissolved or dispersed in a solvent to form a varnish, impregnated in a glass woven fabric, and dried to prepare a prepreg. By forming a plurality of these, a copper foil, which is a metal foil, is arranged on the upper and lower sides or on one side, and heated and pressed to produce a glass cloth base epoxy resin copper-clad laminate. Further, it is also possible to manufacture a composite laminate in which the above prepregs are formed on and under a plurality of glass nonwoven fabric prepregs.

The present invention relates to (a) an epoxy resin, (b) a polycondensate of bisphenol A and formaldehyde, (c)
A prepreg obtained by impregnating a glass woven fabric with a curing accelerator, (d) a thermosetting resin containing high-purity aluminum hydroxide as an essential component and having a bromine content of 5 to 15% by weight, that is, Using a specific polycondensate of bisphenol A and formaldehyde as a curing agent for the epoxy resin, and further adjusting the bromine content of the thermosetting resin to a specific value with high purity aluminum hydroxide containing less Na ₂ O as an impurity. As a result, both heat resistance and tracking resistance can be achieved. Furthermore, the tracking resistance is remarkably improved by using a glass woven fabric which has been subjected to an opening treatment. When the prepreg of the present invention is used on the outside (surface layer) of the laminate, the tracking resistance can be improved. Therefore, other than the surface layer of the laminate, a commonly used prepreg can be used. In particular, a composite laminate is particularly preferable because a prepreg of glass woven fabric is used outside the laminate and a nonwoven fabric is used inside.

[0012] The tracking resistance is a property of a substrate whose surface is wet or contaminated to withstand the formation of a leakage path by an arc discharge, and the tracking is caused by a high voltage between circuits. Resin is carbonized by arc discharge or the like and is generated. In the present invention, in order to prevent this, a specific curing agent is used, and carbonization of the resin is suppressed by using a high-purity aluminum hydroxide having a small amount of Na ₂ O as an impurity contained in the aluminum hydroxide, thereby improving the anti-tracking property. Improved. In addition, by making aluminum hydroxide high in purity, the thermal decomposition temperature is improved, and a decrease in the heat resistance of the laminate can be suppressed. In addition, the present inventors have found that when using a normal glass woven fabric for the glass woven fabric, the amount of resin adhering to the vicinity of the cross line of the glass woven fabric on the surface of the laminated plate tends to decrease the tracking resistance characteristic. I understood that. This is because a small amount of resin adhering to the glass, which is probably exposed near the surface layer of the laminate, is in contact with the glass interface, and the heat, heat conduction, and catalytic action of the arc discharge are entangled, promoting pyrolytic carbonization It seems to be because. Therefore, by using a glass woven fabric that has been opened, the impregnating property of the resin into the glass woven fabric is improved, and the amount of resin adhering near the crosses on the surface of the laminated board is kept uniform and does not become extremely thin. The characteristics could be improved. In addition, by using high-purity aluminum hydroxide having a low content of Na ₂ O, which is an impurity which is supposed to act as a catalyst similarly to glass, it has excellent tracking resistance even with a high bromine content, and has a flame-retardant property. A laminate having the same properties as the conventional laminate was obtained.

Hereinafter, the present invention will be described specifically with reference to examples.

【Example】

(Example 1) Brominated bisphenol A type epoxy resin (epoxy equivalent: 480, bromine content: 21.5 wt%) 60 parts by weight Bisphenol A type epoxy resin (epoxy equivalent: 450) 40 parts by weight Bisphenol A type novolak resin (hydroxyl equivalent 118) ) 24.5 parts by weight of 2-ethyl-4-methylimidazole 0.2 parts by weight of high purity aluminum hydroxide 150 parts by weight (content of 0.03 wt% of Na ₂ 0) dissolving the compound in methyl ethyl ketone, and dispersed, non-volatile A resin varnish having a content of 75 wt% and a bromine content of 10 wt% was prepared. A glass woven fabric (thickness: 0.2 mm, basis weight: 210 g / m ² ) obtained by subjecting the varnish to fiber-opening processing has a resin content of 46 wt%.
And dried to obtain prepreg A. Also,
Glass non-woven fabric (EPM-14 manufactured by Japan Vilene Co., Ltd.)
075), the resin content of the above resin varnish is 90 wt%
And dried to obtain a nonwoven fabric prepreg B.
Three nonwoven fabric prepregs B were used as an intermediate layer, prepregs A were arranged above and below the intermediate layer, and 18 μm copper foils were further arranged on both surfaces thereof. Was produced.

(Comparative Example 1) Brominated bisphenol A type epoxy resin (epoxy equivalent: 480, bromine content: 21.5 wt%) 58 parts by weight Bisphenol A type epoxy resin (epoxy equivalent: 450) 64 parts by weight Dicyandiamide 3 parts by weight 2- ethyl-4-methylimidazole 0.2 parts by weight of ethylene glycol monomethyl ether 25 parts by weight N, (content 0.03 wt% of Na ₂ 0) N-dimethylformamide 25 parts by weight of high-purity aluminum hydroxide 150 parts by weight mixture of the above compound This was dispersed to produce a resin varnish, and a composite laminate was obtained in the same manner as in Example 1.

[0015] (Comparative Example 2) The content of a typical aluminum hydroxide (Na ₂ 0 high purity aluminum hydroxide (content 0.03 wt% of Na ₂ 0) Example 1 0.2 wt
%) To obtain a composite laminate in the same manner as in Example 1.

Comparative Example 3 The varnish compounding ratio of Example 1 was changed as shown below, and the bromine content was 4 wt%.
Otherwise in the same manner as in Example 1, a composite laminate was obtained. 23 parts by weight of brominated bisphenol A type epoxy resin (epoxy equivalent: 480, bromine content: 21.5%) 76 parts by weight bisphenol A type epoxy resin (epoxy equivalent: 450) 25.6 parts by weight bisphenol A type novolak resin (hydroxyl equivalent 118) parts of 2-ethyl-4-methylimidazole 0.2 parts by weight of high purity aluminum hydroxide 150 parts by weight (content of 0.03 wt% of Na ₂ 0)

Comparative Example 4 The varnish compounding ratio of Example 1 was changed as shown below, and the bromine content was 16 wt%. Otherwise in the same manner as in Example 1, a composite laminate was obtained. 92 parts by weight of brominated bisphenol A type epoxy resin (epoxy equivalent: 480, bromine content: 21.5%) 7 parts by weight bisphenol A type epoxy resin (epoxy equivalent: 450) 7 parts by weight Bisphenol A type novolak resin (hydroxyl equivalent: 118) 25 parts by weight 2 - ethyl-4-methylimidazole 0.2 parts by weight of high purity aluminum hydroxide 150 parts by weight (content of 0.03 wt% of Na ₂ 0)

(Example 2) The fiber-opened glass woven fabric of Example 1 was replaced with a general glass woven fabric (thickness 0.2 mm, basis weight 210 g).
/ M ² ), and the others were the same as in Example 1 to obtain a composite laminate.

The composite laminates obtained in Examples and Comparative Examples were evaluated by the following test methods, and the results are shown in Table 1.

(Tracking resistance): I
Test by EC method and CT from tracking voltage curve
The I value (tracking resistance) was determined. (Flame retardancy): Performed according to the UL combustion test. (Solder heat resistance): 50 × 50 mm etched over the entire surface
Of the test piece in a pressure cooker at 121 ° C. and 1215 hPa for a predetermined time,
After immersion for 2 seconds, the presence or absence of abnormality was visually observed. 3 test pieces
Sheets were evaluated, and the results were evaluated for each of them. Those having abnormalities such as blisters were indicated by x, and those without abnormalities were indicated by ○.

[0021]

[Table 1] ―――――――――――――――――――――――――――――――――― Item Example 1 Example 2 Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 ―――――――――――――――――――――――――――――――――― Phenol Phenol Phenol Bromine content (wt%) 10 10 10 10 4 16 Aluminum hydroxide 0.03 0.03 0.03 0.2 0.03 0.03 Na20 content Spreading embedded fabric Yes No Yes Yes Yes Yes Yes IEC method (V) Flame retardancy V-0 V-0 V-0 V-0 V-1 V-0 is PCT1h ○○○ ○○○ ○○○ ○○○ ○○○ ○○○ Heat PCT2h ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ PC PC PC T T T PC PC T PC T T T T T T T T T T T PCT3h ×× ○○○ ○○○ ―――――――――――――――― -------------------

As is clear from the above results, the tracking resistance is improved by the difference in the curing agent (Example 1 and Comparative Example 1), and the use of aluminum hydroxide having a high purity with few impurities is used. The tracking resistance and heat resistance are improved (Example 1 and Comparative Example 2). It is also found that the bromine content is less than 5 wt%, the flame retardancy is reduced (Comparative Example 3), and the bromine content is more than 15 wt%, the tracking resistance is reduced (Comparative Example 4). Further, it was found that more stable tracking resistance can be obtained by using the glass woven fabric which has been subjected to the fiber opening treatment (Examples 1 and 2).

[0023]

The present invention relates to (a) an epoxy resin, (b)
Polycondensate of bisphenol A and formaldehyde,
A prepreg obtained by impregnating a glass woven fabric with (c) a curing accelerator and (d) a thermosetting resin containing high-purity aluminum hydroxide as an essential component and having a bromine content of 5 to 15 wt% is used. By this, it is possible to provide a metal-clad laminate excellent in tracking resistance without lowering general properties such as heat resistance and flame retardancy, and to use a glass woven fabric which has been subjected to fiber opening treatment as a glass woven fabric. Thereby, tracking resistance is further improved and stable characteristics can be obtained.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code FI C08J 5/10 CFC B29C 67/14 G // B29K 63:00 105: 08 309: 08 B29L 9:00

Claims (3)

[Claims] 1. An essential component comprising (a) an epoxy resin, (b) a polycondensate of bisphenol A and formaldehyde, (c) a curing accelerator, and (d) high-purity aluminum hydroxide.
A method for producing a metal-clad laminate, comprising laminating a prepreg obtained by impregnating a glass woven fabric with a thermosetting resin having a bromine content of 5 to 15% by weight and a metal foil, followed by heating and pressing. . 2. The method for manufacturing a metal-clad laminate according to claim 1, wherein the glass woven fabric is a glass woven fabric that has been subjected to a fiber opening treatment. 3. A composite laminate comprising a nonwoven fabric inside and a glass woven fabric outside, wherein a prepreg obtained by impregnating at least the outermost outer layer with the resin according to claim 1 or 2 is used. A method for producing a metal-clad laminate.