JP5382074B2 - Prepreg for printed wiring board and metal-clad laminate - Google Patents

Description

  The present invention relates to a prepreg for a printed wiring board used for an electrical insulating material such as a printed wiring board and a metal-clad laminate using the same.

  The epoxy resin laminate is manufactured by impregnating a glass woven fabric with a varnish solution of an epoxy resin composition, laminating a prepreg that has been dried and made into a B-stage, and heated and pressed.

Along with miniaturization and high performance of electronic devices, printed wiring boards mounted therein are increasing in density by increasing the number of layers, reducing the size of through-holes, and reducing the interval between holes. In addition, the expansion of chips due to the increase in memory capacity and the reduction in the thermal expansion coefficient of mounted components are progressing due to the thinner sealing material. In order to ensure the connection reliability with the mounted component, further lower thermal expansion coefficient and higher elastic modulus are required for the substrate material.
In order to satisfy the demand for a low thermal expansion coefficient and a high elastic modulus, there is a method by adding a filler.
In addition, dicyandiamide, which has been conventionally used as a curing agent for epoxy resins, has poor compatibility with epoxy resins, and dicyandiamide often precipitates when used as a prepreg. For reasons such as a low softening temperature, smears that cause the resin to adhere to the inner circuit copper during drilling are likely to occur, and the long-term heat resistance in air is also poor.
As a resin system that solves these problems, there is an epoxy resin cured with a polycondensate of phenols and formaldehyde. In the printed wiring board by this curing system, smear generation is less than half and the heat resistance in the air is improved more than twice as compared with the dicyandiamide curing system.
However, epoxy resins cured with a polycondensate of phenols and formaldehyde have drawbacks such as low adhesion and are hard and brittle. Especially when inorganic fillers are added, they are sufficiently reliable. You can't get sex.

  The present invention has been made in view of such a situation. A prepreg for a printed wiring board having high connection reliability with a mounting component due to a low coefficient of thermal expansion and excellent heat resistance, and a metal-clad laminate using the same. It is to provide.

The present invention provides (a) an epoxy resin having at least two epoxy groups in one molecule, (b) a polycondensate of phenols and formaldehyde, (c) dicyandiamide, (d) a curing accelerator, and (e) A varnish containing an inorganic filler as an essential component, wherein (e) a glass woven fabric is impregnated with a thermosetting resin varnish whose inorganic filler is 50 to 150% by weight based on the organic resin solid content in the varnish, The present invention relates to a prepreg for a printed wiring board which is heated and dried to form a B stage.
The present invention also relates to a prepreg for a printed wiring board, wherein the epoxy resin (a) is a glycidyl etherified product of a polycondensate of phenols and formaldehyde.
Furthermore, the present invention relates to a metal-clad laminate obtained by stacking at least one prepreg for a printed wiring board, placing a metal foil on one or both sides thereof, and heating and pressing.

  By using the prepreg for a printer wiring board of the present invention, it is possible to obtain a metal-clad laminate for a printed wiring board that has a higher connection reliability with a mounted component than a low coefficient of thermal expansion and is excellent in heat resistance.

  The type of the epoxy resin (a) used in the present invention is not particularly limited as long as it has two or more epoxy groups in the molecule. For example, bisphenol A type epoxy resin, bisphenol F type epoxy resin, There are bisphenol S type epoxy resin, biphenyl type epoxy resin, alicyclic epoxy resin, diglycidyl etherified product of polyfunctional phenol, diglycidyl etherified product of polyfunctional alcohol, hydrogenated products of these, etc. You can also. In order to improve the Tg and heat resistance of the resin system after curing, it is more preferable to use a glycidyl etherified product of a polycondensate of phenols and formaldehyde. Examples of such resins include phenol novolac type epoxy resins, cresol novolac type epoxy resins, bisphenol A novolac type epoxy resins and the like, and these can be used alone or in combination.

  The polycondensation product of phenols and formaldehyde (b), which is an epoxy resin curing agent used in the present invention, has no molecular weight limitation. Examples of such resins include phenol novolak resins, cresol novolac resins, and bisphenol A. A novolak resin etc. are mentioned, These can be used individually or in combination. It is preferable to mix | blend the compounding quantity of a hardening | curing agent so that an epoxy equivalent may become a hydroxyl equivalent / epoxy equivalent = 0.8-1.2 with respect to the hydroxyl equivalent of the hardening | curing agent to be used. If it is less than 0.8 and exceeds 1.2, the heat resistance tends to be inferior.

  The dicyandiamide used in the present invention is preferably blended in an amount of 0.01 to 2 parts by weight with respect to 100 parts by weight of the polycondensate of (a) an epoxy resin, (b) a phenol and formaldehyde. If the amount is less than 0.01 parts by weight, the effect is poor, and if it exceeds 2 parts by weight, the heat resistance of the printed wiring board tends to deteriorate.

  Examples of the curing accelerator (d) used in the present invention include imidazole compounds and amines, but are not particularly limited. Examples of imidazole include 2-methylimidazole, 2-ethyl-4-methylimidazole, 2-undecylimidazole, 2-heptadecylimidazole, 2-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-phenylimidazolium trimellitate, 1-cyanoethyl-2-ethyl-4-methylimidazole trimellitate, 1-cyanoethyl-2-undecylimidazole trimellitate, 1 Cyanoethyl-2-phenylimidazole trimellitate, 1-cyanoethyl-2-phenyl-4,5-di (cyano ethoxymethyl) imidazole, and the like. Examples of amines include dimethylaminomethylphenol, 2,4,6-tri (dimethylaminomethyl) phenol, tri-2-ethylhexane salt of tri (dimethylaminomethyl) phenol, and the like. In addition, boron trifluoride complex compound, boron trifluoride / monoethylamine complex compound, boron trifluoride / triethylamine complex compound, boron trifluoride / piperidine complex compound, boron trifluoride / n-butyl ether And complex compounds such as boron trifluoride / amine complex compounds. The curing accelerator is preferably blended in an amount of 0.1 to 10 parts by weight with respect to 100 parts by weight of the polycondensate of (a) epoxy resin, (b) phenols and formaldehyde. If it 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 tends to be poor.

  The inorganic filler (e) used in the present invention is not particularly limited. For example, calcium carbonate, alumina, mica, aluminum carbonate, aluminum hydroxide, magnesium silicate, aluminum silicate, silica, short glass fiber, aluminum borate, Various whiskers such as silicon carbonate are used. These may be used in combination. This inorganic filler is blended in an amount of 50 to 150% by weight based on the organic tree solid content in the varnish. If it is less than 50% by weight, no effect can be obtained for lowering the coefficient of thermal expansion and increasing the modulus of elasticity. If it exceeds 150% by weight, the workability of coating decreases, the moldability deteriorates, the heat resistance and the peel strength decrease, etc. Cause.

  The above (a), (b), (c), (d) and (e) are essential components, and other solvents, colorants, antioxidants, reducing agents, UV opaque agents, etc. are added as necessary. May be added.

A glass woven fabric is impregnated with a thermosetting resin varnish obtained by blending the above (a), (b), (c), (d) and (e) in a solvent, heated and dried, and B A prepreg for a printed wiring board can be obtained by making the stage. The kind of glass woven fabric used here is not particularly specified, and those having a thickness of 0.02 to 0.4 mm can be used according to the thickness of the target prepreg or laminate. The amount of impregnation is shown as the resin content, which is the ratio of the total weight of the organic resin solids and inorganic fillers to the total weight part of the prepreg, preferably 30 to 90% by weight, More preferably, it is -80 wt%. The resin content is appropriately determined according to the performance of the target prepreg and the thickness of the insulating layer after lamination. The drying conditions for producing the prepreg can be freely selected according to the desired prepreg characteristics, with a drying temperature of 60 to 200 ° C. and a drying time of 1 to 30 minutes.
Solvents include acetone, methyl ethyl ketone, toluene, xylene, methyl isobutyl ketone, ethyl acetate, ethylene glycol monomethyl ether, N, N-dimethylformamide, N, N-dimethylacetamide, methanol, and ethanol. You may mix and use.

  At least one prepreg for a printed wiring board obtained in accordance with the thickness of the target laminated board is stacked, and a metal foil is arranged on one side or both sides thereof, followed by heating and pressing to produce a laminated board. As the metal foil, copper foil or aluminum foil is mainly used, but other metal foil may be used. The thickness of the metal foil is usually 3 to 200 μm.

  The heating temperature during the production of the laminate is 130 to 250 ° C., more preferably 160 to 200 ° C., and the pressure is 0.5 to 10 MPa, more preferably 1 to 4 MPa. It determines suitably by the thickness etc. of a laminated board.

EXAMPLES Hereinafter, although this invention is demonstrated concretely based on an Example, this invention is not limited to this.
[Example 1]
Bisphenol A novolac epoxy resin (epoxy equivalent 205)
100 parts by weight Bisphenol A type novolak resin (hydroxyl equivalent 118) 52 parts by weight Dicyandiamide 0.5 part by weight 2-ethyl-4-methylimidazole 0.2 part by weight Silica 190 parts by weight The above compound is dissolved and dispersed in ethylene glycol monomethyl ether A resin varnish having a nonvolatile content of 75% by weight was prepared. This varnish was impregnated into a 100 μm glass woven fabric (IPC product number # 2116 type) and dried in a dryer at 180 ° C. for 6 minutes to obtain a B-stage prepreg having a resin content of 60% by weight.

[Example 2]
o-Cresol novolac type epoxy resin (epoxy equivalent 210)
100 parts by weight Bisphenol A type novolak resin (hydroxyl equivalent weight 118) 51 parts by weight Dicyandiamide 0.5 part by weight 2-ethyl-4-methylimidazole 0.2 part by weight Silica 190 parts by weight The above compounds are mixed and dispersed to obtain a resin varnish. And a prepreg having a resin content of 60% by weight was obtained in the same manner as in Example 1.

Comparative Example 1
In Example 1, bisphenol A type novolak resin was not added, dicyandiamide was added to 4 parts by weight, silica was added in an amount of 125 parts by weight, and the prepreg having a resin content of 60% by weight was obtained in the same manner as in Example 1. It was.

Comparative Example 2
In Example 1, a prepreg having a resin content of 60% by weight was obtained in the same manner as in Example 1 except that dicyandiamide was not added and the amount of bisphenol A type novolak resin was 58 parts by weight.

Comparative Example 3
A prepreg having a B-stage resin content of 60% by weight was obtained in the same manner as in Example 1 except that the amount of silica in Example 1 was changed to 70 parts by weight.

Manufacturing method of metal foil-clad laminate The four prepregs obtained in Examples 1 and 2 and Comparative Examples 1, 2, and 3 are stacked, and a copper foil having a thickness of 18 μm is arranged on both sides thereof, pressure 3 MPa, temperature 185 ° C. For 90 minutes to obtain a double-sided copper-clad laminate.

  The peel strength, thermal expansion coefficient, Tg and board solder heat resistance test of the double-sided copper clad laminate obtained above were performed. The results are shown in Table 1. The coefficient of thermal expansion and Tg were measured using a DuPont TMA. The substrate solder heat resistance is a result of observing a base material immersed in a solder bath at 288 ° C. for 20 seconds after the moisture absorption treatment described in Table 1. Each symbol means ◯: no change, Δ: occurrence of measling, ×: occurrence of blistering, and three symbols respectively show the results of evaluation using three test pieces.

フェノール：ビスフェノールＡ型ノボラック樹脂
ジシアン：ジシアンジアミド

Phenol: Bisphenol A type novolak resin Dicyan: Dicyandiamide

  From Table 1, the metal-clad laminate using the prepreg for a printer wiring board of the present invention had a high Tg, a high adhesiveness with a copper foil, and a sufficiently low coefficient of thermal expansion. On the other hand, in Comparative Example 1 using a dicyan curing system, Tg was low and the heat resistance was inferior. Moreover, although the comparative example 2 hardened | cured with the polycondensate of phenols and formaldehyde had heat resistance, it resulted in inferior adhesiveness with copper foil. Furthermore, Comparative Example 3 in which the blending amount of the inorganic filler was less than 50 parts by weight with respect to the organic resin solid content had a high coefficient of thermal expansion and inferior heat resistance.

Claims (2)

(A) an epoxy resin having at least two epoxy groups in one molecule, (b) a polycondensate of phenols and formaldehyde, (c) dicyandiamide, (d) a curing accelerator, and (e) an inorganic filler. An varnish as an essential component, wherein (a) the epoxy resin is a glycidyl etherified product of a polycondensate of phenols and formaldehyde, and (b) the blending amount of the polycondensate of phenols and formaldehyde is a polycondensate. The amount of epoxy equivalent is equivalent to hydroxyl equivalent / epoxy equivalent = 0.8 to 1.2 with respect to hydroxyl equivalent, and (c) dicyandiamide is blended with (a) polycondensation of epoxy resin, (b) phenol and formaldehyde 0.01 to 2 parts by weight with respect to 100 parts by weight of the product, and (d) the amount of curing accelerator is (a) epoxy resin, (b) phenols and 0.1 to 10 parts by weight with respect to 100 parts by weight of the polycondensate of rumaldehyde, (e) a thermosetting resin whose inorganic filler is 50 to 150% by weight with respect to the solid content of the organic resin in the varnish A prepreg for a printed wiring board obtained by impregnating a glass woven fabric with a varnish, heating and drying, and forming a B stage. A metal-clad laminate obtained by stacking at least one prepreg for a printed wiring board according to claim 1 , placing a metal foil on one or both sides thereof, and heating and pressing.