JP3342565B2 - Method for producing sintered sheet and laminate for high-frequency circuit - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a substrate for electronic equipment, and more particularly to a method for producing a laminated sheet used in a high frequency range and a sintered sheet as a constituent material of the laminated sheet.

[0002]

2. Description of the Related Art In recent years, with the rapid development of communication systems, frequencies used in the fields of the electronics industry, the communication industry, the computer industry, and the like are gradually shifting to higher frequency bands. In a high-frequency band, a decrease in signal speed and a loss in signal quality greatly affect the performance of a device. Therefore, a printed circuit laminate having a small decrease in signal speed and a small loss in signal quality is required. For this reason, a material having a low dielectric constant and a low dielectric loss tangent is used for the high-frequency circuit laminate.

As a material having a low dielectric constant and a low dielectric loss tangent, a sintered sheet obtained by shaping a thermoplastic resin powder into a sheet and impregnating it with an uncured thermosetting resin is impregnated and cured. There is known a laminated board for a high-frequency circuit in which a cured curable resin-impregnated reinforcing layer is laminated on one side and further provided with a metal conductor layer.

[0004]

However, this laminated board for a high-frequency circuit has a drawback in that, when heated, it causes blistering and has a defect in heat resistance, and also has a disadvantage in that the plating around of the through-hole plating is poor. The present invention has been made to solve such a problem.

[0005]

Means for Solving the Problems The present inventors formed a sintered sheet obtained by shaping a thermoplastic resin powder into a sheet and impregnating and curing an uncured thermosetting resin. Next, the cause of the occurrence of blistering upon heating of the laminated plate on which the cured curable resin-impregnated reinforcing layer was laminated was examined. As a result, the present inventors have found that the sintered sheet is porous and the air confined in the pores expands and expands when heated when impregnated with the uncured thermosetting resin, and has reached the present invention.

According to the present invention, a resin powder is dispersed in a dispersion medium in which a resin soluble in a dispersion medium is dissolved, the resin powder is shaped into a sheet, and the obtained shaped material is heated to form a resin powder. Is a method for producing a sintered sheet by sintering the sheet.

Then, a curable resin-impregnated reinforcing layer 2 is laminated on both sides (or one side) of the obtained sintered sheet 1, and a metal conductor layer 3 is further provided (see FIG. 1).

[0008] The sintered sheet 1 is obtained by dispersing a resin powder and a filler in a dispersion medium such as an organic solvent, coating a carrier film or the like, drying and sintering.

At this time, a thermosetting resin or a thermoplastic resin that is soluble in the dispersion medium is added in an amount of 5 to 50% by weight based on the dispersion material, and dried and sintered. If the blending amount of the thermosetting resin or the thermoplastic resin is less than 5% by weight, the voids cannot be filled, and if it is more than 50% by weight, the electrical characteristics, particularly the dielectric loss tangent characteristics, deteriorate.

The thermosetting resin to be dissolved in the dispersion medium includes polyester resin, epoxy resin, phenol resin, melamine resin, diallyl phthalate resin, polyimide resin, bismaleide / triazine resin, polyphenylene oxide resin, or polyphenylene oxide resin and a crosslinkable polymer. Alternatively, a resin composition with a crosslinkable monomer may be used. Epoxy resins and polyester resins are good in terms of electrical characteristics, price and the like.

As the thermoplastic resin dissolved in the dispersion medium, polyethylene, polypropylene, polystyrene and the like can be mentioned. Polyethylene is preferable in terms of electrical characteristics, price, and the like.

Further, in order to promote sintering and improve heat resistance,
Organic peroxides and coupling agents are also added. The application of the material mixed in the dispersion medium to the carrier film or the like is performed by various methods, and is not particularly limited in the present invention.

The resin of the resin powder is preferably a polyolefin resin. Specifically, a homopolymer or a copolymer of an olefin compound such as ethylene, propylene, 1-butene and 4-methyl-1-pentene is used. Polyethylene is preferred from the viewpoints of electrical properties, workability, cost and the like. Particularly, high molecular weight polyethylene is particularly preferable from the viewpoint of heat resistance.

As the filler, a halogenated organic compound is used. Specifically, decabromophenyl ether,
Brominated or chlorinated organic compounds such as hexabromobenzene are used.

The curable resin-impregnated reinforcing layer 2 is made of a glass woven fabric, a glass nonwoven fabric, or the like generally used for a printed circuit board.
A prepreg is used in which a thermosetting resin is impregnated into a base material such as a synthetic fiber woven fabric or nonwoven fabric and dried. The above-mentioned resin is used as the thermosetting resin, and the amount of the resin is 30 to 70% by weight, preferably 40 to 55% by weight. As the substrate, a glass cloth is preferable, and one having 30 to 200 g / m ² is desirable.

The metal conductor layer 3 is made of copper, aluminum, nickel, iron, stainless steel or the like.

The high frequency circuit laminate according to the present invention can be formed by a dielectric sheet, like a general printed circuit board.
A required number of prepregs and metal foils are stacked, sandwiched between end plates, and hot-pressed by a multi-stage press. Molding pressure is 1-7.8M
The reaction is performed at a Pa and temperature of 120 to 250 ° C., preferably under reduced pressure.

[0018]

[Function] Since the thermosetting resin or the thermoplastic resin dissolved in the dispersion medium fills the voids during drying, the resulting sintered sheet has no voids and does not bulge when heated.

[0019]

The present invention will be described in detail with reference to the following examples. Example 1 Average particle diameter 0.03 mm, melting point 136 ° C., bulk density 0.4
g / cm ³ 100 parts by weight of ultra-high molecular weight polyethylene having a true density of 0.94 g / cm ³ (Miperon XM220, trade name of Mitsui Petrochemical Industry Co., Ltd.), chlorine content 65
%, Average particle diameter 0.003 mm, bulk density 0.67 g / c
1, 2, ³ , 4, m ³ , true density 1.9 g / cm ³
7,8,9,10,13,13,14,14-Dodecachloro-1,4,4a, 5,6,6a, 7,10,10
a, 11,12,12a-dodecahydro-1,4,7,
80 parts by weight of 10-dimethanodibenzono (a, e) cyclooctene (Dechlorane Plus # 25, trade name of Oxidal Chemical Co., USA), 1 part by weight of dicumyl peroxide, γ-methacryloxypropyltrimethoxysilane 0.1 part by weight and 5 parts by weight of a brominated bisphenol A type epoxy resin are mixed with toluene, and the mixture is applied to a polyethylene terephthalate film having a thickness of 50 μm.
After drying at 5 ° C. for 10 minutes, a sintered sheet was obtained.

A prepreg impregnated with a brominated bisphenol A type epoxy resin in a glass cloth having a thickness of 50 μm (resin content: 60% by weight) was placed on both sides of the sheet, and a thickness of 35 μm was obtained.
Of electrolytic copper foil, and using a stainless steel head
Heating and pressing for 90 minutes at 2 ° C and 0.6MPa
m was obtained.

Example 2 A low molecular weight polyethylene having a molecular weight of 1,000 and a melting point of 109 ° C. (High Wax P, trade name of Mitsui Petrochemical Industry Co., Ltd.) was used instead of 5 parts by weight of a brominated bisphenol A type epoxy resin. A sintered sheet was obtained in the same manner as in Example 1 except for mixing the parts by weight, and a high-frequency circuit laminate having a thickness of 0.6 mm was obtained in the same manner.

Comparative Example A sintered sheet was obtained in the same manner as in Example 1 except for 5 parts by weight of the brominated bisphenol A type epoxy resin, and a 0.6 mm thick laminated board for a high frequency circuit was obtained in the same manner.

The relative permittivity, dielectric loss tangent, thermal shock cycle, air heat resistance, and plating void generation rate of each high frequency circuit laminate were examined. Table 1 shows the results.

The test method is as follows. Dielectric constant: by the cavity resonator method of 12 GHz. Thermal shock test: JIS C501 for high frequency circuit laminate
In accordance with the test pattern of No. 2, a hole was drilled, electroless plating was performed with a thickness of 0.5 μm, and electroplating was performed with a thickness of 30 μm using copper sulfate to obtain a sample in which through-hole plating was performed. For this sample, 26
Immerse in oil at a temperature of 0 ° C for 10 seconds.
A thermal shock test was performed in which the operation of dipping for 0 second was one cycle, and the number of cycles was examined until the conduction resistance between the through holes changed by 20% or more. Air heat resistance: The state after holding at 170 ° C. for 30 minutes was observed. Plating void generation rate: Observe the inner wall of the through hole with an endoscope and check for plating voids. Through hole 500
Occurrence rate for 0 holes.

[0025]

[Table 1]

[0026]

According to the present invention, it is possible to obtain a laminated board for a high-frequency circuit which is excellent in heat resistance, plating turning property and through-hole reliability.

[Brief description of the drawings]

FIG. 1 is a sectional view of a high-frequency circuit laminate according to an embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Sintered sheet 2 Curable resin impregnation reinforcement layer 3 Metal conductor layer

Continuation of the front page (56) References JP-A-5-245943 (JP, A) JP-A-5-167211 (JP, A) JP-A-5-299796 (JP, A) JP-A-63-164389 (JP) , A) (58) Fields investigated (Int. Cl. ⁷ , DB name) B29C 67/00-67/04 B29C 41/00-41/52 B32B 15/08 C08J 5/18 H05K 1/03

Claims (2)

(57) [Claims] 1. A resin powder is dispersed in a dispersion medium in which a resin soluble in a dispersion medium is dissolved, the resin powder is shaped into a sheet, and the obtained shaped material is heated to bake the resin powder. A method for producing a sintered sheet, comprising: 2. A resin powder is dispersed in a dispersion medium in which a resin dissolved in a dispersion medium is dissolved, the resin powder is shaped into a sheet, and the obtained shaped material is heated to bake the resin powder. A laminated sheet for a high-frequency circuit in which a cured curable resin-impregnated reinforcing layer is laminated on both surfaces or one surface of a sintered sheet obtained by tying, and further provided with a metal conductor layer.