JPH0682900B2 - Printed wiring board - Google Patents

Description

The present invention relates to a printed wiring board and a printed wiring board which can be easily punched by a mold and have high through hole reliability in punching holes.

(Prior art) Copper-clad laminate of flame-retardant epoxy resin (ANSI grade)
CEM-1 and CEM-3) are used for both industrial and consumer purposes such as personal computers, word processors, communication equipment, industrial instruments, AV equipment, etc.

Conventionally, in order to obtain continuity between the front and back circuits in a printed circuit board for industrial electronics (for industrial electronics), after making a hole with a drill, a copper or silver plated through hole is connected to the drill hole for connection. There is.

Conduction is taken in the die punching hole only when the mounting component lead is inserted and fixed to the front and back circuits, and there was no one that made a copper plated through hole for conductive connection for industrial electronics. .

The punched holes with copper through-holes have the drawback of inferior reliability, and the punched holes have cracks between layers, resulting in delamination and poor inner wall smoothness. This is because there are drawbacks such as fluffing.

(Problems to be Solved by the Invention) The present invention has been made in order to solve the above-mentioned drawbacks and is excellent in punching property by a mold or the like, does not cause cracks or delamination, and allows copper through holes and the like to be formed. It is intended to provide a printed wiring board with high hole reliability.

[Structure of the Invention] (Means for Solving the Problems) As a result of intensive studies to achieve the above object, the present inventors have found that a prepreg using a specific glass cloth is
The inventors have found that the above object can be achieved by laminating the paper base prepreg on top of each other, and have completed the present invention.

That is, the present invention provides a prepreg (I) in which a paper base material is impregnated with a thermosetting resin, and a glass cloth having a fiber diameter of 5 μm or less and a basis weight of 160 g / m ² or less is impregnated with the thermosetting resin on both sides ( II) are overlaid, and copper foil is placed on both sides of the printed wiring board to form a circuit, punching holes, and through-hole plating layers on a printed wiring board that is integrated with heating and pressure. Is.

Examples of the paper substrate used in the present invention include glass paper, kraft paper, linter paper, kraft / linter mixed paper, glass paper / linter mixed paper, and the like.

As the thermosetting resin used in the present invention, an epoxy resin,
Examples thereof include polyester resins and polyimide resins, which may be used alone or in admixture of two or more.

The above-mentioned paper base material is coated with a thermosetting resin, impregnated and dried to obtain a prepreg (I). This prepreg can be used in a combination of a predetermined number of sheets according to need and required characteristics.

The glass cloth used in the present invention has a fiber diameter of 5 μm or less and a basis weight of 160 g / m ² or less. If the fiber diameter exceeds 5 μm, the glass cloth becomes thick and the punching property deteriorates, which is not preferable. Further, if the basis weight exceeds 160 g / m ² , the glass cloth becomes thick, which is not preferable. When the fiber diameter of the glass cloth is 5 μm or less and the basis weight is 160 g / m ² or less, punching property and through hole reliability are excellent. The glass cloth is coated with the thermosetting resin, impregnated and dried to obtain a prepreg (II). If necessary, a predetermined number of the prepregs (II) can be stacked and used.

The copper foil used in the present invention may be either an electrolytic copper foil or a rolled copper foil, and those generally used for copper-clad laminates can be widely used.

A prepreg (II) is laminated on both sides of the prepreg (I) thus obtained, copper foils are further laminated on both sides of the prepreg (II), and heat and pressure are integrally laminated to form a printed wiring board. Then, this printed wiring board is punched with a die, a copper through-hole plating layer is formed in the hole, and then a circuit is formed by a conventional method to manufacture a printed wiring board.

(Examples) Next, the present invention will be described by examples.

[Preparation of varnish] Varnish A: 100 parts by weight of flame-retardant epoxy resin Araldite 8011 (trade name, manufactured by Ciba Geigy), 3 parts by weight of dicyandiamide as a curing agent, and 0.15 parts by weight of benzyldimethylamine as a curing accelerator were mixed. Then, it was dissolved in a solvent to prepare a varnish A.

Varnish B: Varnish B was prepared by adding 30 parts by weight of an inorganic filler to Varnish A.

[Manufacture of prepreg] Prepreg A: Glass cloth A216 / AS450 (trade name, manufactured by Asahi Schwebel) having a fiber diameter of 7 μm and a basis weight of 106 g / m ² is impregnated with varnish A, and the resin content is 42% by weight and the gel time is 120 seconds. Prepreg A was manufactured.

Prepreg B: Glass paper GMC-00-50C (trade name, manufactured by Honshu Paper Co., Ltd.) was impregnated with varnish B to prepare a prepreg B having a resin content of 75% by weight and a gel time of 120 seconds.

Prepreg C: Glass cloth with fiber diameter of 5 μm and basis weight of 48 g / m ² .
Varnish A was impregnated and coated on A1080 / AS450 (trade name, manufactured by Asahi Schebel) to produce a prepreg C having a resin content of 54% by weight and a gel time of 120 seconds.

Prepreg D: Glass cloth A7628W / AS450 (manufactured by Asahi Schwebel, trade name) having a fiber diameter of 9 μm and a basis weight of 211 g / m ² was impregnated with varnish A to produce a prepreg D having a resin content of 42% by weight and a gel time of 120 seconds. did.

Prepreg E: Glass cloth A7628W used for prepreg D
A prepreg E was manufactured in the same manner as the prepreg D except that the mechanical down strength (tensile strength) of the / AS450 was reduced to 1/2 of the usual strength, and the A7628W prototype / AS450 was used (prepreg E).

Example 1 One prepreg C each was laminated on the front and back of seven prepregs B, and a copper foil having a thickness of 18 μm was further laminated on both sides of the prepreg C.
Plate thickness by heat and pressure molding for 90 minutes under conditions of ℃ and pressure of 40 kgf / cm ^2.
A 1.6 mm printed wiring board (equivalent to ANSI grade CEM-3) was manufactured.

Example 2 One prepreg C each was placed on the front and back sides of four prepreg B sheets, and copper foil having a thickness of 18 μm was further placed on both sides of the prepreg C sheet.
Plate thickness by heat and pressure molding for 90 minutes under conditions of ℃ and pressure of 40 kgf / cm ^2.
A 1.0 mm printed wiring board (equivalent to ANSI grade CEM-3) was manufactured.

Comparative Example 1 A printed wiring board (corresponding to ANSI grade CEM-3) was manufactured in the same manner as in Example 1 except that prepreg A was used instead of prepreg C.

Comparative Example 2 Prepreg B Six prepregs D were laid one on each side, and 18 μm thick copper foil was laid on both sides of the prepreg D.
By heat and pressure molding for 90 minutes under conditions of ℃ and pressure of 40 kgf / cm ² , a printed wiring board (equivalent to ANSI grade CEM-3) with a thickness of 1.6 mm was manufactured.

Comparative Example 3 One prepreg D was laid on each side of 3 prepregs B, 18 μm thick copper foil was laid on both sides of the prepreg D, and heat and pressure molding was performed for 90 minutes at a temperature of 180 ° C. and a pressure of 40 kgf / cm ^2. Printed wiring board with a thickness of 1.0 mm (ANSI grade CEM
-3 equivalent) was manufactured.

Comparative Example 4 The same as Comparative Example 2 except that the prepreg E was used instead of the prepreg D in Comparative Example 2, the plate thickness was 1.6 m.
A m printed circuit board (equivalent to ANSI grade CEM-3) was manufactured.

The printed wiring boards manufactured in Examples 1 and 2 and Comparative Examples 1 to 4 were punched with a die to a diameter of 0.9 mmφ and 1.0 mmφ, and then a copper through-hole plating layer having a predetermined thickness was formed and a circuit was formed to form a printed wiring. A board was manufactured. Bending strength, shear strength, punching property, and through-hole reliability of the wiring board thus manufactured were tested, and the results are shown in Table 1. The test results of the through-hole reliability of the drill holes of the substrate of Comparative Example 2 for three times were 43 cycles, 45 cycles, and 35 cycles. The present invention is excellent in punching property and through hole reliability, and the effect of the present invention is recognized as inferior to the drill hole through hole.

The characteristic test was conducted as follows. The flexural strength test was performed according to JIS-C-6481, and the shear strength test was performed according to JIS-K-7057. The punching test is performed by drilling holes of 0.9φ and 1.0φ, plating copper with a thickness of 5μm, and microsectioning.
At 45 °, whitening, delamination, and inner wall roughness were observed, and judged as excellent (corresponding to drilling), good (good), good (good), bad (bad). For the through-hole reliability test, 500 punch holes of 0.9φ were drilled, the inner wall was plated with 25 μm thick copper, and this was put in oil at 260 ° C for 10 seconds and replaced.
Second, then put in trichlorethane at 15 ℃ for 10 seconds, and exchange for 10 seconds as one cycle, and the conduction resistance is 10% from the initial value.
The number of cycles until reaching the drop value was obtained and evaluated (JIS
-C-5012 thermal shock test). This through hole reliability test was performed three times.

[Effects of the Invention] As is clear from the above description and Table 1, the printed wiring board and the printed wiring board of the present invention can be easily punched by a die, and cracks and delamination occur around holes. It was excellent in punching performance, and the through hole provided in the punching hole was also highly reliable.

Claims (2)

[Claims] 1. A prepreg (II) obtained by impregnating a glass cloth having a fiber diameter of 5 μm or less and a basis weight of 160 g / m ² or less with a thermosetting resin on both sides of a prepreg (I) in which a paper base material is impregnated with a thermosetting resin (II). ) Are stacked on top of each other, and copper foils are placed on both sides of the stack, and a punching hole,
A printed wiring board comprising a through-hole plating layer and a circuit. 2. A prepreg (II) obtained by impregnating a glass cloth having a fiber diameter of 5 μm or less and a basis weight of 160 g / m ² or less with a thermosetting resin on both sides of a prepreg (I) in which a paper base material is impregnated with a thermosetting resin (II). ) And a copper foil are superposed on each other and integrated with each other by heating and pressurizing the printed wiring board.