JP2727912B2 - Manufacturing method of through-hole printed wiring board - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a through-hole printed wiring board in which conduction between both sides of the through-hole printed wiring board is formed by a conductive paste.

[0002]

2. Description of the Related Art Conventionally, a silver paste composed of silver powder and an organic binder has been frequently used as a conductive paste. The silver through-hole wiring board is formed by penetrating a hole 2 at a predetermined position of a double-sided copper foil-laminated laminate 1 and filling the hole with a silver paste 3 to form a conductive through-hole.

As a method of filling the silver paste 3, there is a method of inserting a pin into the hole and filling the hole with the silver paste while removing the pin, and a method of filling the silver paste into the hole with a squeegee by a screen printing method. . The silver paste 3 contains 20 to 40% by weight of a solvent because it requires fluidity. After filling the silver paste 3 (FIG. 2) and leaving it to dry, a part of the silver paste 3 is depressed 4 As a result, the sectional shape becomes as shown in FIG. In addition, 5 and 6 are lands.

[0004]

After the silver through-hole wiring board is filled with the silver paste 3, the silver through-hole wiring board is subjected to overcoat printing, pre-flux finishing, etc., and is subjected to acid cleaning and chemical treatment. At this time, as shown in FIG. 3, if there is a depression 4 of the silver through hole, it is difficult to remove the chemical by washing, and a residue is generated, and when electricity is supplied, corrosion proceeds, resulting in a serious accident.

[0005] Using the wiring board 7 shown in FIG.
In the case of 0.7 mm, a life test (MIL-202E) in which cooling and heating cycles at -65 ° C and 125 ° C alternately for 30 minutes are performed.
-107D), a crack 8 occurs between the land 6 and the surface of the silver paste 3 as shown in FIG.

[0006] Even in the conventional case, when the hole diameter is large, FIG.
As shown in Fig. 7, when the depression 4 is large after filling with the silver paste 3 and the through-hole 9 of the silver paste 3 is formed in a hollow state, it can withstand 100 or more times in the cooling and heating cycle and has high reliability. Can be manufactured.

[0007]

The method of manufacturing a printed circuit board with a through hole according to the present invention is a method for obtaining a printed circuit board having a through hole 9 formed at the center of a silver through hole 3 even if the hole diameter is small. provide. The present invention uses a double-sided copper-clad laminate 1 as a starting material, and drills a hole 2 at a predetermined position of the laminate 1;
Conductive circuits including lands 5 and 6 are formed on both sides of the laminate 1 by etching, and conductive paste 3 having a viscosity adjusted to 10 to 35 poise is filled in the holes 2 by screen printing, and the drying furnace is used. The laminar hot air at 40 to 80 ° C. is blown at 5 to 10 m / sec and dried to form a hollow 9 in the center of the hole of the silver paste 3.

If the viscosity is less than 10 poise, the fluidity is large and bleeding occurs in the lands 5 and 6. If the viscosity is more than 35 poise, the fluidity is so small that the filling amount in the hole 2 is insufficient. If the wind speed of the hot air is 5 m / sec or less, the air pressure is weak and the hollow 9 may not be formed at the center of the silver paste 3. If the temperature of the hot air is lower than 40 ° C., the solvent evaporates insufficiently and it takes a long time to dry. If the temperature is higher than 80 ° C., the solvent evaporates quickly and many voids are formed in the holes 2.

The hole 2 for the through hole is usually 0.5-1.
It is used in the range of 2mm, but the hole diameter is 0.7mm
It is effective for the following and can be used up to 0.4 mm. As the conductive paste 3, silver powder, copper powder or silver-plated copper powder can be used as the gold layer powder, and epoxy resin or phenol resin is used as the resin.

[0010]

According to the present invention, a conductive paste having a viscosity adjusted to 10 to 35 poise is used, and 5 to 10 m / sec.
Since the hollow portion can be formed in the hole by drying using hot air of ° C., the hardening proceeds and solidifies while the internal stress is small. Therefore, even if the test is performed 100 times in the cooling / heating cycle test, there is no disconnection.

[0011]

【Example】

(Example 1) Paper phenol resin laminate 1 with a 1.6 mm thick double-sided copper foil attached (MCL-437FR manufactured by Hitachi Chemical Co., Ltd.)
A hole 2 having a diameter of 0.6 mm is drilled at a predetermined position in D), and a circuit including lands 5 and 6 having a diameter of 1.5 mm is formed by a known etching method. A conductive silver paste adjusted to a viscosity of 30 poise (Tokuriki Chemical Laboratory Sylvest PS-6) is formed in the hole 2.
52-1) is filled with a squeegee using a screen printing method, and then the laminate 1 is horizontally arranged at a temperature of 60 ° C. and 8 m
/ Second laminar hot air is applied from above for 1 hour and dried. Next, curing was performed at 160 ° C. for 1 hour to produce a silver through-hole wiring board.

(Example 2) In Example 1, the one having a hole diameter of 0.4 mm was manufactured. (Example 3) In Example 1, hot air at the time of drying was 6 m.
/ Sec at 60 ° C. (Example 4) In Example 1, hot air at the time of drying was set to 9.
It was manufactured at 5 m / sec and 80 ° C. (Example 5) In Example 1, a hole diameter was manufactured with 0.7 mm.

Comparative Example 1 In Example 1, hot air was produced at a rate of 13 m / sec. (Comparative Example 2) In Example 1, hot air was produced at 3 m / sec and the hole diameter was 0.7 mm. Comparative Example 3 In Example 1, the temperature of the hot air was set to 100
Manufactured at ℃. Table 1 shows the characteristics of the through-hole wiring boards manufactured based on the above Examples and Comparative Examples.

[0014]

[Table 1]

[0015]

According to the production method of the present invention, Table 1
As shown in the figure, it can be seen that the through hole can be reliably formed at the center of the through hole having a hole diameter of 0.5 to 0.7 mm, so that the reliability of the through hole is improved.

[0016]

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of the present invention.

FIG. 2 is a cross-sectional view showing a state where a conductive paste is filled.

FIG. 3 is a conventional sectional view.

FIG. 4 is a cross-sectional view showing a state where a conventional crack has occurred.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Laminated board, 2 ... Hole for through-hole, 3 ... Conductive paste, 9 ... Through-hole.

 ──────────────────────────────────────────────────続 き Continuation of the front page (72) Koji Ooi 2-47, Shimotagawa-cho, Toyokawa-shi, Aichi Examiner, Hitachi AC Co., Ltd. Wakoko Okada (56) References JP-A-59-151493 JP-A-62-118598 (JP, A) JP-A-55-12777 (JP, A)

Claims (2)

(57) [Claims] 1. A through-hole is formed in a predetermined portion of a double-sided copper-clad laminate by drilling a through-hole, forming a conductive circuit based on an etching method, filling the hole with a conductive paste, and drying and curing. In the method for manufacturing a hole printed wiring board, a conductive paste having a viscosity adjusted to 10 to 35 poise is filled in the hole, and then the substrate is horizontally disposed at 5 to 10 m / sec and 40 to 80 ° C. A method of manufacturing a through-hole printed wiring board, wherein hot-air drying is performed such that a hollow portion is formed at the center of the conductive paste in the through-hole by applying laminar hot air to the substrate, and then heat-curing is performed. 2. A through hole having a hole diameter of 0.4 to 0.7.
2. The method for producing a through-hole printed wiring board according to claim 1, wherein the thickness is mm.