JPS63260194A - Manufacture of printed wiring board - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION (Technical Field) The present invention relates to a method for manufacturing a printed wiring board. More specifically, the present invention relates to a method of manufacturing a printed wiring board with excellent productivity and reliability by preventing clogging of copper foil after punching.

(Technical background) Printed wiring board substrates, which are widely used in electrical and electronic equipment, communication equipment, computing equipment, etc., are broadly divided into those made of glass cloth base material and those made of paper base material. . A printed wiring board is manufactured using this wiring board by forming a wiring pattern by etching or the like, forming a through-hole part by drilling, or the like. If there is one wiring layer, it will be a single-sided wiring board, if there are two wiring layers, it will be a double-sided wiring board, and if there are more than two wiring layers, it will be a multilayer wiring board.

In the production of such printed wiring boards, drilling or punching methods have been adopted to form through-holes, etc.
Usually, either drilling or punching is selected depending on the strength of the base material. For example, drilling has been performed for glass cloth, which has a high base material strength, and punching has been performed for base materials such as glass paper, glass nonwoven fabric, and paper.

Punching processing has the characteristics of superior processing efficiency and lower processing costs than drilling processing, but conventionally,
This punching process has a problem in that when the punch is pulled up after punching, silver foil of punching residue adheres to the punch, and the attached punching residue remains in the punched hole.

For example, in the production of printed wiring boards, as shown in Figure 3, after etching, through-holes or connecting parts are usually formed in the land area (A) that connects to the circuit area (A). Drilling is performed for this purpose.

This land portion (a) is wider than the circuit width, and a hole is drilled in the central portion of the land portion (a) where the hole is to be drilled. When this hole is made by punching, as shown in FIG. 4, a punch (force) is driven into a printed wiring board made of, for example, a resin-impregnated glass base layer (1) and a copper foil (5). After the punch is finished, the punch is pulled out, but the remaining copper foil may adhere to the punch and remain stuck in the punched hole.

This residue is from the wiring board! Due to R construction, single-sided wiring boards consist of copper foil/resin-impregnated glass substrate, and double-sided wiring consists of copper foil/1M resin-impregnated glass substrate/copper foil, but usually due to shock during punching. The copper foil and the resin-impregnated base material layer separate, and the resin-impregnated base material layer does not fall apart and stick to the punch, and even if it does, it may remain in the punched hole. No, because the punched holes are made of a resin-impregnated glass base layer, it is an electrically insulating layer, but even if one of the many punched holes is made of copper foil, which is a conductor, If any remains, the entire board will be defective.

Conventionally, in order to deal with this problem, the remaining copper foil was removed by high-pressure water washing after punching, and as shown in Figure 5, the board (ke) after punching was made into a female die and The needles (S) with needles (S) planted in the corresponding punching hole (C) positions are used as male molds to pass through the needles, and one board at a time, to prevent copper foil from remaining in the punched holes (C). has been carried out.

However, this conventional high-pressure water washing not only requires a drying process as a post-treatment, but also has the problem that residual steel foil cannot be completely removed depending on fluctuations in the water pressure of the high-pressure water or the angle at which the high-pressure water hits. Ta. Further, in the case of needle threading, it is a widely used method because it does not require a drying step unlike high-pressure water washing, but it is time-consuming, reduces productivity, and increases costs.

For this reason, it has been strongly desired to realize a method for manufacturing a printed wiring board that is free from such problems, has excellent productivity and reliability, and does not leave copper foil behind after punching.

(Purpose of the Invention) This invention was made in view of the above circumstances, and it improves the drawbacks of the conventional method of manufacturing printed wiring boards by punching, and provides a punching process with excellent productivity and reliability. The purpose of the present invention is to provide a method for manufacturing a printed wiring board that does not cause subsequent clogging with copper foil.

(Disclosure of the Invention) In order to achieve the above object, the method for manufacturing a printed wiring board of the present invention etches a printed wiring board, and then removes the land area around the area to be punched. At the same time, the entire surface of the substrate is coated with a resist, and then holes are formed by punching.

The method for manufacturing a printed wiring board according to the present invention will be described in detail with reference to the attached drawings.

FIG. 1 is a plan view showing a portion of a printed wiring board according to the method of the present invention. Moreover, FIG. 2 shows an enlarged cross section of the land portion. As shown in FIG. 1 and FIG. 2, in the punching planned area (2) where a hole is to be made in the land area (1) formed by the etching process,
Cover with resist (3). Also, this resist (3)
Also covers the entire surface of the substrate, except for the land area (4) around the area (2) to be punched.

The land area (4) around the area to be punched (2) is
The copper foil (5) is exposed without being covered with the resist (3). A circuit portion (6) following the land portion (1) is coated with resist. The main purpose of this resist (3) is to protect circuits from the effects of solder heat during drilling after etching and when mounting electronic components such as semiconductors, and also to prevent moisture absorption of wiring boards and protect circuits during mounting. used for a purpose.

If the land portion (1) is entirely coated with resist, soldering cannot be performed after the punching process, so the copper foil (5) is exposed except for the area (2) to be punched. As the resist (3), a commonly used resist is used.

For example, appropriate thermosetting or thermoplastic resins such as phenol resins, polyester resins, polyamide resins, and polyimide resins are used.

The thickness of this resist (3) is usually The distance can be approximately 0.0, ooi to 0.1 m.

Furthermore, it is preferable that the size of the resist coated on the punched part (2) ranges from the same size as the punching area of the punch (7), which is the punching metal fitting, to about 1/20 of that size. If the area is larger than the punching area of the punch (7), resist will remain on the land (1) and will hinder soldering, and if it is smaller than 1/20, the effect of preventing copper foil clogging in the punched hole will be reduced. is small.

The resist (3) can be applied to the area to be punched (2) at the same time as the entire surface of the substrate is coated, or separately by coating, printing, or other appropriate methods.

When punching is performed after coating with this resist, no copper foil remains in the punched holes, making it possible to manufacture a printed wiring board with excellent productivity and high reliability.

Next, the method for manufacturing a printed wiring board of the present invention will be explained in more detail by showing examples.

Of course, the invention is not limited to the following examples.

Example 1 A circuit was formed by etching on the copper foil side of a single-sided copper-clad phenol laminate with a thickness of 1.6-.

A phenol resist with a thickness of 0.05 m+ was coated on the land portion to be punched, along with the entire surface of the substrate, except for the peripheral land portion. The area to be punched was covered with the same area as the punch diameter.

The shape of the tip of the punch was circular, and the shape of the coating on the area to be punched was also circular.

Next, after punching, a mounting process was carried out to obtain a printed wiring board.

As for the punching process, as shown in Table 1, approximately 12
The presence or absence of clogging of the punched copper foil in the land portions at 00 locations was evaluated. No clogging due to residual copper foil in the punched holes was observed.

Furthermore, there was no residual phenol resist on the land surface, and the soldering performance was good.

Example 2 A circuit was formed on the copper foil side of the same laminated board as in Example 1, and a circuit was formed on the entire surface of the board as well as on the land area where punching was to be performed.
A 0.01 m thick phenol resist was coated with a size 1/4 of the diameter of the punch.

The shape of the tip of the punch and the shape of the resist at the land portion were circular.

As in Example 1, there was no copper foil clogging at all.

Example 3 The size of the coating on the area to be punched is set to 1/1 of the punch diameter.
2. A printed wiring board was manufactured in the same manner as in Example eli 2 except that the shape was square.

As in Example 2, there was no #l foil clogging after punching, and the performance as a printed wiring board was good.

The above results are shown in Table 1 together with Example 1 and Example 2, and the following comparative example.

Comparative Example 1 Without coating the area to be punched with resist,
A printed wiring board was manufactured in the same manner as in Example 1.

The incidence of clogging due to residual copper foil in the approximately 1,200 punched holes in the land areas was as high as 2.8%. The rate of defective products for printed wiring boards is extremely high.

Comparative Example 2 A printed wiring board was manufactured in the same manner as in Example 2, except that the size of the resist coating on the area to be punched was set to 1/30 of the punch diameter.

The incidence of foil clogging due to residual copper foil was as high as 1.6%.

Specific Example 3 A printed wiring board was manufactured in the same manner as in Example 2, except that the size of the resist coating on the area to be batched was 1.2 times the diameter of the punch.

Although no copper foil remained, resist remained on the land surface, and the soldering performance was not good.

(Effects of the Invention) As described in detail above, the printed wiring board manufacturing method of the present invention eliminates clogging of copper foil remaining in punched holes after punching for forming through-holes, connection parts, and the like. Therefore, productivity and reliability are significantly improved compared to conventional ones.

[Brief explanation of the drawing]

FIG. 1 is a partial plan view showing a printed wiring board according to the method of this invention. FIG. 2 is an enlarged sectional view of the main part of the land portion. FIG. 3 is a partial plan view showing a conventional printed wiring board. FIG. 4 is a sectional view showing a conventional punching process, and FIG. 5 is a sectional view showing a conventional method for removing residual steel foil using a needle. 1... Land part, 2... Punching planned part, 3
...Resist, 4...Peripheral land part, 5...Copper foil, 6...Circuit part, 7...Punch. Agent Patent Attorney Toshio Nishizawa Figure 2 Figure 3 Figure 4

Claims (1)

[Claims] (1) After etching a printed wiring board, the entire surface of the board is coated with a resist, excluding the land area around the area to be punched, and then the entire surface of the board is coated with a resist, and then holes are formed by punching. Method of manufacturing wiring boards.