JPS59228788A - Method of producing printed circuit 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 Field of Industrial Application The present invention is applicable to extremely high-precision processing (=J
The present invention relates to a method of manufacturing a printed wiring board suitable for use in a printed wiring board that requires cutting.

Conventional Structure and Problems Generally, as shown in FIG. 1, a method for manufacturing a printed wiring board involves forming a conductive pattern 2 on an insulating substrate 1, and soldering a land 3 to the surface on which the conductive pattern 2 is formed. The structure is such that a soldering resistive layer 4 is formed on the entire surface, leaving behind.

However, due to the miniaturization of electronic devices and advances in electronic component technology, more and more chip components are now being used.
High-precision printed wiring boards are required, for example, the misalignment between the soldered land 3 and the soldered resistive layer 4 is required to be less than 0.1, and even less than 0.05. It has become.

When it comes to high-precision printed wiring boards like this, even if the solder resistor layer 4 is formed using the conventional manufacturing method, the precision is 0.2.
The threshold is the limit, and accuracy of 0.1M or less cannot be obtained, which often causes quality problems. This is the solder resistance layer 4.
Misalignment during alignment.

It is thought that this is caused by the expansion and contraction of the screen plate making material, printing conditions (printing pressure, printing speed), etc.

Therefore, conventionally, it is necessary to perform a correction process in which the misaligned solder resistance layer 4 is subsequently scraped off with a cutting edge or the like.

In fact, this is a significant disadvantage in terms of productivity and quality because it causes positional deviation during chip component mounting and increases the number of defects.

The present invention provides a method for manufacturing a printed wiring board that allows highly accurate printed wiring without misalignment with layers.

Structure of the Invention In order to achieve the above object, the present invention forms a conductive pattern on an insulating substrate, and forms a thin film having a uniform thickness and poor adhesion to the soldering resistance layer on the conductive pattern. After that, a soldering resistance layer is formed on the entire surface, and after peeling off the soldering resistance layer and the thin film on the surface of the conductive pattern,
On the conductive pattern where no land is formed, a soldering resistive layer is again applied. ＜-.

It is easy to peel off the soldered resistive layer on a thin film that has poor adhesion to the soldered resistive layer, and it is possible to peel off only the soldered resistive layer on the top surface of the conductor pattern on which the thin film is formed. Yes, the land and half a are the parts where the soldering resistance layer is peeled off.
No displacement of the l+1' resistance layer occurs.

DESCRIPTION OF EMBODIMENTS A method of manufacturing a printed wiring board according to an embodiment of the present invention will be described below with reference to the drawings.

First, as shown in FIG. 2, an insulating substrate 50 made of synthetic resin
A conductor 6 made of copper is provided on one side to form a copper-clad laminate. Then, as shown in FIG. 3, the conductor 6 on the copper-clad laminate of FIG. 2 is etched to form conductor patterns 7a and yb.

Next, as shown in FIG. 4, a conductor pattern 7a is formed.

A thin film 8 having a uniform thickness and poor adhesion to the soldering resistance layer is formed on the soldering resistor layer 7b. This thin M8 is formed only on the surface of copper and is formed by immersion in an alkylimidazole solution that has poor adhesion to the soldering resistance layer.

Alkylimidazoles are hardly soluble in water at room temperature, but when ionized in an acid atmosphere, they become soluble in water, so immersion is possible. Ionized imidazole exhibits a strong chemical reaction with copper, forming a complex with copper and producing a monomolecular film on the copper surface. On the monomolecular film formed in this way, alkylimidazoles aggregate one after another due to the van der Waals bonding force of long-chain alkyl groups, and a film grows to a thickness of approximately 0.2 μm. A uniform thin film 8 is formed. The thin film 3 thus formed exhibits hydrophobicity due to the long-chain alkyl group, and has poor adhesion to the soldering resistance layer formed with ultraviolet curable ink or the like.

Next, as shown in FIG. 5, a conductor pattern γa is formed.

For this purpose, a soldering resistive layer 9 called a solder resist is formed on the entire surface of the insulating substrate 5 on which the transparent film 8 has been formed using a printing method or the like using -oxyacrylate-based ultraviolet curable ink.

Next, as shown in FIG. 6, the solder resistance layer 9 on the surfaces of the conductor patterns 7a, 7b is peeled off by mechanical polishing or the like. Note that the soldered resistance layer 9 on the conductor patterns 7a, 7b is easily peeled off because the alkylimidazole thin film 8 is interposed therebetween.

Then, as shown in FIG. 7, the alkylimidazole thin film 8 on the surfaces of the conductive patterns 7a and 7b is removed by using an acid such as hydrochloric acid or by mechanical polishing.

After that, as shown in FIG. 8, the conductor pattern 7b on which the land 10 to be soldered is provided is left, and the soldering resistance layer 11 is re-soldered.
is formed on the conductor pattern 7a.

Since the soldering resistance layer 9 on the conductor pattern 7b on which the land 10 is provided is removed, there is no positional shift between the land 10 and the soldering resistance layer 9, and a printed wiring board that allows highly accurate printed wiring can be manufactured.

In the above embodiment, a single-sided printed wiring board was used, but the same effect can be obtained with a double-sided printed wiring board. '=1.Although an alkylimidazole film was used as the thin film 8, an oxide film may also be used.

Effects of the Invention As described above, the present invention provides a thin film with poor adhesion to the solder resistor layer on the conductor pattern, and then forms the solder resistor layer on the entire surface of the insulating substrate. By peeling off the upper soldering resistance layer, no matter how high precision is required, there is no misalignment between the land and the soldering resistance layer. As a result, there is almost no need for a correction process to correct the soldering resistance layer with a cutting edge, etc., improving productivity.
It is possible to reduce costs, reduce contact failures due to misalignment during chip component mounting, and produce high-quality printed wiring boards, which is of great industrial value.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of a main part showing the structure of a conventional printed wiring board, and FIGS. 2 to 8 are process diagrams showing a method of manufacturing a printed wiring board in an embodiment of the present invention. 5... Insulating substrate, 7b... Conductor pattern, 8... Thin film, 9, 11... Soldering resistance layer, 1Q...・Rant. Name of agent: Patent attorney Toshio Nakao and 1 other person 2nd
Figure flower 3 figure a, feces 5 figure U1

Claims (1)

[Claims] A conductor pattern is formed on an insulating substrate, a thin film with a uniform thickness and poor adhesion with the soldering resistor layer is formed on the conductor pattern, and then a soldering resistor layer is formed on the entire surface. A method for manufacturing a printed wiring board, which comprises peeling off the soldering resistive layer and the thin film on the surface of the conductive pattern, and then forming a soldering resistive layer again on the conductive pattern where no land is formed.