JPH04115592A - Printed wiring board - Google Patents

Abstract

PURPOSE:To make it possible to increase a barrier between soldered parts and determine defective solder accurately and promptly by installing a resist layer which separates and shields the surrounding surfaces of the neighboring soldered sections and increasing the color contrast ratio to the soldered section. CONSTITUTION:In addition to a resist coding layer 4 and a printed layer of circuit information, a black or other colored solder margin masking section 8 is installed as a third resist coding layer in order to isolate a copper clad section 2 for soldering. When a printed wiring board passes through a solder dip process, solder 3 melted on a part of the copper clad section 2 which has not processed the resist coding for the first layer 4, is built up and solidified. A black-colored third layer resist section 8 provided around the copper clad solder-built up section 3 as a solder allowance masking section suppresses a jet flow of solder and reduces the generation of defective solder, such as solder bridge. This construction makes it possible to obtain information which is proper to determine whether the soldered quality is good or not by means of colored high contrast comprising solder silver-white color and black color.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a printed wiring board for the purpose of mounting electronic circuit wiring and various components constituting the electronic circuit.

BACKGROUND OF THE INVENTION In recent years, competition in the development of electronic devices has become more and more intense. These trends are represented by ■lighter, smaller, shorter, and thinner products, ■shorter product lifespans, and ■diversification. Therefore, the demands and restrictions on the electronic circuits that control the operations of these electronic devices also become severe. As a result, in order to pursue high-density packaging and adapt to the design of electronic equipment, printed wiring boards with uniform external shapes must be developed each time. In addition, an important point in guaranteeing the performance 1 quality of electronic equipment is the degree of perfection of the printed wiring board on which electronic components are mounted. Therefore, various mounting methods and inspection methods are being developed in order to improve the quality level of printed wiring boards.

FIGS. 3a and 3b are a plan view and a sectional view showing the structure of a conventional printed wiring board. In the figure, 1 is a copper-clad board, 2 is a copper foil part etched based on the connection of the electronic circuit, and 3 is solder that has adhered to the copper foil part 2 after soldering, and is connected to the lead terminal 7 of the circuit component. This is the location where the copper foil 2 is connected with zero electrical resistance. Reference numeral 4 denotes a first resist coating layer, which is printed for the purpose of preventing soldering defects between copper foil parts. Reference numeral 5 denotes a printed portion of circuit information generally collectively referred to as a service map (or a road map in the case of a double-sided printed wiring board).

A second resist coating layer 6 is formed together with the service map 5. This is printed together with the first resist coating layer 4 for the purpose of preventing soldering defects between the copper foils 2.

A conventional printed wiring board configured as described above will be explained. The second resist coating 4 and the second resist coating part 6 prevent poor soldering after soldering dip, especially electrical shorts caused by solder adhesion between points of different polarities and different potentials (hereinafter referred to as solder bridges). .

Problems to be Solved by the Invention In such conventional printed wiring boards, soldering has met the need to reduce defects, but it has not been perfect. Therefore, it has been desired to develop a non-contact wiring board that can suppress the incidence of soldering defects and, in addition, can easily and accurately detect soldering defects that have occurred.

The present invention solves the above problems.In printed wiring boards that are mounted in high density regardless of the size of the external shape, soldering reduces the defective rate, and furthermore, the quality of printed wiring boards can be inspected manually or mechanically. The purpose of the present invention is to provide a printed wiring board that can quickly and accurately perform the following steps.

Means for Solving the Problems In order to achieve the above object, the present invention, in addition to the resist coating layer and the printed circuit information layer, uses black or other chromatic colored solder to isolate the copper foil portion where the solder is attached. The printed wiring board includes a white masking portion as a third resist coating layer.

Effects According to the present invention, when the printed wiring board passes through the soldering process, the melted solder adheres to and condenses on the copper foil portions where the first layer resist coating has not been applied. The black third layer resist area provided as a solder masking area around the solder attachment area of these copper foils suppresses the flow of the solder jet and reduces the occurrence of defects such as solder bridges, and as a result, the solder becomes silvery white. The high color contrast with black provides information suitable for easily determining the quality of soldering.

EXAMPLE Hereinafter, a printed wiring board according to an example of the present invention will be described with reference to the drawings.

FIGS. 1a and 1b are a plan view and a sectional view showing the structure of an embodiment of the present invention. In FIG. 1, a black solder margin masking portion 8 is provided in place of the second resist coating 6 of the conventional example shown in FIG. Other components 1~
7 are the same as those in FIG. 3, so their explanation will be omitted.

The operation of the printed wiring board configured in this manner will be described below.

1) In order to reduce the incidence of defects such as solder bridges due to solder dip sagging, the third resist layer is masked to completely isolate the solder attachment area formed by etching. This constitutes a barrier that is stronger both in length and depth than the barrier for preventing dripping. That is, present invention case Conventional case xl>x2 Yl ≧ Y2 xl, Yl: length and height of barrier (see Figure 1) x2. Y2: Length and height of barrier (see Figure 3) The larger the values of X and Y, the greater the barrier effect.

11) Next, after soldering is applied to a predetermined solder attachment location on the copper foil, black is added as the third resist layer color in order to easily and accurately determine whether or not the solder has properly adhered. (Other colors) In conventional printed wiring boards, the second resist coating layer is formed at the same time as the circuit information printing layer, so it is white (or
(similar color to the circuit information printing color). The color contrast ratio between the color of the coating layer formed around the solder attachment portion and the silvery white color of the solder directly affects the visual inspection after solder dipping and the detection accuracy of an automatic inspection device. Figure 2a.

b is a printed wiring board of the present invention and a conventional circuit board.

In the conventional printed wiring board shown in Fig. 3, the first
In the printed wiring board of the present invention shown in FIG. 2, the first resist layer is green and the second resist layer is white.
The first resist layer is green, the second resist layer is white, and the third resist layer is black. In the conventional printed wiring board shown in FIG. 3, the portion with the greatest relative color contrast is the portion where the solder and the first resist layer (green) are adjacent to each other, and this relative color contrast ratio is assumed to be 02. Furthermore, the portion of the printed wiring board of the present invention shown in FIG. 2 with the greatest relative color contrast is the portion where the solder and the third resist layer (black) are adjacent to each other, and this relative color contrast ratio is 01. At this time, C1 and 02
When compared with C1>C2, the printed wiring board of the present invention can visually determine whether or not the solder has exceeded the resist layer more clearly and therefore more quickly than the conventional printed wiring board. Moreover, the effect of the present invention is even greater when compared with the short circuit state in which the white second resist is exceeded in the conventional example. Also,
A large contrast ratio is also effective in increasing the accuracy of the judgment when the judgment is made not by visual inspection but by an optical automatic diagnostic device using an optical converter or the like. As described above, according to the printed wiring board of the embodiment of the present invention, the third resist layer is provided, and its pattern separates and surrounds the peripheries of adjacent solder attachment areas, and the color thereof is adjusted to match the color of the solder. By creating a printed wiring board with a relatively high color contrast ratio, it is possible to increase the barrier between adjacent solder attachment areas, and to clearly identify short-circuit conditions beyond the solder resist. Can be detected quickly.

Effects of the Invention As is clear from the above embodiments, the present invention includes an insulating substrate, a circuit conductor portion on the surface thereof, a first resist layer constituting a solder resist, and circuit information on the surface of the first resist layer. a second resist layer displaying a pattern in a pattern, a third resist layer is provided on the first resist layer;
The pattern of the third resist layer constitutes a resist that separates and surrounds adjacent solder attachment areas, and the color of the third resist layer is determined relative to the solder. By providing a printed wiring board with a high contrast ratio, it is possible to increase the barrier between adjacent soldered parts, and it is also possible to accurately and quickly determine soldering defects that exceed the third resist. can.

[Brief explanation of drawings]

FIGS. 1a and 1b are a plan view and a sectional view showing the structure of a printed wiring board according to an embodiment of the present invention, and FIG. 2a is a sectional view. FIG. 3b is a plan view and a sectional view showing the structure of a printed wiring board according to an embodiment of the present invention, and FIGS. 3a and 3b are a conventional printed wiring board. 1... Copper-clad board (insulating board), 2...
...Copper foil part (circuit conductor part), 3...Solder (solder attachment part), 4...First resist layer, 6...
...Circuit information printing layer (second resist layer), 8...
...Third resist layer. Name of agent: Patent attorney Akira Okaji and two others Figure * Entertainment tfIR91 Supporting Officer Figure

Claims (1)

[Claims] A printed wiring comprising an insulating substrate, a circuit conductor portion on the surface thereof, a first resist layer forming a solder resist, and a second resist layer displaying circuit information in a pattern on the surface of the first resist layer. In the plate, a third resist layer is provided on the first resist layer, and the pattern of the third resist layer constitutes a resist that separates and surrounds adjacent solder attachment parts, and A printed wiring board in which the color of the resist layer of No. 3 has a large color contrast ratio relative to the solder.