JPH05297049A - Pattern inspection method of printed wiring board - Google Patents

Abstract

PURPOSE:To simply and automatically inspect the misalignment of a pattern on a printed wiring board by means of a continuity checker. CONSTITUTION:In individual processes such as a pattern formation process for a board main body 10a, a process for making a through hole and a process for filling a conductive paste, a check pattern 11 is formed in a blank part 10b on a board by using the same method as the processes. Said check pattern 11 is composed of the following: a first copper foil part 12 and a second copper foil part 13 which are formed on the surface side of the blank part at a prescribed interval; a third copper foil part 14 which is formed on the rear side in such a way that both ends correspond to the first and second copper foil parts 12, 13 continuously across them; through holes 15a, 15b which are made in positions to be used as the first and second copper foil parts; and a conductive paste 16 which is filled into the through holes. When the continuity or the continuity defect between the first and second copper foil parts 12, 13 is detected by means of a continuity checker, it is possible to inspect whether a misalignment of a circuit pattern or the like exists or not.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for inspecting a pattern of a printed wiring board, and more specifically, it is possible to inspect the presence / absence of displacement of a circuit pattern, a through hole, etc. by a short / open inspection by a continuity checker. The present invention relates to a pattern inspection method for a printed wiring board.

[0002]

2. Description of the Related Art With the miniaturization of components and high-density mounting, high-definition wiring patterns are required. For example,
The distance between the lands connected to the terminals of the memory or CPU is about 0.25 mm.

Therefore, if a positional deviation occurs when a circuit pattern is printed or when a through hole is punched, it directly causes a defective connection.

FIG. 3 exemplifies a printed wiring board in which a wiring pattern is drawn in a very simple manner. As one of the methods for inspecting the positional deviation of the pattern, a method of actually measuring with a coordinate measuring machine is used. There is.

This is done by obtaining position information (for example, distance) of each land 2 with respect to, for example, the mounting reference hole 1a or the press reference hole 1b formed on the substrate and checking whether or not it is within an allowable value.

However, this method is not preferable in terms of productivity. On the other hand, although there is a pattern recognition device, it is expensive, so that it cannot bear the cost particularly in the case of high-mix low-volume production.

[0007]

Therefore, it is a manual inspection, but it is considerably necessary to visually inspect various deviations such as circuit patterns and through holes in a short time and accurately by visual inspection. However, the inspector had to be proficient and the inspector had to be overloaded.

In particular, in the case of a silver through-hole substrate, in addition to the positional deviation at the time of punching and the screen deviation at the time of printing, there are multiple factors such as the drying condition of the conductive paint, the atmosphere of the manufacturing line, the condition of the raw materials, and the like. There is a risk that cracks may occur in the silver paste filled in the holes,
The need for full product inspection is required.

[0009]

SUMMARY OF THE INVENTION The present invention has been made in view of the above conventional circumstances, and its structural features are a pattern forming step of forming a circuit pattern on both surfaces of a copper clad laminate, and a circuit pattern thereof. In a printed wiring board formed through a punching step of punching a through hole in a predetermined portion where is formed, and a paste filling step of filling a conductive paste that electrically connects the front and back circuit patterns to each other in the through hole, At the time of each of the pattern forming step, the perforating step and the paste filling step, a circuit pattern for inspection is formed on the front and back surfaces of the copper clad laminated board in the same manner as those in the blank portion, and the circuit for inspection is also formed. A check hole is formed by forming an inspection through hole at a predetermined portion of the pattern, and filling the inside of the inspection through hole with a conductive paste. Forming a click patterns, continuity of the check pattern, the conduction failure state, lies in the adapted to electrically inspect the presence or absence of the displacement such as a circuit pattern and the through-hole.

In this case, it is preferable that the check pattern has first and second copper foil portions formed on one surface of the margin portion with a predetermined space and both ends on the other surface side of the margin portion. A third copper foil portion formed in series so as to correspond to the first and second copper foil portions, and perforated at predetermined positions of the first and second copper foil portions. And a conductive paste filled in the through hole.

[0011]

The circuit patterns formed on both the front and back surfaces of the substrate are made conductive by the conductive paste filled in the through holes. Similarly, the check patterns formed on both the front and back surfaces of the blank portion of the substrate are also made conductive by the conductive paste filled in the through holes.

Therefore, in each of the pattern forming step, the punching step, and the paste filling step, if there is no displacement, the check patterns formed on both the front and back surfaces of the blank portion of the substrate are in a conductive state.

On the other hand, when the circuit pattern or the through hole is misaligned or the conductive paste is cracked, the check pattern is non-conductive or has a high resistance value and has poor conduction. Therefore, it becomes possible to inspect the quality of the substrate with the continuity checker.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS. First, double-sided copper-clad laminated substrate 10
(This example uses a paper-based phenolic resin substrate)
For example, a dry film having a predetermined circuit pattern is attached to the substrate, exposed to form an etching resist, and then etched to form a circuit pattern similar to that of FIG. 3 on the substrate body 10a. Part 1
Check pattern 11 is formed at 0b.

That is, the check pattern 11 is formed simultaneously with the circuit pattern by the dry film. The check pattern 11 is formed on the one surface side of the blank portion 10b, that is, the front surface side in this example, with a predetermined interval. 2 of the copper foil portions 12 and 13 and the other surface side of the same blank portion 10b, that is, the back surface side has first and second copper foil portions 12 and 12,
And a third copper foil portion 14 corresponding to overlap with 13 and having a strip shape formed in series between them.

Next, when a through hole is formed in a predetermined portion of the substrate body 10a by, for example, a punching press, the through hole is also formed at the predetermined positions of the first and second copper foil portions 12, 13 by the press. 15a and 15b are drilled.

Then, for example, by screen printing, when the through holes formed in the substrate body 10a are filled with the conductive paste, in this example, the silver paste, the same screen is used to fill the through holes 15a and 15b. Fill with silver paste 16. Then the silver paste is forced to dry at high temperature.

In some cases, the circuit pattern forming step and the through hole punching step may be interchanged.

A continuity checker is used to perform the pattern inspection. That is, the pair of probes Pa and Pb of the continuity checker are connected to the first copper foil portion 12 and the second copper foil portion 12.
It is contacted with the copper foil portion 13 of No. 1 to see if the continuity or the poor continuity.

That is, if the check pattern 11 is conductive, it is determined that the circuit pattern and the through hole on the substrate main body side are not displaced, and that the through hole is accurately filled with the silver paste. It afterwards,
The blank portion 10b is separated from the substrate body 10a.

On the other hand, in the case of non-conduction, it is expected that the circuit pattern and the through holes on the substrate body side are also displaced, and cracks or the like are generated in the silver paste when the resistance value is high. , Judged to be defective.

[0022]

As described above, according to the present invention,
The position of the circuit pattern and the through hole is determined by forming the check pattern in the blank area of the board in the same manner as the pattern forming step, through hole punching step, and conductive paste filling step for the board body. The presence or absence of misalignment and cracking of the conductive paste can be easily and automatically inspected by the continuity checker, and the substrate inspection of stable quality can be efficiently performed.

[Brief description of drawings]

FIG. 1 is a schematic view of a printed circuit board showing an example of a printed circuit board to which an inspection method of the present invention is applied.

2 is an enlarged cross-sectional view taken along the line AA of FIG.

FIG. 3 is an explanatory view showing a substrate to be inspected by a conventional inspection method.

[Explanation of symbols]

 10 substrate 11 check pattern 12 first copper foil portion 13 second copper foil portion 14 third copper foil portion 15 through hole 16 conductive paste

Claims (2)

[Claims] 1. A pattern forming step of forming a circuit pattern on both surfaces of a copper clad laminate, and a step of forming a through hole in a predetermined portion where the circuit pattern is formed,
In a printed wiring board formed through a paste filling step of filling a conductive paste that electrically connects the front and back circuit patterns to each other in the through hole, the pattern forming step, the punching step and the paste filling step A circuit pattern for inspection is formed on both front and back surfaces in the same manner as those in the blank part of the board, and a through hole for inspection is formed at a predetermined portion of the circuit pattern for inspection, and the through hole for inspection is further formed. A check pattern formed by filling the inside with a conductive paste is formed.
A method for inspecting a pattern of a printed wiring board, which is capable of electrically inspecting a circuit pattern or a through hole for a positional deviation. 2. The check pattern includes first and second copper foil portions formed on one surface of the blank portion at a predetermined interval, and both ends of the blank portion on the other surface side are the first and second copper foil portions. A third copper foil portion formed in series between the first and second copper foil portions so as to correspond to the first and second copper foil portions, and a through hole punched at a predetermined position of the first and second copper foil portions. 2. A hole and a conductive paste filled in the through hole, and a conduction checker detects conduction and a conduction failure between the first and second copper foil portions. The printed wiring board pattern inspection method described.