JPH0233994B2 - - Google Patents

Description

[Detailed description of the invention] (Industrial application field) The present invention relates to a circuit continuity testing method for wiring boards.

(Prior art) Wiring boards form necessary circuits on an insulating substrate surface,
Although the circuits on the front and back sides are connected using through holes, it is necessary to inspect the circuits for breaks and shorts between the circuits.

The conventional continuity testing method for such wiring boards is as follows:
For each circuit pattern, a cassette board having contact pins at positions corresponding to the circuit pattern was created and inspected, but this was not suitable for high-mix, low-volume production.
Recently, universal continuity testing machines having a large number of contact pins at grid points have come into use so that it is not necessary to create a cassette board for each pattern. FIG. 1 shows such a universal continuity tester, in which 1 is an insulating plate having a large number of through holes at grid points, and 2 is a contact pin inserted into the through holes. As shown in FIG. 2, the contact pin 2 is supported within a socket 3 fixed to the insulating plate 1 by a spring 4 so as to be movable in the vertical direction.

Even when using such a universal continuity tester, it may not be possible to inspect through-holes that are off the grid points on the wiring board. An auxiliary board 9 is placed between the continuity tester 5 and the wiring board 6 to be tested, and has a correction pin 8 that connects the contact pin 2 of the universal continuity tester 5 to the through hole 7 that has come off, and is connected to the contact pin 2. A connection with a pattern that was not possible was fixed. In addition, as shown in FIG. 4, an auxiliary board 12 having a correction pin 11 that can be connected to the contact pin 2 of the universal continuity tester 5 and the detached through hole 7 is placed on the back surface of the wiring board 6 to be tested, and the contact pin The connection between 2 and the pattern was corrected and then inspected.

(Problems to be Solved by the Invention) This method of correcting the misalignment of a universal continuity tester having contacts at a large number of grid points using an auxiliary plate has the problem of a complicated structure and poor workability. It was hot.

(Means for Solving the Problems) The present invention provides an inspection method using such a universal continuity tester, in which the contact pins do not come into contact between the wiring board and the cassette board, which have through holes at locations other than grid points. A method for testing circuit continuity of a wiring board, comprising: a means for electrically connecting a through hole and a contact pin; and an auxiliary circuit board having a hole through which a contact pin can pass through the through hole located at a grid point. It is.

That is, instead of using the conventional auxiliary board, the present invention enables circuits (through holes) that are off the grid points of the wiring board to be electrically connected to the contact pins of the universal continuity tester. In order to do this, an auxiliary circuit board made of a thin wiring board with pull-out pads provided at grid points is inserted between the contact pins and the wiring board to be inspected. The auxiliary circuit board made of this thin wiring board was made by using the photomask used when creating the wiring board 6 to be inspected, selecting only the through holes that were off the grid points, and placing them on the through holes and the grid points. This is a wiring board in which the pads are connected in a pattern. In addition, if the wiring board to be inspected has through holes at grid points, holes larger than the diameter of the contact pins should be drilled at the corresponding positions on the auxiliary circuit board so that the through holes can come into direct contact with the contact pins.

The inspection method of the present invention will be further explained based on FIGS. 5 and 6.

In FIG. 5, 13 is a cassette board having a large number of contact pins 2 at lattice points, and 14 is an auxiliary circuit having a circuit pattern 15 for electrically connecting the contact pins 2 to the circuit under test that does not come into contact with the contact pins 2. board,
16 is a hole larger than the diameter of the contact pin 2, and 6 is a wiring board to be inspected.

FIG. 6 shows the cassette board 13, the auxiliary circuit board 14,
It is a sectional view showing a state in which the wiring boards 6 to be inspected are stacked, and the through holes at the lattice points of the wiring board 6 to be inspected are directly electrically connected to the contact pins 2 by holes 16 made in the auxiliary circuit board 14. The through hole 18 and the contact pin 2 which are connected to the lattice point
A through hole is provided at a position corresponding to the through hole 18 of the auxiliary circuit board 14, a pullout pad 19 is provided at the grid point, and both are connected to the circuit pattern 15.
It is electrically connected by connecting with . In this way, through-holes located at lattice points and through-holes deviated from lattice points can be inspected with the all-purpose continuity tester 5.
Since it is electrically connected to the contact pin 2 of the wiring board 6, all the circuits of the wiring board 6 to be tested can be tested for continuity.

Note that as the material for the thin wiring board of the auxiliary circuit board 14, a flexible wiring board substrate made of adhesively bonded polyimide film and copper foil or a thin epoxy resin copper-clad laminate can be used.

Example 100 mil (approx. 2.54 mm) lattice points and 75 mil (approx. 1.8
mm) Perform a circuit continuity test on a multi-wire wiring board with through holes at grid points using an auxiliary circuit board created using the following procedure using a universal continuity tester with contact pins at 100 mil grid points. Ivy.

[Creation of auxiliary circuit board] Place a film with marks at all 100 mil grid points on a photomask for the power supply layer or ground layer, which is used as the inner layer of the wiring board to be inspected and only removes the copper foil in the areas where the through holes penetrate. Then select a through hole located at a 75 mil lattice point that is off from that lattice point.

Create a new photomask with a pattern connecting the through holes at the 75 mil grid points and the 100 mil grid points.

Create a data tape for a hole puncher to create through holes at 75 mil grid points, and a data tape for a hole punch to create holes for contact pins to pass through at 100 mil grid points to be used as through holes.

A glass cloth-epoxy resin copper-clad laminate MCL-E-608 (trade name, manufactured by Hitachi Chemical Co., Ltd.) with a thickness of 0.23 mm is prepared as a base material.

Drill through holes at 75 mil grid points.

The inside of the through hole is metallized by electroless plating.

A new photomask with a pattern connecting through holes at 75 mil lattice points and 100 mil lattice points was placed on the surface of a base material laminated with a photocurable resist film to form an etching resist, and ultraviolet rays were applied. Expose.

It is developed to dissolve and remove the portions that were not exposed to ultraviolet light.

The copper foil exposed from the formed etching resist is removed by etching.

100 non-through holes at 100 mil grid points connected to through holes at 75 mil grid points
Drill a hole with a diameter of 2.3 mm at the mill grid point.

Cut out the parts other than the necessary parts and process the external shape.

As a result of conducting the continuity test in this manner, accurate test results were obtained with a single operation.

(Effects of the Invention) As explained above, according to the present invention, it was possible to provide an inspection method having the following effects.

(1) Even if the through-hole is outside the grid of the wiring board, an inexpensive wiring board can be used as an auxiliary circuit board without using an expensive auxiliary board with a conventional complicated structure, making it economical. It hit the mark.

(2) The structure is simpler than the conventional inspection machine that uses an auxiliary panel.

(3) The auxiliary circuit board, which is made of a thin wiring board, is easy to replace and is easier to work with than conventional auxiliary boards.

[Brief explanation of drawings]

Fig. 1 is a perspective view of a universal continuity tester having a large number of contact pins at grid points, Fig. 2 is a sectional view showing the structure of the contact pins, and Figs. 3 and 4 explain the conventional testing method. FIG. 5 is a perspective view showing the inspection method of the present invention, and FIG. 6 is an enlarged sectional view of the main part showing the inspection state of the present invention. Explanation of symbols, 1...Insulating plate, 2...Contact pin,
5... Universal continuity tester, 6... Wiring board to be inspected,
13...Cassette board, 14...Auxiliary circuit board.

Claims (1)

[Claims] 1. In a method of stacking a cassette board having a large number of contact pins at lattice points on a wiring board and inspecting the presence or absence of continuity between each contact pin, between the cassette board and the wiring board having through holes at locations other than lattice points, A wiring board characterized by disposing an auxiliary circuit board having a means for electrically connecting a through hole that does not come into contact with the contact pin and the contact pin, and a hole through which the contact pin can pass through the through hole located at the grid point. circuit continuity testing method.