JPH03144380A - Inspection of ic mounted board - Google Patents

Abstract

PURPOSE:To clarify a defective point quickly through inspection of defective soldering of an IC and a circuit pattern to the IC covered with a package for short-circuiting, by supplying power to a circuit on a mounted board. CONSTITUTION:In application, a package 1 for short-circuiting is made to cover an IC 11 with a guide hole 4 put onto a slide guide 7 and a press plate 2 being assembled with a guide plate 5 and the press plate 2 is pressurized until a probe 3 contacts a pin 12. In other words, the IC11 mounted on an IC mounted board is covered with the package 1 for short-circuiting and a circuit of the IC mounted board is energized to inspect a defective soldering of the IC 11 covered with the package 1 and a circuit pattern to the IC. This enables a pattern checking of a discontinuity of a pattern to the packaged IC, a defective soldering and the like, that is very hard to make in the past thereby allowing the clarifying of a defective point quickly.

Description

[Detailed Description of the Invention] [Industrial Application Field] This invention is applicable to IC (IC parts) mounting boards, especially QFP
The present invention relates to a method for inspecting an IC mounting board on which an LSI such as the above is mounted.

[Prior Art] Due to rapid technological innovation in today's electronics industry, ICs (integrated circuits) have become more diverse and denser, making it extremely difficult to judge the quality of each IC. Similarly, IC mounting boards are also moving toward higher density.

Currently, there is a device called an in-circuit tester as a device for determining the quality of this IC mounting board. The procedure for determining pass/fail using this in-circuit tester is: First, conduct an oven test to check patterns between connectors and ICs, conduct a short test on all nets to check for pattern shorts and bridges, and conduct an analog test to check resistance. (1)Finally, an IC test is performed, and a test pattern is given to each component to determine whether it is good or not.

As described above, this device tests the mounted components individually, and determines that the mounted board is non-defective if all the components are non-defective. Furthermore, when checking patterns between parts, bins are placed at both ends of the pattern to determine whether or not there is a short circuit.

[Problems to be solved by the invention] However, in today's high-density boards,
The individual patterns in the circuit pattern are very thin, and the number of surface mount components (QFP, chip components, etc. with a bin pitch of 1 mm or less) is increasing, and in order to conduct tests, 1 net 1
It has become difficult to even set up a book probe.

In addition, there are limits to the IC test pattern, and in reality it only detects defects in the input/output part, so if it is determined that the IC is defective, it is necessary to separate whether the IC is defective or whether there is a break in the pattern from the bottle stand position to the IC. It is necessary to do so. Therefore,
If the IC is replaced and the IC is still defective, each pattern is checked one by one to see if the pattern is broken. For example, assuming that the IC has 100 pins, it will be understood that this pattern check requires a large amount of time.

The IC mounting board inspection method of the present invention is intended to eliminate the above-mentioned drawbacks of the conventional method, and is capable of pattern checking without replacing non-defective ICs.

[Means for solving the problem] That is, the method for inspecting an IC mounting board of the present invention
A shorting package is placed over an IC mounted on a C mounting board, and power is applied to the circuit of the IC mounting board to detect solder defects and ICs covered with the shorting package.
The present invention is characterized by comprising a step of inspecting the circuit patterns up to and a step of inspecting the above-mentioned IC.

[Function] The method for inspecting an IC mounting board of the present invention covers the IC mounted on the IC mounting board with the short-circuit package and inspecting it as described above, so it is possible to inspect the actual device C, which was difficult in the past. It is now possible to check for pattern defects such as broken patterns and solder defects, and to check for defects on these patterns without replacing the IC.
It was possible to significantly shorten the inspection time for C-mounted boards.

[Embodiment] An embodiment of the method for inspecting an IC mounting board according to the present invention will be described below with reference to the drawings.

In FIG. 1, 1 is an I mounted on an IC mounting board.
This is a short-circuit package that is placed over C to short-circuit between each bottle.

This short package l is for all ICII bins 12
A pressing plate 2 has a large number of probes 3 attached to its side edges corresponding to the above, a guide hole 4 is formed in the center thereof, a through hole 6 is formed in the side edge for inserting the probes 3, and a center portion of the upper surface is provided. and a guide plate 5 on which a slide guide 7 for holding a coil spring 8 is erected. Then, this short package 1 is constructed by fitting the guide hole 4 into the slide guide 7, placing the press plate 2 assembled with the guide plate 5 on the ICII, pressurizing the press plate 2, and bringing the probe 3 into contact with each bottle 12. It is used by letting That is,
The shorting package l is placed over the ICI l mounted on the IC mounting board, and the circuit of the IC mounting board is energized to inspect the solder defects of the IC11 covered with the shorting package l and the circuit pattern up to the IC. .

2 and 3 show the target printed board 21
This figure shows a mechanism for collectively inspecting the plurality of ICIs 1 above.

In this example, each IC mounted on the IC mounting board 21
A plurality of shorting packages 1 of different sizes are prepared according to the I1, and each package is arranged equally to the ICI1 on a holding board 22 having a size corresponding to the IC mounting board 21. When checking the IC11, it is sufficient to press each ICII one by one with the shorting package 1 and confirming that there are no pattern breaks or solder defects.This pressurizing operation of the shorting package 1 can be performed using a solenoid, etc. It can be easily automated.

Figures 4 to 6 show the main parts of the IC mounting board to be inspected. For example, ICA, IC-B, and IC
-A' and IC-B' are each bad ■～■
are connected. Also, 1 to 1 are ICI 1 bottles. During testing, a test pattern is transferred from the in-circuit tester main body to the above-mentioned pads ① to ①, and their continuity status is checked. The main failures at this time are solder defects and pattern breaks.

FIG. 7 is a flowchart illustrating the inspection process for the entire IC mounting board 21.

First, a case will be described in which, after the procedure of determining pass/fail using an in-circuit tester, the process of inspecting solder defects of an IC covered with the short-circuit package of the present invention and the circuit pattern up to the IC is performed.

In other words, using an in-circuit tester, ■ perform an oven test to check between connectors, excluding the pattern check between ICs, ■ perform a short test on all nets to check for pattern shorts and bridges, and ■ perform an analog test to check resistors and Check the mounted components other than the IC such as capacitors, and (1) Finally, perform the IC test and give a test pattern to each component to determine whether they are good or bad.

When the above inspection is completed and an OK judgment is made, the inspection ends.

If the determination result is No, shorting package 1 is placed over ICA to short-circuit all the bottles. As a result, when a short program is applied to I C-A, 1
Solder part and short package 11 from two patterns
Then, a loop is formed between each pattern through the solder portion to the next pattern, and the continuity state between each pattern is checked. If the result is OK, the IC-A is defective, so the defective IC-A is printed and the inspection is completed.

Furthermore, if the judgment result is No, the continuity between each pattern is checked from one pattern to the solder part, to the shorting package l, and then through the solder part to the next pattern, so which bins are connected to each other in the pattern? It turns out it might be broken.

Then, for example, a message indicating that the pattern on the bottle is broken (poor contact) is printed and the inspection is completed.

Next, the IC covered with the shorting package of this invention is
The process of inspecting the circuit pattern up to the IC for solder defects is automated, and after the short test during the pass/fail determination procedure using an in-circuit tester, the process of inspecting the circuit pattern up to the IC covered with the short circuit package of the present invention is performed. The case of inserting it will be explained.

That is, by using an in-circuit tester, 1) an oven test is performed to check between connectors, excluding a pattern check between ICs, and 2) a short test is performed on all nets to check for pattern shorts and bridges.

In a specific IC to be tested for pattern check and solder defects, a shorting package l is sequentially placed over each ICI l below IC-A, and all the bins of each rc11 are short-circuited. For example, if the short program is applied to ICA and the determination result is No, then 4.

Since it is also known which bin has a broken pattern, it is printed that, for example, 3 bins have a broken pattern (poor contact), and the inspection is completed.

In this example, pattern breakage and contact failure when ICI 1 is not defective can be easily detected, and IC
Tests can be omitted and inspection can be done quickly.

[Effects of the Invention] Since the method for inspecting an IC mounting board of the present invention is configured as described above, it is now possible to check patterns for pattern breaks and solder defects up to the actual device C, which was difficult in the past.
It is possible to check for defects on these patterns and clarify the defective parts without replacing the good IC.
We were able to significantly shorten the inspection time for mounted boards.

Furthermore, there is no need to increase the number of bins in the tester body for pattern checking as in the past.

[Brief explanation of the drawing]

FIG. 1 is a perspective view showing an example of a short circuit package used in the IC mounting board inspection method of the present invention, FIGS. 2 and 3 are perspective views showing other examples, and FIGS. The figures are a plan view and a perspective view showing essential parts of an IC mounting board to be inspected, and FIGS. 7 and 8 are flowcharts each showing an embodiment of the method for inspecting an IC mounting board of the present invention. 1...Short package 2...Press plate 3...Probe 4...
Guide hole 5...Guide plate 6...Through hole 7...Slide guide 8...Coil spring 11...IC12...Bin 21...IC mounting board 22...Holding board Fig. Figure 8

Claims (1)

[Claims] 1. A step of covering an IC mounted on an IC mounting board with a shorting package, and energizing the circuit of the IC mounting board to inspect the solder defects of the IC covered with the shorting package and the circuit pattern up to the IC; The above IC
1. A method for inspecting an IC mounting board, comprising the step of inspecting.