JPS58767A - Detecting device of disconnection or short circuit - Google Patents

Abstract

PURPOSE:To reduce a manufacturing cost of a device, by constituting it so that a state of one test signal detecting terminal which forms a pair can be discriminated by sending out a test signal from one test signal sending-out terminal. CONSTITUTION:In case when a circuit to be inspected is normal, when a test signal of a low level is sent out from a test signal output terminal 1, the signal reaches a test signal detecting terminal 5 through a pin 2. Accordingly, both the signal sending-out terminal and the signal detecting terminal 5 are in a low level and coincide with each other. In case when the circuit to be inspected has been disconnected, the test signal of a low level does not reach the signal detecting terminal 5. Accordingly, when the test signal of a low level is being sent to the signal sending-out terminal, disconnection can be detected by deciding a level of the signal detecting terminal 5 forming a pair. According to such a constitution, since the circuit configuration can be simplified, the manufacturing cost can be reduced.

Description

[Detailed description of the invention] The present invention prevents disconnections or short circuits in printed wiring boards, etc.

Or it relates to a disconnection and short circuit detection device.

In recent years, there has been a growing demand for improved reliability of printed wiring boards, and conventional visual inspection alone is no longer sufficient to meet the demands. Various inspection devices have been put into practical use, but they have various problems.

For example, a method of using a computer to compare the inspection results of a non-defective product and an object to be tested for determination inevitably requires complicated and expensive equipment.

Furthermore, since a large amount of data is processed, inspection takes time, and it takes about 1f4 to 10 seconds to check 1000 points, and there is a risk of data reading errors and other errors. In addition, in devices called branching methods, the wiring between the detection bin and the detection device is extremely complicated because it uses a matrix or a pin board, and it may even be impossible for general users to do so, which can lead to significant jig costs and delivery times. There are also many problems. In addition, with either method, detection is often performed point by point, and defective parts are often displayed.

The amount of wiring between the detection bin and the detection device is enormous and tends to be complicated.

The present invention improves the above-described various gates, and one embodiment will be explained below with reference to FIGS.

In Figure 1, when the circuit under test is normal, a low level test signal is sent from the test signal output terminal 1, the signal flows to the circuit under test 3 via pin 2, and then the test signal is detected via pin 4. It reaches terminal 5. Therefore, the test signal sending terminal and the test signal detecting terminal both match at low level. If there is a disconnection in this circuit to be inspected, the low level test signal will not reach the test signal detection terminal, and the levels at the sending terminal and the detection terminal will not match. Therefore, when a low level test signal is being sent to the test signal sending terminal, a disconnection can be detected by determining the level of the paired test signal detection terminal.

Furthermore, if control is performed so that low-level test signals are not simultaneously sent to a plurality of test signal output terminals, all test signals other than the circuit to be inspected to which the test signals are being sent should be at high level. If there is a circuit not to be tested that is short-circuited to the circuit to be tested, its test signal detection terminal will naturally be at a low level. Therefore, the levels of all the test signal detection terminals to which no test signals are sent are checked, and if a low level is detected, it can be assumed that there is a short circuit.

Continuing on, the case where the circuit to be tested is branched will be explained with reference to FIG.

If the circuit under test is normal, when a low level test signal is sent from test signal output terminal 1, pin 2. It reaches the overgate element B via the circuit under test 3a, 3b and pins 4a, 4b. Since all of the OVER gate inputs are at a low level, the OVER gate output is also at a low level, and the test signal detection terminal 5 is at a low level. If the circuit under test 3a, 3b, or both 3a and 6b is disconnected,
Since one or more high level signals are input to the OVER gate input, the OVER gate output becomes a high level and the test signal detection terminal also becomes a high level, and a disconnection can be detected using the same principle as explained in FIG.

Furthermore, short circuits can also be detected using the same principle as in FIG.

Therefore, if you have more pairs of detection circuits than the circuit under test and send the test signal to all the detection circuits at least once without sending it to multiple detection circuits at the same time, you can test all the circuits under test for open circuits or short circuits. can be done.

As described above, the present invention can be manufactured at low cost by using an inspection device with a simple circuit configuration.

In addition, by counting the number of test signals sent, temporarily stopping the inspection when a defect is detected, and displaying the contents of the counter, the defective location can be clearly identified.

Note that in the present invention, a TTL gate element can be used to transmit and detect a test signal. When a TTL gate element with hysteresis characteristics is used to detect a test signal, the resistance value for determining whether it is normal or defective is approximately 3.OMEGA., which is a value sufficient for practical use. It also has sufficient resistance to electrostatic damage, and has a very high detection speed, capable of examining 1,000 circuits in about 100 microseconds. Even for branched circuits to be tested, it is only necessary to connect the detection points to the multi-input power element, so the inspection jig can be easily manufactured.If the power element is provided in the jig, the jig and the device can be connected. The cost is reduced because connectors and wiring are omitted. Multi-input overgate device.

A wired wire may also be used, in which case the wiring will be even simpler.

Test signals can be easily controlled by connecting flip-flops in multiple stages and inputting them in series and outputting them in parallel.

Edge-trigger type flip-flops can be used to judge test results.

It is possible to design a circuit that is resistant to disturbance noise, and since disconnections or short circuits in all parts from the test signal output terminal to the test signal detection terminal are determined to be defective, reliable inspection can be performed.

As described above, the disconnection or short-circuit detection device according to the present invention has the feature that it can perform highly reliable inspections at low cost and stably at extremely high speed due to its simple operating principle and circuit configuration.

[Brief explanation of drawings]

FIGS. 1 and 2 are explanatory diagrams showing one embodiment of the present invention. 1・・・・・・・・・・・・・・・・・・・・・・・・
......Test signal sending terminal 2.4.4a, 4
1) ......Detection pins 3.3a, 3b
・・・・・・Circuit to be tested 5 ・・・−・−・・・・
・・・・・・・・・・・・Test signal detection terminal 6
・・・・・・・・・・・・・・・ Owagate device patent applicant Representative director of Hokuto Controls Co., Ltd. Yamamoto Engraving of Kiyoshi drawing (no change in content) Missing 1 Written amendment of Sono procedure (method) % formula % [ 1 (1. Indication of the case 1982 Patent Application No. 98799 2
, Title of the invention Disconnection or short circuit detection device 3, Person making the amendment Address (residence) of the patent applicant related to the case

Claims (1)

[Scope of Claims] A plurality of pairs of detection circuits each having one test signal sending terminal and one test signal detection terminal are provided. A disconnection or short-circuit detection device includes a circuit that sends a test signal from one test signal sending terminal and determines the state of one paired test signal detection terminal and the states of all remaining test signal detection terminals. , and a device that detects disconnections and short circuits in the object to be inspected by having a gate element with an output function for performing logical operations on test signals from multiple detection points, and sending the output to the test signal detection terminal.