JPH01212373A - Inspection of lsi mounted printed wiring board - Google Patents

Abstract

PURPOSE:To efficiently detect inferiority due to the manufacturing factor on a PWB by separating the same from the internal operation of an LSI, by bringing the terminal of the LSI mounted on the PWB to a high impedance state by applying a signal thereto from the outside. CONSTITUTION:The terminal 7 of an LSI 1 is brought to a high impedance state on the basis of the signal applied to the terminal 7 by a switch group 6. Pin electronics 2 sends out an inspection pattern to the node on a PWB 8 to be inspected and detects the output value of the node to compare the same with an expected value and is connected to the node on the PWB 8 by a probe 3. When the PWB 8 is inspected, a signal for opening the switch group 6 is sent out to the terminal 7 from the pin electronics 2 to send out a pattern not according to the internal logic of the LSI 1 to the node between the LSI 1 and other circuit 5 to perform inspection. By this method, the trouble generated on the PWB 8 by a cause other than the LSI 1 can be efficiently detected.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for inspecting a printed wiring board equipped with an LSI.

[Conventional technology]

Conventionally, when inspecting a printed circuit board (PWB) equipped with an LSI, a test pattern is sent through the edge connector of the PWB, and the output appearing at the output pin of the connector is compared with a pre-prepared expected value to determine pass/fail. Connect the terminals of the LSI and other parts on the PWB with the board tester.
Two types of testers have been used: an in-circuit tester that has a test fixture in the form of a swinging pin, and that mainly checks component connections, constant values, etc.

[Problem to be solved by the invention]

PWB equipped with LSI using the above-mentioned conventional board tester
To test this, it is necessary to prepare a library that describes the operation of the LSI and calculate the expected value. Also, a short circuit in the PWB wiring pattern.

In many cases, the output pattern obtained by the operation of the LSI is insufficient to efficiently detect an open circuit. Furthermore, even if a pre-inspected LSI is mounted, there is a drawback that the inspection time is increased because the LSI must also be inspected in order to inspect the PWB. On the other hand, in-circuit testers are capable of analog measurements from a test fixture, but have the disadvantage that the LSI cannot be separated, and therefore a pattern cannot be sent out from a probe on the fixture.

[Means to solve the problem]

The PWB inspection method of the present invention uses a test fixture that has a function of transmitting and receiving patterns and has multiple probes capable of probing any node on the PWB. When inspecting a PWB equipped with an LSI that can put everything into a high-impedance state according to externally applied signals, the LSI
Apply a probe to the terminal as high impedance,
A logic signal string for inspection is added.

〔Example〕

Next, the present invention will be explained in more detail with reference to the drawings.

FIG. 1 shows a first embodiment of the invention. Here, reference numeral 1 denotes an LSI that can be brought into a terminal high impedance state by a switch group 6 in response to a signal applied to a terminal 7. Further, 2 is a pin electronics that sends a test pattern to the node on the PWB 8 to be tested, and also detects the output value of the node and compares it with the expected value. This pin electronics is connected by probe 3 to a node on the PWB. 5 is other circuitry on the PWB, and 4 is pin electronics connected to the edge connector. When inspecting the PWB 8, by sending a signal to open the switch group 6 from the pin electronics 2 to the terminal 7 of the LSII, a pattern that is not based on the internal logic of the LSI can be detected between the LSII and other circuits 5. Can be sent to and detected by nodes. This makes it possible to efficiently detect failures that occur on the PWB due to causes other than the LSI. FIG. 2 shows a second embodiment of the invention. In this embodiment, a switch group 16 is provided at some of the terminals of the LSIII. This is an application example showing that the input terminal of an LSI can be driven by the pin electronics 12 without providing a switch group.

It goes without saying that this inspection method can be applied not only to printed wiring boards but also to HICs and the like.

〔Effect of the invention〕

As explained above, the present invention provides an LS mounted on a PWB.
The terminals of I are configured so that they can be brought into a high impedance state by applying external signals, and a test fixture is used that has multiple probes capable of probing nodes on the PWB including these LSI terminals. By sending test patterns from edge connectors, etc., and detecting and comparing the conclusions, defects caused by manufacturing factors on the PWB can be separated from the internal operation of the LSI and detected efficiently.

[Brief explanation of the drawing]

FIG. 1 is a plan view showing a first embodiment of the invention, and FIG. 2 is a plan view showing a second embodiment of the invention. 1... LSL with a function to put the terminal in a high impedance state 2... Pin electronics that sends signals to the river/probe, detects and compares, 3...
F-1, 4...Pin electronics for edge connector, 5...Other circuits on PWB, 6...Switch group inside LSI, 7...・
...An input terminal for a signal that puts the LSI in a high-impedance state; ...PWB to be inspected; 12...Pin electronics for probe, 1
3...Probe, 14...Pin electronics for edge connector, 15...Other circuits, 16...Switch group inside LSI, 1
7. River: Input terminal that makes the LSI high impedance. 18. Old: PWB to be inspected. Agent Patent Attorney Oto Uchihara

Claims (1)

[Claims] Using a test device with multiple probes that has the function of sending and receiving a prescribed logical signal sequence and can probe any node on a printed wiring board, input/output terminals are detected by externally applied signals. LSI that can put part or all of the device into a high-impedance state
A method for inspecting a printed wiring board mounted with an LSI, characterized in that when inspecting a printed wiring board mounted with an LSI, input/output terminals of the LSI are set to high impedance, and a logic signal train is transmitted and received by the probe.