JPH04326071A - Method for testing ic mounting board - Google Patents

Abstract

PURPOSE:To markedly enhance the test efficiency of an IC mounting board having electronic parts such as an IC, and LSI or the like mounted thereon in high density. CONSTITUTION:The mounting state of electronic parts 30 is tested using a tester 50 equipped with probe pins 51 coming into contact with the respective circuit nets of an IC mounting board 40. By measuring the electric resistance values between the short circuit point P to which all of the probe pins 51 are electrically connected and the leads 31 of the electronic parts 31 mounted on the IC mounting board 40, the quality of the mounting state of the electronic parts 30 is tested.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for testing an IC mounting board on which ICs, LSIs, etc. are densely mounted.

0002

2. Description of the Related Art FIG. 3 is a schematic side sectional view of a main part for explaining a conventional IC mounting board testing method, and FIG.
) and (b) are a schematic diagram showing the principle of the test device and a side sectional view of the main part showing an example of a failure occurring on an IC mounting board.

[0003] A test device 50 commonly called an in-circuit tester is used to test an IC mounting board. As shown in FIG. 3, this test device 50 connects a probe pin 51 like a "kenzan used in flower arrangement" to an IC to be tested.
The probe pin 51 arranged on the movable plate 53 provided to be movable in the vertical direction (in the direction of arrow U-D) can be inserted through the movable plate 53 equipped to correspond to each circuit net of the mounting board 40. A fixed plate 52 with a guide hole 52a and a ventilation hole 52b for holding the guide pin 52a and an air seal part 58 equipped with an O-ring 59 for sealing the guide pin 56 fixed to the movable plate 53, By discharging the air in the direction of the dotted arrow (a vacuum device (not shown) is used to discharge the air and reduce the internal pressure), the movable plate 53, which has been sucked and raised in the direction of arrow U, returns to its original position. It is composed of a restoring spring 55 and a case cover 54 arranged to cover the entire movable plate 53.

This test device 50 sends information obtained by bringing probe pins 51 into contact with vias 41 and the like of electronic components 30 to a circuit tester 60 via a cable 57 and a connector 65 to test each electronic component 30, 30A etc. is installed reliably.

The procedure for testing the IC mounting board 40 will be described below with reference to FIG. ■． The IC mounting board 40 on which electronic components such as 30A and 30A are mounted is placed on the air seal portion 58 of the test device 50. As a result, the IC mounting board 40 has an air seal portion 5 made of synthetic rubber or the like.
8, the situation will be in close contact. Note that this IC mounting board 40 is positioned using guide pins 56. ■． A vacuum device (not shown) is operated to suck the air inside in the direction of the dotted arrow. As a result, the inside of the testing device 50 is brought into a reduced pressure state, and the movable plate 53 is sucked in the direction of arrow U and rises. By moving the movable plate 53 in the direction of arrow U, each probe pin 51 placed on the movable plate 53 is
It contacts the respective corresponding circuit nets (vias 41 and others) on the mounting board 40 side. ■． The information obtained by contacting each probe pin 51 with a circuit net such as a via 41 is sent to a circuit tester 60 via a cable 57 and a connector 65, where it is compared with test data to determine whether the IC mounting board 40 is The quality is comprehensively tested. Note that the quality of the IC mounting board 40 includes disconnection of the wiring pattern of the IC mounting board 40, short circuit between wiring patterns, quality of the mounting state of each electronic component 30, 30A, etc. (presence or absence of soldering defects, etc.) is included. In the figure, 30,3
0A indicates an electronic component.

The operating principle of this test equipment and an example of a defective phenomenon occurring on an IC mounting board are shown in FIGS. 4(a) and 4(b) below.
). For example, when there is a circuit as shown in FIG. 4(a) on the IC mounting board 40 side, this test device 50 tests each of these circuit nets (a circuit in which connections between components can be drawn with a single stroke is called a net). The connection between the dotted lines in this figure is one net.) The probe pins 51 are brought into contact with the respective positions (corresponding to the positions indicated by ■ and ■ in the figure), and the IC is mounted using the information obtained from these positions. The quality of the board 40 is tested. Figure 4(b)
indicates that there is a failure (poor contact portion) α due to poor soldering between the via 41 on the IC mounting board 40 side and the lead 31 on the electronic component 30 side.

[0007]

[Problems to be Solved by the Invention] In this conventional IC mounting board testing method, the probe pins 51 of the test device 50 are
The fault α is detected by comparing the information obtained by uniformly contacting all the circuit nets of the C-mounted board 40 with the test data in the circuit tester 60. Since each of the 40 circuit nets is data that is intricately intertwined, there are problems such as the fact that even if a large computer is used to create the data, simulations will take several tens of hours, and the cost of creating test data and The situation is such that a realistic solution cannot be found from the viewpoint of the creation turn.

[0008] For this reason, companies have responded by introducing expensive appearance inspection machines and securing a large number of personnel for visual inspection. However, for the above-mentioned reason, it is difficult to set the quality determination level of the visual inspection machine, and as a result, there is a high probability that a non-defective product will be determined as defective, making it difficult to operate it efficiently. In addition, when visual inspection is performed, the rate of detection of defective parts is inevitably low when the density of electronic components is high, as is the case these days.

[0009] The present invention greatly improves test efficiency by individually measuring the electric resistance value between the short point where all the probe pins on the test equipment side are electrically shorted and the electronic components mounted on the IC mounting board. We aim to realize an improved test method for IC mounting boards.

0010

[Means for Solving the Problems] As shown in FIG. 1, the method for testing an IC mounting board according to the present invention (hereinafter referred to as the board testing method) uses a short point P where all of the probe pins 51 are electrically connected. By measuring the electrical resistance value between the leads 31 of the electronic component 30 mounted on the IC mounting board 40, the quality of the mounting state of the electronic component 30 is tested.

[0011]

[Operation] This board test method is based on short points P and I that electrically connect (short circuit) all of the probe pins 51.
Lead 3 of electronic component 30 mounted on C mounting board 40
Since this method tests the quality of the mounting state of the electronic component 30 based on the electrical resistance value between 1 and 2, the reliability of the test results is extremely high because no other circuit net is involved in the judgment criteria.

0012

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail below with reference to embodiment figures. FIG. 1 is a schematic side sectional view of the main part showing an embodiment of the present invention, and FIG. 2 is a schematic side view for explaining the principle of the board testing method according to the present invention. Identical parts are given the same reference numerals.

As shown in FIG. 1, the board testing method according to the present invention includes a test device 50 in which all cables 57 connected to each probe pin 51 are short-circuited at a short point P, and Target circuit net (in this case, the lead 31 of the electronic component 30 mounted on the IC mounting board 40 corresponds to this)
The IC mounting board 40 is tested using a resistance meter 20 that measures the resistance value between the two and a tester rod 15 that is electrically connected to the resistance meter 20.

In this board test method, as shown in the principle diagram of FIG. 2, all the probe pins 51 are short-circuited at the short point P.
By contacting the lead 31 of the electronic component 30 mounted on the C mounting board 40, an electric circuit of the tester rod 15 → lead 31 → via 41 → probe pin 51 → short point P → resistance meter 20 → tester rod 15 is formed. A closed loop is formed. Therefore, leads 31 and I of electronic components
If the vias 41 on the C-mounted board 40 side are in reliable contact, the value indicated by the resistance meter 20 should be "0" or "a value extremely close to 0."

However, if there is a poor contact portion α [see FIG. 4(b)] between the lead 31 of this electronic component 30 and the via 41 on the IC mounting board 40 side (see FIG. 4(b)), the lead 31 may 42), the indicated value of the resistance meter 20 will naturally increase (this is because the electronic components 30 and other circuit patterns are entangled as resistors between the tester rod 15 and the short point P). ). Therefore, by applying this method, it is possible to extremely easily detect the contact failure portion α due to poor soldering or the like.

In this embodiment, the tester rod 15 is operated manually, but it would be more efficient if the tester rod 15 was attached to an automatic machine to automate its operation.

Further, in this embodiment, the quality of the mounting state of the electronic component 30 is detected based on the indicated value of the resistance meter 20, but it is of course possible to use a buzzer, a light emitting body, etc. in place of the resistance meter 20. It is possible.

[0018]

Effects of the Invention As is clear from the above explanation, the board testing method according to the present invention has a resistance meter placed between the tester bar and the test device with all the probe pins shorted.
Since this method judges whether the mounting condition of electronic components is good or bad based on whether or not it shows ", there is no doubt in the judgment, so the reliability of the test results is extremely high. Also,
This method has great economical effects because it does not require a preparation process (creation of test data) for testing the IC mounting board.

[Brief explanation of drawings]

FIG. 1 is a schematic side sectional view of essential parts showing an embodiment of the present invention.

FIG. 2 is a schematic side view for explaining the principle of the board testing method according to the present invention.

FIG. 3 is a schematic side sectional view of main parts for explaining a conventional IC mounting board testing method.

FIG. 4 is a schematic diagram showing the principle of the test device and a side cross-sectional view of a main part showing an example of a failure occurring on the IC mounting board.

[Explanation of symbols]

15 Tester rod 20 Resistance meter 30, 30A, 30B, 30C Electronic component 31 Lead 40 IC mounting board 41 Via 42 Pattern 50 Test device 51 Probe pin 52 Fixed plate 52a Guide hole 52b Ventilation hole 53 Movable plate 54 Case cover 55 Restoration spring 56 Guide pin 57 Cable 58 Air seal part 59 O-ring 60 Circuit tester 65 Connector P Short point α Poor contact part (failure)

Claims (1)

[Claims] Claim 1: Applicable when testing the mounting state of electronic components (30) using a test device (50) equipped with probe pins (51) that contact each circuit net of an IC mounting board (40). A method of connecting all of the probe pins (51) electrically to a short point (
P) and the lead (31) of the electronic component (30) mounted on the IC mounting board (40) to test the quality of the mounting state of the electronic component (30). A test method for an IC mounting board characterized by: