JPS6042662A - Method and device for inspecting printed wiring board - Google Patents

Abstract

PURPOSE:To perform high-reliability continuity inspection by dividing the pattern of a printed wiring board corresponding to networks, and carrying out disconnection in a network and batch short-circuit inspection of all other pins, network by network. CONSTITUTION:Networks 1-2-5, 3-7, and 4-6 are formed in correspondence to the 1st, the 3rd, and the 4th reference pins 1, 3, and 4. Disconnection inspection is performed between pins 1 and 2, and 1 and 5 through a decoding circuit 4 with respect to the reference pin 1 to attain disconnection inspection in the 1st network. An all-active signal is outputted from a signal line D to perform batch short-circuit inspection of all pins except in the 1st network with respect to the reference pin 1. At this time, the latches C for the pins 2 and 5 are already set in the disconnection inspection, so the result of AND E is in failure and the pins in the 1st network are cut. The batch short-circuit inspection is completed momentarily, so network-by-network short-circuit inspection may spend a long time, eliminating the electricity accumulation of the wiring board.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a printed wiring board inspection method and an inspection apparatus therefor, and more particularly, patterns on a printed wiring board are divided into network units, and each network is divided into specific bins ( Testing for disconnections between the reference bin (hereinafter referred to as the reference bin) and other bins in the network, as well as simultaneous short-circuit testing between the reference bin and all other bins that do not belong to the network, can be performed quickly, easily, and reliably sequentially on the entire network. The present invention relates to a printed wiring board inspection method and an inspection apparatus therefor.

In general, a printed wiring board inspection method involves bringing a probe bottle into contact with the lands that are part of the pattern of the printed wiring board that is being tested, and testing whether there is continuity between each land. Control device 11t (
By comparing the reference data of the pattern of a good printed wiring board stored in the IC memory with the data of each pattern to be inspected, defective circuit parts such as disconnections or short circuits in the pattern are discovered. .

For this reason, in the past, to check whether the pattern between a certain reference pin and which pin has continuity, a so-called scan-type all-bin test was performed, in which continuity tests were performed on all pins other than the reference pin. I was worried.

However, in such all-pin inspection, if the number of pins that come into contact with the land of the pattern of the printed wiring board that is the object to be inspected is, for example, one (usually n is a large number of pins in the thousands), then n Since the scanner (all pin inspection operation) must be repeated (n-1)xQ times, high-speed scanning operations must be performed, and the electrical capacity stored in the printed wiring frame that is the object to be inspected remains. do.

Therefore, in such an inspection method that requires a large number of inspection operations, pins between patterns that are not originally short-circuited show a short-circuited state due to accumulation of electricity, which causes incorrect inspection of the printed wiring board. Further, there are disadvantages such as mismatching of characteristic impedance due to high-speed scanning and emission due to standing waves.

Therefore, in order to eliminate the drawbacks of the conventional inspection methods described above, the inventor of the present invention proposed that in a printed wiring board, lands that contact pins such as through holes and pads are connected by conductive patterns to form several networks. Focusing on
When inspecting printed wiring boards, standard data of good printed wiring boards is downloaded to the central control unit in advance.
A reference bin and a group of pin numbers belonging to this network are stored for each network, and at the time of inspection, the group of pin numbers such as the reference bin is sequentially read out for each network from the IC memory of the central control unit, and a disconnection in the network is inspected.
We devised a method to perform a simultaneous short-circuit test with all other pins that do not belong to the network, and a device used for this test.

In other words, it is possible to perform a batch short-circuit test that eliminates the above-mentioned shortcomings and inconveniences associated with the high-speed scanning method of conventional test methods, and on the other hand, short-circuit tests can be performed slowly for each network to eliminate the influence of accumulation of electricity on the printed wiring board, and the overall short circuit test can be performed slowly. It is an object of the present invention to provide a printed wiring board testing method and testing device that can shorten the testing time and perform highly reliable continuity testing.

Embodiments of the present invention will be specifically described below based on the drawings.

FIG. 1 is a schematic circuit diagram of the main parts of a circuit used in the printed wiring board inspection apparatus of the present invention, and FIG. 2 is a functional explanatory diagram showing the open and closed states of switches in the circuit of FIG.

First, in FIG. 1, 1, 2, 3, 4, and 5 indicate the positions of the reference bins, which correspond to the head pin numbers of the group pins of each network.

(A) is a decoding circuit, which is composed of multiple output signals that become "[I" only when the input reaches a specific value. (C) is a reset signal line, and if you send a signal, it will latch. The IC is reset. (C) is a latch IC,
This is a set/reset IC. (D) is a signal line that brings out the active function, and an all-active function is formed by an AND gate (2), an OR gate (F'), an inverter (G), etc. Further, (0) is a detection point, and (T) is a shift register.

Next, in FIG. 2, 1, 2, 3, 4, and 5 indicate the positions of the reference bins, respectively. (5) and (U) are transistors.
(BET) and also has the function of a switch.

FIG. 3 is a partially enlarged plan view of the pattern of the printed wiring board. In this drawing, (P) is the substrate surface of the printed wiring board, 1.2.3.4.5.6.7 indicates each through hole and its land portion, (a), (b),
(e) shows the conduction line between each through hole.

The printed wiring board inspection apparatus of the present invention having the circuit shown in FIG. It is characterized by having at least a decoding function for cutting, an all-active function for all bins, and a latch function for cutting all other bins belonging to the network other than the reference bin.

Therefore, it has a switch opening/closing function as shown in FIG. That is, when the Wl switch is closed and the U2 switch is closed, it is possible to test whether the patterns from bin number 1 to bin number 2 are electrically connected. On the other hand, when Wl and U5 are closed, it means that it is possible to test whether the patterns from bin number 1 to bin number 5 are electrically connected.

Next, the printed wiring board inspection method of the present invention will be explained based on the plan view of FIG.

In this drawing, the 1.3.40 land portion indicates the first reference pin, the third reference bin, and the fourth reference bin, and for each of these reference bins, 1-2-5.3-7.4- 6 networks are formed. Then, the data is written and stored in the IC memory of the central control unit as data, as shown in the data schematic diagram of FIG. 4, for example.

In this case, the procedure for inspecting the printed wiring board is to first output 2 pins of the first reference pin through the decoding circuit, conduct a connection test between pins 1 and 2, and test the 1 to 5 bins in the same manner. In this way, a disconnection test within the first net can be performed.

Next, send an all-active signal from the signal line ■),
All the other bins belonging to the net other than the first net are collectively tested for short circuits with respect to the first reference pin. At this time, the noise latch IC for pins 2 and 5 is set during the disconnection test, and the Q output is
Since it is H, it cannot be ANDed with the all-active signal, and all other bins in the network of the first reference pin are cut.

Therefore, according to the present invention, the simultaneous short-circuit test to determine whether all other bins belonging to the first net are short-circuited can be completed within m- by simply issuing an all-active signal. It has the advantage of being able to This allows inspection of printed wiring boards to be completed within an extremely short time, approximately 1/10 to 1/100 of the time required for scanning all bin inspections using conventional inspection methods. short-circuit inspection can be performed slowly at regular intervals, and as a result, it is possible to eliminate any residual electrical charge in the printed wiring board, and also eliminate the mismatch of characteristic impedance and emission caused by standing waves caused by conventional high-speed scanning methods. There is an advantage that it can be eliminated. Furthermore, the time required for inspecting printed wiring boards can ultimately be shortened to one-tenth of that of conventional methods, and printed wiring boards can be inspected quickly, easily, and with high reliability.

As described above, according to the present invention, for each network of a printed wiring board, the reference bin is inspected for disconnection with other bins in the network, and all other bins belonging to other than the net are inspected. Batch short-circuit inspection can be performed quickly and easily.

Note that the second and third nets also perform the same internal wire breakage inspection for the first reference pin as described above for the third and fourth reference bins, as well as for all other bins that belong to other than the net. Since short circuit inspection (9) can be carried out alternately, the printed wiring board as a whole can be inspected quickly, easily, and with high reliability.

[Brief explanation of the drawing]

Fig. 1 is a schematic circuit diagram of the main parts of the circuit used in the printed wiring board inspection device of the present invention, Fig. 2 is a functional explanatory diagram showing the open and closed states of switches in the circuit, and Fig. 3 is a diagram of the pattern of the printed wiring board. The partially enlarged plan view, FIG. 4, is the second side of a schematic diagram of data stored in the IC memory of the central control unit. In the above drawing, A...decoding circuit (decoder), B
......Reset signal line, C...-
・Latch IC1 D・・・・・・Active function signal line, E...
......AND gate, F...OR gate, G...Inverter, 0...Detection point, P...・・・・・・Substrate surface of printed wiring board, (1
0) T・・・・・・Shift register, Q・・・・・・
...Q gate, U, ...transistor circuit, W...
・−・Transistor circuit. Patent applicant name IBIDEN Co., Ltd. Representative Junichi Taga (11) 340-

Claims (1)

[Claims] 1. Divide the pattern on the printed wiring board, which is the object to be inspected, into networks, store the reference pins for each network and the number group of bins belonging to the network in a central control device, and control the central control at the time of inspection. The device reads the reference bin and the number group of bins belonging to the network for each specific network, and sequentially performs pattern inspection within the network and batch short-circuit inspection of all other bins that do not belong to the network with respect to the reference bin. A printed wiring board inspection method characterized in that the inspection method is performed on a network. 2. A decoding function that divides the pattern on the printed wiring board that is the object to be inspected into network units and specifies a reference bin and a group of bin numbers for each network for each network, and an all-active function for all bins; A printed wiring board having at least a latch function capable of cutting all other bins in the network other than the reference pin, and a mechanism in which a circuit having these functions can be communicated with and controlled by a central control unit. Noyu investigation sozono.