JPH01185452A - Apparatus for testing electric circuit board - Google Patents

Abstract

PURPOSE:To obtain a test apparatus not overlooking the shortcircuit error between circuit pattern layers and enhanced in reliability, by continuously measuring the resistance value between two conductive circuit layers when both electrostatic capacity values measured between a reference conductive plate and two conductive circuit patterns are equal or almost equal to each other. CONSTITUTION:When both electrostatic capacity measured values C1, C2 between circuit pattern layers 1a, 1b and a reference conductive plate 3 by a capacity measuring apparatus 10 are equal or almost equal, the following operation is taken even a case judged to be a good product by the measurement of electrostatic capacity. That is, a control computer 11 holds a contact element 6 as it is when said contact element 6 is brought into contact with the terminal part 1c of the upper circuit pattern layer 1a theretofore and moves a contact element 5 to the terminal part 1d of the lower circuit pattern layer 1b by an X-Y positioning apparatus 7 to bring the same into contact therewith. Subsequently, a resistance measuring apparatus 9 is operated to measure the resistance between the layers 1a, 1b. When the resistance measured value is 0 or almost 0, it is made clear that the layers 1a, 1b are shortcircuited and the overlooking of a shortcircuit error is prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a test device for checking for incorrect wiring (errors) in conductive circuits on an electric circuit board such as a printed circuit board.

[Conventional technology]

Generally, this type of test equipment includes two contacts, each of which is moved independently to a desired location (usually a terminal) on an electrical circuit board under test that is set at a test position. a positioning device for contacting, a resistance measuring device for measuring the resistance between the two contacts, and a predetermined dielectric layer sandwiched between any one of the two contacts and the electric circuit board set surface. The device is equipped with a capacitance measuring device that measures the capacitance between a reference conductive plate placed at an opposing position, and is operated according to a predetermined procedure to test an electric circuit board.

By the way, recently, the number of layers of circuit patterns (conductive circuits) formed on electric circuits, such as printed circuit boards, has been increasing. In some cases, it is not possible to properly detect errors simply by measuring capacitance. In other words, if the circuit patterns in the two layers have the same or similar shapes and completely or almost entirely overlap each other, then even if both circuit patterns are short-circuited in capacitance measurement, if they are not short-circuited. The measurement result is the same as that of , and the short circuit error cannot be detected.

This will be explained in detail with reference to FIGS. 2 and 3.

In both figures, 1 is a multilayer board to be tested having two circuit pattern layers 1a and lb with the same shape, 2 is a test board setting surface of the test equipment, and 3 is a dielectric layer 4 sandwiched between this setting surface 2. These are reference conductive plates arranged at opposing positions. This conductive plate 3 has one input end connected to one contact (
The capacitance measuring device (not shown) is connected to the other input end of a capacitance measuring device (not shown). Further, Sl represents the area of the upper circuit pattern layer 1a, S2 represents the area of the lower circuit pattern layer 1b, and S3 represents the area of the upper and lower circuit pattern layers 1a, lb.
represents the total area of the circuit pattern layers 1a and lb when they are short-circuited. Furthermore, d represents the thickness of the substrate 1, and d8 represents the thickness of the dielectric layer 4. Here, d represents the total area of the circuit pattern layers 1a and lb when In comparison, d2 is sufficiently thick (a, << aX), and in terms of capacitance measurement, each dimension between the reference conductive plate 3 and the circuit pattern layers la and lb can be considered to be almost the same.

FIG. 2 illustrates a case where the circuit pattern layers 1at lb of the substrate 1 have the same shape and completely overlap each other. Therefore, in this case, 5l-32=33, and capacitance measurement (circuit pattern layer 1a (or lb)
and the capacitance C+ between the reference conductive plate 3 (or CZ>measurement)
Only both circuit pattern layers 1a.

Unable to check for short circuit between lb. FIG. 3 exemplifies a case where the circuit pattern layers 1a+lb of the substrate 1 have the same shape, but are slightly shifted and overlapped. In this case, although 51=32, the circuit pattern layer 1a,
Since the circuit pattern layers 1a and 1b are shifted and overlapped, in the event of a short circuit, the substantial total area of the circuit pattern layer 1a in contact with the contactor 1 becomes equal to the projected area S3 of the circuit pattern layers 1a and 1b onto the board setting surface 2. If the capacitance value increased by this area increment (33-31) is larger than the error judgment capacitance value (reference value), it will be detected as an error. In the pattern, the error judgment capacitance value is also large (the possibility of overlooking an error increases).

[Problem to be solved by the invention]

However, conventionally, when the capacitance measurement value differs significantly from the reference value, the short circuit is only confirmed by measuring the resistance, but when the capacitance measurement value is the same as or close to the reference value, confirmation by resistance measurement etc. is not performed. There wasn't. For this reason, short circuits in the circuit pattern layers 1a and lb structures as shown in FIGS. 2 and 3 are not detected, leading to defective products and poor reliability. .

SUMMARY OF THE INVENTION An object of the present invention is to provide an electric circuit board testing device that does not overlook short-circuit errors between circuit pattern layers and has improved reliability in testing multilayer boards.

[Means to solve the problem]

The above purpose is that when both the capacitance values C+ and Ct between the measured reference conductive plate and each of the two conductive circuit layers are equal or almost equal, the capacitance measurement is followed by the measurement of the capacitance between the two conductive circuit layers. This is achieved by providing a means for detecting a short circuit between conductive circuit layers to measure the resistance value of the conductive circuit.

[Effect]

The short-circuit detection means between conductive circuit layers detects when the capacitance values C, , C, between the measured reference conductive plate and each of the two conductive circuit layers are equal or almost equal when testing a multilayer board. Following the capacitance measurement, the resistance value between both conductive circuit layers is measured to detect the presence or absence of a short circuit between both conductive circuit layers, thereby preventing a short circuit error from being overlooked.

〔Example〕

Hereinafter, the present invention will be described in detail with reference to the drawings. FIG. 1 is a block diagram showing an embodiment of an electric circuit board testing apparatus according to the present invention, and in the figure, 1, 1a, 1b, and 2 to 4 are the same as in FIGS. 2 and 3, respectively. 1c is a terminal portion of the upper circuit pattern layer 1a, and 1d is a terminal portion of the lower circuit pattern layer 1b. 5 and 6 are contactors respectively; 7 is an X-Y positioning device that moves the contactor 5 to a desired position (x, y coordinates) on the multi-N board to be tested 1 set at the test position and brings it into contact; 8 is an XY positioning device that similarly moves the contactor 5 and brings it into contact. 9 is a resistance measuring device for measuring the resistance between two contacts 5.6, 10 is one of the contacts,
Here, it is a capacitance measuring device that measures the capacitance between the contactor 6 and the reference conductive plate 3. 11 is a control computer;
Each of the above devices 7 to 1O is operated according to the same sequence as the conventional device, and both capacitance values C+ between the reference conductive plate 3 of the multilayer substrate 1 and the two circuit pattern layers 1a+ lb each layer are
, Cz (see Figure 2.3), and
The following short-circuit detection control between the circuit pattern layers 1a and 1b is performed. That is, both the measured capacitance values C
,,C, are equal or almost equal to each other, following the capacitance measurement, the resistance value between the circuit pattern layers 1a and lb is measured by the resistance measuring device 9, and both circuit pattern layers la and lb are measured. In other words, the presence or absence of a short circuit error is detected.

Next, the operation of the above-mentioned device of the present invention will be explained, but regarding the normal test operation (measurement operation of the capacitance values C, CZ between the reference conductive plate 3 and the circuit pattern Jila or 1b), the conventional device Since there is no particular difference from the case, only the operation related to short circuit error detection will be explained here.
The planar shapes of a and lb are very similar, and almost all of them overlap each other. Further, the thickness dl of the substrate 1 is sufficiently smaller than the thickness d2 of the dielectric layer 4 (
d.

<<aZ) In terms of capacitance measurement, it is assumed that the dimensions of the reference conductive plate 3 and the circuit pattern layers 1a and 1b are almost the same. In this case, there is almost no difference between the capacitance CI between the reference conductive plate 3 and the upper circuit pattern layer 18 and the capacitance C between the same conductive plate 3 and the lower circuit pattern layer lb. Assuming that there is a short circuit between the circuit pattern layers 1a and lb, the substantial total area of the circuit pattern layers 1a and lb relative to the reference conductive plate 3 is equal to their projected area onto the board setting surface 2. That is, even if there is a short circuit error, the increased area is the circuit pattern layer 1a+l
It is only the area of the non-overlapping portion of b. Now, suppose that the capacitance increases by 5 pF due to the increased area, and the error criterion for capacitance measurement is ±15% of the reference capacitance value.
capacitance CI (or C2) between a (or lb)
If it exceeds 33 pF, the short circuit error cannot be detected by capacitance measurement alone.

This is particularly likely to occur when the circuit pattern has a wide area, but in any case, in the present invention, both capacitances measured between the circuit patterns 111a, lb and the reference conductive plate 3 by the capacitance measuring device 10 C ,,C.

When they are equal or almost equal, the following operation occurs unconditionally even if the product is determined to be good by capacitance measurement. That is, in this case, the control computer 11 has previously controlled the terminal section 1 of the upper circuit pattern layer 1a.
If the contact 6 is in contact with the contact 6, the contact 6 is held in that position, and the positioning device 7 moves the other contact 5 to the terminal portion 1 of the lower circuit pattern layer 1b.
d After moving it upward, lower it and bring it into contact with this. Then, the resistance measuring device 9 is activated to measure the resistance between the upper and lower circuit pattern layers 1a and lb. If the measured resistance value is 0 or approximately O, both circuit pattern layers 1a, l
It can be seen that there is a short circuit between B and B, and it is possible to prevent a short circuit error from being overlooked.

〔Effect of the invention〕

As described above, according to the present invention, short-circuit errors between conductive circuit layers in a multilayer board can be prevented from being overlooked, and reliability of test results can be improved.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing one embodiment of the device of the present invention, and FIGS. 2 and 3 are cross-sectional views of a multilayer board set portion during capacitance measurement to explain the problems of the conventional device. DESCRIPTION OF SYMBOLS 1...Multilayer board to be tested, la, lb...Circuit pattern layer, 2...Test board setting surface, 3...Reference conductive plate, 4...Dielectric layer, 5.6...・Contactor, 7,
8... Contact X-Y positioning device, 9... Resistance measuring device, 10... Capacity measuring bag! , 11... control computer.

Claims (1)

[Claims] 1. Two contactors, two contactor positioning devices that independently move and contact the two contactors at desired locations on the electrical circuit board to be tested set at the test position; a resistance measuring device for measuring the resistance between the two contacts; and a resistance measuring device disposed at a position facing any one of the two contacts and the electric circuit board set surface with a predetermined dielectric layer in between. In an electric circuit board testing device that is equipped with a capacitance measuring device that measures the capacitance between a reference conductive plate and a reference conductive plate, when testing an electric circuit board under test that has multiple layers of conductive circuits, one of the electric circuit boards is When the capacitance value between the conductive circuit layer and the reference conductive plate and the capacitance value between the other conductive circuit layer and the reference conductive plate are equal or almost equal, capacitance measurement is performed. Subsequently, the resistance value between the one conductive circuit layer and the other conductive circuit layer of the electrical circuit board to be tested is measured by the resistance measuring device to detect the presence or absence of a short circuit between the two conductive circuit layers. An electric circuit board testing device characterized by comprising circuit layer short circuit detection means.