JPH0344574A - Testing method - Google Patents

Abstract

PURPOSE:To improve the reliability of a probe and the precision in testing at the time of a test by bringing the probe into contact with a probing pad of a dummy test substance before measurement of a substance to be tested and by comparing a measured value thereof with a corresponding estimated value for checking. CONSTITUTION:The normality of a probe 4 and a determination circuit 2 is checked up before a test is conducted, by pressing the probe 4 on a lead of a component 6 provided on a printed circuit board 7 to be tested. The probe 4 being moved on an X-Y table 1, subsequently, it is positioned on a printed circuit board 8 whereon a probing pad 9 and a reference resistor 10 are mounted, and is lowered and pressed on the pad 9 by an air cylinder 3. On the occasion, the determination circuit 2 holds inside an estimated value of a voltage from the pad 9 and it compares a measured value from the probe 4 with it and makes them accord with each other. Thereby it can be checked that there is no sticking substance such as dust at the fore end of a probe pin 5 and that a normal contact pressure is obtained.

Description

[Detailed Description of the Invention] [Summary] This test method involves comparing a measured value obtained by contacting a probe with a component mounted on a printed circuit board and a predicted value corresponding to the measured value. Therefore, regarding the test method for checking the normality of the test object, it is necessary to determine whether a printed circuit board determined to be abnormal by measurement is actually due to a failure of the printed circuit board itself, and to ensure the reliability of the test. The purpose of this test is to improve the performance of the test object, and it has a test object and a probe having a probe pin, and is connected to the probe and compares the measured value of the test object with a predetermined predicted value. A test method for testing with a determination circuit, comprising: a pseudo test object having a probing pad and a reference resistor connected to the probing pad; The determination circuit is configured to bring the probing of the probe into contact with the probing pad of the pseudo test object and compare the measured value with a predicted value corresponding to the measured value.

[Industrial application field]

The present invention relates to a testing method, and in particular to a test object to be tested, in which a measured value obtained by contacting a component with a probe while mounted on a printed circuit board is compared with a predicted value corresponding to the measured value. It relates to a test method for checking the normality of things.

When checking the continuity of a printed circuit board with components mounted, the measured value obtained by touching a specific part with the probe pin of the probe is connected to the probe and has a predicted value corresponding to the measured point in advance. A determination circuit compares the two, and if a predetermined relationship is established (for example, a match), the tested printed circuit board is determined to be normal.

However, even though the printed circuit board was normal, the test equipment sometimes determined that it was an error.

Possible causes of this are firstly poor contact of the probe pin of the probe and secondly erroneous diagnosis of the determination circuit. Of these,
Regarding the second factor, the judgment circuit that processes the signal from the probe pin that contacts the component usually has a self-diagnosis function, so it was possible to recognize the second condition. It was difficult to recognize factor 1.

Therefore, it is desired to be able to reliably recognize the first factor as well.

[Prior Art and Problems to be Solved by the Invention] Conventionally, regarding the first factor, an operator visually determines whether or not there is a poor contact.

However, if a small amount of dust adheres to the tip of the probe pin, it is very difficult to visually detect the presence of the dust, and the contact surface between the probe pin and the contact surface that occurs due to a decrease in contact pressure due to fatigue of the probe, etc. It is also difficult to detect an increase in contact resistance with the surface by visual inspection.

Therefore, due to these abnormalities, a normal measurement signal may not be sent to the determination circuit, and as a result, the printed circuit board may be determined to be defective regardless of whether the printed circuit board is good or not.

Therefore, it is an object of the present invention to improve the reliability of testing by determining whether a printed circuit board determined to be abnormal by measurement is actually caused by a fault in the printed circuit board itself, regardless of the condition.

[Means to solve the problem]

This purpose is to perform a test using a judgment circuit that includes a test object and a probe having a probe pin, and is connected to the probe and compares the measured value of the test object with a predetermined predicted value. The test method includes a pseudo test object having a probing pad and a reference resistor connected to the probing pad, and before measuring the test object, the judgment circuit performs the pseudo test. This is achieved by a testing method characterized in that the probing of the probe is brought into contact with the probing band of the object, and the measured value is compared with a predicted value corresponding to the measured value.

[Effect]

The present invention is a pseudo test object for probing check that has a probing pad and a reference resistor connected to the probing pad, and tests a test object on which components are mounted (main test). I try to check it in advance.

In other words, a signal waiting for a certain value from the reference resistor connected to the probing pad is sent to the judgment circuit, and the judgment circuit compares that value with the corresponding predicted value to determine whether the probe itself is normal. / Abnormalities can be determined.

〔Example〕

Embodiments of the present invention will be described below with reference to FIG.

FIG. 1 is a diagram showing an embodiment of the present invention.

Figure (a) shows the state before testing, Figure (b) shows the state when testing the probe, Figure (
C) shows a diagram showing a state in which a printed circuit board to be tested is tested.

In the figure, 1 is an X-Y table, 2 is a determination circuit, and 3
1 is a cylinder, 4 is a probe, 5 is a probe pin, 6 is a component, 7 is a printed circuit board, 8 is a printed circuit board for blowing, 9 is a probing pad, and 10 is a reference resistor.

In this example, in order to automate the test, the probe 4
is installed on the X-Y table l, and the printed circuit board under test 7
The test is carried out by moving the test piece over the top and positioning it at the measurement point, and pressing it against the lead of the part 6 on the printed M board 7 to be tested by the air cylinder 3.

Before testing the printed circuit board 7 under test with the components 6 mounted, it is necessary to confirm the normality of each device involved in the test, such as the probe 4 and the judgment circuit 2 (among these,
The determination circuit 2 has been described as having a self-diagnosis function as described above, so its explanation will be omitted in this embodiment). Therefore, as shown in FIG. 1, a probing pad 9 that comes into contact with the probing 5 of the probe 4 is formed on the surface of the processing table on which the printed circuit board 7 on which the component 6 is mounted is placed. A printed circuit board 8 made of an insulator for blowback and on which a reference resistor IO connected to a probing pad 9 is mounted is arranged. Note that one end of the reference resistance value 10 is connected to the probing pad 9, and the other end is connected to the printed circuit board 8.
connected to the insulated part of the

Next, the operation of a pre-test before testing a printed circuit board on which components are mounted, that is, a probe reliability test, will be explained.

Probe 4 moves on x-y table l and is positioned on printed circuit board 8 on which probing pad 9 and reference resistor 1o are mounted.

Next, the probe 4 is lowered by the air cylinder 3 and pressed against the probing pad 9. Since the reference resistor 10 is connected to each probing pad, a signal having a predetermined voltage value is transmitted from the probe 4 to the determination circuit 2. Since the voltage value from the probing pad 9 can be predicted in advance, the determination circuit 2 stores the predicted value therein. And this probe 4
The determination circuit 2 compares the two with the measured value transmitted from the determination circuit 2. If the comparison matches, it means that there is no dust attached to the tip of the probe pin 5 of the probe 4 and that normal contact pressure is obtained, and then the main test is carried out.
In other words, the printed circuit board on which the components are mounted is being tested.

If the results of the comparison do not match, the probe 4 is replaced and the reliability test is performed again on the replaced probe.

〔Effect of the invention〕

As explained in detail above, in the present invention, the test equipment retains the check function of the entire probe function including the wiring from the probe, so the reliability of the probe during testing is improved and the test accuracy is improved. do.

Furthermore, since any abnormality in the probe can be discovered before the test, the number of man-hours can be reduced compared to the case where the test is performed without knowing the abnormality.

Especially for probes with a large number of probe pins,
- The advantage is that it can measure many points with one contact, but if even one pin is defective, it is necessary to touch the probe again to re-measure the point measured with that pin. Although the merits of pin probes are reduced by half, the present invention is very effective in preventing this.

[Brief explanation of drawings]

FIG. 1 is a diagram showing an embodiment of the present invention; FIG. 1(a) is a diagram showing a state before testing, and FIG.
) is a diagram showing a state in which a printed circuit board under test is tested. In the figure, 2 is a judgment circuit, 4 is a probe, 5 is a probe pin, 6 is a component, 7 is a printed circuit board, 8 is a printed circuit board for blowing, 9 is a probing pad, and 10 is a reference resistor. show.

Claims (1)

[Claims] Comprising an object under test (1) and a probe (4) having a probe pin (5), connected to the probe (4), and capable of communicating with measured values of the object under test (1). A determination circuit (2) that performs comparison with a predetermined predicted value
), the test method includes a dummy test object (8) comprising a probing pad (9) and a reference resistor (10) connected to the probing pad (9). Before measuring the test object (1), the determination circuit (2) contacts the probing pad (9) of the pseudo test object (8) with the probing pad (5) of the probe (4). A test method characterized in that the measured value is compared with a predicted value corresponding to the measured value.