JPH0627772B2 - Method of creating reference data in circuit board inspection device - Google Patents

Description

The present invention relates to a reference data creating method in a circuit board inspection apparatus.

[Conventional example and its problems]

Generally, in an in-circuit tester, non-defective product data is absorbed from a non-defective substrate, and the non-defective product data is used as reference data for pass / fail judgment. This is convenient because it is not necessary to set reference data or the like on the program, but it has the following drawbacks.

That is, on the assumption that all the substrates which are conventionally considered to be non-defective products are true non-defective products, the data is absorbed from these substrates and averaged to form the reference data, and no particular check is performed on the data. Even if it is a non-defective product, if a relay, a switch, a semi-fixed resistor, etc. are mounted, those parts may not be arranged in the same state for some reason.

Therefore, even if the good product data is obtained from the good product substrate and the reference data is created, the reliability cannot be said to be very high.

[Means for solving problems]

In order to solve the above-mentioned conventional problems, in the present invention, prior to the board inspection, the non-defective data for each measurement point is absorbed from a plurality of non-defective boards, and the non-defective data is used as reference data as a pass / fail judgment criterion. In order to obtain, the data of each measurement point is obtained from the first non-defective board, the same data is stored in the memory as comparison reference data between non-defective boards, and each measurement of the second and subsequent non-defective boards measured under the same conditions. The data at the point is compared with the above-mentioned comparison reference data, and the reference data as the pass / fail judgment reference is obtained from the added value of the data of the acceptable non-defective substrates and the number of the acceptable non-defective substrates.

[Work]

According to the above method, when data is obtained from the second and subsequent non-defective substrates under the same measurement conditions set when absorbing the non-defective substrate data from the first non-defective substrate, the data and the first non-defective product data are When the values are compared, for example, when the values are significantly different, such as range over and registration under, the data of the board is not adopted and only the data within the predetermined range including the first non-defective product data is acquired. Highly reliable reference data is created.

〔Example〕

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

First, taking a circuit network composed of four resistors R1 to R4 shown in FIG. 1 as an example, a device for measuring data at respective measurement points A to D will be described.

This measuring device includes four probes 1 to 4 corresponding to the respective measuring points A to D. That is, the probe 1
For measuring point A, 2 for B, 3 for C and 4 for D
It is planted on a pin board of a fixture (not shown) so as to correspond to the above. For each probe 1-4,
Two changeover switches 1a, 1b; 2a, 2 respectively
b; 3a, 3b; 4a, 4b are connected in parallel. Each of the probes 1 to 4 has one of the switches 1a and 2
It is connected to a measuring signal source, for example, an AC voltage source 5 via a, 3a and 4a. Further, each of the probes 1 to 4 is connected to the signal detection unit 6 via the other switch 1b, 2b, 3b, 4b. In this implementation order, the signal detection unit 6 is composed of a current-voltage converter. An A / D converter 8 is connected to the output side of the signal detection unit 6 via an amplifier 7, and the converted data is processed by a CPU (central processing unit) 9, and the switches 1a-4b are also connected. This CPU9
It is controlled by.

According to this measuring device, each measuring point A is
The measured data in ~ D are absorbed. First, a non-defective substrate is set on a fixture chart (not shown), and a pressing device (not shown) is also operated to bring the probes 1 to 4 into contact with measurement points A to D of the non-defective substrate. And
Of the switches 1a to 4a on the AC voltage source 5 side, the switch 1
"a" is "open" and the other switches 2a to 4a are "closed", and among the switches 1b to 4b on the signal detector 6 side, the switch 1b is "closed" and the other switches 2b to 4 are
Let b be "open". As a result, the measurement points B, C,
Since D has the same potential and only the measurement point A has a low potential with respect to them, in this example, a current flows from the measurement points B and D toward the measurement point A. This current is converted into a voltage, for example, by the signal detector 6. After being amplified to a predetermined level by the amplifier 7, it is converted into digital data by the A / D converter 8. The data thus obtained is the impedance at measurement point A. Next, among the switches 1a to 4a of the AC voltage source 5th speed,
Switch 2a is "open", other switches 1a, 3a,
4a is set to "closed", the switch 2b among the switches 1b to 4b on the signal detector 6 side is set to "closed", and the other switches 1b, 3b and 4b are set to "open". Thereby, the impedance of the measurement point B is measured. Thereafter, the impedances at the measurement points C and D are obtained in the same manner. The CPU 9 sets the optimum range of the signal detector 6 for each measurement point, and the range data is stored in the memory 10. That is, the optimum range of each measurement point is set when data is first absorbed from the non-defective board,
The same range is applied to the second and subsequent measurement points. In this way, fixing the range to the first one is preferable for high-speed processing,
Depending on the case, the range processing may be performed for each substrate by the auto range.

As described above, good product data (impedance) at each measurement point of the good product substrate can be obtained. In the present invention, reference data is obtained from the non-defective product data as follows, and the flowchart thereof is shown in FIG.

For example, if 10 non-defective substrates are prepared, the switch is switched as described above for any one of them to absorb the impedance data from the respective measurement points A to D,
Memory using the same data as reference data for comparison between non-defective boards
Store in 10. Then, the good product data is absorbed from the second and subsequent non-defective substrates in the same manner as described above. However, the second and subsequent non-defective product data is the non-defective product first (during the measurement of the first plate).
It is determined that the range is not deviated from the range set to, and if the range is over or under, the measurement is aborted there and the next non-defective substrate is in the measurement standby state. If it does not deviate from the range, then comparison with the comparison reference data is performed. In this embodiment, the upper limit value is 100% of the comparison reference data and the lower limit value is -50% of the same data.
If the data deviates from this range, the measurement is aborted there and the next non-defective substrate is ready for measurement. If it is within the range, the non-defective product data is stored in the memory 10, and 1 is added to the count value of the number of substrates. After doing this for each non-defective board, the non-defective data stored in the memory 10 is added for each measurement point, and the reference data for the reference inspection is calculated from the added portion and the count value of the number of boards. To be done. The addition value of the non-defective product data also includes the non-defective product data of the first sheet.

After that, the circuit board to be inspected is set on the fixture chart, and the board inspection is performed. That is, the switches 1a to 4a on the side of the AC pressure source 5 and the switch 1 on the side of the signal detector 6 are arranged in the same order as the above-mentioned switch switching order.
b to 4b are switched, the impedance at each measurement point A to D of the circuit board to be inspected is measured, and C
In PU9, the measured impedance is compared with the reference data. In this case, the reference data has a predetermined range, and if the measurement data is within the range, “GO” indicating the inspection success is displayed on the CRT value display device 11, and if it is out of the range, the defective product is defective. Is displayed, for example, "NG" is displayed.

〔The invention's effect〕

As described above, according to the present invention, when the good product data is absorbed from the good product substrate, the good product data itself is compared with the specific comparison reference data to select the good product substrate. Data is obtained.

[Brief description of drawings]

FIG. 1 is a schematic diagram of a measuring device used for carrying out the present invention,
FIG. 2 is an operation flowchart of the present invention. In the figure, 1 to 4 are probes, 5 is a measurement signal source, 6 is a signal detector, 8 is an A / D converter, 9 is a CPU, and 10 is a memory.

Claims (1)

[Claims] 1. A method for creating reference data in a circuit board inspection device, which absorbs non-defective product data for each measurement point from a plurality of non-defective sub- strate boards and obtains reference data as a pass / fail judgment standard from the non-defective product data prior to board inspection. In, the data of each measurement point is obtained from the first non-defective board, the same data is stored in the memory as comparison reference data of non-defective boards, and each measurement point of the second and subsequent non-defective boards measured under the same conditions. In the circuit board inspecting apparatus, which compares the data in the above-mentioned comparison reference data with the above-mentioned comparison reference data, and obtains reference data as a pass / fail judgment reference from the added value of the data of the acceptable good substrates and the number of the acceptable good substrates. .