JPS60104269A - Printed circuit board inspecting device - Google Patents

Abstract

PURPOSE:To decide exactly quality, disconnection, short-circuit and degraded insulation of a printed circuit board by comparing a resistance value read in a storing circuit with a resistance value of a circuit pattern. CONSTITUTION:Relay scan parts 211-2216 are controlled through a CPU25 and the circuit pattern of a printed circuit board is scanned successively. Subsequently, in accordance with the pattern, a mode is selected, and in a high resistance measuring mode, the voltage from a high constant-voltage source is applied to the pattern through a voltage generating and measuring part 20, its resistance value is measured, and in a low resistance meanuring mode, a current from a constant-current source of the measuring part 20 is supplied and a low resistance measurement is executed. The result of measurement of them is compared with the corresponding value of a non-defective unit stored in an RAM18 or a magnetic tape device, and the quality decision is executed through a CPU25. The decision of quality, disconnection, short-circuit and degraded insulation of the printed circuit board can be executed exactly by the decision based on a resistance value without reference to a conducting or non-conducting state of this pattern.

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Technical field to which the invention pertains The present invention relates to a printed wiring board inspection device.
This invention relates to an inspection device that sequentially inspects the connection relationship between two arbitrary terminal areas on a printed wiring board.

(b) Conventional technology Printed wiring board inspection machines, as is well known, conduct electrical connection between two arbitrary terminal areas on each printed wiring board, that is, a conductive state. It has the function of inspecting whether the electrical connections are in an insulated state and identifying those that are not in a normal electrical connection.

Conventionally, this inspection method has been based on inspection data regarding the electrical connections of a printed wiring board that has been inspected by another method and confirmed to be good, and the circuit pattern of this good printed wiring board is used as the standard. A method has been proposed and put into practical use in which the test data of a printed wiring board to be inspected is compared with the standard test data by reading the test data and storing it in a memory as standard test data.

However, in the conventional method described above, when reading circuit pattern data from a good printed wiring board, one of the conductive and non-conductive
7Threshold values are either fixed or can be changed in stages, but when stored in memory, they are simply stored as 1" and 0" data, so any two points in the terminal area can be set. There was a drawback that it was only possible to determine whether there was conduction or non-conduction between the terminals, and it was not possible to determine the insulation resistance between two points in the terminal area or the range of the resistance value. .

(C) Purpose of the Invention The present invention has been made in view of the above-mentioned conventional circumstances! Therefore, an object of the present invention is to solve the above-mentioned drawbacks by reading and storing the resistance value itself, and comparing the resistance values, rather than just the conduction or non-conduction of the circuit pattern when reading data from a printed wiring board. It is an object of the present invention to provide a new inspection device that can accurately determine whether a printed wiring board is good, disconnected, short-circuited, or has poor insulation.

(d) Structure of the Invention In order to achieve the above object, the printed wiring board inspection device according to the present invention includes a high constant voltage generation circuit that generates a high constant voltage, and a constant current generation circuit that generates a constant current. , a measurement mode switching circuit that selects either the high constant voltage outputted from the high constant voltage generation circuit or the constant current outputted from the constant current generation circuit and switches and connects the selected one to the relay scan unit; and the relay scan unit. A
The A/1) converter maintains a constant level of the resistance value to be measured corresponding to all the constant voltage values output during the high resistance measurement mode using the D converter circuit and the high constant voltage generating circuit. A voltage detection circuit that is input to the circuit,
a central processing unit that compares and inspects the M measured resistance value data output from the width converter circuit and mask data; and a control unit that decodes the data from the central processing unit and controls each circuit. and a circuit.

(e) Embodiments of the Invention Next, in order to better understand the present invention, a preferred embodiment of the present invention will be specifically described with reference to the drawings.

FIG. 1 does not show an embodiment of the printed wiring board inspection apparatus according to the present invention. This is a diagram of I. In the figure, reference number 11 indicates a key and display (KEY&1) ISP), and the key and display 11 are keys for setting each mode, editing mask data (circuit pattern data of a non-defective printed wiring board), etc. The key and display controller (I(hjY&DIsPCUNT
λ13 is a printer (PRINTER) that prints the above mask data, inspection results, etc.;
C (JNT), 15 is a cassette magnetic tape (CMT') for recording mask data, 161d cassette 7)
? 6B
CUNT controller (CMT CUNT) is shown respectively. 17t; RO for storing programs, conversion constants, etc.
M (read-only memory), 18 is a RAM (random access memory) for storing the above-mentioned master data, etc., 19
indicate a lamp and a switch, respectively.

20 is a voltage generation resistance measuring section which is the main part of the present invention; 211
~211g HalJ Reine can section, 22 indicates a pin board section, and 23 indicates an electrical box.

240 to 2422 are CPU buses, and 25 is a CPU (central processing unit ii) that controls each of the above groups.

FIG. 2 is a diagram showing a specific example of the block configuration of the voltage generating resistance measuring section 20, which is the main part of the present invention.

In the figure, one embodiment of the voltage generation resistance measuring section 20 includes a control circuit 201 that controls each circuit 202 to 206.20e, which will be described later, a high constant voltage generation circuit 202, and a constant current generation circuit 20.
3. A/1) The high constant voltage generation circuit 202, which is configured to include a converter circuit 204, a measurement mode switching circuit 206, and a voltage detection circuit 206, is mainly used when measuring high resistance and insulation resistance, and 1) C12V. -DCI ■■, 2
Generates 50V or 500V and uses a constant voltage circuit with high frequency switching of 25KHz, for example, to make it compact! II Ja is desirable. Each output voltage is controlled by a control circuit 201.

The constant current generating circuit 203 is mainly used to measure low resistance, and the resistance to be measured is 1, for example, 1.96/, IA~19.
It has the function of not flowing a constant current of 6 liters. Each output current is controlled by a control circuit 201.

~Φ converter circuit 204 has channels CHI, CH
The control circuit 201 has a function of converting an analog signal inputted into the circuit 201 into, for example, an 8-bit digital signal pressure, and is controlled by a control circuit 201.

The measurement mode switching circuit 20 is controlled by the control circuit 201 and has a function of switching the resistance to be measured between a high constant voltage measurement mode and a low constant current measurement mode.

The voltage detection circuit 20g is used in the high constant voltage measurement mode.
H site, Takasada Nari IJE DCloOV, 25
It serves to keep the voltage input to the Φ converter circuit 204 constant regardless of whether the voltage is 0 V or 500 V.

The relay scanning units 211 to 2118 have a function of selecting a measurement location of the resistance to be measured.

The pinboard section 22 has the function of bringing the probe bin into electrical contact with the resistance to be measured.

Next, the operation will be explained. It is assumed that circuit pattern data, ie, master data, regarding a good quality printed wiring board is stored in the cassette magnetic tape device 15 or the R, AM 18.

(a), high constant voltage, high resistance measurement mode (measuring range IMΩ
~100MΩ) Data sent onto the CPU bus 24 is sent to the control circuit 201
The decoded output turns on the high constant voltage generation circuit 20, and the high voltage specified by the CPU 25 is output from the high constant voltage generation circuit 20.Measurement from the control circuit 201 Contacts ■ and ■ of the measurement mode switching circuit 208 are selected by the mode switching signal, and high voltage is applied from the high constant voltage generation circuit 20 to the relay scanning section 21. In the relay scanning section 21, the pin board section 22 is The measuring point of the resistor to be measured is selected.By applying a high voltage to the resistor to be measured, the flowing current is passed through the voltage detection circuit 201K to generate a voltage proportional to the resistor to be measured, and the voltage is ~ Channel CH of ω converter circuit 204
2 and undergoes digital conversion processing as a measured resistance value. The measured resistance value data (usually 8 bits) output from the A/D converter circuit 204 is transferred to the CI) U bus 24.
0, and is compared with the master data stored in the cassette magnetic tape device i15 or AM18 in the CPU 25. The comparison process in the present invention is characterized in that it is a comparison of resistance values themselves.

←), constant current low resistance measurement mode (measuring range 10Ω~2°5MΩ) The data sent on the CP[J bus 240 is the control circuit 20
1, the constant current generating circuit 201 is turned off by the decoded output, and the constant current specified by the CPU 25 is output from the constant current generating circuit 208. Contacts (1) and (2) of the measurement mode switching circuit 205 are selected by the measurement mode switching signal from the control circuit 201, and a constant current is applied to the relay scanning section 21 from the constant current generation circuit 20s. In the relay scan section 21, the pin board section 22
The measurement location of the resistor to be measured attached to is selected. Channel C of the Φ converter circuit 204 shows the voltage generated across the resistor to be measured by passing the constant current through the resistor to be measured.
) (1 and is digitally converted as a measured resistance value. ~Measurement resistance value data (for example, 8 bits) converted into a digital signal in the Φ converter circuit 204 is output to the CPU path 24G, and the resistance value data (e.g., 0) Comparative tests are carried out in the same way.

FIG. 3 is a flowchart showing an example of the operation flow of the present invention.

(f) Effects of the Invention The present invention is constructed and operates as described above.1 According to the present invention, the following effects occur.

First, to read connection information from a good printed wiring board,
The resistance value itself is read and stored, not just the 1" HQ PI bordering on the threshold value.

Similarly, in the inspection, instead of simply information of 1'' and '0'', the resistance value itself between the terminal areas of the printed wiring board to be inspected is read and compared with a pre-stored master data value for inspection. Therefore, it is a good product, but the wire is broken.

It is possible to accurately determine short circuits and insulation defects, and measure insulation resistance, and also to directly read resistance values at locations determined to be defective after inspection on a display or printer.

In addition, it is possible to provide a negative range for the resistance value from a good printed wiring board.

Therefore, it is possible to specify the error for non-defective products.

In addition, the above resistance value can be read and inspected, but
At the same time, the overall threshold value can also be determined. For example, the following passage:

Threshold value for disconnection: ioΩ~1001 (017 stages Short circuit threshold value: 10KQ~IMΩ 9 stages: Insulation resistance threshold value: IMΩ~100MΩ: 9 stages and further. In the case of insulation resistance inspection, 100V, 250■, 500■, etc.) Like,
The applied voltage can be selected.

[Brief explanation of the drawing]

Figure f41 is a block configuration diagram showing one embodiment of the present invention, Figure 2 is a block configuration diagram showing a specific example of the voltage generation resistance measuring section which is the main part of the present invention, and Figure 3 is a block diagram showing the operation flow of the present invention. FIG. 11...Key and display, 12...Key and display controller, 13.@-Printer, 14Φ...Printer controller, 15...-Cassette magnetic tape, 1611...Cassette magnetic tape controller%17・轡、ROM、１８・
・・几AM、19・・・Lamps and switches%20・
...Voltage generation resistance measuring section, 20I...Control circuit, 20
Mushroom: High constant voltage generation circuit, 203: Constant current generation circuit, 204: - Converter circuit, 205: O: Measurement mode switching circuit, 208: Voltage detection circuit. 211-2116...9 replay scan section, 22...
Bin board section 23 @ II m electrical box, 2
4, 246-241! ...-CPU path, 25...
CPU Patent applicant Kyoei Sangyo Co., Ltd. Agent Patent attorney Yutabe Kumagai

Claims (1)

[Claims] A high constant voltage generation circuit that generates a high constant voltage, a constant current generation circuit that generates a constant current, and a high constant voltage output from the high constant voltage generation circuit or a constant current output from the constant current generation circuit. a measurement mode switching circuit that selects one of them and connects it to the relay scanning section; and an A/D converter circuit that converts the resistance value data to be measured obtained through the relay scanning section and the measurement mode switching circuit into a digital signal. , Voltage detection in which the level of the resistance color data to be measured corresponding to all the constant voltage values outputted during the high resistance measurement mode using the high constant voltage generating circuit is kept constant and input to the converter circuit (A/1). a circuit, a central processing unit that compares and inspects the resistance value data to be measured and mask data output from the N small converter circuit, and a control unit that decodes the data from the central processing unit and controls each circuit. Printed wiring board inspection device 0 characterized by comprising a circuit