SU634290A1 - Apparatus for monitoring metallization of printed circuit board apertures - Google Patents

Description

the input of the code converter and the second input of the comparator unit, the third input of which is connected to the second register, the input and the second output of the program distributor are connected to the current generator, and the third output is connected to the program control unit.

The block diagram of the device shown in the drawing.

The device consists of a software control unit 1, a coordinate positioner 2 having an actuating unit 3 and a clamping device 4 for fixing the board, a first probe head 5 with a current 6 and measuring 7 probes, a second probe head 8 with a current 9 and measuring 10 probes, a software the distributor 11, the current generator 12, the voltage meter 13, the first register 14, the second register 15, the comparison unit 16, the output unit 17, the adder 18, the code converter 19 and the registration unit 20.

The control output of the software control unit I is connected to the coordinate positioner 2 by control and feedback buses. This block is used to automatically programmatically control the positioning and feeding of tools installed on the actuating unit 3. The program carrier can be standard punched tape. Probe bays 5 and 8 are installed on the actuating unit 3 as tools so that the same type of probes of opposing heads (current probes 6, 9 and measuring 7, 10) are aligned and directed towards each other, and in the gap between them perpendicular to the probes placed secured in the device 4 is controlled by the board 21.

The measuring probes 7 and 10 are connected to the input of the measuring device 13, which has a code output of the measured voltage. Current probes 6 and 9 are connected in parallel with the output of the current generator 12 and the input of the program distributor 11.

The distributor 11 serves to record the closing moment of the circuit of current probes, the subsequent issuance of control signals to turn on the current, start the control operation and start the continuation of the automatic control program after the end of the control of the next hole. The second control output of the distributor 11 is connected to the input of the generator 12, the third output is connected to the input of the program control unit 1, and the first output is connected to the first (control) input of the comparison unit 16.

Register 15 is used to record and store a number equal to the rejection threshold of the monitored hole in terms of the value of the measured voltage (expressing the resistance value). The register 14, associated with the output of the voltage meter 13, is a buffer register for storing the voltage code received from this meter. The outputs of registers 14 and 15 are connected respectively to the second and third inputs of the comparison unit 16, which serves to compare the value of the measured voltage with the threshold value set at 5. The output of this block is connected to the output of the output block 17. The outputs of the register 14 and the output block 17 are connected respectively to the third and first inputs of the code converter 19, which serves to (j convert the incoming registration codes into the form required for the registering device and distribute the output characters in accordance with the required registration form.

The second (code) output of the software control unit 1 is connected to the input of a sumpmator 18, designed to obtain the absolute values of the coordinates X and Y of the monitored holes on the board by algebraically summing the increments of coordinates when the probes pass from one hole to another. The output of the adder 18 is connected to the second input of the code converter 19, the output of which is connected to the registration unit 20.

A digital printing device can be used as a block 20. And as a coordinate positioner 2, a nrohm-controlled drilling machine can be used for drilling printed circuit boards, which has a drilling and counter-located countersink chipping. In this case, the feed mechanism of the countersink pinch is rebuilt to simultaneously feed it with the drill pin, the voltage on the pin rotation motor is not supplied, and the measuring heads are mounted on the spindles x instead of the cartridges.

The device works as follows.

The board 21 to be monitored is fixed in the clamping device 4 of the positioner 2. The probe heads 5, 8 are brought to the starting point on the board, from which the control is started according to the program. Register 15 registers the threshold value of the voltage corresponding to the level of rejection of low-quality holes. In block 1, a monitoring program is entered and the automatic operation of the device is started.

The probe heads alternately approach each of the holes indicated in the program and automatically press against its contact pads on opposite sides of the board.

Claims (2)

If there is metallization in the hole, the contact of the current probes 6 and 9 with the contact pads causes the electrical circuit between these probes to flush, as a result of which a control operation start signal is generated in the distributor 11. At the second output of unit 1, a current-switching signal delayed by the time of the chatter of the probes appears. which is supplied to current generator 12. This signal from generator 12 into the circuit of current probes 6 and 9 is supplied with a current of a calibrated value, for example, 1a, as a result of which a potential difference is created between measuring probes 7 and 10, which is fed to the input of voltage meter 13. At the output of the meter 13, the measured voltage code appears, which is received in the register 14. After a certain delay equal to the response time of the meter 13, at the first output of the block 11 a polling pulse appears at the first input of the comparison unit 16. H and the two code inputs of block 16 are provided with codes from registers 14 and 15. The polling result signals, determining whether or not the measured voltage exceeds a specified threshold value, are output from block 16 to input of output block 17, which produces an information output signal. This signal and the polling result code from the output of block 17 together with the voltage Kodo from register 14 are fed to the first input of converter 19. To the second input of converter 19 from adder 18, the absolute coordinate codes X and The hole being tested. Using the trigger signal received from block 17 in converter 19, code conversion of the numbers given at its inputs into the form required for registration begins and the information recorded in block 20 is output in such a sequence that is convenient for the consumer. For example, the output information can be recorded in the following sequence: "Measurement number - X coordinate - Y coordinate - Resistance value - Threshold exceeding indicator. The measurement number is set by the measurement number counter included in block 19. The device has two output modes. The first mode is the output mode of the inspection results of each hole, and the second mode is the output mode of the inspection results of only defective holes. After the end of the output information current. supplied to the current probes 6, 9 from the current generator 12, is turned off by the signal that enters the generator from the distributor 11. The probe heads are retracted from the board and the next program frame begins to be processed. If after clamping the probe heads to the circuit of the current circuit does not occur - due to the complete absence of metallization in the hole or due to incorrect positioning of the heads (no probes are installed on the hole), then the start signal of the distributor 11 will not be issued, on the third its output by Wits is the stop signal of the automatic operation of the device, which enters unit 1. Continuation of the automatic control of the program after the correction of the error is performed by pressing the start button again. The use of this device has the following advantages: manual labor for finding a controlled hole is eliminated. installation and installation of measuring probes on it; the probability of missing a hole to be monitored due to loss of attention is eliminated; the subjectivity of the evaluation of the measurement result is excluded, since objective recording of the results is carried out, for example, printing; reduction in labor productivity due to employee fatigue during the manual process is eliminated. As a result, the use of the described automatic device increases the overall productivity when checking the metallization of a large number of holes in printed circuit boards. Claims An apparatus for controlling the metallization of holes in printed circuit boards, comprising a software control block, connected to a coordinate positioner with two current and two measuring probes located therein, connected respectively to a current generator and a voltage meter, and a recording unit differing in that, in order to increase the reliability of the control and speed of the device, it contains a sum.mator, first and second registers and serially connected program distributor, a block with An output unit and a code converter, the second input of which is connected to the program control unit through the sum. The output is connected to the registration block, the input of the first register is connected to the output of the voltage meter, and the output is connected to the third input of the code converter and the second the input of the comparison unit, the third input of which is connected to the second register, the input and the second output of the program distributor are connected to the current generator, and the third output is connected to the program control unit. Sources of information taken into account in the examination: 1. US patent number 3766470, cl. 324-64, 08/13/73. 2. “Electronic Packaging and Production 1974, V. 14., No. 8, p. 68.