SU1580597A1 - Device for checking multilayer printed circuit boards - Google Patents

Abstract

This invention relates to a control technique for printed circuit boards. The purpose of the invention is to increase the reliability and performance of the control. The control device for multilayer printed circuit boards contains a conductive plate 1 with an insulating gasket 2, which is designed to accommodate a controlled printed circuit board 3, under a spring-loaded probe, a capacitance meter 7, the first input of which is connected to the conductive plate 1, and the second with a probe , an additional conductive plate 4 connected to the first input of the capacitance meter 6, and a second insulating gasket 5 placed opposite the first insulating with clamping between it and controlled circuit board. The second conductive plate and the second insulating gasket have openings for the probe to access the conductors on the printed circuit board. The probe, the passage through the holes of the second plate and the second insulating gasket, is in contact with the conductors on the printed circuit board. With a capacitance meter, the capacitance resistance of each conductor of a printed circuit board relative to metal plates is measured and compared with reference values. 2 hp f-ly, 6 ill.

Description

6 is connected to the actuator 10 of the vertical approach of the probe 6 to the test PCB 3 with the help of rod 11. A contact is connected that is connected to the second g of the input capacitance meter.

Each conductor on the printed circuit board 3, regardless of which side of the printed circuit board passes, or even if it passes along both sides of the printed circuit board 3, which is most common, is completely monitored, as it forms one capacitor plate over its entire length, The metal plate 1 and the metal plate A are a friend to the capacitor plate. For accuracy of control, the probe 6 in the control process must contact each end of the conductor, and if the conductor is branched, then with the end of each branch. If the conductor on the printed circuit board has a break (Fig. 3a), then the capacitance measured at one of the points 21 or 22 will be at least two times smaller than the reference for the whole conductor. If the conductor on the printed circuit board is broken (Fig. 3b), then the capacitance measured at point 21 will differ slightly from this and may be within tolerance, but when measuring capacitance at point 22, its value will differ many times from given. It is known that the capacitance is directly proportional to the area of the capacitor plates, therefore, knowing the topology of the printed circuit board, the control device can always calculate the exact location of the break. In the case of a branched conductor (Fig. Sv), the location of the break is found by measuring the capacitance at points 21 and 22 (at these points the capacitance is the same and recalculating it to the area of conductors or measuring the capacitance at points 23-25 and recalculating it to the area. Know the printed layout If the conductors on a printed circuit board with an area of one order are short-circuited with one another (Fig. 3 rj, then the electrical capacitance measured at points 21-24 will have one magnitude and no less than two times as much as If the conductors on the printed circuit board, having areas that differ sharply from one another, have a short circuit to one another (Fig. 3 d), then the electrical capacitance measured at points 21 and 22 will be small. differ from the reference and may be within the tolerance, but when measuring the capacitance exactly

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At 23 and 24, the capacitance value will be much larger than the capacitance value for the reference conductor, and equal to the capacitance measured at points 21 and 22.

Thus, it follows from the above examples that the proposed control device for printed circuit boards is able to detect faults of the type of breakage and short circuit on the printed circuit boards, as well as sufficiently accurately determine the location of the fault of the type of breakage.

In addition, the measured capacitance of the conductors on the printed circuit board and the capacitance value of the reference printed circuit board or the calculated capacitance values of the conductors, the control device, by recalculating the capacitances in the conductor area, determines the overtravel and undertravel values, and controls the quality of the printed circuit board manufacturing of printed circuit boards.

The device works as follows.

A printed circuit board 3 is placed between a metal plate 4 with an insulating gasket 5 and a metal plate 1 with an insulating gasket 2 located on the coordinate table 9. The coordinate table positions the printed circuit board 3 relative to the probe 6. The probe 6 is lowered to the lower position by means of the actuator 10. spring-loaded contact, the passage through the holes in the metal plate 4 and the insulating gasket 5 does not touch the metal plate 4 and is in contact with the conductors on the printed circuit board 3. When the probe 6 contacts the conductor on the plate chutney board controller reads capacitance meter readings and compares them with reference values prepared in advance either by calculation or by deprotection of Great .chin capacitancies on a reference board.

The device control printed circuit boards (figure 5) works as follows.

A printed circuit board is placed on a metal plate 1 with an insulating gasket 2. The coordinate table 9 positions the printed circuit board 3 relative to the probe 6. The probe 6 and the plate 14 with a dielectric pad 15 are lowered to the lower position by means of the actuator 10. A metal plate 14 with an insulating gasket 15 is pressed against the free side of the printed circuit board, forming with the conductors located on this side of the printed circuit board, the capacitor plate (and the probe 6 is in contact with the contact pad of the printed circuit board. Due to the increased dimensions of the plate 14 and gaskets 15 condens1

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The capacitor is formed even when inspecting conductors located on the edge of the printed circuit board. Otherwise, the operation of this device is similar to the operation of the device shown in FIG.

The control unit of double-sided printed circuit boards (Fig. B) works as follows. The probe 20 is lowered to the lower position by the actuator 10. The contact of the probe 20, penetrating through the vias of the printed circuit boards 3 and 17 of the plates 19 and 4 and the gaskets 18 and 5, is sequentially in contact with the metallization of the vias of the monitored printed circuit boards 3 and 17, the Control Unit 1 3 sequentially -j reads information from the capacitance meter 7 The value of the capacitances of the conductors on the test printed circuit boards 17 and 13, In the rest of the operation of this device is similar. operation of the device represented by n, FIG. four.

The examples of specific implementation are not the only possible. The devices shown in FIG. 1, 4-6, capable of controlling multilayer printed circuit boards. For this, the shielding layers of multilayer printed circuit boards need to be connected in the process of control with the first output of a capacitance meter 7 "Additionally installed probes associated with the same drive i 10, as well as connected through a switch control device 13

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Claims (3)

1. A device for testing multilayer printed circuit boards containing a conductive plate with an insulating gasket adapted to accommodate a controlled printed circuit board on it, a spring-loaded probe, a capacitance meter, the first input of which is connected to the conductive plate and the second to spring-loaded probe, which is due to the fact that, in order to increase the reliability and control performance of multilayer printed circuit boards, a second conductive plate was additionally inserted into the device; and the first input capacitance meter and a second gasket izoliruyusha siting | opposite the first insulating gasket with the possibility of clamping a controlled circuit board between them, with openings in the second conductive plate and the second insulating gasket for the probe to access the printed circuit conductors. 2. A device according to claim 2, characterized in that the holes in the second conductive plate and the second insulating gasket are evenly spaced in the grid nodes of the monitored board. 3. The device according to paragraphs. 1 and 2, that is, the holes in the second conductive plate and the second insulating gasket are provided with dielectric conductor bushings. Utnepumesb its eGGOST / 0th SolrotiBesh FIG. 2 g; g; © © © yy but Th P ® yy ghgg Fig.E Compiled by N.Shmelev Editor A. Kozoriz Tehred M. Khodanich Proofreader L. Patay Order 2024 Circulation 695 VNIIPI State Committee for Inventions and Discoveries at the State Committee on Science and Technology of the USSR 113035, Moscow, Zh-35, Raushsk nab. 4/5 ZS Lg5 Subscription