SU1541791A1 - Method and apparatus for testing laminated printed-circuit boards - Google Patents

Abstract

This invention relates to instrumentation technology. The purpose of the invention, the extension of the field of application, is achieved by ensuring control of multilayer printed circuit boards. The microwave oscillator 1, by means of the antenna 2, excites natural oscillations in the printed circuit board 3. The receiving antenna 4 moves with the help of the actuator 5 according to the law defined by block 6 over the surfaces and ends of the board 3. The signal received by the antenna 4 goes to the amplifier 7 and then to the amplitude measuring device 8. Upon completion of the amplitude distribution measurement, a dielectric plate 9 is superimposed on the surface of the board 3 and by means of antennas 10, 11 connected through an attenuator 12 and 13 to the generator 1, self-oscillations are excited in it, interacting with the self-oscillations of the board. The interaction of these oscillations gives an interference pattern on the surface of the plate 9, over which the amplitude distribution is measured. If the amplitude distributions obtained deviate from those obtained on the reference printed circuit board, the supervised circuit rejects. 2 sp.f-ly, 1 ill.

Description

The invention relates to a control measuring technique and can be used in the manufacture of multilayer printed circuit boards for quality control,

The purpose of the invention is to expand the field of application by controlling the multilayer printed circuit boards.

The drawing shows the block diagram of the device for the implementation of the method

The microwave generator is connected to the transmitting antesh 2B of the exciting multilayer printed circuit board. Ze Receiving antenna 4t connected to an actuator 5S connected to unit b for generating command pulses 9 with its output connected to an amplifier 7S measuring 8 amplitude Above the controlled surface of the board 3 a thin dielectric plate 9B is elapsed; two adjacent tords which are excited by additional 10 h 11 linear polarization antennas connected via attenuators 12 and 13 with generator 1 output,

The device operates as follows

The microwave generator i, using antenna 2, excites in a multilayer printed circuit board 3 its own oscillation types associated with printed conductors. If there are foreign objects near the board, then the type of oscillations being excited is identical to the gtp above the normal wave in a single-wire pin surrounded by a dielectric layer. If a multilayer PCB is placed with a small gap over a flat metal surface, then the type of oscillation is identical to the TEM type wave in an asymmetric strip line. If a multilayer PCB is positioned with some space over the same type of known defectless circuit, then the type of oscillation is identical to its own type in two-wire lines.

Electromagnetic waves propagating along the printed conductors interact with each other (since the configuration and arrangement of the printed conductors are quite different since HOD 6 is different, it is not possible to calculate the floor in this case) and create amplitude-phase phase on the surfaces and the ends of the printed circuit board.

distribution (PRA), characteristic of this type of boards (their topology).

A complete defect (partial or complete rupture, thinning of the conductor, undermining, dirt getting into the metallization, the detachment of dielectrics, etc.) behaves as a non-uniformly incorporated into the line and thus changes the amplitude and / or phase of the transmitted and reflected waves5 which, in turn, leads to a change in the resulting PRA.

The block b by means of the actuator 5 moves the receiving antenna 4 according to a certain law over the surfaces and the ends of the board 3. The signal received by the antenna 4 is fed to the amplifier 7 and then to the amplitude meter 8.

Upon completion of the measurement of the amplitude distribution, the dielectric plate 9 is superimposed on the surface of the board 3 and, by means of additional antennas 10 and I connected via attenuators 12 and 13 to generator i, excites in it self-oscillations interacting with the own oscillations of the board associated with the conductors. The interaction of these oscillations produces on the surface of the plate 9 an interference pattern, the amplitude distribution of which is measured by a circuit connected in series by antenna 4, amplifier 7 and meter 8.

If the amplitude distributions obtained are deviated from those received on the reference board, the monitored board rejects.

Claims (2)

1. A method for controlling multilayer printed circuit boards 8 consisting in that the object being monitored is irradiated with an electromagnetic microwave wave, the parameters of the signal interacting with the object are measured, and the presence of defects is measured according to the measurement results, in order to expand the field of application , in a printed circuit board, the eigen oscillations are excited, the amplitude distribution on the surfaces of the plate ends is measured, and then the eigenmodes in the dielectric plate, interacting with their own By the actual board oscillations, the amplitude distribution of the interference pattern thus obtained is measured, and by comparing the amplitude distributions with the corresponding distributions of the reference board, the presence of defects is judged. 2. A device for controlling multi-layer printed circuit boards containing a microwave generator, transmitting and receiving antennas, an amplifier, an amp meter Actuators, actuators associated with the receiving antenna, a unit for generating command pulses controlling the actuator, characterized in that, in order to expand the field of application, a dielectric plate is located on the surface to be monitored, linear polarization antennas are additionally introduced, attenuators with the output of the microwave generator.