SU1659924A1 - Method for testing integrated circuit pin contact quality - Google Patents

Abstract

The invention improves the reliability of control of contacting the IC at the stage of final operations when loading circuits into the contact devices of the electrothermal circuit boards. The purpose of the invention is to increase the reliability of the control. The signal from the pulse generator 4 is input to the chip 2 installed in the contacting unit 1 and connected from the source 3 of the power supply. The measurement unit 5 controls the difference between the voltage of the input and output signals, by which the value of the contact resistance is determined, is compared with the reference one. 2 hp ff, 2 ill.

Description

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The invention relates to an instrumentation technique and can be used in automated devices for controlling integrated circuits (ICs), in particular, at the stage of final operations.

The purpose of the invention is to increase the reliability of the control.

The control of contacting the IC by the deviation of the transient resistance from the specified value is based on the fact that, if the specified value of the transient resistance is observed, the circuit either ceases to function or its output signal levels do not correspond to the specified one.

When the minimum threshold voltage is supplied to the input of the IC, conditions are created under which a decrease in this voltage leads to the fact that the transitions of active elements that are part of the IC cannot open and the circuit stops functioning. Input actions cannot cause output signals, by the absence of which they are judged on the transient resistance in the contact zone.

By comparing the supply voltage and output levels, the difference in these levels is monitored. At the same time, the allowable difference is set as a function of the given resistance values in the contact zone. With any increase in the given (permissible) value of the transition resistance, the difference in levels is judged by which the quality of the contact is judged.

Thus, the method makes it possible to fix not only the two options is contact; There is no contact, but also intermediate values of transient resistance, which allows revealing of circuits with incompletely broken contacts.

FIG. Figures 1 and 2 show the voltage distribution patterns for varying transient resistances.

The control of contacting the IC (Fig. 1) is performed at points 1, 2, 3 and 4, where transient resistances Ri, Ra, Rzi R4 are measured. When the transition resistances Ri, Ra, Ra and R are equal to zero, 1) The output is bought, where k 1 is the coefficient; Uykh - output voltage; UPIT supply voltage, i.e. Contact satisfactory. When RI, R2. Ra and R4, large zero, 1) Output k U8x - (t); Out of voltage, where is the loss Input-voltage at a given frequency f, which indicates poor contacting. A circuit for implementing the method of controlling the contacting of the IC (Fig. 1) contains contact blocks 1.1-1-ps JC2, source 3

power supply, 4 pulse generator and control unit 5,

The IC 2 supplies power from the power source 3, and inputs from the generator 4 pulses are input. Using the control unit 5, control the deviation of the reference (at the input) and the signal being investigated (at the output). The difference in the levels between them was set as a function of the transient resistance. In case the difference is higher than the predetermined value of the transient resistance, the quality of the contact is unsatisfactory and the further route of the circuit is determined by the flow chart. In case the difference is equal or lower than the specified one, the conditions of contact are satisfactory. The desired value of the transition resistance is selected depending on the requirements of the circuit.

When the generator is turned on and the supply voltage is applied, the output voltage appears at the output of the IC under test, the levels O and 1 of which are determined by the transition resistance RI - R4. With RI - R4, equal to zero, Uv, where, in this case, the normalized values of Vin and O and 1 are specified in the unit of measurement. When RI is R4, large zero, the logic levels change, which is fixed by the measurement unit.

Assume that transition resistance R4 (Fig. 1) has become more normal, the current through R4 creates an additional voltage Un4, while in the measurement phase of the voltage Uvykh O the voltage UR4 is added to the IC under test, which will be classified by the measuring unit of poor quality contacting. The magnitude of the maximum allowable transient resistance is pre-entered by the operator in the measurement unit, with which the actual measurement is compared.

The measurement unit can record transients and below the minimum value (5-10 ohms). The values of UR4 and Oout O are determined by the Upit voltage, which is fed to the measurement unit to automate the contact verification process.

It is also possible to implement a method in which a minimum input voltage, UH, is set on the pulse generator, which, with the expected values of transient resistance, ensures the functioning of the IC under test. The measuring unit controls this signal. If there is a transient resistance (say, RI (Fig. 1) is larger than expected), an additional voltage URI appears, reducing the threshold input voltage directly at the IC output, which no longer allows the IC under test to affect the first input of the IC is terminated, which is fixed by the control unit 5. The proposed method makes it possible to fix a transient resistance of 15-100 ohms, which provides an increase in the reliability of control of contacting the IC, since it becomes possible to evaluate the quality of contact for various specified values of transient resistance.

Claims (3)

Claim 1. The method of controlling the contacting of integrated circuits, which consists in supplying voltage and impulse action to controlled circuits, measures an informative parameter, characterized in that, in order to increase the reliability of the control, before starting control on a reliable sample, a relationship is established between five 0 five of the informative parameter and the contact resistance of the microcircuits, during the test, the contact resistance is determined by the measured value of the informative parameter, it is compared with the reference value and the result of the comparison is judged on the quality of contacting the microcircuits, and the difference between the input and output voltage on the microchip. 2. A method according to claim 1, characterized in that when a pulse is applied to the input of the chip, its amplitude is equal to the threshold switching voltage of this type of integrated circuit, control the operation of the chip and, if present, consider the contacting to be satisfactory. 3. A method according to claim 1, characterized in that the difference between the supply voltage and the output voltage of the integrated circuit is taken as an informative parameter.