SU1310754A1 - Method of determining junction-case thermal resistance of digital integrated circuits - Google Patents

Abstract

The invention can be used to control the quality of digital integrated circuits (HC). The purpose of the invention is to improve the accuracy of measuring the thermal resistance of the IC. A device that implements the method contains a terminal block 1 for connecting a digital IC, a power supply source 2, a generator of 3 switching pulses, a modulator 4, a harmonic oscillator 5, a large-scale amplifier 6, a selective voltmeter 7. The logic elements of the IC are supplied with pulses modulated according to a harmonic law with a period that is by an order of magnitude longer than the thermal constant of the time of a given type of IC, the variable component of the electrical temperature-sensitive parameter is measured at the modulation frequency. 1 il. 19 (L O5 about 01 4

Description

eleven

The invention relates to a measurement technique and can be used to control the quality of digital integrated circuits and to estimate their temperature reserves,

The purpose of the invention is to improve the accuracy of measuring the thermal resistance of integrated circuits by measuring the variable component of the temperature-sensitive parameter when modulating the heating power due to the frequency modulation of the pulses applied to the input of the microcircuit.

The goal is achieved by changing the logic state of one or several logic elements (LE) of an integrated circuit by applying switching pulses to their inputs and measuring the temperature-sensitive parameter of that LE whose logical state does not change, while the switching pulse frequency changes according to a harmonic law with a known amplitude and a period of 1, which exceeds by an order of magnitude the thermal constant of time, the transition of the body of a given type of microcircuit, and the variable component emperaturochuvstvitel- Nogo parameter on the frequency modulation

QM ()

To improve the accuracy of measurement, the amplitude of the temperature-sensitive parameter at the modulation frequency Q / "is measured using a selective voltmeter.

The essence of the proposed method consists in the following. The power P dissipated by the microcircuit increases linearly with the switching frequency F

RS

KP-F,

(one)

where PO is the average power dissipated by the chip at a switching frequency F, tending to zero;

Kp is the steepness of the P (F) dependence. In particular, for MOS and CMOS ICs PO, and K

V with AND

.xMon - h - n

R.MOP

 cu;

respectively, where C is the capacitive load of the sync signal; and ,, - the amplitude of the sync signals; С „is the load capacity of the microchip; Uf, is the power supply voltage of the microcircuit.

Thus, when changing the switching frequency according to the law

Fo fo uf. cos,

t

where FU is the average switching frequency;

uf - frequency deviation, the power dissipated by the microcircuit, also harmonically varies with the frequency P m:

P (t) P „+ R

,

(3)

Kpfo

wed

where Pep PO + UP Cr- bf.

If the period of modulation of power T 1 / Q is much longer than the thermal time constant of the transition — the body of the microcircuit TP, then for the crystal surface temperature of the microcircuit can be written

0

five

0

0

cr where T

 T

+ B g

(four)

T P - P

T. t, nk

IT R

Wed t. IO-K

wed

 t +

The average surface temperature of the crystal chip; the temperature of the body of the chip;

thermal resistance of the trans- - microcircuit case.

R

so n

LR

Kp bf.

(five)

 T, nk

Then, measuring the amplitude of the variable component of the temperature-sensitive parameter PT at the frequency P, it is easy to determine

Rr.fi-Al:

TO,

.Dj- - K,

6f

(6)

t P

where temperature coefficient of temperature-sensitive parameter.

In order to increase the useful signal and, consequently, measurement accuracy, it is necessary to increase the modulation depth. To do this, you need to select the average switching frequency F | and frequency deviation equal to half the maximum frequency

Switch O5 F.

The proposed method can be implemented using a device whose block diagram is shown in the drawing.

The device contains a terminal block for connecting a digital integrated circuit 1 containing n LE, power supply 2, generator 3 switching pulses,

31

modulator 4, generator 5 harmonic oscillations, large-scale amplifier 6 and selective voltmeter 7,

The method is carried out by the example of this device as follows.

The microcircuit 1 is supplied with the supply voltage from the power source 2 of size E. The inputs of several (K) LEs (where K p) provide switching pulses with a tracking frequency F from the generator 3. Using the modulator 4 and the generator 5, the switching frequency of the switching pulses change according to a harmonic law with a given period and frequency deviation l. The variable component of the temperature parameter of the nth LE- (voltage I) is amplified with a scale amplifier 6- and measured with a voltmeter 7. With an appropriate selection of the gain factor of amplifier 6, you can get a reading of the voltmeter 7 in units of thermal resistance in the selected system of units ( scale) ..

As a temperature-sensitive parameter, you can use the output voltage O or 1. The temperature coefficient can be

Or A. Ogar 1887/42

Compiled by V.Stepankin Tehred A. Kravchuk

Cor

Under

Circulation 731 VNIIPI USSR State Committee

for inventions and discoveries 113035, Moscow, Zh-35, Raushsk nab., 4/5

Production and printing company, Uzhgorod, Projecto st., 4

0754

five

five

0

determined by known temperature dependencies.

Formula of the invention. The method of measuring thermal resistance of a junction is a digital integrated circuit package, which consists in supplying a voltage to a controlled integrated circuit, inputting one or more logic elements of an integrated circuit, another logic element preset. to a predetermined output logic state, the electrical temperature-sensitive parameters of this logic element are measured; The transition resistance — an integrated microcircuit case, characterized in that, in order to increase the measurement accuracy, the pulse frequency of the input pulses is modulated according to a harmonic law with a period that is much longer than the thermal time constant of this type of integrated circuits, and electrical temperature parameter at the modulation frequency.

Proofreader A.Zimokosov

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Claims (1)

SUMMARY OF THE INVENTION A method for measuring the thermal resistance of a junction is a case of digital integrated circuits, which consists in supplying a supply voltage to a controlled integrated circuit, supplying input pulses to the inputs of one or more logic elements of an integrated circuit, and setting another logic element to a predetermined output logical state, measure the electrical temperature-sensitive parameters of this logic element; the thermal resistance transition - integrated circuit case, characterized in that, in order to increase the measurement accuracy, the pulse repetition rate of the input pulses is modulated according to a harmonic law with a period an order of magnitude greater than the thermal time constant of this type of integrated circuit, and the variable component is measured, an electrical temperature-sensitive parameter at a frequency modulation.