CN1125988C - Steady-state service life test method by controlling junction temp of transistor - Google Patents

Abstract

The invention relates to a steady-state working life test method for controlling transistor junction temperature, which belongs to the technical field of semiconductor devices. According to the approximately linear relationship between the forward voltage drop of the emitter junction and the junction temperature of the transistor, and by using the regular momentary disconnection time interval of the working current during the test, the test sample tube is calculated by measuring the forward voltage drop of the emitter junction under a certain test current. The junction temperature of the semiconductor cooler is used as the heat sink, and the measurement result of the forward voltage drop of the emitter junction is used as the control signal, and the heat dissipation condition is adjusted by changing the current or voltage of the semiconductor cooler to realize automatic control of the junction temperature. The invention has very positive significance for improving the credibility of the test.

Description

In transistor steady state operation life process of the test, measure the method for junction temperature in real time

The invention belongs to technical field of semiconductor device.

Transistor steady state operation life test is to apply with the corresponding maximum rated power of this temperature to transistor under the test temperature of regulation and make it the fail-test project of continuous working in official hour.The test condition of the power transistor steady state operation life test of stipulating among international standard IEC747-7-1988 and China standard GB/T4587-94 that is equal to it and the MILSTD MIL-STD-750B at present, all is maximum rated power and its corresponding shell temperature.Press T _j=P _Tot* R _{Th (j-c)}+ T _cCalculate, with this understanding, have only as transistorized knot-shell thermal resistance R _{Th (j-c)}During for design load, transistorized junction temperature just can reach maximum allowable junction temperature T _JMAnd the R of power transistor reality _{Th (j-c)}Generally all little than design load, for example: press the SJ3128-88 standard code, the P of 3DD820 transistor npn npn _Totmax=30W (T _c=75 ℃), maximum allowable junction temperature T _JM=150 ℃, calculate its R thus _{Th (j-c)}Design load be 2.5 ℃/W.But actual measurement shows: the R of Metal Packaging 3DD820 transistor npn npn _{Th (j-c)}Generally be not more than 1.0 ℃/W, and the steady state operation life test condition of this standard code is P _Totmax=30W (T _Case=75 ± 5 ℃).Obviously, carry out the steady state operation life test with this understanding, transistorized junction temperature T _j≤ 110 ℃, well below maximum allowable junction temperature T _JMAnd power transistor to carry out the time of steady state operation life test be by applying maximum rated power P _TotmaxAnd at maximum allowable junction temperature T _JMFollowing continuous working reaches that a certain cumulative failure probability F (t) calculates.T in the process of the test _jReduction, cause in the test period of regulation, not reaching the F (t) of requirement, this has just reduced the confidence level of test.Thereby make some reliability levels be mistaken as the high reliability device by not high device, use to complete machine and bury reliability hidden danger.In order to overcome the problems referred to above, the test condition with the steady state operation life test among China military standard GJB128A-97 " semi-conductor discrete device test method " and the GJB33A-97 " semi-conductor discrete device general specification " changes maximum rated power and maximum allowable junction temperature into.But have not yet to see the report of the steady-state service life test method that the oxide-semiconductor control transistors junction temperature is arranged both at home and abroad.

The objective of the invention is to improve the confidence level of power transistor steady state operation life test, a kind of steady-state service life test method that can measure junction temp of transistor and junction temperature is maintained the oxide-semiconductor control transistors junction temperature of maximum allowable junction temperature by the regulation and control cooling system in process of the test is provided.

Studies show that emitter junction forward voltage drop V _BEWith junction temperature T _jIn quite wide temperature range, has approximate linear, with V under the different electric currents _BE～T _jThe linear approximate relationship reverse extending to absolute zero, find that they converge at a bit, the voltage of convergent point is about 1267mV.Utilize this relation,, carry out moment disconnection clocklike, can utilize this transient OFF time (being generally less than 100 microseconds) by under certain measuring current, measuring V as long as in the steady state operation life process of the test _BECalculate junction temperature T _jSimultaneously, utilize semiconductor cooler to make heating radiator, with V _BEMeasurement result as control signal, utilize automaton, adjust radiating condition by the curtage that changes semiconductor cooler, can realize the automatic control of junction temperature easily.

Hookup schematic diagram of the present invention as shown in Figure 1.Concrete implementation step is:

The first step, switch S and I _MConnect, measure electric current I _MFlow into sample pipe (T), measure the emitter junction forward voltage drop V of this moment _BE0, corresponding junction temperature is T _J0(common T _J0Equal the gentle room temperature of shell).

Second step is according to V under the steady current _BEWith T _jLinear approximate relationship and converge characteristic, by formula ${\mathrm{\α}}_{V_{\mathrm{BE}}}=\frac{V_{\mathrm{BE}0}-1267}{273+\mathrm{Ta}}$ Calculate the temperature coefficient α of emitter junction forward voltage drop under this electric current _VEB, α _VEB＜0.

The 3rd step, at t=0 constantly with switch S and I _HConnect working current I _HInflow transistor is at t _OnTime is (generally 10～10 ²Second) in, junction temperature is from T _J0Rise to T _J1

The 4th step is at t=t _OnConstantly with switch S and I _HDisconnect and and I _MConnect, at t _OffIn time (being generally less than 100 microseconds),, measure emitter junction forward voltage drop V through after certain time delay _BE1, utilize formula $T_{j1}=\frac{V_{\mathrm{BE}1}-V_{\mathrm{BE}0}}{{\mathrm{\α}}_{V_{\mathrm{BE}}}}+T_{j0}$ Calculate junction temperature T _J1

The 5th step is with T _J1With the junction temperature T that stipulates in the standard _jCompare, and remove to adjust radiating condition according to comparative result.

In the 6th step, the junction temperature measured for n time of repeating step three to four, the is repeatedly: $T_{\mathrm{jn}}=\frac{V_{\mathrm{BEn}}-V_{\mathrm{BE}0}}{{\mathrm{\α}}_{V_{\mathrm{BE}}}}+T_{j0}$ With T _JnWith the junction temperature T that stipulates in the standard _jCompare, and remove to adjust radiating condition, thereby junction temperature is maintained in the temperature range of regulation according to comparative result.This moment the shell temperature should be not less than with this maximum rated power accordingly with reference to the shell temperature.

The purpose that the present invention has realized measuring junction temperature in transistor steady state operation life process of the test and junction temperature maintained maximum allowable junction temperature by the regulation and control cooling system, to the confidence level of implementing GJB, raising and warranty test and the reliability that guarantees military device, and then the reliability that improves the national defence electronic engineering had very positive meaning, and to the waste of avoiding the device production field, reducing production costs has positive impetus.Simultaneously, the present invention's method can be measured the associated hot electrical quantity of device in process of the test and compare in real time, this be control shell temperature test method can't accomplish.This real-time measurement and comparison have positive meaning for selecting of high reliability device.For example, the measurement result according to junction temperature and shell temperature can calculate crust thermal resistance R _{Th (j-c)}, the R that fore-and-aft survey is obtained _{Th (j-c)}Compare, can judge the thermal stability of device.

Below be description of drawings:

Fig. 1 is a hookup schematic diagram of the present invention.

Fig. 2 is a testing equipment block scheme of the present invention.

Fig. 3 is pulse sequence and a junction temperature curve map among the present invention.

Wherein, I _H, working current source, I _M, measuring current source, S, switch, I _E, reometer, T, experimental sample tube, V _CC, working voltage source; 21, bias supply, 22, power source special, 23, experimental sample tube, 24, measuring-signal sampling system, 25, main control computer, 26, control system, 27, cooling system; 31, I _MInjected pulse, 32, V _BEThe sampling delayed pulse, 33, V _BESampling pulse, 34, I _HInjected pulse, 35, T _jChange curve.

Below in conjunction with drawings and Examples the present invention is made the following instructions:

Embodiment:

The testing equipment block scheme of one of embodiment of the invention as shown in Figure 2.Wherein, bias supply provides operating voltage and working current to the sample pipe, power source special provides the measurement electric current to the sample pipe, cooling system provides radiating condition to the sample pipe, the measuring-signal sampling system is taken a sample to the electrical quantity that characterizes sample duct ligation temperature and is sent into main control computer, main control computer carries out signal Processing and sends instruction to control system, the work of control system regulation and control power supply and cooling system.The concrete steps of test such as above-mentioned first to the 6th step.Measuring current pulse I in the process of the test _M, heating current pulse I _H, V _BESampling delayed pulse, sampling pulse, junction temperature T _jVariation as shown in Figure 3.This shows t _OffMore little, variations injunction temperature is more little; t _OnLittler, the control accuracy of junction temperature is higher.The concrete condition that should look experimental sample tube in the test is determined t _OffAnd t _OnSize.

Claims (1)

1, a kind of method of in transistor steady state operation life process of the test, measuring junction temperature in real time, it is characterized in that, the base stage of measured transistor T is as the common port of metering circuit, and the collector junction of transistor T links to each other with voltage source, emitter junction by switch S respectively with measure electric current constant current source I _MWith working current constant current source I _HLink to each other; According to transistor emitter junction forward voltage drop V _BBWith junction temperature T _JLinear approximate relationship and converge characteristic, utilize in the measuring process working current clocklike transient OFF time at interval, by under measuring current, measuring emitter junction forward voltage drop V _BBCalculate the junction temperature T of transistor T _JUtilize semiconductor cooler to make heating radiator simultaneously, with emitter junction forward voltage drop V _BBMeasurement result as control signal, utilize automaton, adjust radiating condition by the curtage that changes semiconductor cooler, realize the automatic control of junction temperature; Measuring process is as follows: (1) switch S and constant current source I _MConnect, measure electric current I _MInflow transistor T measures the emitter junction forward voltage drop V of this moment _BE0, corresponding junction temperature is T _J0, T _J0Equal the gentle room temperature of shell; (2) according to emitter junction forward voltage drop V under the steady current _BEWith junction temperature T _jLinear approximate relationship and converge characteristic, by formula ${\mathrm{\α}}_{V_{\mathrm{BE}}}=\frac{V_{\mathrm{BE}0}-1267}{273+\mathrm{Ta}}$ Calculate the temperature coefficient α of emitter junction forward voltage drop under this electric current _VEB, α _VEB＜0; (3) at t=0 constantly with switch S and working current I _HConnect working current I _HInflow transistor T is at t _OnIn time, junction temperature is from T _J0Rise to T _J1, t _OnTime is 10-10 ²Second; (4) at t=t _OnConstantly with switch S and working current I _HDisconnect and with measure electric current I _MConnect, at t _OffIn time, measure emitter junction forward voltage drop V _BE1, utilize formula $T_{\mathrm{ji}}=\frac{V_{\mathrm{BE}1}-V_{\mathrm{BE}0}}{{\mathrm{\α}}_{V_{\mathrm{BE}}}}+T_{j0}$ Calculate junction temperature T _J1, t _OffLess than 100 microseconds; (5) with T _J1With the junction temperature T that stipulates in the standard _jCompare, and remove to adjust radiating condition according to comparative result; (6) junction temperature measured for n time of repeating step three to four, the is repeatedly: $T_{\mathrm{jn}}=\frac{V_{\mathrm{BEn}}-V_{\mathrm{BE}0}}{{\mathrm{\α}}_{V_{\mathrm{BE}}}}+T_{j0}$ With T _JnWith the junction temperature T that stipulates in the standard _jCompare, and remove to adjust radiating condition, thereby junction temperature is maintained in the temperature range of regulation according to comparative result.This moment the shell temperature should be not less than with this maximum rated power accordingly with reference to the shell temperature.

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