MIL-STD-750 Test Methods For Semiconductor DevicesThis standard establishes uniform methods and procedures for testing semiconductor devices suitable for use within Military and Aerospace electronic systems. The methods and procedures in the various parts of this standard cover basic environmental, physical, and electrical tests to determine resistance to deleterious effects of natural elements and conditions surrounding military and space operations. For the purpose of this standard, the term quot;devicesquot; includes such items as transistors, diodes, voltage regulators, rectifiers, tunnel diodes, and other related parts. This standard is intended to apply only to semiconductor devices. The test methods and procedures described in the various parts of this multipart test method standard have been prepared to serve several purposes: a. To specify suitable conditions obtainable in the laboratory that give test results equivalent to the actual service conditions existing in the field and to obtain reproducibility of the results of tests. The test methods described by this standard are not to be interpreted as an exact and conclusive representation of actual service operation in any one geographic location since it is known that the only true test for operation in a specific location is an actual service test at that point. b. To describe, in a series of standards, all of the test methods of a similar character which now appear in the various joint-services semiconductor device specifications so that these test methods may be kept uniform and thus result in conservation of equipment, man-hours, and testing facilities. In achieving this objective, it is necessary to make each of the general test methods adaptable to a broad range of devices. c. The test methods described by this standard for environmental, physical, and electrical testing of semiconductor devices shall also apply, when applicable, to parts not covered by an approved military sheet-form standard, specification sheet, or drawing.

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MIL-STO-750F

w/CHANGE 1

4.5 Requirements for high temperature reverse bias (HTRB) and burn-in.

a. The temperature of +20°C minimum is the ambient air temperature to which all devices should be exposed during power screening where room ambient is specified.

b. An increase in effective ambient temperature from cumulative induced power to OUT shall not result in device junction temperature exceeding maximum ratings.

c. For HTRB, the coolest ambient temperature shall be below the required minimum when measured in the various locations of convection currents (below or above) or upstream or downstream (fan air) of OUT.

d. Moving air greater than 30 CFM (natural convection) may be allowed for the purpose of temperature equalization within high device density burn-in racks.

e. Power up of burn-in racks may occur when ambient is less than specified. When thermal equilibrium has been reached, or 5 hours (maximum) has passed, the ambient shall be at the specified value. Time accrued prior to reaching the specified ambient shall not be counted for life test duration.

f. If the ambient, at or beyond the 5 hour point is not the specified value, a nonconformance exists and requires corrective action.

g. Time is not chargeable during the period when specified conditions are not maintained. If device maximum ratings are exceeded and the manufacturer intends to submit the lot affected, the product on test shall be evaluated by re-starting the burn-in or HTRB from zero hours at the specified temperature and verifying that the end-point failure rate is typical for this product type from a review of established records.

h. Chamber temperature for HTRB and burn-in shall be controlled to ±3 percent of the specified value (unless otherwise specified 4.1.1). This temperature shall be maintained within the chamber. Forced air may be used to equalize temperature within the chamber but shall not be used as a coolant to increase device power capability.

4.6 Bias requirements.

a. Bias errors at the power supply source caused by changing power supply loads during temperature transitions shall not exceed ±5 percent of that specified value.

b. Bias values at the source, during stabilized conditions, shall not exceed ±3 percent of the specified value. c. Burn-in apparatus shall be arranged so as to result in the approximate average power dissipation for each

device whether devices are tested individually or in a group. Bias and burn-in circuitry tolerances should not

vary test conditions to individual devices by more than ±5 percent of specified conditions.

d. Normal variation in individual device characteristics need not be compensated for by burn-in circuitry.

e. Burn-in equipment shall be arranged so that the existence of failed or abnormal devices in a group does not negate the effect of the test for other devices in the group. Periodic verification will assure that specified conditions are being maintained. Verification shall be performed, as a minimum, at the start and at the end of screening.

f. Lead, stud, or case mounted devices shall be mounted in their normal mounting configuration and the point of mechanical connection shall be maintained at no less than the specified ambient.