MIL- STD-883F 2004 TEST METHOD STANDARD MICROCIRCUITS - 第38页

MIL-STD-883F METHOD 1005.8 1 June 1993 4 3.4 Test sample . The tes t sampl e shall be as spec ifi ed (see 4) . W hen t his t est met hod is empl oyed as an add-on l ife test for a s eries or fami ly of devi ce types , le…

MIL-STD-883F

METHOD 1005.8

1 June 1993

3.3 Measurements

3.3.1 Measurements for test temperatures less than or equal to 150°C

. Unless otherwise specified, all specified

intermediate and end-point measurements shall be completed within 96 hours after removal of the device from the specified

test conditions (i.e., either removal of temperature or bias). If these measurements cannot be completed within 96 hours,

the devices shall be subjected to the same test condition (see 3.5) and temperature previously used for a minimum of 24

additional hours before intermediate or end-point measurements are made. When specified (or at the manufacturer's

discretion, if not specified), intermediate measurements shall be made at 168 (+72, -0) hours and at 504 (+168, -0) hours.

For tests in excess of 1,000 hours duration, additional intermediate measurement points, when specified, shall be 1000

(+168, -24) hours, 2,000 (+168, -24) hours, and each succeeding 1,000 (+168, -24) hour interval. These intermediate

measurements shall consist of the parameters and conditions specified, including major functional characteristics of the

device under test, sufficient to reveal both catastrophic and degradation failures to specified limits. Devices shall be cooled

to less than 10°C of their power stable condition at room temperature prior to the removal of bias.

The interruption of bias for up to one minute for the purpose of moving the devices to cool-down positions separate from the

chamber within which life testing was performed shall not be considered removal of bias. Alternatively, except for linear or

MOS (CMOS, NMOS, PMOS, etc.) devices or unless otherwise specified, the bias may be removed during cooling, provided

the case temperature of the devices under test is reduced to a maximum of 35°C within 30 minutes after removal of the test

conditions and provided the devices under test are removed from the heated chamber within five minutes following removal

of bias. All specified 25°C electrical measurements shall be completed prior to any reheating of the device(s).

3.3.2 Measurements for test temperatures greater than or equal to 175°C

. Unless otherwise specified, all specified

intermediate and end-point measurements shall be completed within 24 hours after removal of the device from the specified

test conditions (i.e., either removal of temperature or bias). If these measurements cannot be completed within 24 hours,

the steady-state life test shall be repeated using the same test condition, temperature and time. Devices shall be cooled to

less than 10°C of their power stable condition at room temperature prior to the removal of bias, except that the interruption

of bias for up to one minute for the purpose of moving the devices to cool-down positions shall not be considered removal of

bias. All specified 25°C electrical measurements shall be completed prior to any reheating of the device(s).

3.3.3 Test setup monitoring

. The test setup shall be monitored at the test temperature initially and at the conclusion of

the test to establish that all devices are being stressed to the specified requirements. The following is the minimum

acceptable monitoring procedure:

a. Device sockets. Initially and at least each 6 months thereafter, (once every 6 months or just prior to use if not

used during the 6 month period) each test board or tray shall be checked to verify continuity to connector points

to assure that bias supplies and signal information will be applied to each socket. Board capacitance or

resistance required to ensure stability of devices under test shall be checked during these initial and periodic

verification tests to ensure they will perform their proper function (i.e., that they are not open or shorted). Except

for this initial and periodic verification, each device or device socket does not have to be checked; however,

random sampling techniques shall be applied prior to each time a board is used and shall be adequate to assure

that there are correct and continuous electrical connections to the devices under test.

b. Connectors to test boards or trays. After the test boards are loaded with devices, inserted into the oven, and

brought up to at least 125°C or the specified test temperature, whichever is less, each required test voltage and

signal condition shall be verified in at least one location on each test board or tray so as to assure electrical

continuity and the correct application of specified electrical stresses for each connection or contact pair used in

the applicable test configuration. This may be performed by opening the oven for a maximum of 10 minutes.

When the test conditions are checked at a test socket, contact points on the instrument used to make this

continuity check shall be equal to or smaller dimensions than the leads (contacts) of the devices to be tested and

shall be constructed such that the socket contacts are not disfigured or damaged.

c. At the conclusion of the test period, prior to removal of devices from temperature and test conditions, the voltage

and signal condition verification of b. above shall be repeated.

d. For class level S devices, each test board or tray and each test socket shall be verified prior to test to assure that

the specified test conditions are applied to each device. This may be accomplished by verifying the device

functional response at each device output(s). An approved alternate procedure may be used.

Where failures or open contacts occur which result in removal of the required test stresses for any period of the required test

duration (see 3.1), the test time shall be extended to assure actual exposure for the total minimum specified test duration.

Any loss(es) or interruption(s) of bias in excess of 10 minutes total duration whether or not the chamber is at temperature

during the final 24 hours of life test shall require extension of the test duration for an uninterrupted 24 hours minimum, after

the last bias interruption.

MIL-STD-883F

METHOD 1005.8

1 June 1993

3.4 Test sample

. The test sample shall be as specified (see 4). When this test method is employed as an add-on life

test for a series or family of device types, lesser quantities of any single device type may be introduced in any single addition

to the total sample quantity, but the results shall not be considered valid until the minimum sample size for each device has

been accumulated. Where all or part of the samples previously under test are extracted upon addition of new samples, the

minimum sample size for each type shall be maintained once that level is initially reached and no sample shall be extracted

until it has accumulated the specified minimum test hours (see 3.1).

3.5 Test conditions

3.5.1 Test condition A, steady-state, reverse bias

. This condition is illustrated on figure 1005-1 and is suitable for use on

all types of circuits, both linear and digital. In this test, as many junctions as possible will be reverse biased to the specified

voltage.

3.5.2 Test condition B, steady-state, forward bias

. This test condition is illustrated on figure 1005-1 and can be used on

all digital type circuits and some linear types. In this test, as many junctions as possible will be forward biased as specified.

3.5.3 Test condition C, steady-state, power and reverse bias

. This condition is illustrated on figure 1005-1 and can be

used on all digital type circuits and some linear types where the inputs can be reverse biased and the output can be biased

for maximum power dissipation or vice versa.

3.5.4 Test condition D, parallel excitation

. This test condition is typically illustrated on figure 1005-2 and is suitable for

use on all circuit types. All circuits must be driven with an appropriate signal to simulate, as closely as possible, circuit

application and all circuits shall have maximum load applied. The excitation frequency shall not be less than 60 Hz.

3.5.5 Test condition E, ring oscillator

. This test condition is illustrated on figure 1005-3, with the output of the last circuit

normally connected to the input of the first circuit. The series will be free running at a frequency established by the

propagation delay of each circuit and associated wiring and the frequency shall not be less than 60 Hz. In the case of

circuits which cause phase inversion, an odd number of circuits shall be used. Each circuit in the ring shall be loaded to its

rated maximum. While this condition affords the opportunity to continuously monitor the test for catastrophic failures (i.e.,

ring stoppage), this shall not be considered acceptable as a substitute for the intermediate measurements (see 3.3).

3.5.6 Test condition F, (class level B only) temperature-accelerated test

. In this test condition, microcircuits are

subjected to bias(es) at an ambient test temperature (175°C to 300°C ) which considerably exceeds their maximum rated

temperature. At higher temperatures, it is generally found that microcircuits will not operate normally, and it is therefore

necessary that special attention be given to the choice of bias circuits and conditions to assure that important circuit areas

are adequately biased without damaging overstresses to other areas of the circuit. To properly select the actual biasing

conditions to be used, it is recommended that an adequate sample of devices be exposed to the intended high temperature

while measuring voltage(s) and current(s) at each device terminal to assure that the specified circuit and the applied

electrical stresses do not induce damaging overstresses.

At the manufacturer's option, alternate time and temperature values may be established from table I. Any time-temperature

combination which is contained in table I within the time limit of 30 to 1,000 hours may be used. The life test ground rules of

3.5 of method 1016 shall apply to life tests conducted using test condition F. The applied voltage at any or all terminals shall

be equal to the voltage specified for the 125°C operating life in the applicable acquisition document, unless otherwise

specified.

If necessary, with the specific approval of the qualifying activity, the applied voltage at any or all terminal(s) may be reduced

to not less than 50 percent of the specified value(s) when it is demonstrated that excessive current flow or power dissipation

would result from operation at the specified voltage(s). If the voltage(s) is so reduced, the life test duration shall be

determined by the following formula:

(100%)

100% - V%

Where T

is the adjusted total test duration in hours, t

is the original test duration in hours, and V percent is the largest

percentage of voltage reduction made in any specified voltage.

MIL-STD-883F

METHOD 1005.8

1 June 1993

3.5.6.1 Special considerations for devices with internal thermal limitation

. For devices with internal thermal shutdown,

extended exposure at a temperature in excess of the shut-down temperature will not provide a realistic indicator of long-term

operating reliability. For such devices, measurement of the case temperature should be made at the specified bias voltages

at several different ambient temperatures. From these measurements, junction temperatures should be computed, and the

operating life shall be performed at that ambient temperature which, with the voltage biases specified, will result in a worst

case junction temperature at least 5°C but no more than 10°C below the minimum junction temperature at which the device

would go into thermal shutdown, and the test time shall be determined from table I for the applicable device class level.

4. SUMMARY. The following details shall be specified in the applicable acquisition document:

a. Special preconditioning, when applicable.

b. Test temperature, and whether ambient, junction, or case, if other than as specified in 3.2.

c. Test duration, if other than as specified in 3.1.

d. Test mounting, if other than normal (see 3).

e. Test condition letter.

f. End-point measurements and intermediate measurements (see 3.3).

g. Criteria for device failure for intermediate and end-point measurements (see 3.3), if other than device

specification limits, and criteria for lot acceptance.

h. Test sample (see 3.4).

i. Time to complete end-point measurements, if other than as specified (see 3.3).

j. Authorization for use of condition F and special maximum test rating for condition F, when applicable (see 4.b).

k. Time temperature conditions for condition F, if other than as specified in 3.5.6.