MIL- STD-883F 2004 TEST METHOD STANDARD MICROCIRCUITS - 第36页

MIL-STD-883F METHOD 1005.8 1 June 1993 2 3.1.2 Ac celer ated li fe tes t durat ion . For c lass level B, the lif e test durati on, when acc elerat ed, shal l be the t ime equivalent to 1,000 hour s at 125°C f or the ambi…

MIL-STD-883F

METHOD 1005.8

1 June 1993

METHOD 1005.8

STEADY-STATE LIFE

1. PURPOSE

. The steady-state life test is performed for the purpose of demonstrating the quality or reliability of devices

subjected to the specified conditions over an extended time period. Life tests conducted within rated operating conditions

should be conducted for a sufficiently long test period to assure that results are not characteristic of early failures or "infant

mortality," and periodic observations of results should be made prior to the end of the life test to provide an indication of any

significant variation of failure rate with time. Valid results at shorter intervals or at lower stresses require accelerated test

conditions or a sufficiently large sample size to provide a reasonable probability of detection of failures in the sample

corresponding to the distribution of potential failures in the lot(s) from which the sample was drawn. The test conditions

provided in 3 below are intended to reflect these considerations.

When this test is employed for the purpose of assessing the general capability of a device or for device qualification tests in

support of future device applications requiring high reliability, the test conditions should be selected so as to represent the

maximum operating or testing (see test condition F) ratings of the device in terms of electrical input(s), load and bias and the

corresponding maximum operating or testing temperature or other specified environment.

2. APPARATUS

. Suitable sockets or other mounting means shall be provided to make firm electrical contact to the

terminals of devices under test in the specified circuit configuration. Except as authorized by the acquiring or qualifying

activity, the mounting means shall be so designated that they will not remove internally-dissipated heat from the device by

conduction, other than that removed through the device terminals, the necessary electrical contacts and the gas or liquid

chamber medium. The apparatus shall provide for maintaining the specified biases at the terminals of the device under test

and, when specified, monitoring of the input excitation or output response. Power supplies and current-setting resistors shall

be capable of maintaining the specified operating conditions as minimal throughout the testing period, despite normal

variations in source voltages, ambient temperatures, etc. When test conditions result in significant power dissipation, the

test 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. The test circuits need not compensate for normal variations in individual device

characteristics, but shall be so arranged that the existence of failed or abnormal (i.e., open, short, etc.) devices in a group

does not negate the effect of the test for other devices in the group.

3. PROCEDURE

. The microelectronic devices shall be subjected to the specified test condition (see 3.5) for the

specified duration at the specified test temperature, and the required measurements shall be made at the specified

intermediate points and end points. QML manufactures who are certified and qualified to MIL-PRF-38535 may modify the

time or the condition independently from the regression conditions contained in table I or the test condition/circuit specified

in the device specification or standard microcircuit drawing provided the modification is contained in the manufacturer's QM

plan and the "Q" certification identifier is marked on the devices. Lead-, stud-, or case-mounted devices shall be mounted

by the leads, stud, or case in their normal mounting configuration, and the point of connection shall be maintained at a

temperature not less than the specified ambient temperature. The test condition, duration, sample size, and temperature

selected prior to test shall be recorded and shall govern for the entire test. Test boards shall not employ load resistors

which are common to more than one device, or to more than one output pin on the same device.

3.1 Test duration

3.1.1 Test duration - standard life

. The life test duration shall be 1,000 hours minimum at 125°C , unless otherwise

specified or allowed (see 3.2.1). After the specified duration of the test, the device shall be removed from the test conditions

and allowed to reach standard test conditions. Where the purpose of this test is to demonstrate compliance with a specified

lambda (8), the test may be terminated at the specified duration or at the point of rejection if this occurs prior to the specified

test duration.

MIL-STD-883F

METHOD 1005.8

1 June 1993

3.1.2 Accelerated life test duration

. For class level B, the life test duration, when accelerated, shall be the time equivalent

to 1,000 hours at 125°C for the ambient temperature selected or specified (see table I). Within 72 hours after the specified

duration of the test, the device shall be removed from the specified test conditions and allowed to reach standard test

conditions without 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.

3.2 Test temperature

. The specified test temperature is the minimum ambient temperature to which all devices in the

working area of the chamber shall be exposed. This shall be assured by making whatever adjustments are necessary in the

chamber profile, loading, location of control or monitoring instruments, and the flow of air or other suitable gas or liquid

chamber medium. Therefore, calibration shall be accomplished in the chamber in a fully loaded, (boards need not be loaded

with devices) unpowered configuration, and the indicator sensor located at, or adjusted to reflect, the coldest point in the

working area.

3.2.1 Test temperature - standard life

. Unless otherwise specified, the ambient life test temperature shall be 125°C

minimum for test conditions A through E (see 3.5), except that for hybrid microcircuits, the conditions may be modified in

accordance with table I. At the supplier's option, the ambient temperature for conditions A through E may be increased and

the test duration reduced in accordance with table I using the specified test circuit and bias conditions. Since case and

junction temperature will, under normal circumstances, be significantly higher than ambient temperature, the circuit should

be so structured that maximum rated case or junction temperatures for test or operation shall not exceed 200°C for class

level B or 175°C for class level S (see 3.2.1.1).

3.2.1.1 Test temperature for high power devices

. Regardless of power level, devices shall be able to be burned in or

life-tested at their maximum rated operating temperature. For devices whose maximum operating temperature is stated in

terms of ambient temperature, T

, table I applies. For devices whose maximum operating temperature is stated in terms of

case temperature, T

, and where the ambient temperature would cause T

to exceed +200°C (+175°C for class level S),

the ambient operating temperature may be reduced during burn-in and life test from +125°C to a value that will demonstrate

a T

between +175°C and +200°C and T

equal to or greater than +125°C without changing the test duration. Data

supporting this reduction shall be available to the acquiring and qualifying activities upon request.

3.2.1.2 Test temperature for hybrid devices

. The ambient or case life test temperature shall be as specified in table I,

except case temperature life test shall be performed, as a minimum, at the maximum operating case temperature (T

)

specified for the device. Life test shall be for 1,000 hours minimum for class level S hybrid (class K). The device should be

life tested at the maximum specified operating temperature, voltage, and loading conditions as specified in the detail

specification. Since case and junction temperature will, under normal circumstances, be significantly higher than ambient

temperature, the circuit should be so structured that the maximum rated junction temperature as specified in the device

specification or drawing and the cure temperature of polymeric materials as specified in the baseline documentation shall

not be exceeded. If no maximum junction temperature is specified, a maximum of 175°C is assumed. Accelerated life test

(condition F) shall not be permitted. The specified test temperature shall be the minimum actual ambient or case

temperature that must be maintained for all devices in the chamber. This shall be assured by making whatever adjustments

are necessary in the chamber profile, loading, location of control or monitoring instruments and the flow of air or other

suitable gas or liquid chamber medium.

3.2.2 Test temperature - accelerated life

. When condition F is specified or is utilized as an option (when allowed by the

applicable acquisition documents), the minimum ambient test temperature shall be +175°C , unless otherwise specified.

Since accelerated testing will normally be performed at temperatures higher than the maximum rated operating junction

temperature of the device(s) tested, care shall be taken to ensure that the device(s) does not go into thermal runaway.

3.2.3 Special considerations for devices with internal thermal limitation using test conditions A through E

. 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 devices equipped with thermal shutdown, operating life test shall be

performed at an ambient temperature where the worst case junction temperature is at least 5°C below the worst case

thermal shutdown threshold. Data supporting the defined thermal shutdown threshold shall be available to the preparing or

acquiring activity upon request.

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.