MIL-STD-202H.pdf - 第52页
MI L - S TD - 202 - 10 8 CO NT E N T S PARAGRAPH PAG E FOREW ORD … ………………………………………………………. ii 1. SCOPE 1 1.1 Purpose …… ………………… …………………. …… .. …………. 1 2. APPLICABLE D O C U M EN T S 1 3. DEFINTIONS 1 4. GENERAL RE Q UI R …
MIL-STD-202-108
FOREWORD
1. This standard is approved for use by all Departments and Agencies of the Department of Defense.
2. This entire standard has been revised. This revision has resulted in many changes to the format, but the most
significant one is the splitting the document into test methods. See MIL-STD-202 for the change summary.
3. Comments, suggestions, or questions on this document should be emailed to std202@dla.mil or addressed to:
Commander, Defense Logistics Agency, DLA Land and Maritime, ATTN: VAT, P.O. Box 3990, Columbus, OH
43218–3990. Since contact information can change, you may want to verify the currency of this address
information using the ASSIST Online database at https://assist.dla.mil.
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北测（上海）电子科技有限公司
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MIL-STD-202-108
CONTENTS
PARAGRAPH PAGE
FOREWORD…………………………………………………………. ii
1. SCOPE 1
1.1 Purpose………………………………………….……..…………. 1
2. APPLICABLE DOCUMENTS 1
3. DEFINTIONS 1
4. GENERAL REQUIREMENTS 1
4.1 Apparatus ……………………………………………..…………. 1
4.2. Procedure……..………………..….…………….………………. 1
4.2.1 Mounting………………………………………………………..… 1
4.2.2 Test temperature………………………………………………… 2
4.2.3 Operating conditions…………………………………………….. 2
4.2.4 Length of test…………………………………………………….. 2
4.3 Measurements………………………………………………….... 2
5. DETAILED REQUIREMENTS 3
5.1 Summary……………..…………………………..………………. 3
6. NOTES 3
6.1 Supersession data………………………………………………. 3
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北测（上海）电子科技有限公司
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MIL-STD-202-108
METHOD 108
LIFE (AT ELEVATED AMBIENT TEMPERATURE)
1. SCOPE
1.1 Purpose. This test is conducted for the purpose of determining the effects on electrical and mechanical
characteristics of a part, resulting from exposure of the part to an elevated ambient temperature for a specified length
of time, while the part is performing its operational function. This test method is not intended for testing parts whose
life is expressed in the number of operations. Evidence of deterioration resulting from this test can at times be
determined by visual examination; however, the effects may be more readily ascertained by measurements or tests
prior to, during, or after exposure. Surge current, total resistance, dielectric strength, insulation resistance, and
capacitance are types of measurements that would show the deleterious effects due to exposure to elevated ambient
temperatures.
2. APPLICABLE DOCUMENTS
This section not applicable to this standard.
3. DEFINTIONS
This section not applicable to this standard.
4. GENERAL REQUIREMENTS
4.1. Apparatus. A suitable chamber shall be used which will maintain the temperature at the required test
temperature and tolerance (see 4.2.2) to which the parts will be subjected. Temperature measurements shall be
made within a specified number of unobstructed inches from any one part or group of like parts under test. In
addition, the temperature measurement shall be made at a position where the effects of heat generated by the parts
have the least effect on the recorded temperature. Chamber construction shall minimize the influence of radiant heat
on the parts being tested. Chambers that utilize circulating liquid as a heat exchanger, free-convection (gravity type)
chambers, and circulating air chambers may be used providing that the other requirements of this test method are
met. When specified, this test shall be made in still air. (Still air is defined as surrounding air with no circulation other
than that created by the heat of the part being operated.) The employment of baffling devices and the coating of their
surfaces with a heat-absorbing finish are permitted. When a test is conducted on parts that do not have the still-air
requirement, there shall be no direct impingement of the forced-air supply upon the parts.
4.2. PROCEDURE.
4.2.1 Mounting. Specimens shall be mounted as specified by their normal mounting means. When groups of
specimens are to be subjected to test simultaneously, the mounting distance between specimens shall be as
specified for the individual groups. When the distance is not specified, the mounting distance shall be sufficient to
minimize the temperature of one specimen affecting the temperature of another. Specimens fabricated of different
materials, which may have a detrimental effect on each other and alter the results of this test, shall not be tested
simultaneously.
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