MIL-STD-202H.pdf - 第44页
MI L - S TD - 202 - 107 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 E…
MIL-STD-202-107
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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MIL-STD-202-107
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
4.1.1 Environmental chambers........................................................ 1
4.1.2 Liquid baths ………………………………...………...…………. 1
4.2. Procedure………………………………………..……..…………. 2
4.2.1 Environmental chambers.….……………………………………. 2
4.2.2 Liquid baths.…………………………………………..…………. 2
4.3 Measurements……………………………………………………. 2
5. DETAILED REQUIREMENTS 2
5.1 Summary……………………………..…………..………………. 2
6. NOTES 5
6.1 Supersession data………………………………………………. 5
6.2 Cancelled Method……………………………..…………………. 5
TABLES PAGE
I Thermal shock test conditions (air)………………….…………….……… 3
II Exposure time in air at temperature extremes………………………...... 3
III Thermal shock conditions (liquid)………………………………………… 4
IV Suggested thermal fluids………………………………………………….. 4
V Exposure time in liquid at temperature extremes…...................……… 5
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北测（上海）电子科技有限公司
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MIL-STD-202-107
METHOD 107
THERMAL SHOCK
1. SCOPE
1.1 Purpose. This test is conducted for the purpose of determining the resistance of a part to exposures at
extremes of high and low temperatures, and to the shock of alternate exposures to these extremes, such as would be
experienced when equipment or parts are transferred to and from heated shelters in arctic areas. These conditions
may also be encountered in equipment operated noncontinuously in low-temperature areas or during transportation.
Although it is preferred that the specimen reach thermal stability during the exposure specified, in the interest of
saving time, parts may be tested at the minimum exposure durations specified, which will not insure thermal stability
but only an approach thereto. Permanent changes in operating characteristics and physical damage produced during
thermal shock result principally from variations in dimensions and other physical properties. Effects of thermal shock
include cracking and delamination of finishes, cracking and crazing of embedding and encapsulating compounds,
opening of thermal seals and case seams, leakage of filling materials, rupturing, or cracking of hermetic seals and
vacuum glass to metal seals, and changes in electrical characteristics due to mechanical displacement or rupture of
conductors or of insulating materials.
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. Suitable temperature controlled systems shall be used to meet the temperature requirements and
test conditions specified in table I or table III. The liquid method is more severe and may damage some components
that might not be degraded by the air method. It is not intended for use on nonhermetically sealed components.
4.1.1 Environmental chambers. A system of sufficient thermal capacity shall be used to change ambient chamber
conditions to meet test requirements and to reach specified temperature conditions of steps 1 and 3 of table I. The
supply air temperature of the chambers shall reach the specified temperature within a recovery time of 5 minutes
after the specimens have been transferred to the appropriate chamber.
4.1.2 Liquid baths. Suitable temperature controlled baths containing liquids (see table IV) shall be chosen to
maintain the specified test conditions (see table III) within the indicated tolerances. A liquid media shall not be used
without prior approval of the qualifying activity.
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