1、 GEIA ENGINEERING BULLETIN Environmental Tests and Associated Failure Mechanisms SSB-1.002 (Annex to SSB-1, Guidelines for Using of Plastic Encapsulated Microcircuits and Semiconductors in Military, Aerospace and Other Rugged Applications) OCTOBER 1999 GOVERNMENT ELECTRONICS AND INFORMATION TECHNOLO
2、GY ASSOCIATION SSB-1.002 A Sector of the Electronic Industries Alliance Copyright Government Electronics distribution is unlimited. Copyright Government Electronics reliability tests can run thousands of hours in order to get useful results.Copyright Government Electronics & Information Technology A
3、ssociation Provided by IHS under license with GEIA Not for ResaleNo reproduction or networking permitted without license from IHS-,-,-SSB-1.00253.6 Highly Accelerated Stress TestThe Highly Accelerated Stress Test (HAST) is performed to evaluate the non-hermeticpackaging of solid state devices in hum
4、id environments. This test uses a high temperature(usually 130C), high relative humidity (about 85%), under high atmospheric pressure conditions(up to 3 atm) to accelerate the penetration of moisture through the external protective material orat the seals around the chip leads. Once moisture reaches
5、 the die surface (as described forTHB), the electric potential helps transform the device into an electrolytic cell. This in turnaccelerates the corrosion failure mechanism.This test is intended to precipitate failure mechanisms associated with metallization corrosion,delamination at material interf
6、aces, wirebond failures, and reduced insulation resistance. Oneshould exercise caution when evaluating results of HAST tests performed at temperatures higherthan 130C. Such tests can precipitate different failure mechanisms that would not be seenduring normal device operation.HAST was developed espe
7、cially for plastic encapsulated solid state devices after it becameevident that autoclave and THB tests were no longer generating failures among certain robustPEMs. HAST detects failure mechanisms similar to those detected by THB , but at a greatlyaccelerated rate. Some device manufacturers substitu
8、te HAST testing for THB based oncomparisons between lots with known moisture sensitivity and verifying that failures were due tothe same failure mode. Acceleration factors are then applied to derive equivalent THB failureresults from HAST test results.Copyright Government Electronics & Information T
9、echnology Association Provided by IHS under license with GEIA Not for ResaleNo reproduction or networking permitted without license from IHS-,-,-Copyright Government Electronics & Information Technology Association Provided by IHS under license with GEIA Not for ResaleNo reproduction or networking p
10、ermitted without license from IHS-,-,-GEIA Document Improvement Proposal If, in the review or use of this document, a potential change is made evident for safety, health, or technical reasons please fill in the appropriate information below and mail or FAX to: Government Electronics and Information
11、Technology Association (GEIA) Standards & Technology Department 2500 Wilson Blvd. Arlington, VA 22201 FAX: (703) 907-7968 Document No. Document Title: Submitters Name: Telephone No.: FAX No.: E-mail: Address: Urgency of Change: Immediate: At next revision: Problem Area: a. Clause Number and/or Drawi
12、ng: b. Recommended Changes: c. Reason/Rationale for Recommendation: Additional Remarks: Signature: Date: FOR GEIA USE ONLY Responsible Committee: Chairman: Date comments forwarded to Committee Chairman: Copyright Government Electronics & Information Technology Association Provided by IHS under license with GEIA Not for ResaleNo reproduction or networking permitted without license from IHS-,-,-Copyright Government Electronics & Information Technology Association Provided by IHS under license with GEIA Not for ResaleNo reproduction or networking permitted without license from IHS-,-,-
