REG NASA-LLIS-0402-1996 Lessons Learned - Solderability Problem with Solder Plated Terminals (~ 1990).pdf

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1、Lessons Learned Entry: 0402Lesson Info:a71 Lesson Number: 0402a71 Lesson Date: 1996-04-19a71 Submitting Organization: JPLa71 Submitted by: J.W. BottSubject: Solderability Problem with Solder Plated Terminals ( 1990) Abstract: Multi-year storage and aging of solder plated terminals for TOPEX and ASTR

2、OS circuit boards affected their solderability. Consider aging and solderability factors, and perform solderability tests, before installing solder plated terminals.Description of Driving Event: TOPEX Microwave Radiometer (TMR)Solder plated terminals supplied to a contractor for installation in TMR

3、multilayer boards failed solderability tests, prior to installation. These terminals were found to have exceeded their useful shelf life, (typically 2 years), and were replaced with new ones. Removal and replacement of these terminals after installation would have meant severe penalties in terms of

4、added costs, schedule slippage and/or potentially destructive rework.ASTROS InstrumentWhen previously built printed wiring board assemblies were removed from long term storage (more than 5 years) for use in new construction, surface deterioration on solder plated terminals necessitated the use of ac

5、tivated (type RA) fluxes to obtain acceptable solder joints. Such acid based fluxes are not normally used due to potential for long term corrosion.Lesson(s) Learned: 1. Solder plated brass terminals have a limited shelf life after initial manufacture or reprocessing.2. Surface deterioration may set

6、in after approximately two years in an air ambient environment.Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-3. Failure to take aging and solderability factors into account before installing solder plated terminals may have serious consequences.Rec

7、ommendation(s): 1. Use fresh stock when installing solder plated terminals. Evaluate date codes on packages of terminals to be used.2. Return residual stocks of solder plated brass terminals to controlled stores, or discard them on completion of the project.3. Perform solderability tests on any lot

8、of solder plated terminals prior to use. Avoid installing solder plated terminals until immediately prior to populating the printed wiring board, if possible.Evidence of Recurrence Control Effectiveness: N/ADocuments Related to Lesson: N/AMission Directorate(s): N/AAdditional Key Phrase(s): a71 Envi

9、ronmenta71 Logisticsa71 Packaging Handling Storagea71 Parts Materials & ProcessesAdditional Info: Approval Info: a71 Approval Date: 1996-02-08a71 Approval Name: Carol Dumaina71 Approval Organization: 125-204a71 Approval Phone Number: 818-354-8242Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-