All services have a stake in the transition to lead-free solders. Each for many of the same reasons, but also for many unique critical applications. Performance issues such as vibration, weather extremes, dust exposure, tin whiskers, etc. are of crucial importance to the operational function and mission capability of many vital military war fighting components including ground combat vehicles, tactical weapons, aircraft, missile systems, intelligent munitions, medical devices, and communications.
Maintenance
Of critical importance during the transition to lead-free solder use is the ability to assess current and supplied components for solder type. One needs to be able to evaluate what materials are being used in military systems & current components in order to ensure material compatibility with existing lead solders during retinning procedures with the new lead-free solders.
Significant questions need to be asked and evaluated:
- What are the performance requirements?
- Will the new lead free solder adversely effect performance?
- If so, what can be done to rectify the issue, if at all?
- Will they cause critical failures?
- What exactly are the impacts to the overall system?
- What are the alternative solutions?
Tin Whiskers
This issue is of most concern to the aviation, missile, and intelligent munitions communities where even one minor failure could have catastrophic results. Tin whiskers are electrically conductive, crystalline structures of tin that sometimes grow from surfaces where tin (especially electroplated tin) is used as a final finish. They have been observed to grow to lengths of several millimeters & in rare instances up to 10 mm.
Numerous electronic system failures have been attributed to short circuits caused by tin whiskers that bridge closely-spaced circuit elements maintained at different electrical potentials.
Management Areas:
- PM/OEM Planning
- Depot Rework
- Configuration Management
Technical Reqs. Analysis:
- Training and Reliability Test Methods
- Mission Critical Components Control
- Part Processing
- Configuration Management
Dem/Val Output:
- Reliability Analysis
- Rework Process Requirements
- Configuration Control