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Definition
Thin immersion coating of Ag co-deposited with organic anti-tarnish or a two-step system (Ag then anti-tarnish).Benefits
- Economical process / price
- Flat Finish with good solderability
- Excellent for high-temperature applications
- Non-porous, airtight seal
- Synergy with accepted Pb-free solder masks
- Aluminum (and possibly Gold) wire bondable
- Surface suitable for electrical contact
- Capable of multiple reflow cycles
- Two-months mid-assembly shelf life
Limitations
- Not good for sliding connectors
- Sensitive to Chlorine & Sulfur (end application)
- Long term storage unknown
- Long term use as an electrical contact surface (1million actuations)
- Electro-migration issues with UL
- Occasional voiding
- Deposit gradually discolors due to air exposure