Immersion Tin Additive
CAS Number: 7772-99-8
Immersion tin additive is a stabilizer and complexant system for immersion tin PCB surface finish baths, producing a thin, flat, solderable tin deposit on copper pads via displacement reaction. It prevents whisker growth and tin-copper intermetallic formation through thiourea-based or alternative complexant chemistries. Immersion tin provides excellent fine-pitch solderability and is a lead-free, RoHS-compliant surface finish.
Technical Specifications
| pH | 1.0–2.0 |
| appearance | Clear to slightly hazy liquid |
| tinContent | 20–35 g/L (as Sn²⁺) |
| tinThickness | 0.8–1.2 µm |
| operatingTemp | 60–75°C |
| whiskerResistance | Passes JESD22-A121 at 1.5 µm |
Applications
- Fine-pitch SMT PCB surface finish
- Press-fit connector PCB finish
- Flat panel display PCB surface treatment
- High-density interconnect (HDI) pad finish
- Lead-free RoHS-compliant PCB finish
Key Features
- Flat, coplanar finish ideal for fine-pitch SMT
- Whisker-resistant formulation for long-term reliability
- Lead-free and RoHS compliant
- Excellent shelf life up to 12 months