Immersion silver (ImAg) is a metallic coating of pure silver (0.1 to 0.4 μm), which acts as a preservative for the copper traces on a printed circuit board. It is a combination of 99% Ag metal with traces of organic material. With time, ImAg forms Sulfide Dendrites that cause a shorting problem. This problem can be avoided by applying a thin organic coat, which acts as a barrier.

An Immersion silver (ImAg) finish on a Multi-layer PCB is suitable for the applications that include flat surfaces like membrane switches, EMI shielding, aluminum wire bonding, and very fine traces.

Properties of Immersion Silver Surface Finish:

Shelf-life: 6 to 12 months

Offers good solderability

Due to its planarity (flatness), suitable for fine-pitch/BGA/Small components placement

Offers good solderability after exposure to various thermal cycles (more than 2)

Suitable for high-frequency applications

Limiting Properties of Immersion Silver Surface Finish:

Sensitive to handle and sensative to contaminants

Has a solder whiskering issue

Difficult for electric testing