Finest tin-needles (Whiskers) generate short circuits between component connections and induces malfunction and component damages possibly.
Whisker Growth
Within the scope of changing to lead-free processes the whole topic of whisker growth attains a new significance. In this connection the accelerated growth of finest tin-needles (Whiskers) generates short circuits between component connections and induces malfunction and component damages possibly. Considering the cause for such autonomous operations of growth, the initiator is mechanical tension in tin layers, often placed galvanically, on the leadframe.
On the one hand our research and investigation confirmed that these tensions result from corrosion/oxidation layers on the tin surface and from mechanical bending/molding procedures for contact pins during production as well as from intermetallic growth of phases (diffusion processes) on the other hand.
The fastest growth takes place in a temperature range of 50 to 90° C and at a relative humidity above 75 %. Here, our procedure also offers the ideal starting point for preventing the growth of whiskers.