Sn whisker growth on Sn plating with or without surface treatment during the room temperature exposure

► Mitigation method of the Sn whisker by thin metal layer formation. ► Au, Pd and Ni layers with the thickness from 50nm to 200nm were deposited on matte Sn plating by flash-coating process. ► No Sn whisker was observed on Au/Sn and Pd/Sn plating samples in room ambient environment over 10,000h. The establishment of lead-free plating technology and countermeasures for whisker formation are some of the critical issues remaining to be solved for lead-free electronics packaging. This study examined a method for mitigating Sn whisker formation by depositing a thin metal layer, such as Au, Pd and Ni, on pure Sn plating. Au, Pd and Ni layers with thicknesses ranging from 50nm to 200nm were deposited on matte Sn plating using a flash-coating process. The Sn whisker growth behavior of pure Sn plating and metal layer/Sn plating samples at room ambient over a period of 10,000h was observed. The metal layer/Sn plating was considerably more stable against Sn whisker formation in room ambient environment than the pure Sn plating.