The Tin Coating Discoloration And Solderability Study In Lead Frame

Currently in the semiconductor packaging process,the die chip connect with Lead frame pin by the chip interconnect to achieve the one step package,and after Trim/Form chip connect with the substrate(PCB board) by the soldering process. Before this process,plating a pure tin coating in the chip lead frame surface to increase the soldering capacity between the pin and the substrate.The performance of lead frame tin coating directly affects the solderability,and whether the tin coating discolor will determine the quality of the tin coating in the lead frame. In the industrial practice ,the tin coating discolor that affect the solderability is main reason for the chip failure.In this paper,the pure tin plating technology in the lead frame surface was introduce .Analysis the cause of two kinds of the tin coating discoloration ,and propose the solution for the two kinds of discoloration.After this paper study ,the tin coating discoloration have been resolved,ensure that the chip with the good solderability. This Paper proposed solutions for the semiconductor chip and package substrate solderability provide useful help and reference information.