Eutectic Au/Sn 80/20 solder is especially
beneficial for flip chip applications where the usage
of flux has to be avoided. Also it is a lead free
alternative for applications where high temperature resistance is indispensable. The process steps
involved in the fabrication of AuSn bumps by
electroplating are described in detail elsewhere
[1, 2]. First the plating base consisting of a
Ti:W(N) and an Au layer is sputtered. The
sputtering is followed by lithography of thick photo
resist as plating mask. After electroplating of the
Au socket and the Sn cap the resist is stripped. In
the last process steps the Au and the Ti:W(N)
layers are etched.