In system reflow of low temperature eutectic bond balls

Abstract

Low temperature bond balls connect two structures having disparate coefficients of linear thermal expansion. An integrated circuit is made to heat the device such that the low temperature bond balls melt. After melting, the bond balls solidify, and the device is operated with the bond balls solidified. In one example, one of the two structures is a semiconductor substrate, and the other structure is a printed circuit board. The integrated circuit is a die mounted to the semiconductor substrate. The bond balls include at least five percent indium, and the integrated circuit is an FPGA loaded with a bit stream. The bit stream configures the FPGA such that the FPGA has increased power dissipation, which melts the balls. After the melting, a second bit stream is loaded into the FPGA and the FPGA is operated in a normal user-mode using the second bit stream.