Adhesion strength and mechanism of poly(imide-siloxane) to Alloy 42 leadframe

Poly(imide-siloxane) containing α,ω-(aminophenoxypropyl)poly(dimethylsiloxane) and α,ω-(aminophenoxypropyl)poly(dimethylsiloxane-co-diphenylsiloxane) were synthesized. The adhesion strength of poly(imide-siloxane)/Alloy 42 leadframe (Fe-Ni alloy, 58% Fe and 42% Ni) joints was studied as a function of the molding temperature, time, pressure, and chemical structure of siloxane diamine (SDA). The thermo-oxidative decomposition of polydimethylsiloxane (PDMS) in poly(imide-siloxane) was examined by attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR). Silanol groups were formed from the thermal decomposition of PDMS above 300°C. The adhesion mechanism of poly(imide-siloxane) with metal oxide was identified as the formation of covalent bonds between the silanol group of thermo-oxidatively decomposed PDMS and hydroxy groups of the metal oxide by time-of-flight secondary ion mass spectroscopy (TOF-SIMS).