Fluxless, no clean assembly of optoelectronic devices with PADS

Abstract

MCNC has developed and is licensing a radically new fluxless, no-clean process that has enjoyed considerable success with a variety of soldering operations. This process is called PADS (Plasma Assisted Dry Soldering) and relies on a pretreatment which enables the subsequent solder reflow in inert, and even oxidizing ambients. Conventional mass production soldering tools can be used; just eliminate the flux dispense and flux cleaning steps and PADS pretreatment steps. This paper illustrates various soldering operations performed using PADS that could be used for assembly of optoelectronic devices. Examples include fiber optic module assembly/pigtailing, display module assembly (flip chip on glass), laser TAB attach of chips for flat panel displays, die bonding of transistors using lead free solder, seal ring attach for hermetic sealing of devices, and several related applications.