Abstract: A solder material 10 suitable for fluxless soldering attachment of a component 12 to a substrate 14 in a microelectronic assembly 16 such as a hybrid package comprises a core 18 and a gold layer 20 on the core. The core can comprise an alloy of tin and lead. The core preferably consists essentially of at least about 30 wt. % tin and the balance lead, so that it melts at temperatures of less than about 250° C. The gold layer is preferably applied to the core using an electroless plating process that forms a highly uniform gold layer. The solder material provides a joint between the component and the substrate comprising less than about 3 wt. % gold.

Abstract: The invention relates to a method for integrating semiconductor device epilayers with arbitrary host substrates, where an indium gallium arsenide etch-stop layer (34) is deposited on an indium phosphide growth substrate (32) and device epilayers (36, 38) are grown on the etch-stop layer in inverse order from their final orientation. The device epilayers are then joined to an aluminum nitride host substrate (42) by inverting the growth substrate and device epilayers. The epilayers are bonded to the host substrate using mono-molecular layer forming bonding material and the growth substrate is selectively etched away from the device epilayers. As a result of the inverse epilayer growth, the epilayers are not removed from the growth substrate prior to bonding to the host substrate, thus protecting the device epilayers and reducing processing steps. Additionally, by mono-molecular bonding, sturdy semiconductor devices are formed with low thermal impedance.

Abstract: A technique is described for the removal of trace metal contaminants from organic dielectrics such as polyimide. Pulsed ultraviolet radiation is used to remove the contaminants from the dielectric, regardless of their chemical nature, by the process of ablation. The process allows prepatterned bulk metal features to be simultaneously exposed to the pulsed radiation and yet remain unaffected.