Hybrid Assembly Cleaning with Non-Halogenated Solvents

Because of xegulatoe, economic and community pressures, halogenated solvents, routinely used for various cleaning operations in the electronics industry, are being aggressively phased out. A fundamental undemanding of the chemical n a t u ~ of process specific contamination is essential to enable thegroper selection of appropriate alternative cleaning agents. In this study, the role and need of CFCs used in hybrid assembly cleaning prior to hermetic encapsulation was studied. The specific case of mishandling contamination removal (i.e., fingerprints) was addressed. Due to the unpredictable nature of this type of contamination, a method of applying "standard" contamination to simulate accidental handling contamination was d The contamination added contained both a non-polar organic component (fat) and a (salt). m groups of commercially available non-halogenated solvents, alcohols, terpene based and ester based, were evaluated for defluxing and general surface cleaning in various hybrid assembly cleaning operations. The abiity of these solvents to remove polar (ionic) and non-polar (organic) contaminants was analyzed and compared to that of the CFCs. Surface cleanliness was monitoTed using surface analytical techniques such as X-Ray Photoelectron Spectroscopy. The results indicate that some cleanem are able to surpass the cleaning efficiency of the CFCs, especially for removing polar species. All of the solvents studied performed well. Judicious and practical choice of alternative solvent, therefore, depends on the specific application. Although this study has targeted hybrid cleaning specifically, the results can be extended to other cleaning applications involving organic contamination removal, e.g., fingerprints. The cleaning materials evaluated here can potentially serve as replacements for the chlomflo"s, pending specific process evaluations.