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Solvent for Removal of Flux Residues

IP.com Disclosure Number: IPCOM000084441D
Original Publication Date: 1975-Nov-01
Included in the Prior Art Database: 2005-Mar-02
Document File: 1 page(s) / 12K

Publishing Venue

IBM

Related People

Schmitt, GP: AUTHOR [+2]

Abstract

An azeotropic solvent composition of methyl ethyl ketone and isopropyl alcohol is found to effectively remove flux residues and corrosion producing elements in assemblies that are to be subjected to liquid cooling encapsulations.

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Solvent for Removal of Flux Residues

An azeotropic solvent composition of methyl ethyl ketone and isopropyl alcohol is found to effectively remove flux residues and corrosion producing elements in assemblies that are to be subjected to liquid cooling encapsulations.

Most of the known solvent compositions for the removal of soldering flux residues from printed-circuit boards and the like do not provide the ultraclean conditions required for liquid cooling encapsulation. The requirement for a minimum of residual contamination in assemblies for liquid cooling is substantially greater than for conventional air-cooled circuitry. Therefore, the effectiveness of solvents in removing flux residues and corrosion contributing elements is very critical in preparation of assemblies to be liquid cooled.

It is found that the azeotropic mixture of methyl ethyl ketone (70 parts by weight) and isopropyl alcohol (30 parts by weight) is very effective in removing flux residues and corrosion contributing elements. This is confirmed by evaluating the solubility parameters: methyl ethyl ketone - 9.4; isopropyl alcohol - 11.4; and the resulting azeotrope mixture - 10.0. This agrees with the solubility parameter of W.W. rosin (7.4 to 10.8) which is the main solid ingredient in the flux used in the process under test.

It is found in laboratory tests that the effectiveness is greater if the solvent's solubility parameter is in the upper range of the solubility parameter of the rosin used...