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Bake Out of Low Solids/No Clean Fluxes for High Reliability Electronics

IP.com Disclosure Number: IPCOM000116234D
Original Publication Date: 1995-Aug-01
Included in the Prior Art Database: 2005-Mar-30
Document File: 2 page(s) / 60K

Publishing Venue

IBM

Related People

Hauptfleisch, EG: AUTHOR [+2]

Abstract

Low Solids/No Clean (LS/NC) fluxes are being evaluated for use on military specification, high-reliability hardware. The LS/NC fluxes are being compared to cleaned rosin or moderate activity rosin (RMA) fluxes for ionic cleanliness and surface insulation resistance. Fluxes based on dicarboxylic acids (adipic acid) show promise because they vaporize during soldering to leave little or no active residues. A reliability concern exists regarding areas of the assembly which are fluxed but not heated to solder temperatures (i.e., areas surrounding touched up or hand soldered zones).

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Bake Out of Low Solids/No Clean Fluxes for High Reliability Electronics

      Low Solids/No Clean (LS/NC) fluxes are being evaluated for use
on military specification, high-reliability hardware.  The LS/NC
fluxes are being compared to cleaned rosin or moderate activity rosin
(RMA) fluxes for ionic cleanliness and surface insulation resistance.
Fluxes based on dicarboxylic acids (adipic acid) show promise because
they vaporize during soldering to leave little or no active residues.
A reliability concern exists regarding areas of the assembly which
are fluxed but not heated to solder temperatures (i.e., areas
surrounding touched up or hand soldered zones).

      Studies indicate that unheated areas fail MIL-P-28809 ionic
contamination test and perform very poorly on Surface Insulation
Resistance (SIR) test.  A five-hour bake at 105ºC has been
demonstrated to remove these residues and give acceptable ionic
contamination and SIR test results.  See Figs. 1 and 2 for comparison
of unheated "raw" flux and flux subjected to various conditions of
soldering and baking.