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A Low-Temperature, Self-Cleaning Solder Reflow Process

IP.com Disclosure Number: IPCOM000103283D
Original Publication Date: 1990-Sep-01
Included in the Prior Art Database: 2005-Mar-17
Document File: 1 page(s) / 41K

Publishing Venue

IBM

Related People

Parente, M: AUTHOR [+4]

Abstract

Disclosed is a unique process for attaching components on ceramic/glass substrates and/or organic component carriers with reflowed low melt solder alloys through the use of water in the form of steam. A typical solder alloy would be a ternary eutectic composition of tin/lead/bismuth which has a melting temperature of 95 deg C. Solder reflow is accomplished without damaging components, chip functions, plating, metallizations, etc., since exposure to elevated temperatures is kept below 125 deg C.

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A Low-Temperature, Self-Cleaning Solder Reflow Process

      Disclosed is a unique process for attaching components on
ceramic/glass substrates and/or organic component carriers with
reflowed low melt solder alloys through the use of water in the form
of steam.  A typical solder alloy would be a ternary eutectic
composition of tin/lead/bismuth which has a melting temperature of 95
deg C.  Solder reflow is accomplished without damaging components,
chip functions, plating, metallizations, etc., since exposure to
elevated temperatures is kept below 125 deg C.

      Also, the use of steam as a vapor medium will provide attendant
technical benefits and process capability of existing
equipment/processes while eliminating the use of expensive and
environmentally dangerous CFC's (choroflourocarbons).  Current vapor
phase applications use a CFC as the heating medium.  The use of water
soluble fluxes provides for a self-cleaning process and eliminates
the use of CFC-based, post-solder cleaning processes. Current vapor
phase applications are incompatible with water soluble fluxes and
require the use of rosin-based fluxes, which require a CFC-based
cleaning solvent.  The use of low temperature solder alloys provides
for strategically sound migration to low temperature processes
whereby EC/repair process capability is increased, electronic
component cost is decreased since low temperature polymers can be
used and CFC's are eliminated.

      Disclosed anonymously.