Browse Prior Art Database

Nickel-Alloyed Solder for Surface Mount Technology

IP.com Disclosure Number: IPCOM000120375D
Original Publication Date: 1991-Apr-01
Included in the Prior Art Database: 2005-Apr-02
Document File: 2 page(s) / 65K

Publishing Venue

IBM

Related People

Kang, SK: AUTHOR

Abstract

Disclosed is a new ternary solder alloy of tin-lead-nickel developed for the applications of surface mount technology. This alloy showed a higher strength and longer fatigue life than the standard tin-lead eutectic solder. Solder joint reliability is an important subject for surface mount technology (SMT), where the IC packages are mounted on the surfaces of a printed circuit board instead of being inserted through the plated-through holes.

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Nickel-Alloyed Solder for Surface Mount Technology

      Disclosed is a new ternary solder alloy of
tin-lead-nickel developed for the applications of surface mount
technology. This alloy showed a higher strength and longer fatigue
life than the standard tin-lead eutectic solder.  Solder joint
reliability is an important subject for surface mount technology
(SMT), where the IC packages are mounted on the surfaces of a printed
circuit board instead of being inserted through the plated-through
holes.

      Additions of Ni up to 2% in weight were made by melting Ni into
the Sn-Pb eutectic solder in a vacuum induction furnace, followed by
rapid solidification of the solder at 100oC/s or higher rates.  Most
of the Ni was precipitated out as a fine dispersion of Ni3Sn4 .  When
the solidification was done at the slower rates, the intermetallic
phase was precipitated out as large needles or aggregates, which had
detrimental effects, rather than any beneficial effects on the
mechanical properties.  The addition of Ni up to 2 wt % did not
change the melting point of the eutectic solder.  However, the
wettability of the solder was affected significantly when the content
of Ni was above 1.5%.  The wettability tests have provided a
guideline in limiting the Ni content in the solder.  Low cycle
fatigue life data of the Ni-alloyed solders were obtained by
performing reverse bending fatigue testing.  The solder with 0.5%
nickel showed the best result, which was about twice longer fatigue
life than the standard eutectic sol...