Converting to lead-free Packages
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Excerpt from Oki
Technical Review
December 2001,
(PDF 447KB)
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Lead-free terminal plating for packages can be achieved by replacing conventional Sn-Pb material with proposed Sn-Bi material. Sn-Bi is harder and more brittle than Sn-Pb but with appropriate mounting conditions and solder material applied, the same reliability level of Sn-Pb can be achieved.
Lead-free plating must provide the following reliability characteristics:
• No cracks in the plating, in particular when pins are shaped to 'gull wings'.
• Ensurance of solderability.
• Long-term reliability of solder joints.
• Elimination of 'needle shaped crystals' (whisker) during long storage periods.
• and also: minimized increase in cost.
No doubt, the soldering process, too, needs to be converted accordingly in order to realize an absolutely lead-free assembly process. Interested? Please download the article and read further:
Excerpt from Oki Technical Review December 2001, (PDF 447KB)
Chemistry Assistant:
Sn: Tin, atomic number 50, atomic weight 118.7, period 5, group 14(IVB)
Pb: Lead, atomic number 82, atomic weight 207.2, period 6, group 14(IVB)
Bi: Bismuth, atomic number 83, atomic weight 209, period 6, group 15(VB)
Ag: Silver, atomic number 47, atomic weight 107.9, period 5, group 11(IB)
Cu: Copper, atomic number 29, atomic weight 63.55, period 4, group 11(IB)
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