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Flip-Chip interconnections using lead-free solders

  • US 6,224,690 B1
  • Filed: 03/12/1996
  • Issued: 05/01/2001
  • Est. Priority Date: 12/22/1995
  • Status: Expired due to Term
First Claim
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1. An interconnection structure suitable for flip-chip attachment of microelectronic device chips to packages, comprising:

  • a two-layer ball-limiting metallurgy comprising an adhesion/barrier layer and a copper-free solderable layer wherein said adhesion/barrier layer is between a microelectronic device and said copper-free solderable layer and wherein said copper-free solderable layer is of a metal selected from the group consisting of Ni, Co, Fe, NiFe, NiCo and NiCoFe, each said metal from said group being sufficiently non-reactive with components of a tin-containing lead free solder, such that said copper-free solderable layer remains after being placed in contact therewith in a soldering action; and

    one or more lead-free solder balls selectively situated on said copper-free solderable layer, said lead-free solder balls consisting of tin as the predominant component and one or more alloying components selected from the group consisting of Bi, Ag and Sb, whereby said lead-free solder ball substantially avoids alpha particle emission and induced soft logic errors which result therefrom.

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