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Enhanced Aluminum Wire Bond Process

IP.com Disclosure Number: IPCOM000040690D
Original Publication Date: 1987-Dec-01
Included in the Prior Art Database: 2005-Feb-02
Document File: 2 page(s) / 39K

Publishing Venue

IBM

Related People

Leslie, GG: AUTHOR [+2]

Abstract

The instability in resistance at the intermetallic bond between aluminum and copper is avoided through coating an aluminum wire with nickel prior to bonding the aluminum wire to a copper pad. An aluminum wire 1 has a very thin layer 2 of nickel, such as 10 to 20 microinches, applied thereto as a coating by an electroless plating technique, for example. When the aluminum wire 1 is bonded to a copper pad 3, for example, the layer 2 of nickel flows to form a nickel barrier 4 between the aluminum wire 1 and the copper pad 3. This prevents formation of an aluminum-copper intermetallic bond so that instability in resistance at the bond does not occur. The wire 1 can be completely coated with the layer 2 of nickel or can be selectively coated wherever it is desired to bond the wire 1 to the copper pad 3.

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Enhanced Aluminum Wire Bond Process

The instability in resistance at the intermetallic bond between aluminum and copper is avoided through coating an aluminum wire with nickel prior to bonding the aluminum wire to a copper pad. An aluminum wire 1 has a very thin layer 2 of nickel, such as 10 to 20 microinches, applied thereto as a coating by an electroless plating technique, for example. When the aluminum wire 1 is bonded to a copper pad 3, for example, the layer 2 of nickel flows to form a nickel barrier 4 between the aluminum wire 1 and the copper pad 3. This prevents formation of an aluminum-copper intermetallic bond so that instability in resistance at the bond does not occur. The wire 1 can be completely coated with the layer 2 of nickel or can be selectively coated wherever it is desired to bond the wire 1 to the copper pad 3. Furthermore, with a polymer on aluminum substrate having copper lands to be connected thereto, the aluminum wire 1 with the layer 2 of nickel can be disposed between the aluminum substrate and the copper land to connect the copper land to the aluminum substrate so that no aluminum-copper intermetallic layer is formed. This avoids the expense of nickel plating of the copper lands.

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