1. Introduction
In semiconductor packaging industry, the use of thin metal wires such as gold and copper to connect between IC chip
and connector pins through thermo- and ultrasonic welding (bonding) are common for various types of packages [1]. These
so called bonding wires are mainly gold, copper and aluminium with silver beginning to be used for low end LED devices.
In late 2008 to early 2009 when gold price was soaring after the economic downturn, the demand to replace gold bonding
wire with much lower cost material was unavoidable and copper being the natural choice due to its proven application in IC
packages. Not only has the demand of copper increases over the years to replace gold, the size of the wire also sees a
decrease from over 25 microns in diameter to less 20 microns as package design requires tens and hundreds of wires to be
bonded in a small landscape layout. However, copper being not malleable material compared with gold and work hardens
when force is applied to it, it post a challenge to user of the wire to avoid damage to the sensitive structure of the IC bond
pad when switched from gold to copper. Many questions arise on how hard the copper wire and the subsequent solidified
1. Introduction
In semiconductor packaging industry, the use of thin metal wires such as gold and copper to connect between IC chip
and connector pins through thermo- and ultrasonic welding (bonding) are common for various types of packages [1]. These
so called bonding wires are mainly gold, copper and aluminium with silver beginning to be used for low end LED devices.
In late 2008 to early 2009 when gold price was soaring after the economic downturn, the demand to replace gold bonding
wire with much lower cost material was unavoidable and copper being the natural choice due to its proven application in IC
packages. Not only has the demand of copper increases over the years to replace gold, the size of the wire also sees a
decrease from over 25 microns in diameter to less 20 microns as package design requires tens and hundreds of wires to be
bonded in a small landscape layout. However, copper being not malleable material compared with gold and work hardens
when force is applied to it, it post a challenge to user of the wire to avoid damage to the sensitive structure of the IC bond
pad when switched from gold to copper. Many questions arise on how hard the copper wire and the subsequent solidified
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