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Laser-Assisted Bonding Method with Solid Phase Interdiffusion

IP.com Disclosure Number: IPCOM000112239D
Original Publication Date: 1994-Apr-01
Included in the Prior Art Database: 2005-Mar-27
Document File: 2 page(s) / 35K

Publishing Venue

IBM

Related People

Wada, T: AUTHOR

Abstract

Disclosed is an Inner Lead Bonding (ILB) method for Tape Automated Bonding (TAB) or TSOP with Cu-Al solid phase interdiffusion by YAG LASER.

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Laser-Assisted Bonding Method with Solid Phase Interdiffusion

      Disclosed is an Inner Lead Bonding (ILB) method for Tape
Automated Bonding (TAB) or TSOP with Cu-Al solid phase interdiffusion
by YAG LASER.

      When we consider concentration of high power at electric
connections for high wattage and high speed package, this Cu-Al
direct bonding method has advantages for 1) low contact resistance,
2) ohmic contact without hysteresis till 280 mA, 3) very thin alloy
layer (0.02 - 0.36 um), and 4) high reliability (activation energy :
1.26 eV) against current inner lead bonding method.

      As shown in the Figure, the disclosed LASER assisted bonding
method uses optical windows with a N2 gas application hole for
cooling and for compression bonding.  This N2 cooling gas protects
chip damages on the LSI chip from the concentrated LASER power and
avoids Al electrode melting.  YAG LASER beam is applied on the Cu
bumps through optical windows and Cu bumps start deformation for
bonding with bonding load at optical windows.

      The characteristic of this bonding method can make connection
between Cu-Al without hydrogen gas atmosphere or ultrasonic
assistance.