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COMPOSITE METAL-CERAMIC TOP PLATE FOR WIREBOND MACHINES

IP.com Disclosure Number: IPCOM000009454D
Original Publication Date: 1999-Sep-01
Included in the Prior Art Database: 2002-Aug-26
Document File: 2 page(s) / 83K

Publishing Venue

Motorola

Related People

Paolo Reyes: AUTHOR [+2]

Abstract

Today's thermosonic wirebond technology uses a combination of thermal and ultrasonic energy to achieve metallic bonding between a die pad surface, the wire and the metal substrate. The leadframe or metal substrate has to rest on a high temperature top plate for the leads to be at a sufficient temperature for intermetallic diffusion to occur. Current top plate materials and designs allow virtually unhin- dered heat flow from heater block to the leadframe, being constructed from tool steels with relatively high thermal conductivity coefficients. This high temperature environment is vital in the formation of good bonds between the gold wire and the lead- frame. Such designs, however, also place the die and flag area in a high temperature environment which can lead to reliability failures. The key to solving this problem is to design a top plate which distributes heat to the leads where it is needed while protecting the flag area from high temperatures.

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6% M-LA Technical Developments

COMPOSITE METAL-CERAMIC TOP PLATE FOR WIREBOND MACHINES

by Paolo Reyes and Thor Yanga

BACKGROUND

  Today's thermosonic wirebond technology uses a combination of thermal and ultrasonic energy to achieve metallic bonding between a die pad surface, the wire and the metal substrate. The leadframe or metal substrate has to rest on a high temperature top plate for the leads to be at a sufficient temperature for intermetallic diffusion to occur. Current top plate materials and designs allow virtually unhin- dered heat flow from heater block to the leadframe, being constructed from tool steels with relatively high thermal conductivity coefficients. This high temperature environment is vital in the formation of

TOO1 Steel

good bonds between the gold wire and the lead- frame. Such designs, however, also place the die and flag area in a high temperature environment which can lead to reliability failures. The key to solving this problem is to design a top plate which distributes heat to the leads where it is needed while protecting the flag area from high temperatures.

DESIGN

  As shown in the Figure, the top plate with the thermal properties above is made possible through the use of a refractory material such as a ceramic, fitted into a tool steel base.

Base Metal

Composite metal-ceramic top plate

0 Motorola. Inc. ,999 100 September 1999

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Developments Technical 0 M MOlOROLA

  Through this design the heat flow through th...