Browse Prior Art Database

Improved Thermode Blade for Thermo-Compression Bonding

IP.com Disclosure Number: IPCOM000106138D
Original Publication Date: 1993-Oct-01
Included in the Prior Art Database: 2005-Mar-20
Document File: 2 page(s) / 66K

Publishing Venue

IBM

Related People

Bickford, HR: AUTHOR [+5]

Abstract

The shape of a commercial thermode blade is modified in a way that the temperature at the blade surface is uniform. With this improved blade, the strength of the inner lead bonds near chip corners increases significantly, to an acceptable level.

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This is the abbreviated version, containing approximately 57% of the total text.

Improved Thermode Blade for Thermo-Compression Bonding

      The shape of a commercial thermode blade is modified in a way
that the temperature at the blade surface is uniform.  With this
improved blade, the strength of the inner lead bonds near chip
corners increases significantly, to an acceptable level.

A thermode blade  which is used in the commercial machines for chip
inner lead bonding is shown in Figs. 1-3.  Fig. 1 shows a
three-dimensional view of a commercial thermode blade.  Fig. 2 shows
a bottom view of the blade of Fig. 1.  Fig. 3 is a side view of the
blade of Fig. 1.  To achieve rapid thermal response, the blade is
heated resistively by electric current passing directly through it.
Because of the geometry of the blade, the local resistance along its
inner edge is lower than that along its outer edge; i.e., referring
to Fig. 3, the local resistance along line AA is lower than that
along line BB.  As a result, the local heat generation rate near its
inner edge (AA) is higher than that near its outer edge (BB).  That
uneven heat generation produces a lower temperature at the blade
corner due to the relatively low thermal conductivity of the blade
material.  The direct result of the non-uniform blade temperature is
a non-uniform strength of inner lead bonds on a chip.  The bond
strength oat the chip corners is much lower than that at the centers.

In order to increase the strength of the inner lead bonds at chip
corners, the temperature at blade corne...