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HERMETIC BOAT

IP.com Disclosure Number: IPCOM000005637D
Original Publication Date: 1987-Oct-01
Included in the Prior Art Database: 2001-Oct-23
Document File: 1 page(s) / 62K

Publishing Venue

Motorola

Related People

Brian Webb: AUTHOR [+2]

Abstract

A hermetic boat used for die attach and wire bonding is shown in the accompanying figures. The prior types of boat are illustrated in figure 1. As shown, a plurality of tabs are used to position a ceramic base on the boat. Because of a 1% tolerances allowed in the dimensions of the ceramic base, the distance between the tabs is generally greater than most ceramic bases. This allows for movement of the ceramic package be- tween the tabs, resulting in location problems in die attach and wire bonding. This problem is particularly felt in the handling of large ceramic bases, as large as of 41 With a tolerance of ? l%, there is the possibility of having a 3.96" ceramic base on a boat with tabs spaced 4.04" apart. This leaves a possible variance of 0.08" between the centers of the base and the die.

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MOTOROLA Technical Developments Volume 7 October 1987

HERMETIC BOAT

by Brian Webb and Frank Polka

   A hermetic boat used for die attach and wire bonding is shown in the accompanying figures. The prior types of boat are illustrated in figure 1. As shown, a plurality of tabs are used to position a ceramic base on the boat. Because of a 1% tolerances allowed in the dimensions of the ceramic base, the distance between the tabs is generally greater than most ceramic bases. This allows for movement of the ceramic package be- tween the tabs, resulting in location problems in die attach and wire bonding. This problem is particularly felt in the handling of large ceramic bases, as large as of 41 With a tolerance of ? l%, there is the possibility of having a 3.96" ceramic base on a boat with tabs spaced 4.04" apart. This leaves a possible variance of 0.08" between the centers of the base and the die.

   In order to reduce this problem the tabs have been moved closer together and one of the tabs is angled, figure 2. This causes at least one side of the base to be placed in a known location thereby reducing the possi- ble variance by half. As shown in figure 2, this can cause the base to be seated at an angle while on the boat. This does not cause problems since the bases are contacted from below by a vacuum chuck and lifted to a work position. The drawing shown in figure 2 also illustrates an alternative to the tabs being formed by stamp- ing. This alternative is the use of a we...