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Transistor Mounting And Connection

IP.com Disclosure Number: IPCOM000121055D
Original Publication Date: 1991-Jul-01
Included in the Prior Art Database: 2005-Apr-03
Document File: 2 page(s) / 77K

Publishing Venue

IBM

Related People

Felton, BC: AUTHOR [+2]

Abstract

This article describes a transistor mounting and connection arrangement having short connections between the transistor's terminals and associated circuitry, while providing a highly efficient thermal coupling to a heatsink.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 54% of the total text.

Transistor Mounting And Connection

      This article describes a transistor mounting and
connection arrangement having short connections between the
transistor's terminals and associated circuitry, while providing a
highly efficient thermal coupling to a heatsink.

      Referring to the figure, a transistor, having a package such as
TO-3 or TO-220 type, is mounted to a mounting sink 1 so that it leads
13 pass through holes 3 in heatsink 1. Printed circuit board 7 slides
between the shelf 2 of sink 1 and the transistor leads 13.  Board 7
is held in place by an insulating pressure bar 11 and clamping screws
10.  Pressure exerted by screws 10 clamps the leads 13 onto the
contact pad 8 on board 7.  Simultaneously, contact is made between
contact pad 9 on the underside of board 8 and the shelf 2 of mounting
sink 1 to complete electrical connection to the grounded (package)
terminal of transistor 12.  Transistor mounting 1 is, in turn,
mounted on heatsink 6 by way of screws (not shown) passing through
holes 4 in sink 1. Mounting sink 1 is electrically isolated from
heatsink 6 by way of a thin thermally conductive electrical insulator
5. The thermal resistance of the insulator 5 is much greater than the
common surface area of contact under transistor 12. Since the
transistor die of transistor 12 is located below pins 13, it is
pressed against sink 1 in the vicinity of the thick section below
shelf 2.  Lead length is essentially limited to the length of pins
13, sinc...