Dismiss
InnovationQ will be updated on Sunday, Oct. 22, from 10am ET - noon. You may experience brief service interruptions during that time.
Browse Prior Art Database

Air Cooled Module with Conformal Inner Fin

IP.com Disclosure Number: IPCOM000051707D
Original Publication Date: 1981-Mar-01
Included in the Prior Art Database: 2005-Feb-10
Document File: 3 page(s) / 67K

Publishing Venue

IBM

Related People

Gupta, OR: AUTHOR [+2]

Abstract

This air-cooled module has increased power dissipation capability due t decreased internal and external thermal resistance resulting from the use of a conformal inner fin.

This text was extracted from a PDF file.
At least one non-text object (such as an image or picture) has been suppressed.
This is the abbreviated version, containing approximately 53% of the total text.

Page 1 of 3

Air Cooled Module with Conformal Inner Fin

This air-cooled module has increased power dissipation capability due t decreased internal and external thermal resistance resulting from the use of a conformal inner fin.

In Fig. 1, a chip 1 is mounted on a substrate 2 via solder balls 3. These are solder elements which, when heated at a later stage, serve to connect the chip to the substrate. A can 6 is crimped to the substrate. Space between substrate 2 and can 6 is filled with room temperature vulcanization (RTV) material. The space inside the module is filled with thermal grease 7 having high thermal conductivity particles 8. The module is mounted on a card or board 9 by means of pins 4. In this arrangement, an inner conformal fin 10 is made to conform to the chips/ substrate/can. The fabrication of the inner fin is described below.

In the manufacturing process (Fig. 2A) the module cap is inverted and filled with a predetermined amount of premixed silicon grease in which 40% of the particles by volume are of high thermal conductivity material. The substrate with chip is placed in the cap and crimped in place. The backseal is applied and allowed to cure. Modules are then placed in a centrifuge (Fig. 2B) such that the centrifugal force is normal to the top of the substrate surfaces.

The rotational speed is such that the force is 50-100 G's. The applied centrifugal force causes the denser particles to flow outwardly and settle on the chip and substrate. This settling forms a conformal fin of uniform thickness over the chip and substrate, bridging both the chip to substrate and substrate to can. This coating is uniform due to the uniform distribution of particles in the grease prior to centrifuging and also because the force causing the particles to settle is uniform and normal to the substrate surface with no transverse component. The applied force causes the particles to interlock, forming a permanent conformal coating; this coating will not separate later in any orientation because the particles have been locked in place by the extreme centrifugal force.

These particles can be beryllium oxide (BeO) or aluminum particles whose surface has been oxidized, which have high thermal conductivity and very high electrical resistivity.

A thermal resistance...