Browse Prior Art Database

Tubular Thermal Conduction Slugs and PCB pads

IP.com Disclosure Number: IPCOM000198227D
Original Publication Date: 2010-Jul-31
Included in the Prior Art Database: 2010-Jul-31
Document File: 3 page(s) / 672K

Publishing Venue

Motorola

Related People

Strzelczyk, Martin: INVENTOR [+3]

Abstract

This disclosure proposes an alternative to solid cylindrical heat slugs in surface mount applications which are subject to misalignment from: solder doming, uneven surface tension, and gaseous expansion in voids present inside vias of modern PCBs (Printed Circuit Boards). By hollowing the cylinder, and modifying the accompanying PCB pad, the mechanical and thermal performance of surface mount thermal slugs can be improved.

This text was extracted from a Microsoft Word document.
At least one non-text object (such as an image or picture) has been suppressed.
This is the abbreviated version, containing approximately 54% of the total text.

Tubular Thermal Conduction Slugs and PCB pads

By Martin Strzelczyk, Robert Strzelczyk, Thomas Zanatta

Motorola, Inc.

Enterprise

Mobility Services

 

ABSTRACT

This disclosure proposes an alternative to solid cylindrical heat slugs in surface mount applications which are subject to misalignment from: solder doming, uneven surface tension, and gaseous expansion in voids present inside vias of modern PCBs (Printed Circuit Boards).

By hollowing the cylinder, and modifying the accompanying PCB pad, the mechanical and thermal performance of surface mount thermal slugs can be improved.

PROBLEM

Thermal slugs are a good solution for absorbing and conducting heat away from electronics. A common type is manufactured by chopping cylindrical metallic stock to desired height. The flat surfaces of the cylinders can be cheaply produced to meet required mechanical tolerance; however, the process of mounting these components with solder reflow can lead to unpredictable alignment with the PCB due to component tilting. This can lead to degradation of thermal conduction because of the non-ideal surface alignments to the surrounding heat sinks.

SOLUTION

Instead of using a solid cylinder as a heat slug, and a circular PCB pad, which can cause "doming" and tilting during reflow, a tube can be used. The solder reflowing on such a pad will not have a doming effect, and the slug will be symmetrically centered by the solder surface tension on both inside and outside cylinder surfaces.

Similar ideas found in this area are fastener-based, which is an expensive process step not inherent in surface mount technology  Surface tension during solder reflow is used to improve mounting results of heat slugs. The flatter top surface (better tolerance) can lead to improved heat flow. Additionally, the slug's surface area is increased. This method can be used in any electronic application where thermal conduction away from PCB is important to prevent damage or functional degradation due to high temperature. It applies mostly to small form-factor radio systems that dissipate significant heat into the PCB.

The hollowed out volume has additional positive effects:

1)    It increases the overall surface area.

2)      It provides a mechanical registry for thermally conductive material.

3)    It provides an escape path for expanding gasses from inside PCB vias.

4)    It provides an escape path and/or...