Browse Prior Art Database

Hybrid Thermode for Solder Attach

IP.com Disclosure Number: IPCOM000101208D
Original Publication Date: 1990-Jul-01
Included in the Prior Art Database: 2005-Mar-16
Document File: 2 page(s) / 81K

Publishing Venue

IBM

Related People

Corbin, JS: AUTHOR [+2]

Abstract

Disclosed is a thermode design for the solder attach of electronic components that addresses many of the problems of existing thermode designs, among them non-uniform temperature, poor thermal conductivity, high current requirements, and exposed voltage.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 52% of the total text.

Hybrid Thermode for Solder Attach

       Disclosed is a thermode design for the solder attach of
electronic components that addresses many of the problems of existing
thermode designs, among them non-uniform temperature, poor thermal
conductivity, high current requirements, and exposed voltage.

      Traditional thermodes used to reflow solder and attach
electrical components to PC boards are simple electrical heaters, as
shown in Fig.  1.  Electrical current passing through the blade heats
the blade itself through Joule heating.  Heat is conducted through
the blade into the component leads, solder, and PC board in order to
melt the solder and attach the component.

      The dimensions of typical blades and materials used result in
very high levels of electrical current Ic in order to generate
adequate temperatures in the blade to melt the solder.  Typical
values of Ic are 100 amps or higher.  In order to minimize variations
in blade temperature from lead to lead, high thermal conductivity of
the blade is desirable.  Because thermal and electrical conductivity
of suitable metals are directly related physically, it is not
possible to achieve both optimum electrical and thermal
characteristics.  For this reason, all such thermode designs are
compromises which have shown marginal thermal performance in actual
use.  The requirement that exposed voltage on the blade be kept low
to prevent board/component damage restricts the design even further,
and also contributes to the need for excessively high currents.

      This disclosure describes and invention which addre...