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Protection of Printed Circuit Panels And Surface-Mounted Components From Thermal Irradiation

IP.com Disclosure Number: IPCOM000101189D
Original Publication Date: 1990-Jul-01
Included in the Prior Art Database: 2005-Mar-16
Document File: 1 page(s) / 41K

Publishing Venue

IBM

Related People

Bonnell, RE: AUTHOR [+3]

Abstract

This article describes a new method for protecting electronic circuit cards and components during an infrared solder reflow operation through surface characteristic modification in order to reduce the maximum temperature of the component and/or panel during assembly.

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This is the abbreviated version, containing approximately 82% of the total text.

Protection of Printed Circuit Panels And Surface-Mounted Components From Thermal Irradiation

       This article describes a new method for protecting
electronic circuit cards and components during an infrared solder
reflow operation through surface characteristic modification in order
to reduce the maximum temperature of the component and/or panel
during assembly.

      Current components and panels in surface mount assembly process
are not manufactured with thermal enhancements. Chips for surface
mount components are typically encapsulated using black plastic
materials.  Most circuit cards come with a protective solder mask
such as PROBIMER*. These do not provide thermal enhancements for
selected regions of the panel.

      Two methods to provide thermal performance enhancements are
described.
1) Coat the body of the component or the board during its manufacture
with a reflective material such as titanium oxide paint that lowers
the absorptivity and increases the reflectivity.

      Surface mounted components coated with a titanium oxide loaded
paint may experience 6 to 10 deg. C differential during an infrared
reflow process.  Selected pads coated with the same material
experience 10 deg. C lower temperatures under similar conditions.

      A significant drop in surface temperature results from use of
the surface coating.  It is estimated, from a knowledge of infrared
oven profiling, that a 10-degree drop in surface temperature gives
rise to a...