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Laser-Welded Thermocouple for In-Situ Temperature Measurement

IP.com Disclosure Number: IPCOM000037456D
Original Publication Date: 1989-Feb-01
Included in the Prior Art Database: 2005-Jan-29
Document File: 1 page(s) / 12K

Publishing Venue

IBM

Related People

Jackson, MW: AUTHOR [+2]

Abstract

Temperature measurement is often a critical process control parameter for electronic component assembly and packaging. Typically, thermocouples provide this information; however, their effectiveness is currently limited by the attachment technique, usually via adhesive or arc-welding (spot welding). Disclosed is a technique to acquire precise and accurate in-situ temperatures of a variety of substrates (circuit cards, silicon chips, ceramics, metal surfaces) which can then be used to enhance development and manufacturing processes.

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Laser-Welded Thermocouple for In-Situ Temperature Measurement

Temperature measurement is often a critical process control parameter for electronic component assembly and packaging. Typically, thermocouples provide this information; however, their effectiveness is currently limited by the attachment technique, usually via adhesive or arc-welding (spot welding). Disclosed is a technique to acquire precise and accurate in-situ temperatures of a variety of substrates (circuit cards, silicon chips, ceramics, metal surfaces) which can then be used to enhance development and manufacturing processes.

The solution is to use a Nd:YAG laser to weld thermocouple wires to a variety of substrates. A pulsed Nd:YAG laser operated at 1064 nm wavelength can easily weld thermocouples to fine pitch copper pads on a glass epoxy circuit card. This will allow in-situ temperature measurements for advanced interconnect process development work. Some applications to the Surface Mount Technology process development work and manufacturing are described below: 1. After thermocouple wires have been welded to the copper pads on a circuit card, solder is applied to the pads such that the thermocouple junction is covered. Only one thermocouple per pad is recommended. During the bonding process, the thermocouple directly measures the solder temperature on a particular pad. This will allow real time monitoring of the heat transfer rate of the solder joint under actual reflow conditions. This infor...