NEPCON West - Fiberoptic Expo Conference Proceedings


LASER SOLDER ATTACHING FOR OPTOELECTRONICS AND MEMS PACKAGES

Author: Elke Zakel et al.
Company: Pac Tech - Pkg. Tech. GmbH
Date Published: 12/3/2002   Conference: NEPCON West - Fiberoptic Expo


Abstract: The packaging of optoelectronic and MEMS devices is challenging the requirements for interconnection and soldering technology. These requirements can no longer be met with standard flux-based processes, which use a long temperature reflow profile and implement a great many mechanical-handling steps and processes. Packaging these new devices requires fluxless soldering, a lack of thermal stress by localized heating, and low or no mechanical contact with and damage to sensitive membranes in MEMS or optical components, respectively.

Some of these applications even require three-dimensional (3D) packaging and selective solder application in 3D structures like cavitiesand vertical assemblies. An additional, very challenging, requirement is great flexibility in solder alloys, because eutectic tin/lead and other lead-based solder alloys are not applicable. Instead, gold/tin- and indium-based solder alloys are required.

To fulfill the specific needs in these applications, a new laser-based solder technology has been developed. This technology fulfills all the needs of fluxless soldering: local heating and reflow, lack of mechanical contact and stress during soldering, great solder-alloy flexibility, and capability for 3D packaging. Prior to developing the Solder Ball Bumping Jet (SB2-Jet) process, many potential applications had been developed using the Solder Ball Bumping (SB20 technology.

The advantages the SB2-Jet basically consist of higher throughput: 10 balls/s. The process also fulfills most of the requirements for today’s packaging of optoelectronic and MEMS devices now in production. A further increase in speed to 20- and 30-balls/sec will be the next-generation product. An additional feature of this technology is the repair option and repair capability. This permits removal and replacement of individual solder balls and solder contacts, increasing the yield and productivity of cost-intensive high-end devices.



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