Pan Pacific Symposium Conference Proceedings


Author: Patrick B. Hassell
Company: AkroMetrix, LLC
Date Published: 2/13/2001   Conference: Pan Pacific Symposium

Abstract: Warpage characterization of components and substrates began to gain in importance with the development of area array devices – most notably the BGA. Today, packagers and assemblers are faced with a multiplying amount of packaging formats and advanced substrates that demand tight mechanical tolerances. While designs have advanced tremendously, the extent to which we routinely characterize warpage has progressed limitedly at best.

In-process warpage evaluation of devices and substrates is proving to have significant value not just in the design and reliability phases, but also in the roll of production diagnostics and production yield improvement. In-process warpage analysis is being used in pre-production applications to qualify each component and substrate design to be assembled on a flow-line (package assembly and board assembly).

By fully characterizing device and substrate behavior prior to production, assemblers can significantly reduce in-line defects related to adverse mechanical behaviors. Two cases where pre-production investigations resulted in significant processing yield improvements are examined. Data presented shows that characterizing the type and characterizing the location of warpage can be as critical as characterizing the magnitude of warpage.

Advanced warpage characterization is hypothesized to be valuable to solder joint reliability investigation. Interconnect analysis, together with reliability analysis, will be two critical areas of mechanical property focus with the introduction of lead-free solders and bromine-free laminates.

It is concluded that advanced characterization of warpage can be an important means for reducing interconnect defects. Fewer soldering defects result in fewer units requiring rework – one of the single highest cost elements of assembly and manufacture. Advanced characterization of warpage by evaluating location and type of warpage in addition to magnitude can further enhance defect-free manufacturing initiatives.

Key words: warpage, defects, rework, thermomechanical behavior, characterization.

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