Understanding PCB design and material warpage challenges

The presentation, “Understanding PCB Design and Material Warpage Challenges Which Occur during B2B/Module-Carrier Attachment,” is scheduled to take place during session APT7, “Package and PCB Interactions,” on Wednesday, September 28^th at 4pm.

PCB warpage has been identified as one of several key contributors to unacceptable yield rates during reflow assembly of a PCB module to a PCB carrier board. The module has a land grid array pattern and is placed directly on solder paste on the carrier board. This results in low-profile solder joints that are sensitive to the co-planarity of both the module and the carrier boards. The typical failure mode occurs when one or more solder joint opens are caused by a lifted corner of the module during/after reflow.

This paper and presentation will present graphical and statistical details of at-room-temperature metrology on a large sample of modules with differing design variables. Shadow Moiré technique will be used to provide accurate warpage profiles of the 6-up module arrays before and after top- and bottom-side assembly, and again before and after attachment to the carrier board. A large volume of samples will be tested in order to gain statistical relevance of the data and correlate any yield problems to initial warpage. The objective is to isolate the key design parameter(s) that contribute most to attachment problems while also observing and reporting on the at-temperature warpage behavior of the substrates during reflow.

Curry is the Technical Account Manager at Akrometrix, having shifted to this role after almost 11 years of experience as a Test and Applications Engineer. He is a subject matter expert in at temperature warpage and strain measurement techniques. Curry has experience with frequent use of Akrometrix measurement tools for contract testing services and demonstration work, along with domestic and international customer support, technical sales, outgoing system quality assurance, software and NPI development work, and Akrometrix system installation and user training. He has a degree in Mechanical Engineering from the Georgia Institute of Technology.