SMTA International Conference Proceedings

Automated Site Redress Method Application For Pb-Free Rework

Authors: Sven Peng, Wayne Zhang, PK Pu, Phil Isaacs, William Uy and Henley Zhou
Company: IBM Corporation and Flextronics Zhuhai
Date Published: 10/14/2012   Conference: SMTA International

Abstract: As the transition to lead free solder assembly for server product with higher complexity and density, the new rework challenges for both Ball Grid Array (BGA) and Pin Through Hole (PTH) components arise. With the conventional site redress method by solder iron with/without solder wick at elevated lead free temperature, pad damage, pad oxidization, excessive solder and flux residues post site redress could be more easily seen on BGA rework. The longer contact time of PTH solder fountain rework is also driving increasing concerns on Cu dissolution. There are other concerns as well.

Automated Site Redress (ASR), with its advantages of automation, repeatable results and better heat transfer efficiency with the utilization of optional bottom heater etc., has been increasingly used for hot gas rework site redress, as well as for removing the solder in PTH holes after component removal.

This paper will present the introduction of different site redress methods on reworks from a server-level complexity and lead free assembly. The application of ASR for both BGA and PTH component rework, in terms of appropriate process parameter development, process validation and comparison of results to other methods. In addition, the construction analysis post reworks will be discussed.

Key Words: 

Lead Free, Rework, Automated Site Redress, PTH, BGA

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