SMTA International Conference Proceedings


RELIABILITY AND PASTE PROCESS OPTIMIZATION OF EUTECTIC AND LEAD-FREE FOR MIXED PACKAGING

Author: Prof. S. Manian Ramkumar et al.
Company: Rochester Institute of Tech.
Date Published: 9/22/2002   Conference: SMTA International


Abstract: BGA, fine pitch BGA and chip scale packages are becoming common for commercial applications and are increasingly being used in unique high reliability applications. This is due to the reduced size of these packages, higher pin count and increased performance benefits. The package complexity has increased the demand for faster implementation of optimal assembly methods.

The goal of this study is to characterize the effects of numerous paste print parameters using experimental design techniques. It is aimed to understand the impact of various print process parameters, BGA and CSP pitch density and area aspect ratio (AAR) on the solder paste print quality and volume, for both eutectic and lead-free pastes.

This paper reports the results of an experiment that utilized the JPL’s (Jet Propulsion Laboratory’s) area array consortium test vehicle design, containing a myriad of mixed technology BGAs and CSPs (ball grid array and chip scale packages) with an OSP finish. No-Clean and No-Lead solder pastes (Type III and IV), with viscosity ranging from 900-1200 Kcps were used in this study.

Reliability of the test vehicles with lead-free and eutectic pastes was evaluated by subjecting the PWB with paste to specified number of reflow cycles representative of lead-free and eutectic assembly. The reliability evaluation is aimed at determining solder joint quality and Microvia integrity, when subjected to multiple reflow heating cycles. The details of the reliability study are also presented in this paper.

Key words: DOE, BGA, CSP, eutectic, lead-free, reliability, AAR, SMT.



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