SMTA International Conference Proceedings


EFFECTS OF BACKGRIND AND PLASMA CLEAN ELIMINATION IN THE MANUFACTURING PROCESS FLOW ON PACKAGE PERFORMANCE

Authors: Jesse Phou and Trent Thompson
Company: Motorola Semiconductor
Date Published: 9/22/2002   Conference: SMTA International


Abstract: Many theories exist about the contaminants that may accumulate onto Silicon wafers during shipping, storage, and handling. It is not well understood whether wafer backside grinding immediately prior to assembly makes a difference as opposed to the assembling of a backgrinded wafer after a period of transport or storage.

The wafer carriers currently used in industry are not airtight, and are susceptible to many different types of contamination. But backgrinding just before assembly may remove all the undesired particles. Hence it has been theorized that wafer level plasma could potentially be an eliminated step upon implementing wafer backgrinding as part of the assembly flow.

This paper investigates the correlation between wafer backgrinding, wafer level plasma, and their effects on die with and without a polyimide coating in the MAPBGA package. The results of the evaluations show that wafer level plasma is needed for packages encountering MSL1 and higher reflow temperatures (i.e. 260°C), despite backgrinding shortly before assembly. Backgrinding location also appears to have no significant difference on package reliability.

Key words: MAPBGA, wafer level plasma, backgrind, contact angle, delamination.



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