Pan Pacific Symposium Conference Proceedings


IMPROVEMENT OF THE ACCURACY OF HIGH SPEED MILLING ON SO-DIMM DEPANEL PROCESS OF PCA

Author: C.Y. Ho et al.
Company: St. John's & St. Mary's Inst.
Date Published: 2/25/2005   Conference: Pan Pacific Symposium


Abstract: This study presents an investigation to improve the dimensional accuracy of high-speed milling during the SO-DIMM (Small Outline Dual In-line Memory Modules); Depanel is a milling process to singulate the PCA (Print Circuit Board Assembly) panel into single piece of SODIMMs. If the length of SO-DIMM exceeds the tolerance limits, the whole DRAM module has to be scrapped.

The parameters affecting the depanel accuracy include the working tables, fixtures location, tool position, tool wear and cutting temperature. This study proposes the use of combining grey relation analysis with SPC (statistical process control) to identify that progressive tool wear is the dominant factor affecting the depanel process accuracy. In grey relation analysis, transformation model of data normalization is used to correlate the measured depanel data.

Use of the grey relation analysis resulted in fewer data analysis to understand the trend of fabrication process characteristics. Nevertheless, this study also uses SPC to manifest the improvement, showing a Cpk value changing from 0.788 to 2.175, and the tool life of mill extended from milling of 25 to 45 panels.

Key words: depanel process, tool wear, SO-DIMM, grey relation, SPC.



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