SMTA International Conference Proceedings


STENCIL PRINTING AND REFLOW PARAMETER 'OPTIMIZATION' DURING ASSEMBLY OF 0201 COMPONENTS BY A DESIGNED EXPERIMENT APPROACH

Author: Praveen Kumar Manjeshwar et al.
Company: State University of New York
Date Published: 9/25/2005   Conference: SMTA International


Abstract: The assembly of miniature components on Printed Circuit Boards (PCBs) poses numerous challenges to each process step. The 0201 components are miniature components which are 0.020" in length and 0.010" in width. The assembly of 0201s using process settings that are currently in-place may result in defects including bridging, tombstoning and solderballing.

The objectives of this research are to evaluate two no-clean eutectic solder pastes, determine ‘optimum’ print parameters, and develop good reflow profiles to eliminate defects that are commonly observed during the assembly of 0201 components. The two no-clean solder pastes are evaluated and the ‘optimum’ print parameters were determined through a full factorial experiment. Statistical tests, such as the paired t-test and the calculation of the coefficient of variation of the volume of the solder paste deposited, helped to evaluate the two solder pastes.

A comprehensive literature review was conducted to arrive at the initial reflow parameters. The solder paste printing and reflow processes were modified as per the findings and were implemented to assemble several PCBs (test vehicles) with 0201s on them. The assemblies were inspected for defects, both visually and using a 10X microscope. In addition, the assemblies were also inspected using automated optical inspection equipment.

No defects were observed during these inspections. Consequently, it can be concluded that the recommended changes to the printing and reflow soldering processes have resulted in the successful development of a viable ‘drop in’ process for the assembly of 0201 components.

Keywords: Surface Mount Technology, 0201, Stencil Printing, Solder Reflow, Design of Experiments.



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