iNEMI solder paste deposition project - First stage review optimizing solder paste printing for large and small components

The widely recognized industry standard IPC-7525 has been used as the starting point for an experimental program that explores the effect of varying the keep out distance for 0201 and 0402 chip components, CSP and SOP with pitches down to 0.4 mm, and larger components represented by CCGA. Other variables that were included in the experimental program to determine if they had an effect on the sensitivity of paste transfer to keep-out distance included stencil type, step height and solder type. In the first stage of the project the printing to each pad was measured with automated 3D SPI systems and optimum combinations of parameters identified by statistical analysis. In this paper the authors will explain the methodology chosen to achieve the project objectives and indicate the direction of likely future work. Early results indicate that a key objective of the project, to provide evidence to support the case for a reduction in the keep out distances below the current industry standard, might be achievable.