Authors: Jeff Schake and Mark Whitmore Company: ASM Assembly Systems Date Published: 5/9/2016
ICSR (Soldering and Reliability)
Abstract: The challenges associated with miniaturized component stencil printing in heterogeneous assembly are well documented with proven printing solutions. Now with the reality that the ultra-small Metric 0201 passive component is being introduced to market, printing capability is once again not assured. A series of focused Metric 0201 experiments investigating printing process sensitivity to circuit board properties, including pad dimensional accuracy and landscape topography, identified stencil gasket as significantly important on achieving print process control. The effects of pad size influencing print quality were found to be less using a nano-coated stencil. The print quality produced on undersized Cu pads was significantly degraded with an un-coated stencil, whereas full Cu pads printed better. The stencil with an applied nano-coating improved print volume uniformity on all Cu pad sizes more significantly than improving overall paste transfer efficiency. Based on this test, the recommended print process used an 80µm thick nano-coated foil, which outperformed a 50µm thick stepped stencil of equivalent aperture size.
0201, 008004, passive, fine pitch, stencil printing, nano-coating, miniaturization