29 Sep 2015 -
30 Sep 2015
Nordson MARCH presenting on "Evaluating the Effects on Electronic Assemblies of Employing Plasma Treatment Technology Prior to Conformal Coating to Enhance Adhesion and Coverage" - Rosemont, Illinios
Donald Stephens Convention Center
Evaluating the Effects on Electronic Assemblies of Employing Plasma Treatment Technology Prior to Conformal Coating to Enhance Adhesion and Coverage
An Industry Partnership collaboration between Airborn Electronics, Akron, OH, in conjunction with The Richard Desich SMART Commercialization Center for Microsystems at Lorain County Community College, Elyria, OH and Nordson MARCH and ASYMTEK for the benefit of Electronic Manufacturers
The reliability and performance of modern advanced electronic assemblies continues to steadily increase in order to meet market requirements and demands. Many of these market requirements and demands dictate the need for conformal coatings to be applied to electronic assemblies to enhance reliability and to protect the assemblies from a wide range of detrimental environmental conditions, more specifically, moisture, dust, chemicals exposure, electrical crosstalk and dendritic growth to name a few. RoHS mandated materials and advanced component characteristics can create challenges for conformal coating coverage and adhesion. Nickel-Palladium-Gold leads for instance can be difficult to deposit conformal coating on to, in particular the knees. With electronic assembly performance being driven to ever higher levels to take advantage of higher frequency bands for telecommunications and military applications. Higher frequency applications require low dielectric constant (DK) materials to minimize cross talk and signal losses. Typically these materials consist of PTFE which inherently has poor adhesion to most materials. Not only is conformal coating adhesion a challenge but delamination is a fundamental issue during the board manufacturing process.
Additional challenges for conformal coating adhesion are contaminants such as mold release compounds and residual flux. The effects of residual mold release on various surface mount components, quad flat packs, dip packages and the like. Visually these devices appear to be clean and void of contaminants, quad flat packs and although the packages have passed various levels of outgoing QC metrics as well as incoming inspection metrics, they often times display the effects of residual mold release when conformal coating is applied via select coating equipment. To a similar extent, manufacturers of printed circuit board assemblies have dealt with excess flux residues, both traditional and no-clean chemistries. With high lead count devices, minimal lead spacing, thus correspondingly high aspect ratios, often time’s residual flux can be left behind even after extensive aqueous cleaning and/or not sufficiently consumed in either the soldering or reflow processes. Given this reality, often applied conformal coatings can be inhibited from sufficiently adhering to the critical junction points at the device body to lead, the knee of the lead and lead to pad.
For more information visit http://www.smta.org/smtai/index.cfm