Authors: Mike Bixenman, DBA Company: Kyzen Corporation Date Published: 5/4/2011
ICSR (Soldering and Reliability)
Abstract: The distances between conductors, and the under clearance gaps from the board to the bottom of the components on printed circuit boards, are smaller due to miniaturization. Smaller spacing increases the probability that flux residues or surface contamination will be sufficient to bridge all or most of the under clearance gap between conductors. Flux bridging conductors opens the pathway to form a conductive cell between two points on the board assembly. As a result, higher density board designs increase reliability risks, which are commonly mitigated by cleaning all flux residues and ionic contamination on the surface and under components on the assembly. One of the problems is that the low spacing under components requires increased wash time and pressure for the cleaning agent to penetrate and remove all flux residues under component gaps. The purpose of this research is to study cleaning process factors and levels as a function of the gap height.
Key words: Cleaning, Defluxing, Electrical Chemical Migration, Leadless Components, Miniaturization