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74 DESIGN007 MAGAZINE I JANUARY 2020 Sensible Design by Alistair Little, ELECTROLUBE For this month's column, I'm going to pro- vide some useful advice on encapsulation res- ins to help designers achieve even higher levels of reliability when it comes to protecting cir- cuitry. Potting compounds are increasingly im- portant in the electronics industry where they serve to protect sensitive components from moisture, dust, and damage, and help to ex- tend the lifetime of devices. Appreciating the subtle characteristics of resin systems will go a long way in helping you choose the most suit- able resin for your application requirements, making the process a lot less complicated and, more importantly, helping you avoid any seri- ous implications for the performance of your application. Let's take a closer look at five critical factors affecting encapsulation resins, which will include potential contaminants, no- Five Top Resin Tips clean/cleaning processes, adhesion, and best mixing practice. 1. What potential harm can contaminants wreak if present on a PCB? Can this cause long term problems ultimately resulting in board failure? There are a number of different contami- nants that can cause long-term problems for a PCB, ranging from dust and grease to flux resi- dues. Since the resin will stick to the contami- nant rather than the board substrate, this pro- duces weak points within the PCB-resin inter- face, which, over time, can lead to cracking of the resin or adhesion failure between the resin and PCB. Once a fault appears, it can grow in size to allow other contaminants to attack the