“We use two-part epoxies and UV-curable cements to seal Viton- or PVC-bending rubber onto the distal end of flexible endoscopes. Our current epoxy works well when it is sterilized using Steris or glutaraldehyde solutions. With the introduction of Sterrad H2O2 plasma processes, the epoxy fails after 20 to 30 cycles. What do you recommend that will hold up to more than 100 cycles?”
When ASP introduced Sterrad low-temperature hydrogen peroxide gas plasma, they tested many UV-curable adhesives and epoxies from different suppliers. The results showed that many adhesives were compatible and did not exhibit any material damage after 200 cycles. But some products were not compatible with this sterilization method. The article with the results can be viewed here: http://www.mddionline.com/article/compatibility-medical-devices-and-materials-low-temperature-hydrogen-peroxide-gas-plasma.
Since this article is more than 10 years old, some products may not be available anymore, but it is a helpful guide to identifying the most suitable product.
“Can someone suggest a material to use for bonding a Ball Grid Array (BGA)? We currently use 3M™ Scotch-Weld™ Epoxy Adhesive EC-2216 A/B. Also, will corner bonding a BGA prevent failure from vibration? “
There are a number of different adhesive technologies available for corner bonding. One of the newer technologies is light-curable adhesives. The adhesive is applied to the circuit board post-reflow and cured in seconds. Flow is engineered to wet the edge of the component while minimizing flow underneath. This is important for BGAs where the outside edge of balls can be very close to the edge of the BGA. It’s also needed to ensure all material gets exposed to light and cures. If fast process speed is critical for the application, this technology may be worth a look. DYMAX 9422-SC was specifically designed for corner bonding. More information on this product is available in Lit 244 – Leadless Component Ruggedization.
As for your question regarding vibration, there is no published data specifically on this issue. The most common reason for using corner bond is to increase reliability for drop testing. We have seen instances where drop tests went from less than a 50% passing rate to 100% with the adhesive in place. The secondary benefit is higher reliability through thermal shock.