Adhesives For Electronic Assembly

How do adhesives for electronic assembly differ from general engineering adhesives? Are they stronger? Faster? Do they resist higher temperatures? Have less volatiles or odor?

Certain specifications and requirements are unique to the electronics industry. For example electrically conductive epoxies are silver filled for the required conductivity. These epoxies are understandable very expensive which would make them inappropriate for other applications. Other requirements for some electronic applications make adhesives designed for the application undesirable to other industries. For example, the very fast cure of single component adhesives required in electronic assemble results in products with very short shelf life that require frozen storage.

However, most adhesives marketed specifically for electronic assembly are really no different from general engineering adhesives. The marketing of the products is geared toward a specific industry to include only that information that is relevant to that industry.

The same single part epoxy that is marketed to electronic engineers to encapsulate relays, microchips and bond heat sinks may also be marketed to engineers in the filter industry to bond and pot an end cap onto a filter and engineers looking to bond a motor magnet in a brushless motor or a biomedical engineer to bond an insulin needle into the hub. The difference is that the motor manufacturer is not concerned with the products biocompatibility and the needle manufacturer is not concerned with the impact strength on neodynium.

An epoxy is an epoxy; be it meant for a toy train, a medical device or the latest computer technology, it is an epoxy. Providing the manufacturer has proper quality in place to provide a consistent product and that that specific epoxy suits your requirements, there is no magic in it being tagged an Electronic Epoxy. It is however likely that it will have a higher price tag. (All that marketing costs money that has to come from somewhere!).

Similarly cyanoacrylates with specific properties cross from one industry to another. Adhesive manufacturers produce cyanoacrylates that resist high temperatures for a variety of applications; only one of which is to resist solder reflow processes.

Low odor cyanoacrylates are preferred by many manufacturers in countless industries to improve the workers comfort, however, the same adhesives are marketed as low blooming to electronic manufacturers as the blooming or chlorosis (the white powdery effect on the area surrounding the bond) can be problematic on sensitive electronic components. Whether the adhesive is used to bond plastic dice on clocks sold in Las Vegas or to keep the electronics clean the product of choice is a low bloom/low odor cyanoacrylate.

So when sourcing an adhesive, chose a material based on the specifications, the quality and the desired process – not the hype.