Reworkable v. non-reworkable

In addition to the various types of application and formulation, epoxies used in die-attaching can either be reworkable or non-reworkable. Because soldering operations are not 100% reliable, sometimes defective assemblies are produced. If a non-reworkable epoxy has been applied, generally it’s impossible to remove and reattach the die. Reworkable epoxies allow chips to be removed after underfilling and then resoldered. Another option is to test solder connections before applying an underfill, but this can be a prohibitive cost to throughput speeds. Reworkable epoxies usually work by softening at high-temperature, allowing chips to be removed. The decision about if and when to use a reworkable epoxy depends on the cost of the final assembly, reliability of soldering and throughput needs.

 

Other specialty epoxies

Because of the rapid pace of technological advancement, new methods for die attaching and bond strengthening are always being developed to meet current needs. New formulations that allow flip-chip attachment onto flexible circuits are available, providing protection and flexibility for those applications. Epoxy flux compounds are also available that encapsulate individual solder connections. Whatever the combination of factors, including throughput speeds, reliability requirements and chip-board interactions, epoxy formulations are available to meet those needs.

 

The content for this month’s blog post was provided by Gluespec® – a partner of Ellsworth Adhesives.

Gluespec helps engineers to discover adhesives and other materials for their industrial applications.