Electrically conductive adhesives connect their way to the future

Electrically conductive adhesives connect their way to the future

As electronic devices continue to shrink in size, increasing circuit board densities are being packaged in ever tighter spaces. Component miniaturization and SMT are forcing manufacturers to contend with shorter component leads and interconnects to make electrical connections.

Traditional soldering methods used to make these connections are beginning to confront practical limitations in terms of their minute application. There are also growing thermal concerns as heat sensitive components are more easily exposed to the higher temperatures of the soldering process.

While solder manufacturers are trying to meet these challenges, one viable alternative being used in a growing number of applications is electrically conductive adhesives (ECAs).

ECAs are nontoxic polymer-based resins that are impregnated with metallic (for example, silver or nickel) or conductive carbon particles. When cured, these filler particles form a connective matrix within the resin and make it electrically conductive. Their level of conductivity is determined by the type of filler particles used, their size, and the quantity injected into the mix.

This flexibility in composition not only applies to the filler material but to the formulation of the resin itself. As a result, manufacturers have the ability to alter the electrical, thermal, and mechanical characteristics of the adhesives so they can be optimized for specific applications or environments — a distinct advantage over solders.

While ECAs have been around a while, improvements in materials processing, formulation chemistries, and curing methods are getting them increased attention. Further advances in nanotechnology and thin films only look to enhance their potential.

ECAs are currently used in applications such as die attachment, flip chip packaging, SMD placement, and PCB assembly. In addition, with their adaptability and ease of dispensing, they are ideally suited for use in emerging technologies such as printable electronics and flex circuits. From this vantage point, it looks like ECAs might have a very busy future.

Michael J. Kawa