Low warpage: DELO enables large-area chip encapsulation

Cost-efficient production is playing an ever-growing role also in applications requiring high reliability. Therefore, DELO Industrial Adhesives has attached particular importance to its new encapsulant having a low coefficient of expansion to enable large-area chip encapsulation without warpage.

Both, chip production and chip processing are experiencing a strong trend towards rationalization, for example in the field of chip encapsulation. On the one hand, more and more companies place a vast number of equal assemblies onto a printed circuit board, which are then completely encapsulated and finally singulated. On the other hand, complete PCB assemblies are fully encapsulated instead of using housings for protection from environmental influences.

“Large-area encapsulation significantly shortens the process time and holds great savings potential”, says Gudrun Weigel, Director Engineering and Vice President at DELO. “However, this approach often reached its limits in practice.”

In applications subject to high chemical and thermal stress, large-area encapsulation has previously caused warpage of the PCB during curing. This effect caused tensions within the assemblies and made singulation of the packages by sawing difficult. This warpage is the result of dissimilar coefficients of expansion of PCBs (10 – 20 ppm/K) and encapsulants (more than 20 ppm/K in most cases). DELO has developed an enhanced encapsulant that achieves a CTE value of 11 ppm/K. Warpage is reduced to a minimum, which makes this encapsulant perfect for large-area chip encapsulation.

Overview of further properties:

Excellent flow properties even without heating the substrate
Combination with Dam is possible (Dam & Fill process)
Variable curing parameters: Fast curing (up to 20 minutes) or low curing temperature (down to 100 °C)
Temperature of use from -65 to 165 °C
Excellent resistance to chemicals and humidity

Source: DELO/