RAFI Eltec GmbH, Überlingen, Germany, uses the DELO MONOPOX anhydrides as Dam&Fill. For the assembly, solder deposits are attached to the bottom in the form of BGA ballings, followed by one-side SMD assembly. The SMD assemblies produced are subsequently Dam&Fill-encapsulated.
In this method, two beads of adhesive are circumferentially dispensed as “Dam” on top of each other, which are subsequently “Fill”-ed. For this purpose, a screw dispensing valve is used in order to ensure that the components are evenly dispensed. Afterwards, the components are laser-marked on the encapsulation that has been cured in an air convection oven at +150 °C for 20 min.
Adhesive processing is reliable, and planar, large-area encapsulation geometries are possible. In addition, the adhesive fulfills all requirements on solder resistance. The dispensing profile can easily be adjusted to the specific package geometry, enabling high flexibility in production. It also gives a very homogeneous processing behavior, protects the component resp. the sensitive electronic parts from environmental influences, and performs excellently in reliability qualification tests. The material’s properties minimize the stress in the package. Thanks to the planar encapsulation, the component can be assembled just like a BGA module.