Curing

Some encapsulants require heating to a specific temperature for a specific period of time to cure. Thermal curing is a fast curing process where the time to curing typically are in the range of 2 – 10 minutes. The disadvantage is that all the contents of a package go through high temperature which may be unsuitable for certain components of a package, or may add stress to delicate components such as wire bonds.

Thermal curing can utilise temperature induced chemical change for cure. It can also be based on evaporation of solvents in a formulation. Like the air curing encapsulants, thermal curing encapsulants could also consist of two part formulations. Thermal curing requires the oven to be preheated to the specified curing temperature. If the deposition is heated at a higher temperature or for shorter time period than curing specifications it may result in bubbles and voids.

Curing is the final step in the encapsulation process and although a less complex process step it still requires careful consideration and execution.

It is a process where visible and ultraviolet light combine to trigger a photochemical reaction for curing. UV curing is able to instantly cure an encapsulant formulation depending on the intensity of the UV light shown on the deposition. UV curing is the fastest curing process where a material can be cured within a minute. The contents of a package to be encapsulated is not heated. The disadvantage is there is less time for the encapsulant to fill any void if present.

UV curing requires a user to prevent any possible shadows on the deposition as it may lead to under cured or uncured areas. UV curable encapsulants may not be suitable for applications where the components are likely to create shadow areas on the deposition.

Curing is the final step in the encapsulation process and although a less complex process step it still requires careful consideration and execution.