Chip on Board - More Encapsulation
Chip on Board Contents
Choosing An Encapsulant
Epoxy or Silicone Based
The choice of a silicone or epoxy based encapsulant depends on the application, however the
most commonly used encapsulants are those made by Dexter - Hysol, Grace and Ablestick.
It is important to choose a product that is adapted to the application and the conditions
under which it is to be subjected.
One or Two Component Product
There are major differences between one and two component products.
The first is the fact that a one component product does not require any mixing.
The second is the temperature at which they need to be stored, which can vary from ambient to
-40 degrees Celsius. (Source: GJ Technology)
Three Step Encapsulation
| STEP ONE. Pre-heat encapsulant to 60 degrees Celsius Pre-heat substrate to 100 degrees Celsius Dispense dam around the chip to define area |
 |
 |
STEP TWO. Pre-heat encapsulant to 60 degrees Celsius Pre-heat substrate to 100 degrees Celsius Dispense some encapsulant around bonding areas |
| STEP THREE. Pre-heat encapsulant to 60 degrees Celsius Pre-heat substrate to 100 degrees Celsius Dispense encapsulant to fill in complete area |
 (Source: Techlead) |
Dam & Fill Encapsulation
- Gives a very flat encapsulation profile.
- Requires the dispensing of two products within the same program.
- Different encapsulants with different viscosity's.
- May or may not require heat to the product and/or the substrate.
| STEP ONE. Pre-heat substrate to 100 degrees Celsius Using a high viscosity encapsulant Dispense very high dam around the chip to define area |
 |
(Source: Techlead) |
STEP TWO. Pre-heat substrate to 100 degrees Celsius Using a low viscosity encapsulant Dispense into the dammed area |
Encapsulation Inspection
Inspection includes:
- Coated Area
- Resin Height
- Air Voids & Pit
- Resin Crack (line)
- Resin Crack (Peel Off, Delamination)
- Color, Surface Condition
- Wire Appear
- Foreign Material