Sensitive electronic components mounted on a circuit board often require protection from exposure to harsh environments. While there are several ways to accomplish this, the dam and fill method offers many benefits. Dam-and-filling entails dispensing the damming material around the area to be encapsulated, thereby restricting the flow of the fill from spreading to other parts of the board.
By using a damming compound such as Supreme 3HTND-2DM-1, you can create a barrier around the component. Then, with a flowable filler material like EP3UF-1, the component can be completely covered for protection.
To start, apply the damming compound, Supreme 3HTND-2DM-1, around the component. Supreme 3HTND-2DM-1 is readily dispensed to create a structurally sound barrier. This material will not run and will cure in place in 5-10 minutes at 300°F, in essence forming a dam.
Supreme 3HTND-2DM Photo: MasterBond
After the damming compound has been applied and cured, a filling compound such as EP3UF-1 is dispensed to fill the area inside the dam and cover the component to be protected. EP3UF-1 is a specialized, low viscosity one part system with a filler that has ultra small particle sizes, which enables it to flow even in tiny spaces. This system cures in 10-15 minutes at 300°F and features low shrinkage and high dimensional stability once cured.
Both Supreme 3HTND-2DM-1 and EP3UF-1 are thermally conductive, electrically insulating compounds and are available for use in syringes for automated or manual dispensing.
Despite being a two step process, dam and fill offers the following advantages over glob topping:
- Flow of the filling compound is controlled and restricted
- It can be applied to larger sections of the board
- Filling compound flows better than a glob top, allowing better protection underneath and around component