Quick tack-free curing helps prevents rejects
1 min read
A light-curable encapsulant, which reaches full cure even in shadowed areas, has been launched by Dymax, the US based manufacturer of light-curing materials, dispensing and curing equipment. The products will be available in the UK from Intertronics.
The 9100 series of encapsulants will also cure with moisture and have been developed for protection of small areas of PCBs where sensitive chips or other devices can be encapsulated by a glob top process. In particular the Dymax 9101, 9102 and 9103 now provide a rapid secondary moisture cure for shadowed areas.
The additional curing process gives a more secure cure where the adhesive may flow under the encapsulated device. This could be a chip-on-board application where there is a need to lend mechanical support to fragile wire connections – also of course chip-on-flex, chip-on-glass and traditional wire bonding. Localised protection may thus be selectively provided to a particular area for vibration damping, structural integrity, mechanical protection or environmental protection reasons.
These materials cure tack free after UV cure, so boards can be handled sooner with less potential for damage. The two-day moisture cure – versus the seven days typical with other systems – shortens the time for further handling as well as final testing and assembly.
The three new materials have varying viscosities of 7,000, 17,000, and 25,000 cP, allowing for performance and dispensing to be optimised, and are jet dispensable for more accurate placement and more efficient material usage. The cured materials are flexible and expand with heat, reducing stress on board components. No refrigeration is required for transporting the uncured material, so no additional associated costs are incurred.
