Being a UV curing ink it has 100% solid content and will therefore not shrink in the hole. The clear version is recommended to allow a proper cure to be achieved in the centre of the hole. Any pigment in the ink will block the penetration of UV light and thus full cure may not be achieved. One disadvantage of using an unpigmented ink is that it is difficult to see the ink if it is smeared onto pads during the plugging process. However in order to withstand the subsequent process steps like HASL a full cure is essential.

The resist is applied by means of a horizontal screen unit. It is essential to ensure good registration, otherwise smearing and poor hole-fill will occur.

Printing conditions will be dependant on size of holes and thickness of boards being plugged. A single flood and print stroke should be sufficient to plug the holes. Multiple passes may be necessary for high aspect ratio holes, it is advisable that 100% hole fill is achieved in one pass to avoid the inclusion of air in the plug.

Full UV Cure should be achieved with around 3.5 J/cm² depending on machine used, board design and fill level.

Pack code CFSN6030 - XV1200 Clear Solder resist, also used for hole plugging. (Click the pack code number for technical information.)