This process flow is: board surface soldering → HAL → plug hole → curing. The non-plugging process is used for production. After the hot air is leveled, the aluminum foil screen or ink retaining screen is used to complete the customer's required via plug holes for all the fortresses. Plug ink can be used photosensitive ink or thermosetting ink, in order to ensure the same color of the wet film, plug the ink is best to use the same surface ink. This process can ensure that the through hole does not drop oil after leveling the hot air, but it can easily cause ink contamination on the surface of the plug hole and unevenness. The customer is vulnerable to false welds (especially in the BGA) at the time of placement. So many customers do not accept this method.
Hot Air Leveling After Plug Hole Process
- May 26, 2018-