Shiny Mask

Soldermask finish inconsistencies

This is aesthetic only and will not affect board function in any way. Boards do meet IPC-SM-840 requirements as well as IPC-A-600.

Saturn utilizes photoimageable soldermask which is first applied using a spray coater. The entire panel is coated with soldermask at this process and the soldermask isn’t completely uniform in thickness after application. Upon exit of this conveyorized line, the panels are tack dried and sent to the imaging machines for the imaging process.

shiny-mask1

The panels are placed in a glass drawer with soldermask artwork on each glass piece. The glass is drawn down tight against the panel by pulling a vacuum. When this happens the artwork, which is smooth plastic, presses down against the PCB panel and flattens out any higher spots in the mask. Since the artwork is super smooth, it generates a shiny appearance on those spots, which is what we are seeing in the picture. Since the mask is still there, IPC deems this an acceptable condition per Class 3 standards.

STEP 1:
Film is placed in imaging tray and vacuumed to glass

soldermask-imaging

STEP 2:
Production panel is placed on film

STEP 3:
Tray is closed, machine automatically aligns film and panel before exposing to UV light
During this automatic alignment, the panel slightly rubs against the film resulting in the shiny appearance.