Coverlay is a material laminated to the outside layers of the circuit to
insulate the copper conductor. Below are types of coverlays used at All Flex.
These materials are normally produced with a drilling process and therefore the coverlay is limited in its features and characteristics. The coverlay openings typically must be round and oval holes and cannot have square cornered or dense features. Both polyester and polyimide coverlay can be punched or blanked in lieu of the drilling process and is normally done for large coverlay openings.
|Via Hole||Covered with coverlay|
|Component Hole||.005″ (.127mm) minimum per side larger than the copper pad|
|Feature Definition||.008″ (.20mm) minimum|
Note: Coverlay openings can be individual bared
pads or group bared pads depending on area available.
Photoimagable Coverlay & Soldermask (Covercoat):
Both photoimagable coverlay and soldermask are produced by a photo controlled process and are used for tight pad spaces. This process enables unique shapes to be applied anywhere on the circuit. Photoimagable coverlay is usually not used with 2 oz. copper or above. Due to the thickness of the copper, photoimagable coverlay and soldermask will not conform around the area of some copper features.
|Via Hole||Covered with soldermask|
|Component Hole||.003″ (.076mm) minimum per side larger than the copper pad|
|Feature Definition||.005″ (.127mm) minimum|