Coverlay or “coverfilm” is used to encapsulate and protect PFC external circuitry to withstand extreme temperature, vibration and other harsh environments. Its purpose is the same as solder mask to rigid PCBs.
Kapton® and other polyimide films in aircraft insulation and cabling as it can withstand temperatures from –269°C to 400°C. Photovoltaics use similar films for silicon modules and CIGS applications due to CTE, moisture, and electrical performances. Bondplys, coverlays, and similar adhesive systems are used in the medical industry involving permanent implantation, device packaging, and medical equipment.
Prior to coverlays being aligned and laminated on production panels, MLT can laser drill or rout the coverlay for the component feature openings. For post coverlay lamination, laser skiving processes are used remove the coverlay to expose underlying circuitry or pads.
Coverlay skiving is used to form openings smaller than mechanical drilling or routing or openings too small to accurately align during lamination. Other typical applications include ‘window’ skiving of floating contacts (fingers) prior to tin, solder, or plating.
Coverlays that attached with adhesive can exhibit “squeeze out” of the adhesive on to a pad land. Design standards recommend access openings be large enough to allow for squeeze-out while providing a good solder fillet. To eliminate squeeze out issues in an area, laser skive the coverlay pad exposures or fingers after lamination. For more information about laser removal of coverlay or prepreg squeeze-out, click to READ MORE…
DuPont™ Kapton® FPC-MBC black polyimide coverlay laser processes with the same precision as other polyimide films or coverlays. The matte black polyimide film can be conductive and can prevent reverse engineering of the circuit designs it covers. MLT has processed all varieties of coverfilm from DuPont, Hitachi, and Sheldahl to name a few. To request a quote or discuss application details, contact our sales staff .
Kapton Window Skive
Coverlays and Adhesives:
Kapton® -DuPont’s trademark for polyimide film
Pyralux® -DuPont’s trademark for flexible circuit materials (Cu clad laminates, coverlays and bonding adhesives)
Coverlay –Kapton coated with adhesive on one side (insulating material that is applied over a conductive pattern)
Bondply –Kapton coated with adhesive on both sides
Black Coverlay Skive
Coverlay Standard Routing & Skiving Tolerances
|Infrared (CO2)||Ultraviolet (UV)|
|Positional:||+/-.002” (50um)||+/-.001” (25um)|
|Dimensional:||+/-.002” (50um)||+/-.001” (25um)|
|Depth:||Application Dependent||Application Dependent|
CAD or Data Requirements
CAD system integration and custom file converters enable flexible, laser manufacturing from customer-provided data. Although most file types are accepted, the preferred file types are Gerber, Excellon, DXF, or other 2D formats. In most cases, non-scaled data is required as MLT will make the appropriate scaling or offsets to meet part dimensions.
If concerned about compatibility of your data format or CAD/CAM tool, please contact MLT Sales for more information. For more CAM/CAD guidelines and detailed requirements, click CAD Requirements.