Thick copper (high-build copper or deep copper) printed circuit boards are used in high power circuits to allow high currents to pass through the conductors without significant heating effects. A reliable surface protection with solder mask is basically possible, may, however, cause severe problems with edge coverage on the copper tracks. To overcome such problems and to ensure end user reliability in critical environments like automotive, the so-called thick copper filler (or gap filler) process is the method of choice. In a first step the spaces between high copper tracks are filled and then the surface is leveled after curing. Thereafter a thin layer of Soldermask is coated on the planar surface according to given requirements. This way perfect edge coverage with Soldermask and highest insulation and reliability is achieved.

Thick Copper Filler General Process Description

Both of our current products are applied by horizontal (screen) printing. As the lacquer contains 100% solids a flash-off is not required. After UV-curing the surface is leveled by grinding and carefully cleaned before the solder mask application. As the best fitting soldermask we recommend SD 2460 FLEX a thermal curing flexible solder mask able to take up thermal and mechanical stress.

Thick Copper Filler Features and Benefits

• Reliably fills spaces between high copper tracks
• No edge coverage problems with solder mask
• High reliability especially in reliability sensitive automotive application
• High flexibility to take up thermal stress
• Excellent electrical properties
• Qualified by major OEMs
• Recommended solder mask: SD 2460 FLEX (for highest in-use reliability)
• Compliance with UL 94 V0

Thick copper filler, manufactured by Lackwerke Peters, distributed and serviced in Asia by Atotech.