TGFR stands for Track Gap Filled Resin. TGFR is the technique and process for filling the conductor spaces, which copper thickness is over 4oz, with special resin. Thick copper PCBs are used for power related applications like DC/DC converters, planar transformer, and automobile parts. These kinds of thick copper PCBs are required for high current and high voltage, and cannot be manufactured with standard solder mask process due to insufficient edge coverage of thick patterns.
By filling conductor space with the specially manufactured resin, thick copper PCBs are manufactured in flat surface and perfect condition for solder mask process. It also provides excellent reliability to prevent the possible electrical spark because of solder mask skip or insufficient coverage on the edge of the conductors. When thermally conductive resin for filling the space, PCBs can obtain the maximum thermal effect.
As TGFR makes surface flat, manufacturing thinner MLB is possible regardless of the thick copper. Interleaving 1 ply of 1080 prepreg will be enough for constructing MLB.