These things were never “designed” in the first place.
7135 data sheets call for up to 1000 ^2 mm trace area per chip for heat sinking at max load. Not only do we not have that we insist on putting them within a few mm of a powerful heat source.
And the 105c board doesn't even have a complete trace under the middle of the 7135s, just a little pad connected to nothing for the pin and a little pad in the back for the tab.
If you have the space for multiple boards, use them and don't use more than 8 chips each. But that's just not practical in most cases. The main bottleneck is the vias for ground & LED-. There's only 3 for each and the ones for LED- are smaller than the ones for the ground planes. So if you have the space for multiple boards, use a separate jumper wire for each side of the boards for both ground & LED-. And don't use the PCB as the carrier for the BAT+ to LED+ path, either. It only needs a small wire to run the MCU but run the LED+ around the driver and straight to the battery/contact board.
Good to know, thanks guys! I will be sure and keep all that in mind when reconfiguring my Terminator.
Excellent info for a newbie.