I'm just guessing:
Usually a too high current caused by a dead short would cause damage seen in the second picture. Rather not simple thermal overload by having too much current heating the trace too much. Maybe arcing, but I'd suspect 50V and 15A wouldn't be enough to make this damage by thermal overload alone.
For upwards bent copper, my first thought is mechanical stress that broke the trace. One could be able to see if the damage is caused by mechanical stress or electrical overload by closely inspecting the broken trace (look for signs of heat, an overheated trace looks different as a mechanically broken trace).
external mechanical stress shouldnt occure in this particular place, can the mosfet vibrate while switching and cause this?
i will inspect the broken trace next time it happens, i guess thermal stress will cause a black color on the soldermask?
A too high current could cause the symptoms you describe, but in my opinion the layout should take the 15A without overheating
Yes i was pretty shure the layout should handle the current thats why i ask for a second opinion to be shure
Maybe it's not a 105um copper clad in the first place !?
Yes that was my thought too, i am currently checking what thickness the copper layer has
This is a DIY H-bridge - have you checked that you don't have shoot-through? That would cause the second picture
The gate drivers are two UCC20520 (
http://www.ti.com/lit/ds/symlink/ucc20520.pdf). I guess that could happen when the control signals are not synchronised i will check that.
Agreed. I'd take a close look at your H-bridge driver timing. Do you have a current monitor anywhere on the system (high side or low side, input or output of H-bridge)? If so, watch that with a scope to see if you're getting current spikes at the switch points. If not, you can try monitoring the rail voltage right at the input to the H-bridge to make sure it's relatively flat, if you're getting shoot through you'd probably have large voltage dips at the switch points.
What is this H-bridge powering? If it's an inductive load, do you have freewheel/flyback diodes on it?
I will check the timing and the voltage/current at the output, thanks.
The load is inductive, i look into if freewheeling diodes make sense there.