The GaN evaluation kit I have here at home died because of a power disruption @Cumps Castle.
There was a power failure in the perk of Brussels where I live. Power dropped from 240V to 110.
And here's the rub: I was providing the different voltages to the evaluation board from two different power supplies. The big power from a supply that takes virtually any input voltage between 100 and 250V.
But the bias power came from a supply that's 220-240V only.
TL;DR the LMG5200 power driver on the board didn't survive this (as documented in its datasheet).
That chip comes in a QFN package. This is my first attempt to replace such a package
Baking the Chip
From the datasheet:
If we than check that report (our package is MLS3, 2mm thick), we're in for a long baking time.
I didn't bake it that long.
I used my microwave/combi oven - in the non-microwave mode - at approx 120° (all temperatures in Celsius) during 4 hours.
And I crossed my fingers.
I'm using an Aoyue Int 968 A+ rework station. For this exercise, I used the hot air part only.
Since there are no pins on QFN packages, there's little use for a soldering iron.
The evaluation kit uses lead-free solder. And the LMG5200 is in the way of the heat path.
That means that you have to apply the heat to the package, and that in turn will transfer that heat to it's solder pads.
I bombed the thing with 330°, low air plow - I couldn't risk that all the surrounding parts would fly away.
It took good 2 minutes before the solder melted and the IC could be removed.
To avoid that I have to heat the pads with the new chip in place, I first pre-heated the area around the board with hot air for a few minutes.
I had the temperature set to 120°.
I then applied solder paste and put the IC in place, as good as possible.
That wasn't really easy because you don't see the pads, and the PCB didn't have an outline drawing for the chip.
So I placed the IC where I thought it would cover the right pads with the right pins, and pulled out the hot air nossle again.
After again a good 2 minutes, the chip pulled itself to the right position (the magic of reflow).
I let the whole thing cool down, and checked with my multimeter if there were any short-cuts.
When that test gave good results, I decided to put the board to the test. I powered it on and validated the circuit at the key points.
All behaves normal, and I consider this little project a success.
Customer Action Photos: