Tecra M4 cooking

The problem

The GPU on the motherboard displayed signs of cold or cracked
joints, showing lines and causing bluescreens.
I'll attempt a reflow and hopefully it will work again.

Teardown to bare PCB

Opening the laptop and removing the motherboard,
all plastic parts needs to be removed.

As it needs to be heated to 120°C and above, no parts that can melt should be on the pcb.

Pcb is now ready for foil.

Tools needed

Heat gun, IR thermometer, foil

This type will not work, too wide readout area.

A pen style version is more suitable.
1:1 read area and can reach 300°C

And wrapped with owen gill foil

Protect all but the GPU.

Preheating

Standoffs used and stoveplate heated.

When the chip reads 120°C, heatgun time!

You cannot read the temperature of any "reflective" surface.
Use thermal tape (black) or find a rough non reflective part to read off.

Heatgun needs to push the temperature to 240-270°C for a
few seconds, and then used to slowly lower the temperature
back to 100~ish. degrees.

Now let the motherborad cool down slowly to room temp.

Some damage, but it has no impact.

Final