Step 4: Low Temperature Oven Bake
Alright, so the purpose of this step is twofold. First, it helps to gently unflex the mainboard, and second, it serves to evaporate moisture that has trapped itself in the board over time, which is critical to get rid of in order to perform a good re-flow. However, the motherboard can't just be tossed on a pizza tray and then into the oven. This is where the bolts come in. They will be used to create a simple stand for the board, so no parts of it will be directly touching the tray.
First, put a nut about 10mm down on a bolt you are going to use. The smaller M4 bolts go around the outside of the board, and the M5's go in two of the big holes in the middle (see pictures). Then, place it in a hole on the board. Now, take another nut and screw it down until the top of the nut is flush with the top to the bolt. Then tighten the nut underneath the board until it "pinches" the board tightly. No need to crank down on these - finger tightening is good enough. Do this for all the bolts. Make sure when you do the M5's that the nut on top of the board does not come into contact with any chips or other small components.
Then, set the board on an even surface like a counter-top. You want to look straight on at the board and make sure it is level. If it sags or curves in the middle, adjust the middle bolts so that it does not.
Once this is done, it's time to cook. Preheat the oven to 150 degrees Fahrenheit. If your oven will not go this low, you can go as high as 170 without insulation, but any higher and you risk damaging the board. If you simply cannot get your oven to do this you can skip this step, but it is very beneficial to do it if possible.
Alright, when the oven is ready put the board on a pizza tray and pop it in the oven for 8 HOURS. That's right, 8 hours. This ensures a completely dry and straight board, and is totally worth the wait. If possible start the bake early - then you will have time to re-flow later in the same day.
Once the wait is over, take the mainboard out of the oven and let it cool completely. Now it's time to insulate.