Is PCB Baking Always Necessary?

The oven could allow extra time for water trapped under IC chips and other such components to evaporate. I think placing the boards in a centrifuge first would help too, if such a device existed.

for non-production, 1-off boards, I wash it, then wash it again lightly in denatured alcohol to dry up the water, then air-dry by either putting it in front of a fan, or 'waving' it in the air.

Much of the reason for baking the boards is to remove water that has diffused into the board material as well as components. If the boards are heated gently, the water diffuses out slowly, and causes no harm. If the boards are heated to elevated temperature rapidly (as in wave soldering) the entrained water turns to high pressure steam and can cause severe damage to boards and components.

Back in the olden days, we would use water soluble flux in the wave machine... then load the boards into a dish washer to first clean and then dry the boards in one operation.

Bill

Hello jaisonvalooran:

If this is for manufacture.......................... and you do not want a very valuable piece of gear, IE: the IC and components.

YES, take the time and dry it. There is always reasons why things get done in a certain way, and you could sell what you make to a radio or computer factory and all could seem fine. Until most if not all the chips fail. Is it worth putting all the effort into designing it only to be sued or bankrupted because of bad judgement?

Only you can answer that.

Take care and have a wonderful holiday....................

I definitely would dry the boards if they went through the washer; We solved that problem (mainly because of micro-BGAs) by switching to a no-clean solder/flux. No more washing.

Maybe something to consider?

When we were doing the dish washer thing was back in the '70s. Jeez!! That was over 30 years ago!! all ICs were 8 pin to 40 pin DIPs on .1 inch lead spacing. No such thing as BGAs and such. Also no surface mount devices.

Bill

PCB baking depends on the amount of moisture the PCBs have absorbed BEFORE actually starting the assembly process. First thing to do is to check the humidity markers which are normally in the sealed bag. depending on these then baking or not is decided. Bake slowly 80deg celcius for 4 or more hours (check IPC table). After reflow if you did not bake then "bubbles" ( delamination of the board) will appear at which point you can throw it away!!.

Water cleaning and then drying would be enough since water absorbtion is a slow process and the drying from the wasing machine should be enough.

I mostly agree with you but it is dependant on what kind of components are placed on the boards. Micro-BGAs and "flip chips" (Leadless ICs) will trap potentially damaging moisture underneath...