Baking of PCB's and Delamination

We receive pcb's from China and recently we have had problems with delamination during their passage in the oven.

I hear about " bake " . Note that this is the first time we have this kind of problem. Could we assume that moisture was taken in China? During transportation (boat or plane) ? Probably from my humble point of view.

It would be very interesting to have statistics on this subject by the way ( average humidity in China by region) - Soes someone can suggest me a good source of info on the web?

To return to my baking problem, people from production report their frustration saying that there is such a pressure ( from customers and sales ) that once the PCB is received, it is moved almost immeditely on the line ...

Others tell me that we do not have cabinets, others tell me that if we do a bake , we can find ourselves with an oxidation problem ...

In short, there must be a standard that covers this? What is the practice in other EMS ? Is this problem covered in J -STD- 033 or elsewhere ... eg in J -STD- 001 ?

Can someone help me?

Re: Baking of PCB's ?

IPC-A-610E clause 10.2.2 covers what is acceptable regarding Blistering and Delamination of pc boards.

Re: Baking of PCB's ?

Reading the answer of Paul, maybe my questions were not clear enough.

What I'm looking for is a requirement to bake the boards prior to put them on the line (in the oven) ? Does such requirement exist ? If so, where (in which standard) ?

Re: Baking of PCB's ?

IPC-1601 deals with this ....
See HERE

Re: Baking of PCB's ?

No, LesPiles, re-reading your question it was quite clear. I simply misread it. My mistake.

Somashekar, on the other hand, has read it and answered it perfectly ... as he always does.

Thanks to both of you guys !

Best regards,


Les piles

Re: Baking of PCB's ?

somashekar said:

IPC-1601 deals with this ....
See HERE

Click to expand...

in IPC 1601, it also mentioned upon opening of the moisture barrier bag and the 10% HIC turn pink, we should suspect the bag sealing is compromise.

but in actual scenario, most of the PCBs we check at IQA will fail the 10%, most manufacturer will recommend 50% instead, anyone have any thought on these?

i'm in doubt we should be checking for HIC card at IQA at 10% as judgement to reject.

Re: Baking of PCB's ?

[FONT=&quot]Generally once remove from the bags boards will start to absorbed moisture and that is why you should always bake them prior to thermal processing (assembly). Most contract manufactures (assemblers) are unaware of this requirement though.[/FONT]

not really, OSP boards cant be baked.

Can delamination only come from moisture? Also, aren't the PCB delivered to you in seal bags with the humidity card? Is it that long between the moment you open the bag and do the assembly+reflow?

These are genuine questions. I assemble PCBA in China, and we purchase the PCB in here and they are perfectly packaged against humidity, that's standard practice. But once we open the bag they got assembled and reflow within 1h max I'd say.

I only got the delamination problem once on an hybrid kind off PCB for which we don't know well the properties and cooked many times for some reasons. But on regular 4-layers stuff, never (unless heavily twisting the boards mecanically later).