Dear all,

 

No IPC call for the longest storage time of SMT and PCB on left un-used in production line. However, we have much PCB experience that the boards stayed on production line over the week end and without baking before resume production, delamination occurred.

 

If no special control on production floor, the RH can be up to 90% if the temp setting is low when the air condition area is left idle without operators. 

 

SMT area may contain MSD ( moisture sensitive device) so the same problem will occur. Left on production floor without re-pack in vacuum is a dangerous.

 

So your customer question your shop floor management is reasonable.

 

 

 

 

 

Seems to me there is no IPC standard regards the shelf life time. But the issue you should concern is the moisture absorption of the PCB. Most likely your SMT area shall a/c control, in this case I don't think it is a big deal.

But I doubt your PTH area....as you may know PCB without a/c or vacuum seal packing may have delimination during reflow/wave due to moisture absorption. And I believe this is the reason why your customer concern.

Just my 2 cents..

On 20 Apr 2009 16:24, James lee wrote:

Dear Friends,

 

One of our customer question our PCBA WIP management procedure since he saw some of SMT / PTH subassemblies boards were keeping in production area longer than 3 days,

Some of the boards are longer than one weeks and even a few pcs longer than 1 month, so we had a big discussion about the shelf life of the assembly boards but end of our discussion

It seems he was not convinced, hereby I need your help to let know is there any IPC standards to describe this rule?  

 

Thanks & Regards

 

James Lee