Partially completed PCBA Storage

As Davef mentioned above, I would be very precautious too with storing assembled boards in general. Especially because its OSP and the quantity is very high. Why would you build these with shortage on the assembly? Can't this wait until you have the transformers? What is the main worry here?

reply »

Hello Rifat, We have had good success with ImAg finish up to 18mos but PCB's must be stored in a controlled fashion of most CM's as well as being sealed very well from Fab house (thick plastic bag vacuum shrunk minimum/film bag optimally). Also, on the other comments...If you feel you MUST pre-assemble the boards, you CAN do this, but I would MASK the holes that still require soldering of components at a later date. Additionally, WE decided not to go this route due to additional handling (ESD/packing of PCBA to bag/bag to Carton/Carton to Storage/reverse all steps/etc.), as well as the amount of storage taken up during this time (boards/carton/rack/etc.) Ideally, this should be controlled storage (T/RH) which still requires sealing of each PCBA in their bag and maybe Dessicant as well. All of this adds up as added cost and impact likely at some level to Quality. Again, it can be done if your product allows this Risk/Cost, but we had decided the risk was too high to build ahead ourselves when in this situation as we needed to wait about 9mos in storage to prevent scrapping PCB's. Alternate suggestion: Do Not Build Ahead, but instead wait for the components and maybe be prepared to move to a slightly more aggressive Flux system within your solders. Baking will not be a very good option with OSP (generally speaking), but if boards were sealed properly at FAB and the enclosed HIC cards are reading OK, you might have a shot at some longer life...really depends on application-brand of OSP. I would Sort boards based on packing date, NOT the Lot-code, and start with Wetting Test on oldest packs first when you start back up. What you may find is the oldest Sub-Lots fail, but the newer Sub-Lots survive and WET ok! ((You just wont know until you know !!)) In the meantime...pull-in PCB orders to cover the scrap loss if you end up having some. > Good luck if you pursue Rifat

Les Beller

This message was posted the Electronics Forum @ SMTA

reply »