Electronics Forum | Mon Nov 07 08:27:56 EST 2005 | chunks
It could be you are drying out your solder paste. Most flux formulations are alcohol based and after a few hours can dry out. This can can lead to dewetting and solder balling as well. Especially if you do not homeplate your R's and C's. A simple
Electronics Forum | Tue Nov 08 20:58:49 EST 2005 | davef
We buy humidity as a potential cause of solder balls, but we're not biting on dewetting. Something else is causing that. Questions are: * What's the temperature and RH of your SMT production area? * What kind of paste are you using? [Some water was
Electronics Forum | Wed Nov 09 02:24:49 EST 2005 | laxman
Hi Dave, Normally in our country (India) during rainy season the temperature will be 25to 30 �C and RH of 50 to 60%. The reason behind this humidity issue is that recently we have moved to our new facility with centralised air conditioner with Chill
Electronics Forum | Mon Nov 07 06:16:59 EST 2005 | laxman
Hi, We have faced the solderability issue (Dewetting and solder balls)in all the Boards after reflow.When we found this issue we discarded the old paste and started using the new paste then for some hours the solderability found to be O.K. After so
Electronics Forum | Mon Dec 31 09:00:06 EST 2001 | davef
Baking before assembly does nothing good. It: * Increases costs. * Adds steps to the process and makes scheduling more cumbersome. * Increases the amount corrosion on solderable surfaces. We used to bake to remove the moisture from boards that caus
Electronics Forum | Sat Jun 06 15:14:35 EDT 2009 | ysutariya
If the concern is the increased moisture absorption associated with lead-free capable materials, you probably have the most experience with phenolic materials like Isola IS410 or 370HR. The best move would be to switch to an IPC 4101/99 or /124 mate
Electronics Forum | Thu May 06 18:31:29 EDT 2004 | Dreamsniper
"Polymide Films absorb a great deal of moisture. Polymide laminates must be baked at more than 1 hour at 100'C or better for a double sided PWB prior to exposing the laminate to elevated temperatures such as that required for soldering. Moisture abso
Electronics Forum | Wed Jun 18 07:26:42 EDT 2003 | rmurtuza
Do BGA packages absorb moisture to a great extent if kept exposed to an atmosphere of 300C and 60% relative humidity overnight? Should they be backed before reuse. How long can they be kept exposed without the requirement of baking. Are there any spe
Electronics Forum | Thu May 09 17:28:33 EDT 2002 | davef
There is no IPC specification, nor should there be. * There are just too many peculiarities in the design and fabrication of PWB. * The issue is not defining how to store boards. The issue setting expectation for reliable products and allowing you th
Electronics Forum | Tue Jun 24 07:16:08 EDT 2003 | sanjeevc
The moisture sensetive bags that carry your BGAs will have the specs in regards to your baking cycles.But definetly you have to bake the BGAs if its been stored at 60% humidity.Normally the shop floor area should not be at such higher humidity.You ca
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