Electronics Forum | Wed Aug 09 10:51:22 EDT 2017 | cbeneat
I have a question for the experts. After a panel is printed, how long is too long for the panel to sit prior to reflow? I understand each paste will be different, wondering if there is a general rule of thumb?
Electronics Forum | Thu Aug 10 11:32:34 EDT 2017 | dleeper
You could always take a scrap board, paste it, and let it sit out over night. Reflow it and then you should have a nice visual aid, covered in solder balls and grainy, irregularly shaped solder mounds.
Electronics Forum | Wed Aug 09 12:34:54 EDT 2017 | jdengler
It also varies with the types of deposits. Small deposits of paste (as seen on fine pitch parts or small chips) seem to be more affected by exposure. Jerry
Electronics Forum | Tue Aug 15 07:27:03 EDT 2017 | emeto
Most important factor - temperature. Back in the days I worked for a place without AC, and summer time this paste couldn't make it for more than an hour. In controlled environment you will be safe for hours or even a shift.
Electronics Forum | Wed Aug 09 11:59:19 EDT 2017 | dleeper
As you already know, it depends on the paste. There isn't really a rule of thumb, but less time exposed it better. The issue is the flux exposure to the air and ambient conditions. The flux can evaporate or absorb moisture from the air. If the paste
Electronics Forum | Wed Aug 09 14:55:42 EDT 2017 | cbeneat
Trying to show documentation/expert opinion to an operator or 2 why it's important to not let a first piece, that they so diligently built for the next shift to let sit for an hour, why that's not a good idea...other than me telling them so. And tel
Electronics Forum | Mon Aug 14 15:09:14 EDT 2017 | charliedci
In my experience, in a temperature/humidity controlled environment, 1 hour, no big deal. 4 hours still ok. Overnight your pushing the limits but will probably reflow without issues. Any longer, could be a problem. Again, a lot depend on type of past
Electronics Forum | Tue Apr 03 13:10:15 EDT 2007 | slthomas
Personally I wouldn't count anything but minutes. You need to know how long it takes to perform each task in order to balance your line. What I'm gathering is that you've got one printer feeding 4 machines, all running different jobs or maybe a pai
Electronics Forum | Tue Apr 03 03:31:51 EDT 2007 | chrissieneale
Apparently because the machines are old and prone to break down they do all the printing for the day (maybe 6/7 different board types) up front. This doesn't make any sense to me - if the machine is going to break down, the machine is going to brea
Electronics Forum | Fri Mar 16 07:10:53 EDT 2007 | davef
1 Print paste on a bare board or laminate. 2 Place components in the paste. 3 Gently invert and support the board above a table. 4 At one hour intervals, record the number of components that have fallen from the board.
