[time-nuts] I love the smell of tantalum in the morning

Bob Camp kb8tq at n1k.org
Sat Nov 5 16:24:10 EDT 2016


A *lot* depends on how many planes there are in that board. The weight of he copper
also maters a bit. If there is enough thermal mass, you will need a pre-heat process. 
There are lots of ways to do it ranging from the kitchen oven to various “frame and 
lightbulb” setups and on into ever more complex heating approaches. 

If the hot tweezers / soldering iron / hot air tool does not reflow the solder quickly (10 seconds 
or less) stop. Get a pre-heat setup and try again. With proper heat you should have the part
off in under 4 seconds. People don’t tend to use stopwatches when soldering. 4 seconds is quite 
a while on a joint. Ten seconds is pretty much forever ….


> On Nov 5, 2016, at 3:12 PM, Tom Van Baak <tvb at LeapSecond.com> wrote:
> See C13 in the attached photo. I need to replace some blown caps on a few boards [1]. In one instance the cap got so hot it melted itself off the board. Quiet convenient, actually -- it acts like its own fuse -- but I don't think the 5071 designers had that clever feature in mind.
> Having not done SMT before, how should I do it with minimal risk to the very precious PCB. Or, what equipment should I use this as a good excuse to buy?
> Thanks,
> /tvb
> [0] http://www.imdb.com/title/tt0078788/quotes
> [1] http://leapsecond.com/museum/hp5071a/A1-mother.htm
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