[sdiy] ASM Capacitors/Bench Power Supplies

[Ian Fritz]

Jay --

Great post!  Thanks for all the tips.

I see now that Digi carries the PEN and PPS units.  I usually just look for 
thru-hole parts.  I suppose if I wanted to experiment with these I would 
just put them on a surfboard, being very careful to follow all your advice.

   Ian

At 11:58 AM 7/31/2003, Jay Schwichtenberg wrote:
>Ian and all,
>
>Digikey has had the Panasonic lines ECW-U (PEN) and ECH-U (PPS) for quite
>some time. I used ECH-U caps in audio DAC filters. I don't know if they
>added to the sound characteristics. I do think that they made a difference
>in the consistence between boards.
>
>A word of warning when using these puppies (at least the Panasonic ones).
>Read the data sheet before using them!
>
>When we were using them there was an issue with pad size. I went back to see
>if I could find a reference to this on Panasonic's WEB site but couldn't.
>They do spec the pad size in the data sheet but I no longer have the
>standard sizes around so I can't compare them. If you aren't going to have
>boards flow soldered it's probably irrelevant anyway. But they were having
>problems with the caps floating. Got looking into it and in the data book
>from Panasonic they recommended a slightly bigger pad size.
>
>Next remember this things are plastic and plastic melts. If you are hand
>soldering them be very, very, very careful. You can melt them and if you are
>using something to hold them down it can deform them very easily. I would
>take a round tooth pick, clip the end off with dykes, squeeze the end with
>my needle nose to flatten it and very carefully (ie as lightly as possible)
>put pressure on the opposite pad I was soldering to hold it down. Also I
>found if you have to remove these it will probably be toasted in the
>soldering/desoldering process. Toss the part and get a new one. Also if you
>a choice of size, use a bigger part.
>
>I would solder a few on a test/junk board before I would go to a real board.
>Another thing is I'd save soldering these to after the board has had the
>final wash and until the last possible point in assembly soldering them with
>no-clean flux solder.
>
>When building SMT by hand it gets weird and you have to be smart about how
>you lay things out and build them. Since you can't just stick parts in a
>board and have easy access to the bottom to solder it gets a lot trickier.
>SMT stuff is all soldered on one side and you have to be critical of access
>(getting that big soldering iron tip close to the solder joint) issues. You
>typically build from the bottom (lower components) up (bigger components)
>just because of access. There is an issue of thermal conductivity when doing
>surface mount by hand too. You can have a bunch of parts down on a board and
>go to solder another part down and the heat is transferred to the other
>parts pads desoldering it. This is more of a problem with boards that don't
>have a solder mask. So be smart when you do your board layout. Don't go for
>max density on your first board.
>
>Sometimes thru hole is so much easier.
>Jay