Ok here comes dumb question from SMD newbie.
If you want to run traces on both the component and solder side of say an 0805 resistor, you put a pth on the pad(s) ?
If so, if it's an 0805 part what size hole? 20 mil maybe?
I'm goofing around with some SMD art on my ancient software and I'm placing an
0805 art on side 0 and side 1 -- then connect with the hole?duh ?
or are copper side traces a no no ?
The usual practise is to run topside traces into the pad. Then if you want to connect to another layer, plop a via a bit away from the part pad and go down from there.
Leave a bit of trace between the part pad and the via, 10-20 mils at least, so the via doesn't scavenge solder from the pad.
20 mils is a reasonable via drill. 10 mils is our "microvia" for dense stuff. If you have tons of room, go 35 and a scope probe will hang in the via.-- John Larkin Highland Technology, Inc lunatic fringe electronics
n 0805
ing an
maybe it is just me but traces at weird angles just looks horrible to me
vias usually have soldermask
-Lasse
On Sat, 4 Jun 2016 12:18:29 -0700 (PDT), mkr5000 Gave us:
You place the via sized hole right next to the pad at the part 'foot' side. You can place the mask over it or not. You can stencil paste over it or not. Still works. Do NOT place the 'hole' *in* the pad region as it leeches solder from the part at reflow time and *could* cause a solderability issue.
On Sat, 4 Jun 2016 13:06:10 -0700 (PDT), Lasse Langwadt Christensen Gave us:
Depends. Some designs mask NO vias.
Surface mount gets messed up by holes in the pads. Put a via next to the pad.
-- Tim Wescott Control systems, embedded software and circuit design I'm looking for work! See my website if you're interested http://www.wescottdesign.com
Generally not on the pad, rather next to it.
Depends on your groundrules, current, and all sorts of things.
A via, sure, but not in the pad. The via will tend to suck the solder out of the connection. There are ways to prevent this but walk before you run.
Seems kind of huge, and if you want to do paste and reflow a hole placed there will drink all the solder, but if you're hand-soldering you can manually add solder and make it work
Usual practice is to put the hole outside of the pad under the solder mask, although for a price you can get plugged vias from some vendors .
-- \_(?)_
It is just you. I laid out that board myself. It's beautiful. And it works. The good bits, the fast stuff, is off to the right. When I do fast stuff, I delete unnecessary corners.
A scope probe tip, with some natural side force, usually connects. If not, twirl an ex-acto in the hole a bit.
-- John Larkin Highland Technology, Inc lunatic fringe electronics
I know a guy who is doing a board that has 0.25 mm pitch BGAs, and he has to do via-in-pad. And 2 mil traces!
-- John Larkin Highland Technology, Inc lunatic fringe electronics
Doesn't he use filled vias? Such things can be done, certainly, but you're spending quite a bit already, the cost of filled vias won't hurt. Much. We don't do blind and buried vias very often, either, but sometimes they're necessary when doing boards with more than six, or so, layers. The money's already being spent, a little more is easier to justify.
On Sat, 04 Jun 2016 17:10:57 -0700, John Larkin Gave us:
2 mil traces is just begging for a high failure rate.Better off coming up with a nanowire process. :-)
Why for the "fast stuff"? A few weeks ago you said a 30ps TDR showed nothing from 90 degree angles and very little from vias.
(I hope you're suitably gladdened that I'm paying attention.) :-)
y an 0805
lacing an
you still have just as many corners, but with all those random angles it just looks amateurish
go crazy and use the TopoR autorouter,
-Lasse
Yes, and with that he is using microvias which have very tiny holes or are plated shut.
-- Rick C
Traces add capacitance in proportion to length. Longer traces make some things more likely to oscillate.
Beeline traces are logical. Some people just don't like they way they look. That's an artistic judgement on their part. Once a board is solder masked and assembled, the difference is pretty much invisible.
I'm always happy when people are interested in electronics.
-- John Larkin Highland Technology, Inc lunatic fringe electronics
No, I deleted a lot of corners on that board after everything was routed.
But amateurish? Adding unnecessary corners and trace length and capacitance is somehow professional? That's an emotional concept, not a rational one.
That's certainly interesting.
-- John Larkin Highland Technology, Inc lunatic fringe electronics
On Saturday, June 4, 2016 at 5:10:59 PM UTC-7, John Larkin wrote: ...
...
That's commonly done in mobile consumer electronics such as the iPhone and reproduced in 100's of millions.
kevin
Yeah, it's some startup wearable IoT gadget. I doubt it will be a commercial success.
-- John Larkin Highland Technology, Inc lunatic fringe electronics
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