We use them sometimes, but not for bypassing.
I'm fond of MeanWell.
I've practically never done a board that only had components on one side. You do have to pay for solder stencils for both sides. I am not set up for glue, so I paste, stuff and reflow the back side, then repeat for the front. Parts never fall off, even really big ones like TO-220 (SMT) power regulators.
Jon
Some suppliers offer this on high density multilayer boards, but I imagine you'd have an extra step as with blind vias to mill the pockets, and another step to solder the caps onto the inside layer. I think this is done with conventional parts rather than trying to put thick film printing on internal layers. Probably a bit $$, but I've not gotten a quote so far.
Best regards, Spehro Pefhany
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An antique. I can remember laying out a few.
-- Bill Sloman, Nijmegen
Worry not! Just use 0.1 pounds of butter! WD-40 works almost as well. :)
-mpm
Would routing traces UNDER parts help enough in space savings? 7 mil traces, 7 mil spacing for rough stuff, 6 mil / 6 mil for finer?
Auto pick and place can work for double-sided boards just as easily..pop on side one, bake, plop on side two, bake; done - just add icing.
Gee..i used to do 2-sided cordwood (3-D) circuits 40 years ago all by hand. What is this "accustomed" thing anyway?
"top" and "bottom" ...
At the PPoE, there was no cost assigned to placing components (not production limited) so arrays made no sense. Now, placement is about 10x the cost of a
0402 resistor, so they're pushing arrays. If they're handy, for things like terminators, fine. I don't use them for other uses, though. I don't have to worry about cost, at least to the first order but eventually someone is going to make a product out of it, so to make it easier I try to pick reasonable components.
You can force all sorts of circuits into equal-value networks.
I just did an FPGA-to-gaasfet gate level shifter with one r-pack.
+----r----+ | | d fpga----+----r----+------+-----g | | s | | | r r | | | gnd | | gnd -5v
One of our people wanted to put BGAs on both sides.
Until you want to change one resistor value. The other problem is that cheap arrays are 5% and more accurate arrays are not cheap. For uses other than terminators, pullups, and such, I always use 1%, or better, resistors. That completely changes the game.
I've done it without problems. PTH components on both sides is an issue, though.
1% arrays are pretty common nowadays. Sure, it's more challenging to design with parts that can't be changed if you goof up.
No, not for power supplies anyway. I was thinking of the MAX3232. We used them for RC filtering multiple signal channels, before an ADC usually.
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I once did a 62mil, 8 layer board, 1.25 x 8 inch long. for 5 boards cost of $21,000 fab only. I think the fab house still proudly displays the board on their wall to demonstrate to potential customers that they can make ANY board. They were one of two fab houses I found who would even bid on it - out of some 30+ contacts..
[...]
I guess that is $80 each?
Is your VME the double-eurocard size, ~220x160mm?
That size 2-layer is $12 at 15pcs for me, including tooling and shipping to UK.
Might have trouble with the BGA though...
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