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Power Planes and Bypass Capacitors

You are right about warping. I inspected a five layer board I have already designed and fabbed. There is a little bit of warp. Not enough to affect performance this time. From now on I will only design with an even number of layers.

I have also become aware that the amount of copper on each layer will affect warping. So now I must take care to put copper where it is not needed electrically just to fill spaces with it. An while doing this I must be consider increased capacitances where it is not wanted and cross talk problems it may also cause where a copper fill area is not grounded or connected to anything.

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Reply to
Artist
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I've never seen an unstiffened board without a "little bit" of warp. If it needs to be perfectly flat you need to put it in some sort of frame that is flat.

Sounds like the cow-orker an hour after he was convinced that decoupling caps actually did something; the board was *covered* with the things! ILMAO!

Reply to
krw

If someone doesn't support those capacitor manufacturers, are YOU going to be the one whose tax dollars pay for their bailout?

Oh, wait, they'll almost all foreign companies these days anyway.

Nevermind.

I think at least 1 cap per square centimeter of board space is adequate for most designs. High-speed designs might need more... maybe as many as 1 per square millimeter...

Reply to
Joel Koltner

Does that matter?

LOL. The speed doesn't matter so much as the edge rates. The stuff I'm designing now is as slow as I've ever done, yet the edge rates of the cheapest logic is faster than the ECL when I started out. ...and a lot pickier on decoupling (ECL is easy).

Reply to
krw

You can often go to a cross-hatch structure for (some) planes if warping becomes a serious problem. Or place some dummy copper pour on the opposite layer to improve the thermal balance.

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Regards, Joerg

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Reply to
Joerg

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