Talk:PCB layout guidelines
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"Many practical circuits can be laid out easily if the lumped element model holds for the particular circuit. In radio especially, we cannot make this assumption and we must minimize parasitic effects due to layout of components, or take them into account with a more general model and use simulation software such as SPICE." - This introduction seems confusing...
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[edit] Ground Plane Cuts
Ground Plane Cuts: I Would like to see some discussion on recommended usage (if any) of cuts in the ground plane. Some recommend placing ground plane cuts in strategic locations in an effort to control the return paths of high frequency currents and keep these currents away from sensitive portions of a circuit. Others say that placing cuts in the ground plane is a bad idea because it effectively makes the PCB into an antenna which radiates noise both to other parts of the board and to anything placed in close proximity to the board. -CDB
The best article I've seen is:
- "partitioning and layout of a mixed signal pcb" article by Henry W. Ott (EMI consultant) in _printed circuit design_ magazine (june 2001) http://www.hottconsultants.com/techtips/split-gnd-plane.html http://www.pcdmag.com/db_area/archives/2001/06/0106_1.html , which recommends "Do not split the ground plane. Use one solid plane under both analog and digital sections of the board."
On the other hand, I've been told that physical cuts -- not just etching away the copper, but cutting a gap in the circuit board as well -- is recommended for some high-voltage circuits, to prevent arc-over. I wish I had more details. --70.189.77.59 05:06, 15 October 2006 (UTC)
[edit] "Most consumer electronics..."
The article states that most consumer electronics use one- or two-layer PCBs: this may have been true a few years ago, but increasingly, most consumer electronics like iPods, cellphones, PDAs, etc. need to make use of multilayer PCBS (e.g. 4-8 layers) to acheive the compactness that consumers desire, as well as to reduce EMI and acheive EMC compatibility.
[edit] Re: Most Consumer Electronics
Perhaps, but a majority of the electronics still around are from the old days when 1- and 2-layered boards were the norm. Hence, it will be decades before equipment containing 4+ layered boards outnumber equipment with 1- and 2-layers. Stovetopcookies 03:19, 21 June 2006 (UTC)
[edit] Mounting components
Perhaps it can be mentioned as a few tips.
- Certain axial components like resistors, diodes, etc. may be mounted vertically to save board area.
- Large components, like radial electrolytic condensers, may be folded horizontally when vertical clearance is an issue.
- In computer circuitry, crystals are often mounted horizontally, with the metal case laying flat to an exposed ground plane, and the case may or may not be soldered to the ground.
- Rarely is a component soldered to the foil-side of a single-sided board. This should probably be minimized, but it does come up often enough to warrant mentioning it.
Stovetopcookies 03:17, 21 June 2006 (UTC)
