Etching and ground planes

[DavyJones]

First I apoligize if this isn't the correct catagory I should be asking this type of question it was the closest I saw off the bat. Anyway I am just about to etch another board and thought I could save some time and checmicals if I put a big back plane on the entire board. Up until now I've only etched very small boards and wasn't much overhead to etch off most of the copper. I'm about to etch a much larger board from my previous projects. Allot of boards I've seen I see big back planes on there that don't seem to connect to anything so is this standard practice? Should a back plane be kept away from certain components such as input from my AC power source before it passes through my rectifier circuitry? Can/should the back plane encompass the entire circuit and is it ok letting it float or should they always be tied to ground?
Thanks for your assistance and expertise.
David

[Dave]

DavyJones, The boards I have designed for test equipment always have the "extra" area layed out as ground plane. This is true for both sides of the board. Then the areas are then stitched together to make 1 ground circuit. This allows for the lowest resistance path for the return. If I had to make my own pcb's this is what I would do also as to save the amount of etching of the copper and prolong the usefullness of the acid...

Dave Purola,
N8NTA

[DavyJones]

DavyJones, The boards I have designed for test equipment always have the "extra" area layed out as ground plane. This is true for both sides of the board. Then the areas are then stitched together to make 1 ground circuit. This allows for the lowest resistance path for the return. If I had to make my own pcb's this is what I would do also as to save the amount of etching of the copper and prolong the usefullness of the acid...

Dave Purola,
N8NTA

Dave, Thanks For my projects I don't think I would ever have a double sided board. I do like the idea of saving etchant and time. Do you actually tie the ground plane in to all the grounds on all the components too? I've seen some boards that do and I see some that just do it for what looks like saving etchant and time. Not sure what the school of thought there is.
Thanks
David

[Dave]

DavyJones, If you need a low resistance path for the return or in other words path for high current then by all means, tie the ground planes or unused areas together. Even a single sided pcb can benefit from connecting the unused plated areas...

Dave Purola,
N8NTA

[mackrackit]

Never saw a need to remove extra copper. When prototyping it sometimes helps to have a little extra if you need to change something.

[mister_e]

Ground plane are nice for various things. However they also have their culprits. You may do a little search and sure enough you will find some documentation on how to implement them the right way (assuming the author know how to )

You want to avoid unconnected islands, those may give you strange results and maybe screw up your whole design.

Take a bit of your time to read those bellow.
http://www.ce-mag.com/ce-mag.com/arc...103CE_028.html
http://www.radioing.com/eengineer/pcb-tips.html
http://www.amd.com/files/connectivit...86cc/22507.pdf

HTH

[DavyJones]

I appreciate everyones advice. Thanks for the links Mr. E very helpful reading.

Thanks again

David