Re: Guidelines to shrink the PCB size
- From: "Paul E. Bennett" <Paul.Bennett@xxxxxxxxxxxx>
- Date: Fri, 23 Nov 2007 18:57:05 +0000
Ali wrote:
Hello,
Are there any basic guidelines in embedded system when it comes to
shrinking the size? what are the probelms/limitations or interferences
one should consider while shrinking/sandwiching the board.
I was thinking that should be something like this:
0- Calculate the empty space in given housing. Thats the space actual
available for putting all the electronics.
1- Draft the physical dimensions of all components.
2- Now do simple PCB with few layers.
2.0- Break the PCBs in parts to fill the empty space,
connections can be done with ordinary connectors. Why not modularizing
the whole thing; LAN, Image sensor and Power circuitry etc. etc.
2.1- If the size is greater than free space then increase the
layers to adjust the components. (sure, we got to keep in mind the
heat emission and EMI if analog is involved)
3- Try to find components with different sizes with same specs.
4- And here we are in vicious cycle to fit all the thing in such a
small place , so lets start from point '2' again and keep iterating
unless we find the way-out of this puzzle.
Many times I have been confronted by the request to get gargantuan amounts
of functionality into a pico-sized box that my first question will be about
the requirements for such functionality in such small spaces. There are
sometimes other ways to do the job that will keep the client happy and ease
your burden.
There are limits to how much you will be able to shrink the physical
emanation of your design. Certainly, in my line, we have to deal with the
really harsh world of high energy physics and physical hard knocks. Look at
the sort of layout rules that are being placed on your design.
* Track separations to cope with high transient voltages.
* Track widths to carry the currents you expect
* Placing of circuit sections to maintain safety isolations
* The need for protection circuitry
* Room around the circuit to allow cooling airflow
The above criteria should be programmable in your CAD layout package.
Of course, you can select small physical sized components (mostly surface
mount devices) and even consider things like circuit modules which
incorporate part of the design on a thin-film device (these can sometimes
use the chip die directly and place micro-sized additional components
around to make up more of the whole system).
If you have volume, then multiple boards connected together can help (each
board with some part of the functionality) but be careful with insulation
separation between boards (use intermediate blank boards if necessary) and
choose good quality inter-board connectors.
--
********************************************************************
Paul E. Bennett...............<email://Paul_E.Bennett@xxxxxxxxxxxxx>
Forth based HIDECS Consultancy
Mob: +44 (0)7811-639972
Tel: +44 (0)1235-811095
Going Forth Safely ..... EBA. www.electric-boat-association.org.uk..
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- Guidelines to shrink the PCB size
- From: Ali
- Guidelines to shrink the PCB size
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