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Subject: Re: [Homebrew_PCBs] 4 Layer boards

From: Trevor White <trevor.white100@...>
Date: 2009-12-14

Thanks for the responses. My reasons for asking are a mix really. I am
an engineer by trade but also I am just really being curious. I do not
have a specific need for a 4 layer board right now. I have laid out 4
layer boards in the past though and for some reason always fancied
making them myself. I have never tried yet.

I like to make things smaller and smaller so 4 layer boards enable that.
For one company I worked at a few years ago I did the cad work for a
board that was 12mm x 10mm and needed to be 4 layers because of all the
tracks.

Last year I quite fancied making a board based on the AVR32 and this
looked like it would have to be 4 layers at least. Getting a couple of
prototypes made would cost both time and money and well I did not have a
real need for the board. I just wanted to make one. So that project got
shelved.

So I think I would probably use the skills in my work occassionally but
i am not sure if I was truely doing it for professional reasons it would
make financial sense. I certainly do not have cash to invest to prove
that. I think I just want to make more and more complex, small boards.

Trev






Andrew Mathison wrote:
>
> Dear Trevor White
>
> with regards to your question about 4 layer boards (which are easily 4
> times more expensive to have made,in my experience, than double sided
> ones....), are you a hobbyist or professional? Because if you are a
> professional, the price (almost !) does/should not matter.....
>
> If you are Hobbyist, then you should give some thought to redesigning
> the board for double layer, even if its a bit bigger because of
> that.... Fault finding on 4 layer PCBs is not for the faint hearted
> either and repairs can be a nightmare.....
>
> If you are developing something privately, for maybe later selling,
> may I still suggest that until the design is working perfectly, that
> you stay with double layer, get some experience with that and when you
> really go for "IT", do the 4 layer design. You may get some new
> problems but YOU WILL KNOW EXACTLY WHY!!! Which is like money in the
> bank!!!
>
> I would be most interested in learning why (if) you feel that a 4
> layer is the only way to go in your particular case......
>
> (I have to admit that my personal (not business I hasten to add, we
> used multilayer pcbs all the time there) PCB level is far less
> complicated than yours, I design using my PCB software at first double
> sided (my old software makes a mess/gives up when telling it to design
> single sided!) and then try and redesign by hand to fit a single sided
> PCB - it appears that I like wire links a lot!!! Or better said, they
> do not bother me at all......I can usually manage to get probably 90%
> of my designs (thats probably between 4 and 8 boards a year!!) onto
> single sided - not that I am anticipating you changing a 4 level
> design to ever fit single sided PCB, that was NOT my meaning!! Double
> at least I would still guess.....)
>
> Stay well and regards from
>
> Andy
>
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>
>