> One other possibility is to make the board double sided, with 3 Oz foil
> on each side.  This will be easier for them to etch/plate, and
> paralleling the
> high current traces on two layers gives the same resistance.  I guess this
> won't work if this is a thermal board to be bonded to a heat sink.
>
> Jon

    I don't like making power supply PCBs with power traces on both sides.
Especially with large snap-in caps.  It is too difficult to ensure that the
top of the PCB under the cap has a good solder to the huge fat traces just
like the bottom.  I've experienced such designs where power supply sections
get a fine odd crackling type noise, which may be mistaken for a bad caps,
but it really was fine cracks in the solder on the top layer just under the
cap.  With a 1 layer board, such a problem is easily caught.


_____________
Brian Guralnick
[EMAIL PROTECTED]


----- Original Message ----- 
From: "Jon Elson" <[EMAIL PROTECTED]>
To: "Protel EDA Forum" <[EMAIL PROTECTED]>
Sent: Monday, August 04, 2003 1:59 PM
Subject: Re: [PEDA] PCB Copper thickness VS mounted rails.


>
>
> Brian Guralnick wrote:
>
> >I'm designing a power supply with will have a large ripple current.  This
> >power supply will be on it's own PCB and it's 1 layer.  Am I better off
> >mounting high current rails, or, increasing the PCB copper thickness from
> >1oz to something like 4-6oz?
> >
> >The power supply will be 90 vdc, continuous dc current of 4 amps, with
> >current surges & ripple current above 15 amps.
> >
>
> >Check with your PCB vendor on how much the extra thickness of copper
> >
> will cost you.  Then, compare with the rails, including the cost of having
> the assemblers deal with it.  If the 4 or 6 Oz foil will carry the
> current with
> acceptable electrical characteristics, it sounds like the best solution,
> unless
> the extra cost is prohibitive.  My guess is the extra foil thickness will
be
> cheaper than all the extra handling to assemble the whole thing.
>
> One other possibility is to make the board double sided, with 3 Oz foil
> on each side.  This will be easier for them to etch/plate, and
> paralleling the
> high current traces on two layers gives the same resistance.  I guess this
> won't work if this is a thermal board to be bonded to a heat sink.
>
> Jon
>
> >
> >
>
>
>



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