> -----Original Message-----
> From: piclist-bounces@mit.edu [mailto:piclist-bounces@mit.edu]On Behalf
> Of Phil Keller
> Sent: 18 January 2007 17:04
> To: PICLIST Post
> Subject: [EE] PCB Via size
> 
> 
>   I have a design that is controlling an incandescent lamp with a 
> current of about 1 Amp.  I am not as concerned with the voltage drop as 
> I am with overall reliability and ensuring that the via does not become 
> a fuse.  There are many places that help in calculating the suggested 
> PCB trace width for a given current but what about the via?
> 
>   The calculators tell me that the trace should be 30 mils wide.  (I use 
> 40 to be safe.)  Now when I need to go from top to bottom metal, what 
> size via (also called feed-thru holes) is required? 
i'd imagine the first thing you'd want to find out is the thickness of the plating (which is likely to be substantially thinner than the top/bottom copper) from there you can calculate the holesize required to give your via equivilent CSA to your track.

multiple vias are probablly a good idea as hole area goes with the square of hole diameter while plating CSA only goes linearly with hole diameter.

another option if you are pushed for space is to put a peice of suitablly rated wire through the via and solder it on both sides.


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