[SI-LIST] Re: PCB solder current carrying capacity

In one of the articles on our web site re current carrying capacity 
of traces, we include this observation (which is approximate).
The resistivity of solder (depending on its composition) is 
approximately ten times higher than that for copper. Thus, you can 
think of the trace (pad) and solder as being two conductors in 
parallel --- one with 10x the resistance of the other (assuming 
similar widths and thicknesses.)

On standard traces, we tell our customers to ignore the current 
carrying capacity of the solder and just consider the copper itself. 
Then it is determined just by the cross-sectional area of the copper.

Doug Brooks
UltraCAD
http://www.ultracad.com




At 11:03 AM 7/21/2009, Gumaste, Vijaylaxmi wrote:

>Hi,
>
>
>
>I want to determine current carrying capacity of solder pads - 
>effect of solder material/ land-pad size for very high current 
>applications (>5A-10A per solder pad)
>
>
>
>I can use IPC spec to design appropriate metal layer trace 
>widths/thickness for a required temp rise.
>
>However, I am looking at options to estimate/calculate/simulate 
>current carrying capacity for solder pads.
>
>
>
>
>
>-Vijaya.
>
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Check out our resources at  http://www.ultracad.com 

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