Re: gEDA-user: IPC standard SMT footprints (0603, 0402 vs. RESC0603N etc.)

[Colin D Bennett <colin@xxxxxxxxxxx>]

On Wed, 25 May 2011 06:41:26 -0700
Colin D Bennett <colin@xxxxxxxxxxx> wrote:

> (1) Why is RESC0603L/N/M much smaller than '0603'?
> (2) Why is there no similarly named set of RESC0805L/N/M for 0805
> size? (3) Why does RESC1608M nearly match the '0603' footprint?
>     Is there an imperial/metric naming confusion happening?  I thought
>     0603 was a standard name for this size.

I think I've answered some of this for myself... from Wikipedia's
âSurface-mount technologyâ article:

    01005 (0402 metric) : 0.016" à 0.008" (0.4 mm à 0.2 mm)
    0201 (0603 metric) : 0.024" à 0.012" (0.6 mm à 0.3 mm)
    0402 (1005 metric) : 0.04" à 0.02" (1.0 mm à 0.5 mm)
    0603 (1608 metric) : 0.063" à 0.031" (1.6 mm à 0.8 mm)
    0805 (2013 metric) : 0.08" à 0.05" (2.0 mm à 1.25 mm)
    1206 (3216 metric) : 0.126" à 0.063" (3.2 mm à 1.6 mm)

So the source of the confusion over footprints is that '0603' is a valid
name for both a metric and an imperial size.. both different?  Whoever
decided to name the packages that was must have been on crack.

That explains why there is no RESC0805N .... since 0805 is not a valid
metric package size.

Regards,
Colin


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