Hi Nigel,

One example of a dual footprint experience I'll share. It was when I was
working out in California for a company that made memory modules. At that
time they were wanting to make 1206/0805 dual use footprints for the
de-coupling caps. We found that they kind of worked, but wasn't without
issues. We saw an increased incidence of tombstoning with the 0805 caps and
a greater incidence of solder beads which were a big problem because we
were trying to go no-clean at the time.

I had heard that it's the cell phone industry that is responsible for
driving the size of the passive components down, and once a component
manufacturer tools their line up to produce 0201 components that's pretty
much it for months and months. They're not tearing the line down to make
bigger chips which is a smaller percentage of the revenue.

Steve

On Tue, Jun 26, 2018 at 7:48 AM Nigel Burtt <[log in to unmask]> wrote:

> Of course, hence "...suitably limited implementation..." in my post.
>
> I'm thinking of assembly problems: printing, SPI, placement, reflow, AOI
> etc -  even if one could come up with a suitable mixed footprint stencil
> aperture, would the resulting solder joint meet IPC-A-610 visual inspection
> acceptability conditions for example.
>
> Then there is the in-service-reliability aspect of the solder joints
>


-- 
Steve Gregory
Kimco Design and Manufacturing
Process Engineer
(208) 322-0500 Ext. -3133

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