FreeLists / pcdlist / [pcdlist] Re: Component Polarity

[Doug Boone <dboone@xxxxxxxxxxxx>]

Strange, most Caterpillar's I see are pretty big! Guess all those pig iron 
ballast take up most of the room.  Anyway my two
bits worth is to make whatever marking you use very clear.  Nothing is more 
frustrating than to encounter a code or mark
which does not have a common meaning.  Why not go ahead and use the IPC 
standards?  They were created with some forethought
for both assembly and for troubleshooting and test after assembly.  And if the 
collective memory of all involved fails, they
can always reference the published standards.  In my experience shortcuts are 
not short.  Meanwhile we will all get out of
your way when you field test those beautiful yellow brutes.
grins.
doug.

"Jack C. Olson" wrote:

> Here at Caterpillar we are starting to do some designs that are dense
> enough that the silkscreen gets in the way.
>
> We would like to have some method of identifying component polarity even
> without a silkscreen and without a drawing, and about the only thing we can
> think of  is to lengthen the "pin one" pad for ICs, and cut the corners off
> the anode or positive side of diodes and caps. What worries me is the
> shaved corners. After preaching to everyone the value of having some kind
> of standard land patterns, I'm now advocating six sided geometries?
>
> but anyway,
>
> Have any of you seen soldering or reliability problems by cutting the
> corners off a pad?
> Is there a "trimming ratio" I should maintain?
> Any other ideas?
>
> Jack
>
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