kicad-lib-committers team mailing list archive

[Kerusey Karyu <keruseykaryu@xxxxx>]

W dniu 03.04.2014 02:24, Carl Poirier pisze:

> About pin length, what about using SI units?
At this point, we shall to ask: How many users use SI units when drawing 
schematics? Most of them will look at grid only and doesn't care about 
mm or inches.
Units of measurement are important, but where they are actually required 
to maintain strict dimensions.


> Symbols:
>
> 1. A pin length of 4mm is used, except for components without pin
> numbers which use 2.5mm.
>
If we force 4mm or 2.5mm of pin length these pins will be outside of the 
grid when somebody uses inches. IMO this is not the way we should follow.


> Footprints:
> (...)
> 2. Pad 1 is placed at the top left corner
>
(...) unless the manufacturer places the components in a different 
orientation in tubes, tapes or trays (Important for P&P).


> 3. For through-hole components, origin is set on pad 1.
> 4. For surface-mount devices, origin is placed in the middle of
> the chip.
>
There are also machines for automatic insertion of THT components, so 
mandatory putting origin point at pad 1 is a bad idea.
We can assume to put origin at pin 1 when we are sure that this 
component will be inserted manually, for example terminal blocks.


BTW: I don't like the idea for using A,C(K) pad names for diodes; BCE, 
GDS for transistors or +- for polarized capacitors. This is apropos of 
the back-side discussion among the developers list.

Regards
Kerusey Karyu