Re: gEDA-user: Test pads in PCB

[sdb@xxxxxxxxxx (Stuart Brorson)]

Hi DJ --

Thanks.  However, a test pad is  more than just a test
point.   Here are some points:

*  Actually, the test pad is just a pad with no soldermask on it.
No silkscreen either, since it's not a real component.  Here's an
example: 

Element["" "" "" "" 0 0 0 0 0 100 ""]
(
        Pad[0 0 0 0 3500 2000 5500 "" "1" ""]
)

This is basically your file with no silk layer.

*  However, this isn't enough.  For one thing, since the test pad
doesn't appear in the netlist, PCB doesn't allow you to just place a
test pad and then wire it.  PCB also flags a DRC with this testpad.
(I tried.)  Since a testpad is more like a via (i.e. non-netlistable
structure on the PCB), it may need a special flag allowing it to be
placed and connected to without causing a DRC.

*  Later I can create a screenshot of a board wiht testpads and post
it.  I will also look around the web for info about testpads and
automated test systems to better explain what I am looking for.

*  Finally, here's a footprint for a testpoint I use with the
Mouser 151-202-RC (Kobiconn) through-hole test point:

Element["" "TestPoint" "" "unknown" 0 0 0 0 0 100 ""]
(
        Pin[0 0 8200 3000 9200 4500 "1" "1" ""]
        ElementArc  [0 0 6000 6000 0 360 1500]
 
        )

This is a real test point, i.e. a component which appears on the
schematic, and from which you can hang a scope probe.  It is not a
test pad.  I proffer this as an offering to the gEDA community for
listening to my whining for a test pad.  :-)  

Stuart



> 
> 
> > Anyway, these reasons suggest that PCB be capable of handling test
> > pads independently of the schematic.  I agree they shouldn't be vias.
> > Rather, they are analogous to vias in that they  are layout specific
> > structures which PCB could/should support someday.  Maybe I can look
> > at doing it myself someday . . . .
> 
> Here you go, one 35 mil testpoint element...
> 
> Element["" "" "" "" 0 0 0 0 0 100 ""]
> (
> 	Pad[0 0 0 0 3500 2000 5500 "" "1" ""]
> 	ElementArc [2 2 2502 2502 270 90 1000]
> 	ElementArc [-2 2 2498 2498 0 90 1000]
> 	ElementArc [-1 -1 2501 2501 90 90 1000]
> 	ElementArc [0 0 2500 2500 180 90 1000]
> )
>