> >> a) Ensure the ground connection connects before any other signals,
> >> perhaps making it longer or using a special connector;
> > Yes, will try to achieve that with standard 0.1" head pins by leaving t=
he GND pins=20
> > slightly higher.=20
>=20
> Simply displacing some pins up may not work, they may not be soldered
> correctly to the board or they may limit the insertion of the ones that
> weren't displaced and those may not make good contact. Besides, the
> amount of displacement would be very limited, perhaps not ensuring that
> the ground pins always make contact first.
>=20
> Right now I'm designing with a bottom-entry 0.1" receptacle and I think
> it may help you.
>=20
> The bottom entry receptacle doesn't limit the length of the pins. If a
> pin is too long it will appear over the top of the receptacle, while the
> other pins still are correctly connected and at their normal height.
>=20
> All you need is to remove some (ground) pins from the header and replace
> them with pins of a header with longer pins. This way, the ground pins
> will be taller than the others and will make contact first. As you push
> the daughter board down, the ground contacts will slide along the ground
> pins, ensuring good grounding while the remaining pins begin to make
> contact.

Thanks Isaac, good idea, might go with that nex time. Can't change receptac=
le=20
easily now as it would require a board mod.

I did have a quick go at offsetting the pin heights on the standard 0.1" he=
ader pins=20
I'm using. I found I can extend the GND pins out 0.75mm before they hit the=
 stop in=20
the receptacle. Will still solder OK as board is D/S PTH. The rest of the p=
ins could=20
be pulled back say 1.25mm (there is at least 2.5-3mm of "contact sliding" d=
istance)=20
making my GND pins stick out a usefull 2mm further than the others. Could f=
easibly=20
make a simple jig to press the pins to the correct lengths. Undecided about=
 wether=20
I'll do this or not for production, depends on how favourable the assembly =
company=20
is to the idea.

--=20
Brent Brown, Electronic Design Solutions
16 English Street, St Andrews,
Hamilton 3200, New Zealand
Ph: +64 7 849 0069
Fax: +64 7 849 0071
Cell: +64 27 433 4069
eMail:  brent.brown@clear.net.nz


--=20
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