I've used x=03 giving 11mm between board surfaces.
There are two reasons for this:
a) This clears the CF socket area with height for components in this
area. The CF socket sticks out about 6.5mm so this gives 4.5mm for
components under the CF area.
b) The Hydra daughter board is bigger than the Balloon and extends up
above the back of the CF socket (the lower, bus connector, edge is
coincident). Many CF cards fatten after they clear the socket
(particularly WLAN cards) (Also note that it is a Type I socket), so it
was important to give as much space in this area as possible.
There were a number of different physical design constraints that forced
this particular arrangement for the Hydra daughter boards. One being
that I needed to stack several cards together, in different
combinations, so the connectors on each side of the board needed to be
in the same plane.
In a design that is less constrained I'd suggest making the
daughterboard so that its upper edge is coincident with the loon edge
from which the CF card protrudes, this would allow better clearance for
CF cards. If the daughter board needs to be larger than the Balloon
board it may be better to extend it in the opposite direction i.e. below
the Bus connector. This has the advantage that PCB tracks to the Bus
connector have more routing space (i.e. both above and below the
connector) and this may allow a cheaper daughter board to be made where
via size is larger and with possibly fewer layers, even if this is not
the case routing will be much easier.
Cheers
David.
-----Original Message-----
From:
balloon-admin@balloonboard.org
[
mailto:balloon-admin@balloonboard.org] On Behalf Of Laurie van Someren
Sent: 21 June 2004 16:58
To:
balloon@balloonboard.org
Subject: [Balloon] Question for Dave Bissett
I think Dave Bissett may have actually used the CF socket and the large
GPIO connector on a Balloon, so he is well placed to answer this query.
The standard connector QTE-100-01-L-D-A-K is the one standing lowest off
the board surface, and so a PCB attached to its counterpart QSE
connector
interferes with the CF socket.
Connectors which stand further off are available; the -01- is 5mm thick
and 8mm and 11mm and more are options. It looks as if the -02- part
with
its additional 3mm height will hold a PCB clear of the CF socket,
(though
there would be almost no room for components on it where the CF socket
is).
Dave, what value of X have you used for a QTE-100-0X- >with< CF socket,
please ?
Thanks
LvS
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