There are several things that can be done to eliminate solder shorts on 
connectors through a wave solder machine. I have not found that 
orientation makes a lot of difference.

How long do the pins protrude?  Reducing the length to <=1.5mm on a 0.1"
pitch connector will minimize shorts due to lead length.
Longer pins seem to attract shorts.

I would suggest that you also look at the set up of the wavesolder 
machine.  I have successfully used the following procedure to 
troubleshoot in the past. 

1.You may need to check that the conveyor rails are level side to side 
and ramp with an angle specified in the Manufacturers Manual (typically 
7 degrees).  Adjustment is tricky and you should ensure that the PWBs 
sufficiently contact the Fluxer (wave and Foam types) and the solder 
wave. (see manufacturers instructions)

2. In my experience, the most critical wavesolder parameter is the Contact 
Time in the solder Wave (contact time is the period of time that any 
one point on the PWB remains in contact with the solder wave).
Everything else is set up with respect to this value.  The Contact Time
can be determined using a Lev-Chek glass plate ($60 from Hexacon 
Electric).  The optimum contact time is a function of the CCA thermal
density, the speed of the conveyor and the PWB depth in the solder wave.  
Contact times vary from 2 to 4.5 seconds depending on the above
characteristics.  NEVER change the speed of the conveyor without 
considering the contact time. (changing speed also affects the Top
Board temperature from the preheat)

3. Next determine the correct preheat temperature (top board temperature)
for the flux that you are using (typically 70-85degrees C for RMA).
You can use temperature sensitive labels (Cole & Parmer (708) 647 7600
- p/n 8068-02) attached to various points on the top surface of the PWB
to determine what the actual preheat is at the exit of the preheater 
section.  Adjust the ONLY the preheater control to obtain the optimum 
preheat on the board (Remember adjusting the conveyor changes the Contact
Time). (use a scrap board for this as you will have to run several times
to obtain the optimum temperature)

4. Finally ensure that the fluxer is operating correctly and the Specific 
Gravity (RMA fluxes) or Flux activity is within the manufacturers 
specification.  You can use the LEV-CHEK to confirm you have good 
coverage.

You should now be able run some tests and modify one paramter at a time 
to determine the optimum set up for the boards.  You will need to use 
SPC techniques to fine tune the process.

Good luck and if you have any comments/questions feel free to contact 
me.
---------------------------------------
Martin Kennett - [log in to unmask]
Design Engineer
SED Systems Inc.
18 Innovation  Blvd
Saskatoon, Saskatchewan, CANADA
ph (306) 931 3425, Fax (306) 933 1486