Backplane

Plane in the Neck

Yes, I messed up the spacing of my slots,
apparently incapable of even following my own marking-out. 

280 solder joints and one stonking headache later, the backplane is finished and tested, all that remains now is to apply the pinout labels I printed beforehand. One thing that became apparent when positioning the slots is that the headers are rarely perfectly straight in any direction and the technique I adopted when soldering them in place was to solder the end pins of each header, let the joints cool and then check for any gaps between the header and board, then reheat the joint while applying pressure to that end of the header to make it sit flush against the board. Another good thing to do at this stage is to make sure that the header is at a proper right angle to the board, because there's only two pins soldered in place it's much easier to make corrections now than later.

Finished backplane - complete with pinout labels.

Once you're satisfied everything is where it should be, solder another two pins, four or five tracks in from each side and check the alignment again, I think it's probably easiest to start with the two end-most slots and work your way in, this way the board sits level when upside down and makes soldering the rest of the headers in place much less frustrating, check for any gaps in between header and board in the middle of the slots before soldering a couple of pins nearer the centre, applying gentle pressure if necessary to close them before making the joints, again - making corrections at this stage is much easier than when you have most or all of the pins soldered.

When you have finished soldering, be sure to check for shorts between tracks with a multimeter set to the 20k range, most shorts will be obvious solder bridges that are visible to the naked eye but others will not, a few extra minutes spent checking could potentially avoid a mushroom cloud later on.