Parts Substitution Woes
I've written a bit about parts substitution before and how it a simple sub can either not matter or cause a board to go up in smoke. Here's a case where the component was 100% electrically okay to be put in the design, but the form factor messed everything up.
The PCB was laid out with a tantalum cap in mind, but somewhere in the process, a metal can electrolytic was tossed in. Sometimes tantalum vs. standard electrolytic can make an electrical performance difference, but here it just mucked with the mechanics.
The pads are the wrong size and spacing and the base of the cap is too big so it gets in the way of other parts. Just a little cautionary tale. If someone else is doing the parts ordering for you, make sure that either they don't make any subs without contacting you first, or give them an approved subs list.