A lot of boards with predominantly SMT components have TH connectors on them for things like headers and power connectors. Take a standard barrel power jack for example:
TH:
SMT:
When designing a board, how do you decide whether a connector can be SMT or not?
The choice of through-hole versus surface-mount comes down to you, the designer of the PCB. To make that choice, you have to consider things like:
Assembly and tooling. Does the company or person assembling the PCB have the necessary tooling for the desired form factor?
Device construction and clearance. Does the device ultimately need to be space-saving? Are through-hole leads going to cause clearance problems in a restricted form factor? Is there another PCB or something nearby which through-hole leads and the resulting solder could be too close to?
Strain/durability. Is the DC jack going to be regularly exposed to physical wear and tear? Are users going to be plugging and unplugging the device often? Through-hole may afford some additional strain resistance and durability.
Cost. If you're building 100k units, a small difference in cost between the TH and SMT version of this component might matter.
The shear strength of SMT pads on a frequently jarred power cord gives rise to metallurgic fatigue.
The reliability of this interface is poor unless there is significant pressure on the connector to resist strain from stress on the pad joint from mechanical torque.
Unless you can provide this extra durability protection or prove that the plug is infrequently used, you must choose THT.
If you're going to production, the cost of the selective soldering process will add considerably to assembly cost per board, particularly if its the only TH part. If not, try to localize THs to one part of the board to try to control cost.
