Chicago screws consist of two parts, and one half is flat-headed. That half is inserted through both pieces of tack that you’re trying to connect. Then the other half, which includes a notch for a screwdriver, is driven in through the other side and tightened into place. Theoretically, the Chicago screw is a solid, reliable piece of handy hardware they need to be selected and applied correctly and not cross threaded.
Periodically check all Chicago screws to make sure they haven’t loosened with use.