I would like to weld the relay to the circuit board, the rated current is 5A, the voltage is 110VDC. Will the need to add a diode on the coil what model
AC contactor coil should be installed plus resistance, plus diode useless
If it is used to protect the freewheeling diode, should be used 1N5404 ~ 1N5408, these models of reverse voltage is not less than 400V, the maximum continuous current 3A, the maximum pulse current 200A.
Your parameters are conceptually problematic: 5A is certainly the contact current, 110VDC may also be the contact load voltage, of course, may also be coil voltage, but is not based on what you intend to weld to the circuit board, the relay is certainly not how big Of the coil voltage even 110VDC, in the coil at both ends of a diode with a 1N4007 on it.