Through-hole assembly (“thru-hole”), in which electronic components are mounted thru leads. These leasds are inserted into copper plated holes drilled in printed circuit boards (PCB) and soldered to pads on the opposite side either by the manual soldering or waver soldering. Thru hole assembly is time consuming and in turn increases your cost. These assemblies are generally bigger and chunkier but the their solder connections are superior than SMT connections. Military and Aerospace use this technologies since they have to operate IN EXTREME ENVIRONMENT.