A common procedure for industrial manufacturing of electronic gear on a printed circuit board (pcb) is to glue the components in place with a sticky mixture of flux and solder powder, applied on the soldering pads. On boards with components on a second side they will be glued in place with an additional dot of glue amongst each part (a common glue for this a 1-component epoxy resin, as available from Loctite). Afterwards the board is heated with hot air or infrared radiation to melt the solder (reflow soldering). The flux will be removed in a washing process. No human will touch the board during the process, as the complete glueing-soldering-washing is made by industrial robots (like Siemens, which play a leading role in this buisiness). You just put a stack of pcbs and some reels of belt linked components into the factory and it spits out a bucket full of completely assembled boards.
-> Because of this portions of glue under most industrally mounted smd components you not only have to liquify the solder but also have to melt the glue and remove the part with some patience to pull it slowly off the board.