This is just an ultra low resolution picture of flip chip attachment flux, however ultra low residue flip chip attachment flux is clearly a great solution for no-clean applications which involve subsequent capillary underfilling (pun intended).
There are low residue fluxes designed for dipping, pin transfer, printing, spinning, or spraying. But low residue fluxes do have a unique limitation. Because the solids content of the flux is low and it offers less protection from oxygen at high temperatures, low residue fluxes generally need to be used in an inert atmosphere. And now the good news: most of us are already using