Patent ID: 8348135

Claim:
A method of checking a component for the presence of adequate solder flux within an assembly operation the method comprising the steps of: (a) illuminating with a light source a component having a solder flux composition applied thereon, wherein the solder flux composition comprises: (i) a carrier vehicle comprising a polyethylene glycol ether solvent; (ii) an activator component present in an amount of 30% to 70% by weight of the total flux composition for activating a metal surface for soldering; (iii) a gelling component to control flux rheology; and (iv) a colour-imparting component with an appropriate colour to facilitate optical detection of flux on a component to which the flux is applied; (b) optically detecting the presence of flux; and (c) rejecting the component if sufficient flux is not present, wherein the colour-imparting component is soluble in the solder flux composition and wherein the light source emits a red light and the colour-imparting component is blue.