| 摘要 |
1,212,144. Soldering. J. C. HOOD Jr. 13 March, 1969 [18 March, 1968], No. 13193/69. Heading B3R. [Also in Division C7] A solder removing wick consists of braided copper strands, the braid having an exterior surface of copper directly in contact with and substantially entirely coated with a non- corrosive flux. To unsolder the connection between a copper wire 16, Fig. 2, from a component and a printed strip 12 on a printed circuit board 10 a length of flux-coated braided copper wire forming a wick 20 is placed on the solder globule 18, a hot soldering iron bit 24 is placed on the wick to melt the solder which flows up into the wick and the wick and bit are removed to leave the wire 16 and strip 12 free of solder. The flux coating is applied to the wick by the apparatus shown in Fig. 5, wherein the tubular wick is flattened by rollers 28 and is fed over guide rollers 29 through a tank 30 of flux solution the coated wick then passing a hor air blower 34 and finally when dried is fed on to a roller. The flux may be methyl ester of abietic acid, methyl ester of pimaric acid, pine rosin or rosin obtained from tall oil by removal of fatty acid components and the solvent may be acetone, cyclohexane, methyl formate, tert-butyl alcohol, ethyl bromide, vinyl acetate, n-propylamine, ethylene chloride, methyl sulphide, n-hexane, isopentane, methyl acetate, methyl alcohol, n-propyl formate, acetyl chloride, carbon tetrachloride, ethyl acetate, ethyl alcohol, methylene chloride methyl ethylketone, ethyl formate isopropyl alcohol and mixtures thereof. Dimethylamine or acetaldehyde under defrigeration may also be used. In an example, 25 parts by weight of rosin is dissolved in 75 parts by weight of a 4 : 1 mixture of methyl acetate and methyl alcohol to form the fluxing solution and the wick is submerged in the solution for 0À5-1 second and then dried. The surface tension of the solvent is low enough that the braid is entirely coated externally with the flux and yet, when the solvent is volatilized, the wick retains sufficient capillarity to draw up molten solder. |
