Patent GB-684082-A (GB)
Title: Improvements in or relating to the soldering of metals
IPC: B23K35/36
Filed: 1947-07-30
Abstract: Addition compounds are prepared by combining together a boro-fluoridic compound and an organic compound having at least 2 carbon atoms and at least 2 amino groups.  Specified components are boron-trifluoride, hydrofluoboric acid and heavy metal fluoborates such as the zinc, cadmium, tin and lead salts and ethylene diamine, diethylene triamine, triethylene tetramine and p  tetraethylene pentamine.  The addition compounds may be prepared from equimolar proportions of the components as in the addition compound BF3-diethylene triamine or excess of either may be used.  Preferably, the boro-fluoridic component is a mixture of hydroborofluoric acid and a heavy metal fluoborate.  The boro-fluoridic component may be added to an excess of the polyamino compound whereby a solution of the addition compound in the latter is obtained.  The addition compounds are utilized in solder fluxes (see Group II).  Fluxes mentioned are (1) a mixture of 12 grams HBF4 and 8 grams Cd(BF4)2 dissolved in 100 grams of diethylene triamine and (2) a 10 per cent solution of the diethylene triamine-HBF4 addition compound in diethylene triamine.  Specification 684,081, [Group II], is referred to in a disclaimer.ALSO:A method of joining metal parts by soldering comprises applying to said parts a flux comprising an addition compound of an organic compound containing at least 2 carbon atoms and at least 2 amino groups with one or more boro-fluoridic compounds such as BF3, hydrofluoboric acid and heavy metal fluoborates such as the cadmium, zinc, tin and lead salts.  The polyamino organic compounds may be used singly or in mixtures, examples being ethylene diamine, diethylene triamine, triethylene tetramine and tetraethylene pentamine.  The addition compounds may be formed by combining equimolar proportions of the components, as in the addition compound BF3-diethylene triamine, or excess of either component may be present.  Preferably, the boro-fluoridic component is a mixture of hydrofluoboric acid and a heavy metal fluoborate.  The flux may also comprise a flux vehicle such as water, alcohol, or a polyamine which may be the same as that used in forming the addition compound and may be the excess of the amino compound used in that preparation.  Other flux ingredients may be present such as the fluorides of zinc, cadmium lead, tin and other, heavy metals and plasticizers such as stearic acid, mineral jelly, oleic acid or paraffin.  The method may be applied to the soldering of aluminium and its alloys, especially by soft soldering procedure, copper, iron, nickel, brass, certain steels and magnetic iron base alloys containing aluminium. Particular fluxes described are (1) a mixture of 12 grams HBF4 and 8 grams Cd(BF4)2 dissolved in 100 grams of diethylene triamine and (2) a 10 per cent solution of the diethylene triamine-hydrofluoboric acid addition compound in diethylene triamine.  Specification 684,081 is referred to in a disclaimer.  The Specification as open to inspection under Sect. 91, states that the flux may also contain amino alcohol addition compounds of boro-fluoridic compounds.  This subject-matter does not appear in the Specification as accepted.