Patent GB-1418827-A (GB)
Title: Process and apparatus for forming a layer of solder on a metall ised surface of a sheet of glass and a process of making a soldered glazing unit involving such solder-layer formation
IPC: C03C27/06
Filed: 1973-02-16
Abstract: 1418827 Soldering GLAVERBEL-MECANIVER 16 Feb 1973 [18 Feb 1972] 7840/73 Heading B3R [Also in Division C1] In forming a layer of solder on a metallized surface portion of a sheet of glass, e.g. for use in a glazing panel soldering flux is sprayed on to the metallized surface portion to form a coating extending up to a pre-determined boundary and then solder is applied on to the flux coating and spreads or is caused to spread out on the flux coating up to at least a portion of said boundary. A sheet of glass 4 in contact with a side edge guide is conveyed on rolls 3 in the direction of the arrow 5, Fig. 1, having been metallized along a margin with a film of copper based alloy. The film is preferably brushed, preferably passed beneath a reducing flame 7 and sprayed with finely atomized flux by an atomizer 8 adjustable laterally of the path of movement of the sheet, the flux extending from the side edge of the sheet up to a boundary line which may coincide with the inner boundary of the film or may be nearer the edge than that boundary and a pipe 18, Fig. 2, connected to a suction pump collects the flux in the atomized discharge cone 19 which does not deposit on the margin of the sheet. A stream 12 of molten solder is discharged from a nozzle 13 in a vessel 11 and a sensing member located in the path of the glass sheets causes the solder discharge nozzle to open when the forward edge of a sheet is sensed and to close when the trailing edge is sensed. The solder discharges as thin thread and is spread by a shoe 15 heated internally by gas burners 16. The shoe which is carried on a frame preferably supported by a wheel running on the glass sheet is provided with grooves in its lower surfaces to assist spreading and distribution of the solder. Conduits beneath the spreading shoe are provided to automatically project streams of nitrogen over the shoe when a glass sheet is not beneath the shoe. Two opposite margins of the sheet may be metallized, fluxed and coated with solder to a width less than that of the metal films. Then a metal film is deposited on an adjacent edge to key directly to the exposed portions of the first two margins before being fluxed and solder coated. Finally the last margin is metallized, fluxed and solder coated. In a modified process when flux is applied over the whole of the metallized area molten solder is sprayed so that solder droplets impinge on an area narrower than the metallized area and spreads out under gravity and surface tension. Alternatively spaced drops of solder may be applied to the flux coating. Solder employed may be Sn, 50%-Pb, 50% and the flux may be abietic acid, triethanolamine, diethylene glycol, and isopropanol. The solder alternatively may include 2% bismuth. Instead of protecting the shoe 15 with nitrogen molten solder in a receptacle may be raised into contact with the shoe on completion of spreading operation and two or more shoes may be provided. To restrict the flux to a predetermined area a guard or screen may be used and solder drops may be allowed to solidify, being spread after re-melting. Solder may be supplied as solid strips or thread. Glass sheets metallized, fluxed and solder coated are assembled with a spacer or strips and the assembly is soldered together to form a glazing panel.