GB825297A - Improvements in or relating to the production of soldered joints on circuit carrying panels - Google Patents

Abstract

825,297. Soldering. GENERAL MILLS Inc. Feb. 5, 1957 [Feb. 16, 1956], No. 3992/57. Class 83 (4). [Also in Group XVIII] In making soldered joints at selected locations on a circuit carrying panel, the panel is brought into contact with a masking template mounted above a solder bath for movement towards and away from the bath and having a plurality of apertures to expose the panel at the locations and the template and panel are first lowered and then after a predetermined period raised together with respect to the bath to dip the template and panel into the solder to cause the solder to rise in the apertures to temporarily contact the locations; the panel is finally removed from the template. A panel 146 having electric components 148 on the top side thereof with their connections 158 extending through the panel into contact with a printed circuit on the lower side is positioned in slots formed by rivet heads 98 and bars 94 in which the rivets are fixed, the bars forming part of an adjustable support head secured to a piston in a pneumatic cylinder 114 on a machine frame. A stainless steel template 82 having recesses 90, Fig. 8, and apertures 84 corresponding with the connections 158 on the panel is screwed to a frame 76 having lugs 78 resting on springs in guide members 64 carried on uprights 60 on the frame. A pot 11, carried by the piston of a pneumatic cylinder 14 on the frame, contains solder 12 heated by electrical elements and temperature controlled by means 58, the upper surface of the solder being in contact with the template. The level of the solder is maintained by a float 34 operating a switch 44 controlling a motor 26 for feeding solder rod from a reel 22 through a duct 30 into the solder-bath. The float device also operates an indicating pointer on a dial. In operation with flux applied to the connections 158 a switch is pressed to actuate a solenoid valve allowing air into the cylinder 114 to lower the panel 146 into contact with the template. The rivets 98 engage the recesses 90 and the template and panel are together pushed into the solder against the spring-loading provided in its support mounting. Solder rises through the holes 84 and effects soldering of the connections 158 to the printed circuit. A switch 118 operated by a stop 116 on the descending piston-rod actuates a timing device which, after a predetermined time, de-energizes the solenoid valve to effect raising of the piston to allow raising of the template and panel together and then effect the lifting of the panel from the template. The cylinder 14 is provided to allow lowering of the pot 11 before shut down, so that damage due to the machine being operated with the solder solid, is prevented.