# US 4,011,980 A · Flow-over mass soldering > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 4,011,980 A - Document ID: US4011980A - Status: Granted - Kind: A - Application number: 05/670,466 - Filed: 1976-03-25 - Granted: 1977-03-15 - Earliest claimed: 1976-03-25 - Assignees: Western Electric Company, Inc. - Inventors: Howard A. Dvorak; William R. Studnick - Web page: https://patentgrep.com/patent/US4011980A ## CPC - B23K 3/0653: {with wave generating means, e.g. nozzles, jets, fountains} - H05K 3/3468: Application of molten solder, e.g. dip soldering - B23K 2101/42: Printed circuits - H05K 3/3447: Lead-in-hole components - H05K 2203/1527: Obliquely held PCB - B23K: SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM - H05K: PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS ## Abstract A printed wiring board is oriented with a wiring surface facing up for mass soldering. Molten solder is pumped from a tank onto a trough and flows in a thin, wide stream across the upper surface of the printed wiring board which is held down to prevent the board from floating on top of the solder. ## Claims ### Claim 1 The method of connecting lands on opposite sides of a printed wiring board to electrical terminals which have been inserted through apertures in the lands, and the board, which comprises: supporting the printed circuit board in a position at an inclination to the horizontal; flowing molten solder from an upper edge of the printed circuit board over an upwardly-facing surface of the board so that portions of the molten solder flow by gravity into the apertures and onto the lands on the underside of the board; interrupting the flow of molten solder over the upwardly facing surface of the printed circuit board after a predetermined time period sufficient to flow the solder onto the lands on the underside of the board; and permitting the molten solder in the holes in the printed circuit board to solidify to connect the lands of the board to the terminals in the holes. ### Claim 2 (depends on 1) The method of claim 1, which further comprises: providing means on a downward facing surface of the printed circuit board to preclude the flow of excess molten solder downward and out of the apertures in the board. ### Claim 3 (depends on 1) The method of claim 1, which further comprises: controlling the volume of flow of the molten solder to regulate the depth of the solder flowing over the upwardly facing surface of the printed wiring board, to limit the portions of the terminals which are exposed to the molten solder. ### Claim 4 (depends on 1) The method of claim 1 which further comprises: flowing the molten solder in a continuous circulating system along a first flow path; positioning the printed circuit board in its inclined position in a second flow path of the molten solder in the continuous circulating system; diverting molten solder from the first flow path to the second flow path to cause the molten solder to flow over the upwardly facing surface of the printed circuit board; and removing the printed circuit board from the second flow path after the predetermined time period, to interrupt the flow of the molten solder over the upwardly facing surface of the board. ### Claim 5 (depends on 4) The method of claim 4, which further comprises: skimming dross from the surface of the molten solder before the molten solder enters the first or second flow paths. ### Claim 6 (depends on 4) The method of claim 4, which further comprises: accelerating the flow of molten solder along the first flow path just prior to diverting the molten solder to the second flow path, to preclude the formation of dross on the surface of the solder and the flow of dross over the upwardly facing surface of the printed circuit board. ### Claim 7 A method of soldering an upstanding terminal having an effective area into a printed wiring board having an underface provided with printed wiring thereon and a hole extending through the printed wiring and the board including the steps of: inserting the terminal through the hole in the board to the underface of the board said terminal being of such size so as to leave a gap between the terminal and the wall of the hole; orienting the board with the printed wiring facing in a generally downward direction; and flowing solder by gravity across the upper surface of the printed wiring board at a depth below the effective area of the terminal and through the gap onto the printed wiring. ### Claim 8 The method of simultaneously fusing solder slivers and solder plating on a surface of a printed circuit board and connecting solder terminations extending through holes in the board to electrical terminals which have been inserted through the holes to project from opposite sides of the board while leaving gaps between the sides of the terminal and the walls of the holes. supporting the printed circuit board with the surface containing the solder slivers and solder plating at an incline and with the surface upwardly exposed; flowing molten solder across the upwardly exposed surface of the printed circuit board to melt the solder slivers and solder plating and surface portions of the solder terminations, and to gravity flow molten solder into the gaps about the terminals; interrupting the flow of the molten solder over the upwardly exposed surface of the printed circuit board after the molten solder has filled the gaps in the board about the terminals; and solidifying the molten solder in the holes in the printed circuit board and about the terminals, including the melted surface portions of the solder terminations, to connect the terminations to the terminals. ### Claim 9 A method of applying solder through holes formed in a circuit board wherein the holes are lined with copper which communicate with copper termination areas formed about the holes on opposite sides of the circuit board, and the board supports terminal pins extending through the holes while leaving gaps between the pins and the copper linings, which comprises: supporting the boards in angular orientation with the terminal pins projecting from the board in an upward direction; flowing a sheet of molten solder from an upper edge of the board and over the upper surface of the board to gravity flow the solder through the gaps between the terminal pins and the copper linings and then onto the copper termination areas on the underside of the board. ### Claim 10 A method of soldering terminal posts to solderable conductors formed on the underside of a circuit board, which comprises: forming holes extending through the circuit board and the conductors; placing terminal posts in said holes, each of said terminal posts being square and having a diagonal dimension which is less than the diameter of the associated hole to provide gaps between the sides of the terminal and the wall of the hole; mounting the board at an incline with conductors beneath the board; flowing a ribbon-like stream of solder down the upper surface of the board for a time sufficient to gravity flow the solder through the gaps and onto the conductors; and then interrupting the flow of the stream over the board to allow the solder to solidify in the gaps and on the conductors.