Cleaning of printed circuit boards by solid and coherent jets of cleaning liquid

Claim 3

A method of cleaning printed circuit boards, as claimed in claim 1, in which, to assure cleaning of the entire bottom surface of each printed circuit board, the printed circuit board is vibrated vertically to be slightly shifted on its support while being impacted by said multiplicity of first and second jets of cleaning liquid.

Claim 4

A method of cleaning printed circuit boards, as claimed in claim 1, in which said printed circuit boards are cleaned in successive stages in each of which the printed circuit boards are supported on perforated supports and subjected to the impact of said multiplicity of first and second high velocity solid and coherent jets of cleaning fluids; in an initial stage, utilizing a cleaning liquid comprising solvents for residues resulting from the fluxing and soldering operations; and, in at least one succeeding stage, utilizing water as the cleaning liquid to wash away any solvent residues.

Claim 5

A method of cleaning printed circuit boards, as claimed in claim 3, in which, in a further stage following the washing with water, the printed circuit boards are subjected to an air drying operation to remove moisture therefrom.

Claim 6

Apparatus for cleaning printed circuit boards having components mounted on their upper surfaces, and which have been fluxed and soldered and have had leads of the components connected to the printed circuitry thereof by fluxing and soldering, said apparatus comprising, in combination, a perforated support receiving each printed circuit board and on which the printed circuit board is held initially solely by gravity; means operable, while a printed circuit board is supported on said support, to direct a multiplicity of closely laterally spaced, high velocity first solid and coherent jets of cleaning liquid, having a substantially continuously uniform small corss-section, perpendicularly against the entire upper surface of the printed circuit board and against the components thereon, to impact the board at high velocity to penetrate the overlying liquid residue, resulting from the fluxing and soldering, on the upper surface of the printed circuit board and to be deflected laterally over the board surface to sweep the liquid off the printed circuit board to clean the upper surface thereof, and to impinge laterally against the components and the component leads to clean the same; and means operable, while the printed circuit board is pressed against the support by said first solid and coherent high velocity liquid jets, to direct a multiplicity of closely laterally spaced, high velocity second solid and coherent jets of cleaning liquid, having a substantially continuously uniform small corss-section, perpendicularly against the entire bottom surface of the printed circuit boards to impact the board at high velocity to penetrate the liquid residue, resulting from the fluxing and soldering, on the bottom surface of the printed circuit board and to be deflected laterally over the board surface to sweep the liquid off the printed circuit board to clean the bottom surface thereof, while the printed circuit board is maintained on said perforated support by the pressure of said first solid and coherent jets; said jets directing means including vertically spaced and substantially parallel upper and lower manifolds; said perforated support comprising an endless screen trained around support rollers to have a substantially horizontal upper run positioned substantially midway between said upper and lower manifolds; said manifolds having substantially planar and substantially rectangular walls facing the upper run of said endless screen and extending substantially parallel thereto; each of said walls being formed with a multiplicity of closely laterally spaced openings each receiving a respective discharge nozzle having its discharge axis extending substantially perpendicular to the plane of the upper run of said perforated screen; and high pressure pump means having an inlet connected to a source of cleaning liquid and an outlet connected to both of said manifolds and supplying cleaning liquid at high pressure to both of said manifolds for discharge through said nozzles in the form of high velocity solid and coherent jets of cleaning liquid impacting against the surface of printed circuit boards supported on the upper run of said endless screen for movement along a path of travel extending between said manifolds; said openings being uniformly spaced in successive rows extending laterally of said endless screen, and successive rows being progressively offset laterally through a small distance relative to the immediately preceding row; whereby substantially every discrete area of the board surfaces is impacted by a jet of cleaning liquid.

Claim 7

Apparatus for cleaning printed circuit boards having components mounted on their upper surfaces, and which have been fluxed and soldered and have had leads of the components connected to the printed circuitry thereof by fluxing and soldering, said apparatus comprising, in combination, a perforated support receiving each printed circuit board and on which the printed circuit board is held initially solely by gravity; means operable, while a printed circuit board is supported on said support, to direct a multiplicity of closely laterally spaced, high velocity first solid and coherent jets of cleaning liquid, having a substantially continuously uniform small corss-section, perpendicularly against the entire upper surface of the printed circuit board and against the components thereon, to impact the board at high velocity to penetrate the overlying liquid residue, resulting from the fluxing and soldering, on the upper surface of the printed circuit board and to be deflected laterally over the board surface to sweep the liquid off the printed circuit board to clean the upper surface thereof, and to impinge laterally against the components and the component leads to clean the same; and means operable, while the printed circuit board is pressed against the support by said first solid and coherent high velocity liquid jets, to direct a multiplicity of closely laterally spaced, high velocity second solid and coherent jets of cleaning liquid, having a substantially continuously uniform small corss-section, perpendicularly against the entire bottom surface of the printed circuit boards to impact the board at high velocity to penetrate the liquid residue, resulting from the fluxing and soldering, on the bottom surface of the printed circuit board and to be deflected laterally over the board surface to sweep the liquid off the printed circuit board to clean the bottom surface thereof, while the printed circuit board is maintained on said perforated support by the pressure of said first solid and coherent jets; said jets directing means including vertically spaced and substantially parallel upper and lower manifolds; said perforated support comprising an endless screen trained around support rollers to have a substantially horizontal upper run positioned substantially midway between said upper and lower manifolds; said manifolds having substantially planar and substantially rectangular walls facing the upper run of said endless screen and extending substantially parallel thereto; each of said walls being formed with a multiplicity of closely laterally spaced openings each receiving a respective discharge nozzle having its discharge axis extending substantially perpendicular to the plane of the upper run of said perforated screen; and high pressure pump means having an inlet connected to a source of cleaning liquid and an outlet connected to both of said manifolds and supplying cleaning liquid at high pressure to both of said manifolds for discharge through said nozzles in the form of high velocity solid and coherent jets of cleaning liquid impacting against the surface of printed circuit boards supported on the upper run of said endless screen for movement along a path of travel extending between said manifolds; said openings being uniformly spaced in successive rows extending laterally of said endless screen, and successive rows being progressively offset laterally through a small distance relative to the immediately preceding row; whereby substantially every discrete area of the board surfaces is impacted by a jet of cleaning liquid.

Claim 8

Apparatus for cleaning printed circuit boards, as claimed in claim 5, in which, considered in the direction of travel of the upper run of said endless screen, said upper manifold is substantially longer than said lower manifold, with said lower manifold being substantially centered longitudinally of said upper manifold; whereby a printed circuit board on said endless screen is initially impacted by the high velocity jets directed thereagainst from the nozzles of said upper manifold before being impacted by the high velocity jets directed thereagainst from the nozzles of said lower manifold, with the printed circuit board being held against said endless screen by the high velocity jets from said upper manifold after having passed out of the range of the high velocity jets from said lower manifold.

Claim 9

Apparatus for cleaning printed circuit boards, as claimed in claim 5, including a substantially closed tank in which said manifolds are mounted, said tank having a pair of end walls formed, respectively, with an inlet opening and an outlet opening for the upper run of said endless screen carrying printed circuit boards; said tank being adapted to contain a quantity of cleaning liquid for communication with the inlet of said pump; means receiving fluxed and soldered printed circuit boards from a fluxing and soldering apparatus and depositing the printed circuit boards on the upper run of said endless screen in advance of said inlet opening; and means receiving the printed circuit boards leaving said outlet opening on said endless screen.

Claim 10

Apparatus for cleaning printed circuit boards, as claimed in claim 7, including eccentric roller means in said tank and engaging the undersurface of the upper run of said endless screen to impart a slight vibratory motion thereto to displace printed circuit boards a slight amount parallel to the upper surface of the upper run of said endless screen; whereby said second solid and coherent jets of cleaning liquid can impact the entire area of the bottom surface of each printed circuit board.

Claim 11

Apparatus for cleaning printed circuit boards, as claimed in claim 7, including means directing a curtain of air across said inlet opening and said outlet opening to inhibit escape of cleaning liquid from said tank.

Claim 12

Apparatus for cleaning printed circuit boards, as claimed in claim 7, including plural successive stages each including one of said tanks and each tank having one of said upper manifolds and one of said lower manifolds mounted therein; the upper run of said endless screen extending through all of said tanks to transport the printed circuit boards successively through each of the stages; the pump in an initial stage supplying a solvent for flux residues to said upper and lower manifolds in said initial stage; the pump in a succeeding stage supplying water to said upper and lower manifolds thereof to wash solvent residue from the printed circuit boards.

Claim 13

Apparatus for cleaning printed circuit boards, as claimed in claim 10, including a further stage having the upper run of said endless screen passing therethrough; the pump of said further stage supplying air under pressure to said upper and lower manifolds to remove moisture from the surfaces of the printed circuit boards.

Claim 14

Apparatus for cleaning printed circuit boards, as claimed in claim 11, including means following said further stage and directing currents of heated air against the printed circuit boards on the upper run of said endless screen to dry the printed circuit boards.