US 4,589,926 AGranted

Method and compact machine for treating printed circuit cards

AssigneeAB Holmstrands Platindustri

InventorRune H. Holmstrand

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Abstract

In order to remove impurities from one surface of printed circuit cards which have been subjected in a seperate step to a soldering operation using fluxing agent the invention suggests a method and compact machine for treating the cards. The method comprises the steps of feeding the printed circuit cards through the machine along a horizontal track and carrying out the treatment in a treating chamber having a plurality of successive treating zones comprising a washing and brushing zone for removing impurities from the lower surface of the printed circuit cards by the action of brushes and liquid solvent, and a subsequent drying zone in which the printed circuit cards are subjected to a hot air flow to remove solvent therefrom, and returning solvent used in the treating chamber to a distiller means mounted in the machine for vaporization and condensation of said solvent in order to obtain pure solvent which is supplied to said washing and brushing zone in a closed cycle.

Claims12

Dependent claims

A method of dispensing printed circuit cards in a compact machine for removing impurities from a surface of the printed cards subjected in a separate step to a soldering operation using a fluxing agent, said machine having an inlet and an outlet end section and an intermediate section having upper and lower, separated from one another, spaces, the upper of which defines a treating chamber having a plurality of successive treating zones comprising at least a washing and brushing zone, for removing impurities from the lower surface of the printed circuit cards by the action of brushes and cold solvent, and a subsequent drying zone in which the printed circuit cards are subjected to hot air flow for removing solvent therefrom, said method comprising feeding the cards through the machine sections along a horizontal transport track from the machine inlet end section to and through the machine outlet end section, providing a first closed loop within said intermediate and outlet sections for recycling solvent used in the treating chamber and containing impurities removed from the cards and collected in a trough means in the upper space of the intermediate section, said solvent with impurities therein being passed from an upstream end of the trough means to distiller means in the outlet end section of the machine for vaporizing and condensing the vaporized solvent, condensed cold solvent, substantially free of impurities, being returned to the downstream side of the trough means in the treating chamber;

providing a second closed loop path in the intermediate section for said hot air flow for removing solvent from solvent wetted cards as they pass along said track through said intermediate section, said second path including a cooling means and blower means in the upper space of the intermediate section and an air compressor in the lower space thereof, solvent contained in the air being condensed in the cooling means and passed to said distiller means while the air freed of solvent is fed to said air compressor to heat the air between 0.degree.-10.degree. C. above the boiling point of the solvent, and supplying the thus heated air to said blower means for discharge unto the solvent wetted cards;
and providing a third closed loop for distilling solvent and comprising said distiller means including a heat exchanger in a solvent tank in a lower space of the outlet end section for vaporizing solvent therein and a cooler in an upper space of the outlet end section for condensing the vaporized solvent.

A compact machine for cleansing printed circuit cards to remove impurities from one surface of said cards which have been subjected in a separate step to a soldering operation using fluxing agents, comprising an inlet and an outlet end section and an intermediate section therebetween and having upper and lower, separated from one another, spaces, the upper of which defines a treating chamber having a plurality of successive treating zones comprising at least a washing and brushing zone for removing impurities from the cards, and a drying zone wherein the cards are subjected to hot air flow, a horizontal transport track extending through said machine sections, a first means in the intermediate and outlet end sections of the machine for recycling solvent and comprising distiller means for vaporizing solvent and for condensing the solvent thus vaporized and including trough means in the treating chamber, said trough means having an upstream and a downstream end, solvent with impurities therein in the upstream end of the trough means supplied to the distiller means for vaporization and condensation, cold condensed vaporized solvent being supplied to the downstream end of the trough means;

second means in the intermediate section of the machine for circulating hot air in a closed loop and comprising a cooling means, blower means and an air compressor, said second means being effective to separate solvent in the air from the air by said cooling means, the separated solvent being supplied to said distiller means, the air stripped of the solvent being heated by said air compressor and supplied to said blower means for blowing said heated air onto solvent wetted cards as they move along said track;
and third means, including said distiller means comprising heating means in a solvent tank and a cooler, for supplying heat values to the heating means produced on cooling solvent to liquid form and including for this purpose a solvent compressor at the inlet section of the machine.

Dependencies are inferred from the claim text.