GB1132794A - Improvements in or relating to the manufacture of film-type resistors - Google Patents

Abstract

1,132,794. Rotary presses; special inks. MATSUSHITA ELECTRIC INDUSTRIAL CO. Ltd. 4 April, 1967, No. 15407/67. Headings B6B and B6C. [Also in Division H1] A method of manufacturing film-type resistors on flat phenolic resin laminate sheets comprises passing said sheets through a rotary offset printing press using conductive ink. A suitable ink comprises carbon powder, graphite powder and/or a metallic powder as the resistance material and an organic binding agent such as a phenolic resin or an epoxy resin in an appropriate volatile solvent such as benzyl alcohol, tetraline or triethyleneglycol. Another appropriate ink is a vitreous enamel resistor ink comprising a silver or palladium powder together with a glass frit and an organic binding agent in a volatile solvent. A further example of ink comprises an organic binder and an organo-metallic compound such as nickel formate or nickel oxalate either of which is converted into a nickel film when suitably heated.. The rotary press 4 shown, comprises printing, offset and impression cylinders 19, 18, 20 respectively, and a forme roller 11 inked by an automatically controlled motor driven inking train 12, 13. The press is fed by a feed device 2 through a registration device 3. The wet freshly printed sheets are passed through a surface treatment device 3 comprising a pair of pressure rollers. Subsequently the sheets are passed through an infra-red heated oven 8 on pallets placed on a conveyer 7. The electrical resistance of the finished resistors is then measured in an inspection device 14 which is electrically connected to an automatic resistance controller 16. The latter is connected to adjust a variable reduction gear 23 through which an electric motor 22 drives the inking train 12, 13. When any deviation of the value of the resistors from their predetermined value is detected by the device 14 an electric signal from the controller 16 adjusts the gear 23 to produce an appropriate change in the rate of ink feed. Sheet feed.-The feed device 2 comprises two sheet feed stacks 50, one on each side of a belt conveyer 54. A carrier 55 is positioned above each stack 50 and may be moved by a pneumatic cylinder 62 between a position above the stack to a position above the conveyer 54. Each carrier 55 has two vertically movable suction nozzles 64, the movement of the latter being effected by a pneumatic cylinder 66. Automatically actuated valve means control the pneumatic cylinders to effect the transport of a sheet from a stack 50 to the belt 54. The removal of successive sheets from the top of a stack lowers the top level. Through detector means a screw 70 is automatically actuated to raise the stack until it is exhausted. When exhausted further detector means automatically ensure feed from the other stack 50 and lowering of the exhausted stack for sheet replenishment.