GB1249972A - Improvements in or relating to fluidics devices - Google Patents

Abstract

1,249,972. Electro-forming. PLESSEY CO. Ltd. Aug.28, 1968 [Sept. 22, 1967], No.43258/67. Headings C7B and C7F. A fluidics device, comprising a body enclosing a shaped flow-conducting cavity with at least one input passage, an output passage and at least one further conduit penetrating the surface of the body and communicating with the cavity, suitable for use at elevated temperatures is produced by deposition of a suitable metal on a thin smooth electro-conductive layer which itself has been produced non-electrically on the surface of a core formed of plastics or wax-like material. Preferably the smooth conductive layer is of electroless Cu or Ni and the walls of the body e.g. of Ni are deposited by electro-plating. Typically a thin layer of electroless Ni is deposited on a core of wax, ABS plastics or epoxy resin, a further layer of Ni is electro-deposited over it from a sulphamate bath and the resultant nickel body is separated from the surface of the core and thereafter heated to 400‹ C. to harden the electroless nickel. If instead the core is rendered conductive with an electroless Cu deposit this is dissolved away e.g. with nitric acid after separation of the nickel body from the core. Instead of electroless coating with metal the core may be sprayed with metal. In a modification the device is made in two stages. First a core structure representing the cavity and passages of the device integral with a backing plate is electroless coated and electroplated on the passage defining surfaces and the adjacent portions of the backing plate, the core and plate are removed leaving a body in which the passages are open at the plane of the backing plate. The passages in this body are then filled with wax to the level of this plane and metal is then deposited as before to form a closure surface and the wax is melted out. Instead of using an electroless deposit, the filling of the passages may be effected with a mixture of 95% Al and 5% wax, the surface being smoothed with abrasive paper.