In a number of industrial applications thin metal plates with very fine holes are needed. For example, orifice plates, also known as nozzle plates, are used in the ink-jet printing industry. These plates consist of thin sheets of metal with a pattern holes of typically circular cross sections 1 to 2 mils in diameter. For high resolution printing, these holes must be closely spaced. For example, an orifice plate might be six inches long by one-half inch wide and have along its center a five inch long array of circular holes each of which are 1 to 2 mils in diameter and which are spaced 4 to 5 mils apart from center to center.
A preferred method for making such plates is to use electroformed nickel. The electroform process can produce the hole cross sections found to be helpful in the formation of ink droplets, and nickel is compatible with corrosive inks sometimes used for ink-jet printing.
Because of the small sizes and the close spacing of the holes, however, the mounting and support of orifice plates is critical. Orifice plates are typically electroformed to a thickness of about 1 mil. Because of this thickness the thin plate must be supported very close to the holes. One manner is through use of a bi-metal process. For example, a thin nickel orifice plate is electroformed onto a stainless steel plate of several mils thickness. Stainless steel is then chemically etched away from the area directly behind the holes, leaving the nickel orifice plate closely supported by the attached stainless steel plate. The problem with this process, however, is that it is very difficult to etch away the stainless steel in a manner which leaves proper support between adjacent holes. The structure therefore is very weak in the immediate area of the holes.