The essence of the solution, which is now subject to industrial property rights (patent), is a method for plating the inner wall of holes (with a diameter of 2 mm to 0.1 mm) made of ceramics, glass or plastic. The solution is distinguished by attaching a nozzle, connected to an air pressure regulator - from vacuum to overpressure, to the upper end of the hole. The lower end of the hole is submerged in a liquid with an electrically conductive component, e.g. silver flakes. At first, negative pressure causes the liquid to be sucked into the hole and then overpressure pushes the liquid from the hole back to the reservoir. Thus a thin layer of liquid adheres to the walls of the hole. This process produces, after suitable drying and/or firing, an electrically conductive layer on the inner surface of the hole.
By continuously refining the parameters of the products of microwave technology, the problem arises of ever smaller shape details which must be production-controlled. In the case of ceramic parts containing small holes with internal plating (e.g. coaxial resonators and filters), currently used technologies enable the use of ink containing silver on the inner surface of holes that are 1mm in diameter and larger. The technique of spraying with conductive ink and subsequently firing at 550°C is used.
