Method of forming contacts through bores in multi-layer circuit boards

Abstract

A method and apparatus for creating through-connections in holes (5) in multi-layer printed circuit boards (2), in which the circuit board (2) is laid on a supporting frame (3) which leaves the area beneath the holes (5) free, and conductive paste (10) is injected by a dispensing apparatus (8, 9) into the holes (5) in the circuit board (2) with the formation of marginal overlaps (12), such that a protruding, outwardly spreading plug (11) of conductive paste is formed. In accordance with the method, a cartridge needle (8) of the dispensing apparatus (8, 9) is placed against the circuit board (2) at the location of each hole (5) that is to be provided with a through-connection, and solderable conductive paste (10) is dispensed into the hole (5), after which the cartridge needle (8) is removed. A vacuum probe (9) of the dispensing apparatus (8, 9) then is placed against the circuit board (2) at the location of the hole (5), and the conductive paste (10) is partially sucked up, such that the conductive paste (10) forms contacting marginal overlaps (12, 13) around each hole (5) on both sides of the circuit board (2) and a continuous layer of conductive paste (10) remains on inside walls of the holes (5) leaving the holes with a defined minimum hole diameter.

Dependencies are inferred from the claim text.