a circuit pattern on a circuit board , as used in telecommunications systems and other electrical apparatus , often has contact positions for switches , such as pushbutton switches , and for other purposes . the normal copper circuit pattern is covered at the contact positions to give improved contact conditions . carbon ink has been proposed by obtaining the necessary high level of alignment of carbon ink with the copper pattern at contact positions is difficult as such contact positions have very close members . the invention proposes contact positions having closely spaced inter - digital contact members , in which the circuit pattern extends to and stops at the peripheral region of a contact position , the contact members being of carbon ink and overlapping conductors of the circuit pattern at the peripheral region .