Abstract: A printed wiring board has a non-conducting substrate with first and second major outboard surfaces; printed electrical conductors over at least the first major outboard surface; and an electrically insulating coating selectively disposed over the printed electrical conductors such that the coating forms an outermost layer over the first major outboard surface. In various embodiments, the coating is screen printed dielectric carbon ink which is also disposed over keypads on the second major outboard surface. There is no need for a soldermask layer as the keypads and electrical conductors are protected by the carbon ink from oxidation due to humidity and from shorting against other components. A method for making the PWB is also detailed.

Abstract: A printed wiring board has a non-conducting substrate with first and second major outboard surfaces; printed electrical conductors over at least the first major outboard surface; and an electrically insulating coating selectively disposed an over the printed electrical conductors such that the coating forms an outermost layer over the first major outboard surface. In various embodiments, the coating is screen printed dielectric carbon ink which is also disposed over keypads on the second major outboard surface. There is no need for a soldermask layer as the keypads and electrical conductors are protected by the carbon ink from oxidation due to humidity and from shorting against other components. A method for making the PWB is also detailed.