An electronic device having a printed circuit board is provided. In one embodiment, the printed circuit board includes a plurality of external pads to be coupled with an external device and a plurality of bypass pads for testing an electric circuit. The external pads are exposed and at least one of the plurality of bypass pads are not exposed from an outer surface of the PCB. A system using the electronic device and a method of testing an electronic device are also provided.

A flexible circuit board having a flexible graphite substrate is provided. The flexible circuit board includes a dielectric layer formed on the surface of the flexible graphite substrate and an electrically conductive layer formed on the surface of the dielectric. Electronic components are mounted to the flexible circuit board to form a circuit arrangement. A thermally conductive conduit can be disposed in thermal and physical contact with a surface of the electronic component and the surface of the flexible graphite substrate to. The high in-plane thermal conductivity graphite substrate provides enhanced heat transfer capability to effectively move of heat away from the electronic components for improved cooling of the heat generating electronic component and surrounding devices.

A display device is provided. The display device includes a light engine having light emitting components mounted to a flexible circuit board having a flexible graphite substrate. The flexible circuit board includes a dielectric layer formed on the surface of the flexible graphite substrate and an electrically conductive layer formed on the surface of the dielectric. The high in-plane thermal conductivity graphite substrate provides enhanced heat transfer capability to effectively move of heat away from the light emitting components for improved cooling of the heat generated by the light emitting component and surrounding devices.

Applying a solderable surface to conductive ink may include partially curing a conductive ink trace; applying, to the partially cured conductive ink trace, a conductive paste comprising conductive particles; and curing the partially cured conductive ink trace and the conductive paste.