Abstract: An improved and simplified process of forming a flexible circuit board for ink jetting is disclosed. The method includes the steps of: providing a substrate, wherein the substrate comprises a first surface and a second surface opposite to the first surface and the first surface is for forming conductive traces; and burning the substrate, by using laser-ablation, to form a plurality of contact holes which expose the conductive traces. The above-mentioned method further comprises the steps of sputtering a copper film on the first surface of the substrate; forming a photo-resistor layer over the copper film, wherein a pattern of the photo-resistor layer is complementary to the conductive traces and a portion of the copper film is exposed; plating a copper layer over the exposed portion of the copper film as the conductive traces; removing the photo-resistor layer; and burning the insulation tape to form the contact holes, using laser-ablation.

Abstract: A pressure-compensation device for ink reservoirs includes an accumulator bag, a resilient element and an air-compensation means. The accumulator bag is installed inside the ink reservoir and provides a duct for air communicating with the atmosphere. While the ink inside the ink reservoir is running off, external air can be led automatically through the duct to inflate the accumulator bag. The resilient element has a lower end to engage with a bottom end of the accumulator bag for stabilizing a back pressure inside the ink reservoir by acting contraction against the inflating of the accumulator bag. While the accumulator bag is expanded to a saturated state, the air-compensation means can introduce automatically external air into the ink reservoir for maintaining the back pressure and thus for avoiding any ink leakage and stalling of the print head.