Abstract: A production method of a wired circuit board that can prevent corrosion of a first thin metal film inwardly of a conductor layer, which is due to the forming of an undercut portion caused by a skirt portion of a plating resist, to prevent the peeling of a wiring circuit pattern. An insulating base layer 1 is prepared, first, and, then, a first thin metal film 2 is formed on the insulating base layer 1. Then, a plating resist 3 is formed in a reversal pattern to a wiring circuit pattern 4 on the first thin metal film 2, and a conductor layer 6 is formed in the wiring circuit pattern 4 on the first thin metal film 2 exposed form the plating resist 3. Thereafter, the plating resist 3 is removed and, then, a second thin metal film 8 is formed on the conductor layer 6 and first thin metal film 2. Thereafter, the second thin metal film 8 is removed. Then, all portions of the first thin metal layer 2, except portions thereof where the conductor layer 6 is formed, are removed.

Abstract: An inexpensive, high-performance pH sensor measure the surface of a solid substance in a simple manner, comprising an ion sensing part 2 which responds to pH, a reference electrode 3, a gel-form ion permeable substance 10, which has a predetermined pH value and covers the ion sensing part 2 and reference electrode 3, and a cover member 9, which houses the ion permeable substance 10 and has an opening 9a formed at a position near the abovementioned ion sensing part 2.

Abstract: An inexpensive, high-performance pH sensor measure the surface of a solid substance in a simple manner, comprising an ion sensing part 2 which responds to pH, a reference electrode 3, a gel-form ion permeable substance 10, which has a predetermined pH value and covers the ion sensing part 2 and reference electrode 3, and a cover member 9, which houses the ion permeable substance 10 and has an opening 9a formed at a position near the abovementioned ion sensing part 2.

Abstract: After a flexible printed circuit is left under an atmosphere of a water vapor pressure of not lower than 30 mmHg so as to absorb moisture, a voltage is applied between two wiring portions to thereby measure an insulation resistance value between the wiring portions during the voltage application. The quantity &Dgr;log(R) of the change of the insulation resistance value at regular intervals is obtained. An examination is made as to whether the maximum of the quantity &Dgr;log(R) of the change of the insulation resistance value is not larger than a predetermined reference value or not. From this examination, a judgment is made as to whether the flexible printed circuit is good or not.