Abstract: In a printed circuit board manufacturing process, a resist stripping solution blending organic amines with water is used for stripping the photoresist completely from the board. An apparatus for controlling this resist stripping solution comprises a toroidal conductivity controller for measuring the solution conductivity, which correlates to solution concentration. This same apparatus is equipped with a resist stripping solution discharge device for discharging the resist stripping solution and water replenishing device for replenishing water by detecting the liquid level of the resist stripping solution by a liquid level gauge. As the water is replenished, the solution conductivity is lowered; thereby activating the toroidal conductivity controller to add concentrated resist stripping chemistry proportionally to the deviation from the conductivity controller set point. This same apparatus is equipped with a measuring device for measuring the total consumed organic amine reactants.

Abstract: An electronic device has a dielectric substrate with first and second surface and a via through the substrate connecting the first and second surfaces. A first and second sacrificial copper structure surrounds the via on the first and second surfaces, respectively, wherein each of the sacrificial structures covers an area of less than three times the horizontal cross sectional area of the via. Contemplated sacrificial structures are preferably formed in a photolithographic process.