Fuel cells have the potential of providing energy storage densities several times than those possible using current state-of-the-art lithium-ion batteries. Thus, small fuel cells seem to be suitable to mobile applications such as next generation cellular phone that more energy storage is required than at present. To apply small fuel cell to cellular phone, compact volume and quiet operation is necessary. For quiet operation, air supply pump shouldn’t be used because a repulsive air supply makes a noise inevitably. Air is supplied to cathode by air free convection and stack volume need to be minimized. The common graphite bipolar plate has a limit to miniaturize the stack size due to graphite's brittleness. Therefore, in this paper, the current collector is about 180um thickness flexible printed circuit board, which has an Au coating of 80um thickness on polyimide membrane of 100um thickness. Two end plates are made from light aluminum alloy plate with anode flow channel as well as with cathode open holes and their surfaces are wholly oxidized for electrical insulation. The cathode hole opening rate is around 70% that determined through experiment results of various opening rates. The performance is measured at room temperature, atmospheric pressure condition without any repulsive air supply. The MEA’s active area is 10.08cm2 of six 1.68cm2 unit-cells and peak power density is around 290mW/cm2 at 3.6V. Therefore, the air breathing planar stack of 3W is achieved successfully as a small size of 18ml and high volumetric power density of 160W/L.