A method of constructing an inflatable electrode assembly configured for irrigation, comprises: providing a flex circuit having a substrate with a pre-formed aperture, the substrate constructed of a material having a greater heat resistance or a first melting temperature； providing a balloon member with a membrane, the membrane constructed of a material having a lesser heat resistance or a second melting temperature lower than the first melting temperature of the substrate； affixing the substrate to the membrane wherein a surrounding portion of the substrate around the pre-formed aperture masks a surrounding portion of the membrane so as to expose a target portion of the membrane； and applying heat to the target portion of the membrane through the pre-formed aperture of the substrate, wherein the heat applied, without melting the substrate, melts the target portion of the membrane in forming an aperture in the membrane.
