Filter for purifying hydrogen and method for manufacture thereof

A hydrogen-purification membrane fabrication process, comprising:

• a resist-formation step of forming a resist pattern having a plurality of openings on a front surface of an electrically conductive support substrate, and forming on a back surface of said support substrate a resist pattern having a plurality of openings in alignment with the openings in the first resist pattern,
• an etching step of etching said support substrate from front and back sides thereof using said resist patterns as masks to make a porous support substrate having a plurality of pores, wherein each pore has a narrowest portion therein;
• 1.0≦D1/T≦5.0 and 1.0≦D2/T≦5.0 are satisfied with respect to relations of an opening diameter D1 of the pore on a front surface side and an opening diameter D2 of the pore on a back surface side to a thickness T of said support substrate;
• D3/D1<0.8, D3/D2<0.9 and D3<250 μm are satisfied with respect to relations of an opening diameter D3 of said narrowest portion to said opening diameters D1 and D2;
• and a total area of the openings on the front surface side accounts for 20 to 80% of an area of said porous support substrate,
• a filling step of applying an insulating film onto the back surface side of said support substrate, and forming a plating layer on said porous support substrate from the front surface side thereof by electrolytic plating in such a way as to fill in said pores,
• a film-formation step of removing said insulating film, polishing said plating layer in such a way as to expose the front surface of said porous support substrate, and forming a Pd alloy film on the thus polished surface side by plating, and
• a removal step of removing said plating layer and said electrically conductive undercoat layer from the back surface side of said porous support substrate by means of selective etching.

A hydrogen-purification membrane fabrication process, comprising:

• a resist-formation step of forming a resist pattern having a plurality of openings on a front surface of an electrically conductive support substrate, and forming on a back surface of said support substrate a resist pattern having a plurality of smaller openings in alignment with the openings in the first resist pattern and with a smaller area than that of the first openings or having no such smaller openings,
• an etching step of etching said support substrate from the front and back surfaces or the front surface thereof using said resist patterns as masks to make a porous support substrate having a plurality of pores wherein 1.5≦D1/T≦5.0 and 0.2≦D2/D1≦0.8 are satisfied with respect to relations of an opening diameter D1 on the front surface side and an opening diameter D2 on the back surface side to a thickness T of said support substrate;
• and a total area of the openings on the front surface side accounts for 20 to 80% of an area of said porous support substrate,
• a filling step of applying an insulating film onto the back surface side of said support substrate, and forming a plating layer on said porous support substrate from the front surface side thereof by electrolytic plating in such a way as to fill in said pores,
• a film-formation step of removing said insulating film, polishing said plating layer in such a way as to expose the front surface of said porous support substrate, and forming a Pd alloy film on the thus polished surface side by plating, and
• a removal step of removing said plating layer and said electrically conductive undercoat layer from the back surface side of said porous support substrate by means of selective etching.