Method for electrochemical cleaning of metal residue on molybdenum masks

Claim 2

An electrochemical method for selective removal of metallic residual stain from a molybdenum mask comprising: (a) providing a molybdenum mask stained by metallic residue; (b) forming an electrolytic cell having: (i) said mask as the anode, (ii) an electrolyte of phosphoric acid and glycerol, (iii) a cathode, and (iv) a power supply; (c) electrochemically cleaning said mask in said electrolytic cell to form a surface film and electrolyte layer on said mask which includes said metallic residual stain; (d) rinsing said mask with water to remove said surface film and electrolyte layer on said mask which includes said metallic residual stain; and (e) drying said mask.

Claim 3

A method as claimed in claim 1 wherein said electrolyte is two parts phosphoric acid and one part glycerol by volume.

Claim 4

A method as claimed in claim 1 wherein the step (c) electrochemically cleaning said mask in said electrolytic cell lasts for at most approximately two minutes.

Claim 5

A method as claimed in claim 1 further comprising neutralizing said mask before the step (d) of rinsing said mask with water.

Claim 6

A method as claimed in claim 4 wherein said neutralizing step includes dripping said mask in a solution of NaOH.

Claim 7

A method as claimed in claim 1 wherein the step (d) of rinsing said mask with water includes directing a jet of distilled water toward said mask.

Claim 8

A method as claimed in claim 1 wherein said cathode is a pair of parallel, stainless steel plates.

Claim 9

A method as claimed in claim 1 wherein the step (c) of electrochemically cleaning said mask in said electrolytic cell is done at a constant voltage of between 5 and 10 volts.

Claim 10

An electrochemical method for selective removal of metallic residual stain from a molybdenum mask comprising: (a) providing a molybdenum mask stained by metallic residue; (b) forming an electrolytic cell having: (i) said mask as the anode, (ii) an electrolyte of two parts phosphoric acid and one part glycerol by volume, (iii) a cathode, and (iv) a power supply; (c) electrochemically cleaning said mask in said electrolytic cell, to form a surface film and electrolyte layer on said mask which includes said metallic residual stain, for at most approximately two minutes; (d) rinsing said mask by directing a jet of distilled water toward said mask to remove said surface film and electrolyte layer on said mask which includes said metallic residual stain; and (e) drying said mask.

Claim 11

An electrochemical method for selective removal of metallic residual stain from a molybdenum mask comprising: (a) providing a molybdenum mask stained by metallic residue; (b) forming an electrolytic cell having: (i) said mask as the anode, (ii) an electrolyte of two parts phosphoric acid and one part glycerol by volume, (iii) a cathode, and (iv) a power supply; (c) electrochemically cleaning said mask in said electrolytic cell, to form a surface film and electrolyte layer on said mask which includes said metallic residual stain, for at most approximately two minutes; (d) rinsing said mask by directing a jet of distilled water toward said mask to remove said surface film and electrolyte layer on said mask which includes said metallic residual stain; and (e) drying said mask.

Claim 12

A method as claimed in claim 9 further comprising neutralizing said mask before the step (d) of rinsing said mask with water.

Claim 13

A method as claimed in claim 10 wherein said neutralizing step includes dripping said mask in a solution of NaOH.

Claim 14

A method as claimed in claim 9 wherein said cathode is a pair of parallel, stainless steel plates.

Claim 15

A method as claimed in claim 9 wherein the step (c) of electrochemically cleaning said mask in said electrolytic cell is done at a constant voltage of between 5 and 10 volts.

Claim 16

A combined chemical and electrochemical method for selective removal of terminal metal stack and metallic residual stain, which comprises Fe, Ni, C, Cr, Cr/Cu, Cu, Au, and PbSn, from a molybdenum mask, said method comprising: (a) providing a molybdenum mask stained by the metallic residue and having terminal metal stack; (b) chemically removing PbSn from said mask; (c) chemically removing Cr, Cu, and Au from said mask; (d) forming an electrolytic cell having: (i) said mask as the anode, (ii) an electrolyte of two parts phosphoric acid and one part glycerol by volume, (iii) a cathode, and (iv) a power supply; (e) electrochemically cleaning said mask in said electrolytic cell, to form a surface film and electrolyte layer on said mask which includes said metallic residual stain, for at most approximately two minutes; (f) rinsing said mask by directing a jet of distilled water toward said mask to remove said surface film and electrolyte layer on said mask which includes said metallic residual stain; (g) applying Freon to said mask; and (h) drying said mask.

Claim 17

A combined chemical and electrochemical method for selective removal of terminal metal stack and metallic residual stain, which comprises Fe, Ni, C, Cr, Cr/Cu, Cu, Au, and PbSn, from a molybdenum mask, said method comprising: (a) providing a molybdenum mask stained by the metallic residue and having terminal metal stack; (b) chemically removing PbSn from said mask; (c) chemically removing Cr, Cu, and Au from said mask; (d) forming an electrolytic cell having: (i) said mask as the anode, (ii) an electrolyte of two parts phosphoric acid and one part glycerol by volume, (iii) a cathode, and (iv) a power supply; (e) electrochemically cleaning said mask in said electrolytic cell, to form a surface film and electrolyte layer on said mask which includes said metallic residual stain, for at most approximately two minutes; (f) rinsing said mask by directing a jet of distilled water toward said mask to remove said surface film and electrolyte layer on said mask which includes said metallic residual stain; (g) applying Freon to said mask; and (h) drying said mask.

Claim 18

A method as claimed in claim 14 further comprising rinsing said mask with water after the steps (a) and (b).

Claim 19

A method as claimed in claim 14 further comprising neutralizing said mask after the step (e) of electrochemically cleaning said mask.

Claim 20

A method as claimed in claim 16 wherein said neutralizing step includes dipping said mask in a solution of NaOH.

Claim 21

A method as claimed in claim 14 wherein the step (b) of chemically removing PbSn uses a solder stripper.

Claim 22

A method as claimed in claim 14 wherein the step (c) of chemically removing Cr, Cu, and Au is done by undercut using HCl.