Automatic process of etching copper circuits with an aqueous ammoniacal solution containing a salt of a chloroxy acid

Claim 1

A METHOD FOR THE SELECTIVE AND CONTINOUS DISSOLUTION OF COPPER COMPRISING A. PROVIDING AN ETCHANT SOLUTION CONSISTING ESSENTIALLY OF WATER, FROM ABOUT 0.001 TO 0.1 MOLE/LITER OF AN ALKALI METAL OR AMMONIUM SALT OF A CHLOROXY ACID, FROM ABOUT 0.4 MOLE/LITER TO LIMIT OF SOLUBILITY OF CUPRIC AMINE CHLORIDE, AN AMMONIUM SALT BUFFER AND SUFFICIENT AMMONIA TO PRODUCE A PH RANGE OF ABOUT 8-12; B. CONTACTING A COPPER COATED SUBSTRATE WITH SAID ETCHANT SOLUTION FOR A PERIOD SUFFICIENT TO DISSOLVE THE DESIRED AMOUNT OF COPPER THEREFROM; C. CONTROLLING THE PH OF THE ETCHANT BY FEEDING THE SINGNAL FROM A PAIR OF ELECYRODES IMMERSED IN THE ETCHANT SOLUTION TO A PH METER, THE OUTPUT OF WHICH IS CONNECTED TO A VOLTAGE SENSITIVE RELAY WHICH TURNS ON A PUMP OR A VALVE WHEN THE PH FALLS BELOW A PREDETERMINED SET POINT WITHIN THE PH RANGE THEREBY INTRODUCING AMMONIA INTO THE ETCHANT UNTIL THE PH EXCEEDS THE PREDETERMINED SET POINT AT WHICH POINT THE RELAY TURNS OFF THE PUMP OR VALVE; D. CONTROLLING THE CHLOROXY ACID SALT CONCENTRATION, BY FEEDING THE EMF SINGNAL DEVELOPED BETWEEN A PLATINUM AND A REFERENCE ELECTRODE IN THE ETCHANT SOLUTION TO A VOLTAGE SENSITIVE RELAY WHICH TURNS ON A PUMP OR VALVE WHEN THE EMF FALLS BELOW A PREDETERMINED SET POINT WITHIN THE RANGE OF 50-250 MILLIVOLTS THEREBY INTRODUCING CHLOROXY ACID SALT SOLUTION INTO THE ETCHANT UNTIL THE EMF EXCEEDS THE PREDETERMINED SET POINT AT WHICH TIME THE RELAY TURNS OFF THE PUMP OR VALVE THEREBY MAINTAINING THE ETCHANT IN AN OXIDIZING CONDITION AND THE LEVEL OF CHLOROXY ACID SALT NOT EXCEEDING ABOUT 0.1 MOLES PER LITER; E. RETAINING THE WORKPIECE IN THE ETCHANT UNTIL THE COPPER HAS BEEN ETCHED OUT; AND F. REMOVING THE ETCHED WORKPIECE FROM THE ETCHING SOLUTION.

Claim 2

A METHOD FOR THE SELECTIVE AND CONTINOUS DISSOLUTION OF COPPER COMPRISING A. PROVIDING AN ETCHANT SOLUTION CONSISTING ESSENTIALLY OF WATER, FROM ABOUT 0.001 TO 0.1 MOLE/LITER OF AN ALKALI METAL OR AMMONIUM SALT OF A CHLOROXY ACID, FROM ABOUT 0.4 MOLE/LITER TO LIMIT OF SOLUBILITY OF CUPRIC AMINE CHLORIDE, AN AMMONIUM SALT BUFFER AND SUFFICIENT AMMONIA TO PRODUCE A PH RANGE OF ABOUT 8-12; B. CONTACTING A COPPER COATED SUBSTRATE WITH SAID ETCHANT SOLUTION FOR A PERIOD SUFFICIENT TO DISSOLVE THE DESIRED AMOUNT OF COPPER THEREFROM; C. CONTROLLING THE PH OF THE ETCHANT BY FEEDING THE SINGNAL FROM A PAIR OF ELECYRODES IMMERSED IN THE ETCHANT SOLUTION TO A PH METER, THE OUTPUT OF WHICH IS CONNECTED TO A VOLTAGE SENSITIVE RELAY WHICH TURNS ON A PUMP OR A VALVE WHEN THE PH FALLS BELOW A PREDETERMINED SET POINT WITHIN THE PH RANGE THEREBY INTRODUCING AMMONIA INTO THE ETCHANT UNTIL THE PH EXCEEDS THE PREDETERMINED SET POINT AT WHICH POINT THE RELAY TURNS OFF THE PUMP OR VALVE; D. CONTROLLING THE CHLOROXY ACID SALT CONCENTRATION, BY FEEDING THE EMF SINGNAL DEVELOPED BETWEEN A PLATINUM AND A REFERENCE ELECTRODE IN THE ETCHANT SOLUTION TO A VOLTAGE SENSITIVE RELAY WHICH TURNS ON A PUMP OR VALVE WHEN THE EMF FALLS BELOW A PREDETERMINED SET POINT WITHIN THE RANGE OF 50-250 MILLIVOLTS THEREBY INTRODUCING CHLOROXY ACID SALT SOLUTION INTO THE ETCHANT UNTIL THE EMF EXCEEDS THE PREDETERMINED SET POINT AT WHICH TIME THE RELAY TURNS OFF THE PUMP OR VALVE THEREBY MAINTAINING THE ETCHANT IN AN OXIDIZING CONDITION AND THE LEVEL OF CHLOROXY ACID SALT NOT EXCEEDING ABOUT 0.1 MOLES PER LITER; E. RETAINING THE WORKPIECE IN THE ETCHANT UNTIL THE COPPER HAS BEEN ETCHED OUT; AND F. REMOVING THE ETCHED WORKPIECE FROM THE ETCHING SOLUTION.