| abstract |
THIS INVENTION IS FOR A SOLUTION FOR ETCHING CUPREOUS METALS COMPRISING A SOURCE OF CUPRIC IONS, AT LEAST ONT COMPLEXING AGENT FOR CUPRIC IONS WHICH AGENT IS CAPABLE OF FORMING A SOLUTION SOLUBLE COPPER (II) COMPLEX AT SOLUTION PH, A SOURCE OF BROMIDE OR CHLORIDE IONS AND A SOLUTION SOLUBLE MOLYBDENUM, TUNGSTEN OR VANADIUM COMPOUND. CUPRIC ETCHING SOLUTIONS HAVE BEEN FOUND TO ATTACK TIN AND TIN-LEAD SOLDER PLATE SUCH AS THAT USED IN THE FABRICATION OF PRINTED CIRCUIT BOARDS. THE ADDITION OF A MOLYBDENUM, TUNGSTEN, OR VANADIUM COMPOUND TO THE ETCHING SOLUTION RETARDS OR ELIMINATES SUCH ATTACK. |