Abstract: A composition that enhances the acid resistance of copper oxide. The composition includes a solution of an alkali metal borohydride and a quaternary ammonium ion in amounts selected such that when the composition is applied to copper oxide, the composition enhances the acid resistance of the copper oxide. The preferred alkali metal borohydride is sodium borohydride or potassium borohydride, and the preferred quaternary ammonium ion has the formula ##STR1## wherein each R1, R2, R3, R4 independently comprises a lower alkyl, hydroxylalkyl or carboxyalkyl group.

Abstract: A composition that includes an aqueous solution of nitric acid and an additive having the formula ##STR1## or a salt thereof, in an amount sufficient to improve the oxidative stability of the aqueous nitric acid solution relative to the oxidative stability of that aqueous solution in the absence of the additive.

Abstract: A process for treating an aqueous alkaline spent mixture produced during preparation of circuit boards and comprising a photopolymer resin. According to the method, first, an acid, a polyvalent cation and a coagulation aid are mixed with the spent mixture to produce a heterogeneous treated mixture comprising coagulated, precipitated photopolymer resin and an aqueous phase. Then, the coagulated, precipitated photopolymer resin is separated from the aqueous phase to produce a non-tacky, non-gumlike photopolymer resin sludge.

Abstract: A composition of matter comprising sulfuric acid and guanidine, aminoguanidine, or formylated aminoguanidine. The composition is useful in the preparation of sulfuric acid/hydrogen peroxide etching solutions and in methods for etching copper, most particularly in the manufacture of printed circuits.

Abstract: Improved metal dissolution rates are obtained when using a solution containing sulfuric acid, hydrogen peroxide and a catalytic amount of a glycol ether such as diethylene glycol butyl ether or ethylene glycol butyl ether.

Abstract: Improved metal dissolution rates are obtained when using a solution containing sulfuric acid, hydrogen peroxide and a catalytic amount of .epsilon.-caprolactam.

Abstract: Improved metal dissolution rates are obtained when using a solution containing sulfuric acid, hydrogen peroxide and a catalytic amount of pyrrolidone such as 2-pyrrolidone or N-methyl-2-pyrrolidone.

Abstract: Improved metal dissolution rates are obtained when using a solution containing sulfuric acid, hydrogen peroxide and a catalytic amount of a lactone such as .gamma.-butyrolactone, .epsilon.-caprolactone or .gamma.valerolactone.

Abstract: Improved metal dissolution rates are obtained when using a solution containing sulfuric acid, hydrogen peroxide and a catalytic amount of a furan derivative such as tetrahydrofurfuryl alcohol or tetrahydrofuran.