The report that based on physical property data, x-ray evidence, and behavior on annealing, pyrophosphate deposits produced without organic addition agents have a large grain size. For deposits produced in baths containing organic additives. With increasing concentrations of brighteners, a superimposed lamellar structure is obtained. Extremely fine grained brittle copper (200-1000 A grain size, elongation 0.5 % or less, and hardness greater than 190 KHN50) which may result from improper bath operation can be identified metallographically by etching the plated sample in an ammonium hydroxide solution.
Copper pyrophosphate deposits show tensile strength variations from 27 to 70 kg/mm2, yield strengths from 14 to 36 kg/mm2, hardness from 83 to 250 kg/mm2, and elongations from 1 to 39 %. Several investigators have related these variables to solutions content and operating conditions. Some property data are included on effects of proprietary additives. Strength and ductility became less with amounts of one proprietary additive, while strength and ductility increased with use of another proprietary. Concentration of up to 1 g/l of 2.5 dimercapto-1,3,4 thiadiazole in fresh solutions lowered strength and hardness and increased elongation. Concentrations greater than 1 g/l restored values to those shown for the original solution.
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