Cleaning agent complete removal

Hydrochloric acid/thiourea [thiocarbamide, CS(NH2)2], The procedure for cleaning iron oxides containing copper and copper oxides is the same as for cleaning iron oxides alone. A typical formulation is 5% HC1 with 2% thiourea, plus corrosion inhibitor, wetting agent, and antifoam. A complete removal of copper is required because the passivation process otherwise will not be effective. 

The techniques are limited to reactions which effect the removal of impurities as volatile products and are probably best used in conjunction with other techniques. It is sometimes necessary to exercise great care e.g. in oxidation reactions to prevent complete reaction of the cleaning agent with the surface being studied. 

By adding a degreasing agent to the blasting slurry, any oil and grease on the metal part s surface is completely removed thus providing a clean component for presentation to the phosphating section. 

The visual inspection for residues, the ionic contamination measurement test, as well as the quantitative color-reaction test exhibited very satisfactory results on most solvent-and water-based cleaned substrates. Slight levels of remaining residues were detected with less than 5% of the total number of substrates cleaned. The latter were removed completely through a minor adjustment of the previously used process parameters. Testing performed with surfactant-based cleaning agents did provide unsatisfactory cleaning results (Table 5). 

The removal of flux residues from soldered assemblies with solvent- and water-based cleaning agents also provided satisfactory cleaning results. Ninety-five percent of examined test substrates were residue-free. For tbe remaining 5%, which resulted in partial residues, testers were able to remove the latter completely after some minor... 

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