Two-color electroplating process for plastic parts

- Jul 07, 2017-

1. Process and Precautions

Except stress → chemical oil → chemical coarsening → hydrochloric acid wash → colloidal palladium direct activation → solution glue → electroless nickel plating → brush Wash → flash plating (pyrophosphate copper) → acidic bright copper plating → Bright nickel plating → dilute acid activation → plating imitation gold → passivation → drying → local check paint → drying → remove the local imitation gold layer → dilute $literal activation → chrome → dry → test. The above process omits the washing process. But wash must have, and to clean thoroughly. The water washing after activating and dispensing is strictly prohibited. Each operation to prevent scratches between the parts to touch hair. Parts of the network, loading baskets or from the nets, baskets in the pouring out to gently operate, it is best to pour in the water basin, the buoyancy of water to prevent parts between scratches.

1.1 In addition to stress will be placed in the oven plastic parts, 70 ℃ under the insulation 2h.

1.2 Chemical Oil Remover

Sodium hydroxide 40g/l, sodium phosphate 30g/l, sodium carbonate 20g/l, op emulsifier 1~3g/l, Θ60~70℃, t10~15min

In the process of oil removal, the plastic parts should be stirred gently to speed up the oil removal. can also be thickened after the recovery solution to heating up to not more than 70 ℃ oil.

1.3 Chemical coarsening [1]cro3 400g/l, $literal (d=1. $number) 200ml/l, $literal 600ml/l relative density 1.45 θ 70 ℃, t10~15min as long as strictly follow this formula and working conditions, there will be no coarsening or excessive coarsening.

1.4 Hydrochloric Acid Wash HCL (d=1) 100~200ml/l, t1~3min hydrochloric acid washing can remove the plastic surface residue of the coarse liquid and adsorption of cr3+. After hydrochloric acid washing, can be observed with the naked eye of the plastic surface by a faint dark green become white some.

1.5 Colloidal Palladium Direct activation method PDCL2·2H2O 0.5~1g/l, Sncl2·2h2o 50~100g/l, HCl (d=1) 200~300ml/l, Θ50~60℃, t5~10min palladium chloride concentration not too high, otherwise the cost of the tank, with a large loss. Some materials [2] reported that the quality of palladium chloride was less than 0.5G/L, the author confirmed in the production is not feasible, even if the extension of activation time to more than 30min, temperature increase to 60 ℃ above, still will appear plastic, low production efficiency, low product rate. In order to prevent the water from being washed to dilute the activation liquid to precipitate, the plastic parts into the colloid Palladium direct activating liquid before, first in the colloidal Palladium solution after the recovery of 5min, do not clean directly colloidal palladium activation. It is forbidden to directly enter the colloidal Palladium solution to supplement activation by electroless nickel plating unqualified plastic parts, so as to avoid the introduction of colloidal palladium activator into ni2+ and reduce the activity and stability of activating liquid.

1.6 Solution of NaOH 100~300g/lt3~5min alkali solution is faster than acid solution, complete and no need to heat, and acid solution of the glue needs a thicker acid and heating.

1.7 Chemical nickel, pyrophosphate copper, acidic bright copper plating, bright nickel, plating imitation gold and chromium plating solution composition, preparation, use and maintenance of the same as conventional plating, can refer to the relevant information.

1.8 Brush Wash Chemical nickel layer surface may exist solid particles or other dirt, after electroplating easy to produce rough and painted face, which is very obvious on large-area plating, so added a brush washing process. Do not use too hard brush when brushing to avoid scratching the electroless nickel layer.

1.9 Point varnish plating imitation gold, after the passivation of the transparent varnish can improve the gold layer's ability to resist discoloration, also played an insulating role, to prevent the imitation gold layer on the chrome plating. Plastic parts are not temperature-resistant, require transparent varnish is at room temperature dry or low-temperature drying type. The local point transparent varnish should be carefully, to prevent the need to chrome in the pattern of the spot paint. If you need to dry the paint film, the temperature should not exceed 70 ℃.