In the electroplating process, there is often a phenomenon in which the paint is sprayed on the plating layer, which is caused by oil stain on the surface after plating, resulting in poor adhesion. However, when the parts are plated, pinholes often occur after plating. Today we talk about pinholes and treatment solutions caused by improper pretreatment.
1) The parts are not completely degreased or improperly stored during machining. The dust falls on the surface and is left for a long time. The dust and grease are mixed together and it is difficult to remove them, resulting in inconspicuous fine oil spots and bubbles during plating. A pinhole is formed on it.
2) When the parts are polished, the abrasive and polishing paste are embedded in the micro-pits of the surface, which is difficult to clean, and the pits are not deposited on the plating layer to generate pinholes.
3) The parts are pickled and rust-removed or the pickling time is too long, causing excessive corrosion. The surface is dispersed with carbon enrichment points. When plating, the plating layer can only be deposited around these non-conductive particles to form pinholes.
(1) Adopt reasonable pre-treatment process to ensure pre-treatment quality and pre-treatment process: hanging on parts → chemical degreasing → hot water washing → running water washing → pickling and derusting → washing water twice → electric de-oiling → Hot water wash → flow water wash → weak corrosion → two flow water wash, strictly implement the process operation rules, strengthen the maintenance and management of the bath.
(2) The surface of the parts before plating is unclean, such as oily dust particles and other non-conductive particles. It can be brushed with a brush moistened with alkaline water, and then oil can be discharged. Small parts are preferably pulverized.
(3) When the oil layer appears in the chemical degreasing or electrochemical degreasing tank, it should be salvaged in time. Care should be taken to remove the polishing paste thoroughly after grinding and polishing.
(4) It is necessary to control the pickling time. Once the rust is cleaned, it should be taken out and cleaned immediately. In order to prevent over-corrosion of the parts, a certain amount of corrosion inhibitor should be added to the pickling solution.
Source: PCB Process Technology
Contact Person: Mr. Mank.Li