Study On Electrolytic Etching System For Preparation Of PCB With Fine Lines

As a carrier of electronic components,Printed Circuit Board?PCB?is an important part of electronic products and the basis for realizing the functions of electronic products.As the functions of electronic products continue to grow and the styles continue to be new,the requirements for PCBs are becoming more and more miniaturized and high-ordered,especially for high-density interconnect?HDI?printed circuit boards.Widely used in a variety of electronic products.However,existing miniature high-order PCBs have been difficult to meet the needs of the 5G communication technology field.Therefore,research and development of high-definition,high-regulation,high-quality PCB fine line production technology that meets the requirements of 5G communication technology has become an urgent task for the PCB industry.Based on electrolytic etching,a new electrolytic etching technique integrating electrolytic etching and copper recycling was designed.The electrolytic etching system was studied,and the quality of fine lines was greatly improved.The mechanism of slow release agent to suppress the side line erosion of fine lines was studied.The specific research contents and related conclusions are as follows;1.Study on the improvement of PCB fine circuit quality by electrolytic etching inhibitor?1?The effects of CuCl₂ concentration,HCl concentration,2,5-dimercapto-1,3,4-thiadiazole?DMTD?concentration,current density,temperature,aeration stirring speed and board spacing on the etch factor of PCB fine line were studied.The results showed that when the concentration of CuCl₂ was 30-50g/L,the concentration of HCl was 0.36-0.60mol/L,the concentration of DMTD was 10-20mg/L,the current density was 2.0-2.8A/dm²,and the temperature was 25-35°C,the agitation speed is medium speed and the pole distance is 5.0-6.0 cm,the etching factor of the fine line can reach 5 or more,and the line quality is high.?2?The orthogonal optimization experiment of L₉?3⁴?was carried out with four main influencing factors:CuCl₂ concentration,HCl concentration,DMTD concentration and current density.The optimal electrolytic etching parameters were DMTD concentration of 15mg/L and CuCl₂ concentration of 30g/L,HCl concentration is 0.48mol/L,current density is 2.4A/dm²);the average etch factor of the fine line reached 7.53,much higher than the subtractive method?2.57?and the etching factor without corrosion inhibitor electrolytic etching?3.94?.?3?Based on the sustained release agent,the experimental results of the fine line quality can be greatly improved,further explored the improvement effect of other corrosion inhibitors on fine line quality.The results showed that the L-benzoic acid?PHA?etch factor reached 6.39,the L-tryptophan?TPA?etch factor reached 5.40,and the benzotriazole?BTA?etch factor reached 5.71,all tested corrosion inhibitors can greatly improve the quality of PCB fine lines.And the flatness,regularity and uniformity of PCB fine lines are far superior to those of corrosion-free electrolytic etching lines.?4?The analysis of the metal recovered by electrolytic etching by XRD and EDS shows that when the electrolytic circuit is made into a fine circuit of PCB,the synchronously recovered product is copper,and the recovery rate reaches more than40%,which is beneficial to prolong the service life of the electrolytic etching solution.2.Research on the mechanism of corrosion inhibitor on the quality of PCB fine circuit?1?The corrosion inhibitor molecules are enriched in the copper?111?crystal plane,and the N,S elements in the molecule easily react with the metal copper to form a coordination bond to form a dense protective film,which inhibits the side etching during the electrolytic etching process.?2?Quantum chemical calculations show that:the HOMO of DMTD concentrates on the S atom on the two thiol bonds and the two N atoms on the ring.The LUMO is mainly on the S atom and the C,N atoms on the ring;the HOMO of PHA is concentrated on the heteroatoms N and O,and the LUMO is mainly on the benzene ring;the HOMO of TPA is concentrated on the anthracene ring,and the LUMO is mainly N and O atoms on the carbon branch;the HOMO and LUMO of BTA are concentrated on the benzene ring and the N ring.?3?Molecular dynamics simulation results show that on the Cu?111?crystal plane,the four inhibitor molecules are adsorbed on the copper surface in an optimal form in a manner parallel to the copper surface.The adsorption energies of the four inhibitors were DMTD?-62.73 kcal/mol?,PHA?-63.87 kcal/mol?,TPA?-92.39 kcal/mol?,and BTA?-44.35 kcal/mol?,respectively.3.Discussion on the factors affecting the uniformity of electrolytic etchingImproving the distribution of the power supply chuck of the electrolytic etching equipment and improving the uneven distribution of the current on the surface of the board can effectively improve the etching uniformity of the electrolytic etching,and lay a solid foundation for the industrial application of electrolytic etching.