Journal of the Microelectronics and Packaging Society (마이크로전자및패키징학회지)

The Korean Microelectronics and Packaging Society (한국마이크로전자및패키징학회)
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Electrochemical Evaluation of Etching Characteristics of Copper Etchant in PCB Etching

PCB 구리 에칭 용액의 에칭 특성에 대한 전기화학적 고찰

  • Lee, Seo-Hyang (Department of Materials Science and Engineering, Hongik University) ;
  • Lee, Jae-Ho (Department of Materials Science and Engineering, Hongik University)
  • 이서향 (홍익대학교 신소재공학과) ;
  • 이재호 (홍익대학교 신소재공학과)
  • Received : 2022.12.21
  • Accepted : 2022.12.29
  • Published : 2022.12.30
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Abstract

During etching process of PCB, the electroplated copper line and seed layer copper have different etching rates and it caused the over etching of copper line as well as undercut of lines. In this research, the effects of etchants composition on copper etching characteristics were investigated. The optimum concentration of hydrogen peroxide and sulfuric acid of etchants were obtained using polarization and OCV (open circuit voltage) analysis for both rolled copper and electroplated copper. The inhibiting effects of different inhibitors were investigated using OCV and ZRA (zero resistance ammeter) analysis. The galvanic current between electroplated copper and seed layer copper were measured using ZRA method. Inhibitors for least galvanic current could be chosen based on galvanic coupling in ZRA analysis.

PCB 기판의 구리 식각 시 전기도금된 배선과 기지층의 전도층은 다른 에칭 특성을 가지며 이로 인한 배선의 과에칭과 배선기저부의 언터컷 현상이 보고되고 있다. 본 연구에서는 구리 에칭의 조성 변화에 따른 구리 에칭 특성에 대하여 연구하였다. 분극법과 OCV (open circuit voltage)를 이용하여 에칭액의 전기도금 구리와 기지층 구리의 최적 과산화수소와 황산의 농도를 얻었다. OCV와 ZRA (zero resistance ammeter)분석법을 이용하여 억제재의 효과를 비교하였다. 구리배선과 기지층간의 갈바닉 전류를 ZRA 방법을 이용하여 측정 비교하였다. 갈바닉 전류를 최소화하는 억제재를 ZRA를 이용한 갈바닉 쌍으로부터 선택할 수 있었다.

Keywords

Acknowledgement

본 연구는 한국연구재단 기초연구(NRF 2021R1F1A1060048)와 창업성장 기술개발 사업 지원을 받아 수행된 연구임.

References

  1. R. Schwerz, B. Boehme, M. Roellig, K. J. Wolter, and N. Meyendorf, "Reliability of embedding concepts for discrete passive components in organic circuit boards", Proc. 63rd Electronic Components and Technology Conference(ECTC), Las Vegas, 1243-1251, IEEE Components, Packaging and Manufacturing Technology Society(CPMT) (2013).
  2. O. J. Kwon, S. K. Cho, and J. J. Kim, "Electrochemical metallization processes for copper and silver metal interconnection" Kor. Chem. Eng. Res., 47(2), 141-149 (2009).
  3. K. H. Dietz, "Challenges and limitations of subtractive processing in PWB and substrate fabrication", Proc. 3rd International Microsystems, Packaging, Assembly and Circuits Technology Conference(IMPACT), Taipei, 231-234, IEEE Components, Packaging and Manufacturing Technology Society(CPMT) (2008).
  4. H. S. Shin, "Fabrication of multilayered structures in electrochemical etching using a copper protective layer", J. Korean Soc. Manuf. Process Eng., 18(2), 38-43 (2019).
  5. F. Vasilyev, V. Isaev, and M. Korobkov, "The influence of the PCB design and the process of their manufacturing on the possibility of a defect-free production", Przegl. Elektrotech., 97(3), 91-96 (2021).
  6. Y. J. Kang, M. E. Hong, and D. H. Kim, "Study on soft etching material development to improve peel strength between surface of copper and solder resist ink", Appl. Chem. Eng., 20(2), 172-176 (2009).
  7. L. Jiang, Y. Lan, Y. He, Y. Li, Y. Li, and J. Luo, "1, 2, 4-triazole as a corrosion inhibitor in copper chemical mechanical polishing", Thin Solid Films, 556, 395-404 (2014). https://doi.org/10.1016/j.tsf.2013.12.047
  8. N. K. Allam, A. A. Nazeer, and E. A. Ashour, "A review of the effects of benzotriazole on the corrosion of copper and copper alloys in clean and polluted environments", J. Appl. Electrochem., 39(7), 961-969 (2009). https://doi.org/10.1007/s10800-009-9779-4
  9. J. W. Lee, M. C. Kang, and J. J. Kim, "Characterization of 5-Aminotetrazol as a corrosion inhibitor in copper chemical mechanical polishing", J. Electrochem. Soc., 152(12), C872-C831 (2005).
  10. S. Lee and S. J. Moon, "Preparation of soft etchant to improve adhesion strength between photoresist and copper layer in copper clad laminates", J. Kor. Appl. Sci. and Technol., 32(3), 512-521 (2015).
  11. J. H. Lee, "PCB quality and reliability affected by galvanic reaction" Proceedings of the Korean Institute of Surface Engineering Conference, 38-56, Kor. Inst. Surf. Eng. (2012)
  12. S. W. Lee and J. J. Kim, "Study on the effects of corrosion inhibitor according to the functional groups for Cu chemical mechanical polishing in neutral environment", Kor. Chem. Eng. Res., 53(4), 517-523 (2015). https://doi.org/10.9713/kcer.2015.53.4.517
  13. H. R. Yoo and Y. D. Son, "A study on safety management and control in wet-etching process for H2O2 reactions", J. of Kor. Academia-Industrial, 19(4), 650-656 (2018).
  14. T. G. Woo, I. S. Park, and K. W. Seol, "Main effects of plating parameters on mechanical and surface properties of electroplated copper" Kor. J. Met. Mater., 56(6), 459-464 (2018). https://doi.org/10.3365/kjmm.2018.56.6.459
  15. D. A. Jones, Principles and Prevention of Corrosion, pp.168-196, New York, Macmillan Publishing Co. (1995)