Skip to main content
SpringerLink
Log in

Direct micro-joining of flexible printed circuit and metal electrode by pulsed Nd:YAG laser

  • Published:
International Journal of Precision Engineering and Manufacturing Aims and scope Submit manuscript

Abstract

Laser micro-welding has proven to be a very successful tool for micro-joining in the electrical and electronic industries, where the miniaturization, the high strength and the high heat resistance are constantly requested. Recently, a flexible printed circuit (FPC) is expected as a new connection technology between electrical conductors according to the improvements of reliability and controllability with the diversification of the design concept. In this technology, it is required to weld a several tens μm thickness of FPC and a several hundreds μm thickness of metal electrode. This material combination accompanies the difficulty to control the welding phenomenon due to the differences of thermal property and heat capacity. As a good alternative, laser micro-welding has advantages of non-contact tool, low heat distortion and consistent weld integrity. In this study, the overlap welding of thin copper circuit on a polyimide film and a thick brass electrode was experimentally and numerically investigated by using a pulsed Nd:YAG laser. In addition, the shearing stress of overlap welding was evaluated with and without the control of pulse waveform, which can provide a well-directed controlling of the heat input with high energy density. The results showed that a porosity was observed as the major weld defect in the welding process without a pulse control. However, the appropriate controlled laser pulse configuration of micro-welding could remove the weld defects in the molten zone, improve the weld penetration stability and increase the weld strength. The potential benefits of controlled pulse waveform were discussed for the direct laser micro-welding process. It is clarified that the direct laser micro-welding of a thin copper circuit on a polyimide film and a thick brass electrode could be successfully achieved by appropriate controlled pulse waveform and heat input.

This is a preview of subscription content, log in via an institution to check access.

Access this article

Log in via an institution

Price excludes VAT (USA)
Tax calculation will be finalised during checkout.

Instant access to the full article PDF.

Institutional subscriptions

Similar content being viewed by others

References

  1. Katayama, S. and Kawahito, Y., “Laser Direct Joining of Metal and Plastic,” Scripta Materialia, Vol. 59, No. 12, pp. 1247–1250, 2008.

    Article  Google Scholar 

  2. Ozeki, Y., Inoue, T., Tamaki, T., Yamaguchi, H., Onda, S., Watanabe, W., Sano, T., Nishiuchi, S., Hirose, A. and Itoh, K., “Direct Welding between Copper and Glass Substrates with Femtosecond Laser Pulses,” Applied Physics Express, Vol. 1, Paper No. 082601, 2008.

  3. Kim, J.-W. and Kim, C.-G., “Design of a Laser Welded Thin Metal Tube Structure Incorporating Welding Distortion and Residual Stress,” Int. J. Precis. Eng. Manuf., Vol. 11, No. 6, pp. 925–930, 2010.

    Article  Google Scholar 

  4. Otte, F., Stute, U. and Ostendorf, A., “Micro Welding of Electronic Components with 532nm Laser Radiation,” Proc. of SPIE, Vol. 6458, Paper No. 645804, 2007.

  5. Takahashi, K., Watanabe, T., Matsusaka, S. and Wada, T., “Direct Microjoining of Copper Materials using Laser Beams,” JSME International Journal Series C, Vol. 49, No. 1, pp. 128–134, 2006.

    Article  Google Scholar 

  6. Shannon, G. and Severloh, P., “Laser Microwelding of Copper,” Industrial Laser Solutions, pp. 1–3, 2009.

  7. American Welding Society, “Welding Copper and Copper Alloys,” pp. 10–13, 1997.

  8. Migliore, L., “Laser Materials Processing,” Marcel Dekker, pp. 176–178, 1996.

  9. Ion, J. C., “Laser Processing of Engineering Materials,” Butterworth-Heinemann, pp. 431–433, 2005.

  10. Blom, A., Dunias, P., Van Engen, P., Hoving, W. and De Kramer, J., “Process Spread Reduction of Laser Microspot Welding of Thin Copper Parts Using Real-time Control,” Proc. of SPIE, Vol. 4977, pp. 493–507, 2003.

    Article  Google Scholar 

  11. Japan Society of Thermophysical Properties, “Thermophysical Properties Handbook,” pp. 23–25, 2008.

  12. Naeem, M., “Controlling the Pulse in Laser Welding,” Welding, pp. 1–4, 2004.

  13. Biro, E., Weckman, D. C. and Zhou, Y., “Pulsed Nd:YAG Laser Welding of Copper Using Oxygenated Assist Gases,” Metallurgical and Materials Transactions A, Vol. 33, No. 7, pp. 2019–2030, 2002.

    Article  Google Scholar 

  14. Rohde, M., Markert, C. and Pfleging, W., “Laser Micro-Welding of Aluminum Alloys: Experimental Studies and Numerical Modeling,” Int. J. Adv. Manuf. Technol., Vol. 50, No. 1–4, pp. 207–215, 2010.

    Article  Google Scholar 

  15. Zhang, J., Weckman, D. C. and Zhou, Y., “Effect of Temporal Pulse Shaping on Cracking Susceptibility of 6061-T6 Aluminum Nd:YAG Laser Welds,” Welding Journal, Vol. 87, No. 1, pp. 18s–30s, 2008.

    Google Scholar 

  16. Schmidt, M. and Weigl, M., “Laser-Bonding in High Power Electronics,” Journal of Laser Micro/Nanoengineering, Vol. 5, No. 3, pp. 242–247, 2010.

    Article  Google Scholar 

  17. Witte, R., Liebers, R., Holtz, R., Wilden, J. and Neumann, T., “Laser Welding with Pulsed Solid State Lasers: Strategies and New Developments,” Proc. of the 11th International Symposium on Laser Precision Microfabrication, Paper No. 10-75, 2010.

  18. Naeem, M., Lewis, S. and Chinn, J., “Microwelding Performance Comparison Between a Lower Power (125W) Pulsed Nd:YAG Laser and a Low Power (100–200W) Single Mode Fiber Laser,” Proc. of the 3rd Pacific Int. Conf. on Applications of Lasers and Optics, pp. 721–726, 2008.

  19. Kannatey-Asibu, E., “Principles of Laser Materials Processing,” John Wiley & Sons, pp. 232–235, 2009.

  20. Duley, W. W., “Laser Welding,” John Wiley & Sons, pp. 25–27, 1999.

  21. Laser Institute of America, “LIA Handbook of Laser Materials Processing,” pp. 320–322, 2001.

Download references

Author information

Authors and Affiliations

  1. Graduate School of Natural Science and Technology, Okayama University, 3-1-1, Tsushima-naka, Kita-ku, Okayama, Japan, 700-8530

    Mohd Idris Shah Ismail, Yasuhiro Okamoto, Akira Okada, Yoshiyuki Uno & Kentaro Ueoka

Authors
  1. Mohd Idris Shah Ismail
    View author publications

    You can also search for this author in PubMed Google Scholar

  2. Yasuhiro Okamoto
    View author publications

    You can also search for this author in PubMed Google Scholar

  3. Akira Okada
    View author publications

    You can also search for this author in PubMed Google Scholar

  4. Yoshiyuki Uno
    View author publications

    You can also search for this author in PubMed Google Scholar

  5. Kentaro Ueoka
    View author publications

    You can also search for this author in PubMed Google Scholar

Corresponding author

Correspondence to Mohd Idris Shah Ismail.

Rights and permissions

Reprints and permissions

About this article

Cite this article

Ismail, M.I.S., Okamoto, Y., Okada, A. et al. Direct micro-joining of flexible printed circuit and metal electrode by pulsed Nd:YAG laser. Int. J. Precis. Eng. Manuf. 13, 321–329 (2012). https://doi.org/10.1007/s12541-012-0041-3

Download citation

  • Received:

  • Accepted:

  • Published:

  • Issue Date:

  • DOI: https://doi.org/10.1007/s12541-012-0041-3

Keywords

Search

Navigation