Authored By:
C. Christine Dong, Gregory K. Arslanian, Ranajit Ghosh, Victor Wang, Paul Lin, and Jerry Wu
Air Products and Chemicals, Inc., Allentown, PA USA
Vic Leou and Neo Lin
Advantech Co., Ltd, Taipei, Taiwan
It is well known that nitrogen inerting in wave soldering can significantly reduce dross formation and improve solder wetting. For lead-free wave soldering, the benefits of N2 inerting are even higher. However, there is still a lack of a mature N2 inerting technology for wave soldering, which largely impedes its wide application. This paper presents a new generation N2 inerting system for wave soldering to make the technology more cost effective and user friendly.
Both lab-scale experiments and production trials were conducted, which demonstrates the following superior performances and benefits of applying the developed N2 inerting technology:
1. Low N2 consumption for inerting.
2. Low tendency of diffuser clogging.
3. Low retrofitting cost.
4. An option for flux vapor collection.
5. Reduced dross formation.
6. Reduced machine down time for cleaning.
7. Reduced flux usage, and
8. Reduced soldering defects.
Summary
It is well known that nitrogen inerting in wave soldering can significantly reduce dross formation and improve solder wetting. For lead-free wave soldering, the benefits of N2 inerting are even higher. However, there is still a lack of a mature N2 inerting technology for wave soldering, which largely impedes its wide application. This paper presents a new generation N2 inerting system for wave soldering to make the technology more cost effective and user friendly. Both lab-scale experiments and production trials were conducted, which demonstrats the following superior performances and benefits of applying the developed N2 inerting technology: 1) low N2 consumption for inerting, 2) low tendency of diffuser clogging, 3) low retrofitting cost, 4) an option for flux vapor collection, 5) reduced dross formation, 6) reduced machine down time for cleaning, 7) reduced flux usage, and 8) reduced soldering defects.
Conclusions
A range of new design concepts have been incorporated into the nitrogen inerting system for wave soldering applications to demonstrate significant reduction in dross formation, solder defects and machine maintenance. A fundamental study involving CFD modeling of the flow fields inside the solder pot and permeability tests were undertaken to optimize the diffuser selection and positioning. Other design improvements including the front/back diffuser covers, middle diffuser fin and double-layered top cover have been demonstrated to minimize solder and flux clogging, resulting in reduced machine downtime. Through the initial beta site implementation at Advantech, the benefits of the system were re-affirmed on scale-up to a production environment. To minimize customization and accommodate a wide variety of production-scale wave soldering machines, several standard design options are currently being evaluated. These include further design optimization of the middle diffuser for reduced clogging and more efficient inerting as well as design flexibilities to address size/shape variations.
The new design for nitrogen inerting of wave solder systems has demonstrated that it is robust and flexible, which allows for simple modifications to accommodate equipment variations. Through improvements in productivity, quality and reduced maintenance, the new system should be able to reduce overall cost of ownership for the electronics printed circuit board assembly industry.
Initially Published in the IPC Proceedings
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