Lead Free Manufacturing: Cleaning
From B2P Portal
| Fred W. Verdi | |
| ACI Technologies, Inc. | |
| One International Plaza, Suite 600 | |
| Philadelphia, PA 19113 | |
| 3/6/09 |
Contents |
Introduction
| This Lead-Free Electronics Manufacturing Guidelines is meant to establish practices and procedures that may be used to allow the utilization of Lead-Free electronics in military systems.
These Pb-free Manufacturing Guidelines are compiled from both the hands-on experience of manufacturing, reworking, and repairing electronic systems hardware using lead-free processing at the EMPF (Electronic Manufacturing Productivity Facility), which is a COE (Center of Excellence) for U.S. Navy ManTech. This is a living document, representing benchmark presently used Pb-free electronics processing. Processes will be updated as new developments and techniques become available. |
Cleaning Guidelines
The use of more aggressive solder flux, coupled with the higher soldering temperatures, results in making the lead-free electronics cleaning process more difficult. The difficulty in removing lead-free soldering residues is dependent upon:
For example, a tin-lead (SnPb) cleaning process, which utilized only deionized (DI) water to clean the hardware, may require semi-aqueous or aqueous cleaning materials, to remove residues which could not be removed with only DI water. When using lead-free solders, with water soluble fluxes, DI water may not be sufficient to remove residues. The user may be forces to use a cleaning solution, a mild saponifier or surfactant, to completely remove solder residues. For high reliability applications, RMA and RA fluxes are still being used. This is especially found in the military and aerospace electronics manufacturing community. Therefore, these fluxes will be more difficult to clean due to higher soldering temperatures. To counter this, the cleaning agents used, saponifier or surfactant, may have to used at a higher concentration levels and / or higher temperatures. This will be dependent on the cleaning agent used. No clean / low residue fluxes will be the most difficult to remove. This makes sense since these residues were not designed to be removed. While these fluxes may leave a minimum amount of flux residues on the hardware, when compared to water soluble and rosin fluxes, no clean / low residue fluxes are not as active as water soluble and rosin fluxes. Depending upon the soldering process used, these fluxes may not support lead-free soldering as efficiently as water soluble and rosin fluxes. |
References
1. IPC J-STD-001D - Requirements for Soldered Electrical and Electronic Assemblies, IPC Standards
2. IPC A-610D -Acceptability of Electronic Assemblies, IPC Standards
3. "Issues And Solutions To Implementing Lead-Free Soldering" by L. Whiteman. American Competitiveness Institute; SMTA Boston Conference; Boston, Massachusetts, May, 2000
4. "Test Results From The Lead-Free Component Focus Group" by L. Whiteman, American Competitiveness Institute, Philadelphia, Pa; M. Kwoka, Intersil, Palm Bay, Fl; J. Cannis, Amkor Technology Inc., Chandler, Az; G. O'Brien, Photocircuits, Glen Cove, N. Y.; D. Hillman, Rockwell Collins, Cedar Rapids, Ia; M. Toben, Shipley Ronal, Freeport, N. Y.; R. Schetty, Technic, Inc., Freeport, NY; SMTA Boston Conference; Boston, Massachusetts, May, 2002
5. "Guidelines for Lead-Free Hand Soldering" by L. Whiteman, American Competitiveness Institute, R. Northam, American Competitiveness Institute; Circuits Assembly Magazine
6. "Converting Wave Soldering Equipment From Tin-lead To Lead-Free" by L. Whiteman, American Competitiveness Institute, J. Stong, American Competitiveness Institute, D. Alavezos, Technical Devices Company; Circuits Assembly Magazine
7. "Assembly Of JCAA/JG-PP Test Vehicles" by A. L. Campuzano-Contreras,BAE Systems, SMTA International Conference, Chicago, Illinois; September, 2005
8. "Lead-Free Process Implementation Tactics" by C. Shea, Cookson Electronics Assembly Materials Group
9. "Lead-Free Wave Soldering: Tighter Process Windows Require Tighter Controls" by C. Shea, Cookson Electronics Assembly Materials
10. "Optimizing Stencil Design For Lead-Free SMT Processing" by R. Pandher and C. Shea; Cookson Electronics Assembly Materials, SMTA International Conference, Chicago, Illinois; September, 2004
