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Sunday, September 22 • 1:30pm - 5:00pm
PDC05: Stencil Printing – Advanced Topics

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PDC05: Stencil Printing – Advanced Topics

*Chrys Shea, Shea Engineering Services
Sunday, September 22 | 1:30pm — 5:00pm

Course Objectives
This advanced course on SMT solder paste stencil printing builds upon the basics to give the attendees a larger toolkit for troubleshooting and process improvement. The session starts with the handling and verification of incoming stencils, and continues with detailed methods of troubleshooting suspected stencil issues, showing images and data from multiple real-world stencil trials. Stencil underwiping is presented, reviewing types of wipe sequences, wiper papers and solvents, particularly as they relate to modern lead-free solder pastes and the preservation of nanocoatings. Videos and ultraviolet images of the effects of cleaning and nanocoatings are shown. The course then moves to automated Solder Paste Inspection (SPI) and discusses basic types of SPI equipment. It continues with tips for production implementation and setting inspection tolerances. It then introduces simple experimental methods that can be performed quickly and easily to improve yields using SPI data. The differences between accuracy and repeatability are discussed, as are the effects of setting of reference planes and measurement thresholds. This year's new updates include results of recent stencil stepping, aperture optimization, nanocoating and miniaturization studies.

Topics Covered
1. Stencil Verification
1.1. SPI verification
1.2. Test coupons
1.3. SEM images
1.4. Cleaning before using
2. Stencil Troubleshooting
2.1. Physical damage
2.2. Foil thickness
2.3. Aperture size
2.4. Aperture location
2.5. Impact on AR & TE
2.6. Cut Quality
3. Underwiping
3.1. Purpose and methods
3.2. UV Test results
3.3. Solvent requirements
3.4. Solvent compatibility with solder pastes
3.5. Solvent and paper compatibility with nanocoatings
4. Automated Solder Paste Inspection (SPI)
4.1. SPI basics
4.2. Production implementation
4.3. Setting inspection tolerances
4.4. Improving print yields
4.5. Accuracy and Repeatability
4.6. Reference planes and measurement thresholds
4.7. Special features to improve performance
5.0 Recent studies
5.1 Step stencil keepout zones
5.2 Getting Cpk >2.0 on 008004's or 0201M's
5.3 Aperture design print repeatability for discretes
5.4 Fresh look and head-to-head comparison of nanocoatings

Sunday September 22, 2019 1:30pm - 5:00pm CDT
Room 51

Attendees (4)