Summarized below are some typical solder paste printing defects along with recommended corrections or preventative actions to improve your (PCBA) Printed Circuit Board Assembly manufacturing process and overall product quality. At Optima Technology Associates, Inc. we have over 25 years of experience manufacturing PCBs, PCBAs and providing engineering services to help you meet your quality standards and expectations. Contact us today to learn more about working together on your next project.
| Defect |
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Cause |
Action |
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Slump
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Printing process operating in environmental conditions outside recommended range
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Installation temperature control module to regulate temperature and humidity within printer.
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Scooping
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Squeegee pressure too high, stencil damaged or oversized aperatures
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Optimize squeegee pressure, redesign stencil aperatures to reduce size
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Bridging
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Stencil tension low, PCB support insufficient, poor cleanliness, poor paste quality
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Correct stencil tension, cleanliness, improve PCB support and verify paste quality
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Peaking
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Stencil process speed too high, stencil condition/cleanliness or aperature damage
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Modify PCB separation speed, check stencil
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Bleeding
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Poor gasket between PCB and stencil, PCB support, squeegee pressure high, poor stencil or cleanliness
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Ensure stencil aperture size is smaller than pads on PCB, improve PCB support, reduce squeegee pressure, check stencil for damage.
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Mis-alignment
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Printer alignment error, PCB shrink or stretch, insufficient PCB support.
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Verify PCB to stencil alignment, fiducial marks are flat and well positioned
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Incomplete Print
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Blocked stencil aperatures, squeege pressure low, paste too cold or not well mixed
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Check paste, clean stencil, and adjust pressure
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Paste in holes or vias
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Misprinted PCB, dirty PCB
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Fully clean PCB
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