In brief
Troubleshoot print defects by location and time pattern first, then examine substrate, stencil, ink, squeegee and environment in a controlled sequence.
Pinholes can arise from substrate dust, blocked stencil openings, bubbles or poor wetting; contamination spots can come from particles and handling
Pinholes can arise from substrate dust, blocked stencil openings, bubbles or poor wetting; contamination spots can come from particles and handling. Record web position and repetition interval to see whether the defect repeats with each screen cycle.
Open conductive lines change resistance or create circuit failure
Open conductive lines change resistance or create circuit failure. Check stencil resolution, ink rheology, blade pressure, off-contact and substrate flatness. Ragged edges may also reflect mesh tension or excess pressure. Change one variable at a time to preserve traceability.
Measure deposit thickness or resistance at several locations, then compare with blade travel and web width
Measure deposit thickness or resistance at several locations, then compare with blade travel and web width. A conductor that looks even may still vary electrically. Henkel reports sheet resistance at specified dry coating thickness, so thickness must accompany resistance comparisons.
Retain start-up, normal and failed samples with material lots, settings, cleaning history and stencil life
Retain start-up, normal and failed samples with material lots, settings, cleaning history and stencil life. Define sampling points and acceptance limits for the customer instead of relying on a vague visual approval.
How do we start a trial?
Provide substrate, controlled artwork, material data, process flow and acceptance criteria. Use representative samples to confirm configuration and process window.
References and fact sources
Original process guidance. Verify equipment fit and performance with customer samples.
Mr. Yang can discuss a trial plan from your film, drawing and acceptance requirements.
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