SMT Electronics Assembly Line

## Line stages Paste printing → SPI → high-speed / flexible placement → reflow → AOI → depanel ## Where yield comes from Most SMT defects originate at printing (~60%), not placement. So we put SPI right after printing to stop bad paste on the spot, rather than catching it at post-reflow AOI where rework costs several times more. ## Changeover is the flexibility lever The pain in mid-volume is changeover. With pre-staged stencils, offline programming and pre-loaded feeders, changeover compresses to under 20 minutes. Without that, high-mix is a nightmare and utilization stays low. ## Honest capacity note Vendor CPH (placements/hour) is a peak under ideal components and layout. Real mixed boards typically reach 60–75% of the rated figure. We quote against realistic mixed-board rates, not the peak. Named references available on request. ## Technical Specifications | Item | Range | |---|---| | Placement | 40,000-250,000 CPH per line | | Components | 01005 to 55 mm connectors | | Soldering | 8-12 zone reflow, N2 option; selective/wave for THT | | Inspection | SPI + AOI (3D) + optional AXI | | Traceability | Panel-level MES with feeder verification | ## Typical Line Configuration Loader, solder paste printer + SPI, pick-and-place machines, reflow oven, 3D AOI, unloader, MES with feeder setup verification. ## Case Study An EMS startup in Penang reached 92% first-pass yield in month one on a LUNA-integrated line with full SPI/AOI closed loop. ## FAQ **Q: What line capacity should a startup EMS begin with?** A: A single line around 60,000 CPH with one high-speed and one flexible mounter covers most NPI-to-mid-volume needs and scales by adding mounters. **Q: Is nitrogen reflow necessary?** A: For lead-free fine-pitch (<0.4 mm) and bottom-terminated components, N2 improves wetting and reduces voiding; otherwise air reflow is adequate. **Q: How does the closed loop between SPI and printer work?** A: SPI feeds paste offset data back to the printer, which auto-corrects squeegee/stencil alignment, keeping print CpK above 1.33.