LAMOST stencil cleaning pins clear solder paste from clogged apertures in SMT printing stencils and help prevent print defects. The item in stock on this page is the LAMOST CUW-15 single pin; other pin diameters and matching handles can be quoted.
The LAMOST stencil cleaning pin is a quick inline repair tool for SMT stencils. When an aperture is blocked by dried or leftover paste and printing goes wrong, a pin matched to the aperture size pushes the blockage out at that one point and restores print quality. Compared with taking the whole stencil off for cleaning (30–60 minutes of downtime) or relying on the stencil wiper (which cannot clear deep blockages), the pin is used inline and greatly shortens unplanned downtime — a cost-effective daily consumable for SMT lines.
This series is the LAMOST single pin (P/N CUW-15); other diameters and handles can be quoted. Typical uses include stencil maintenance on EMS / SMT lines, clearing fine-pitch QFN / BGA apertures and recovering from SPI defects.
Supply: please ask us about pin diameters, handles and quantity.
Trademarks: LAMOST is a trademark of its owner. JIAHON is not the authorized distributor of LAMOST in Taiwan.
Specifications
| Item | Spec |
|---|---|
| Brand | LAMOST |
| Product type | Steel pin for clearing SMT stencil apertures |
| Pin diameter range | 0.15 / 0.20 / 0.25 / 0.30 / 0.40 / 0.50 / 0.65 / 0.80 / 1.0 mm |
| Pin length | 30–50 mm |
| Pin material | Stainless steel (standard) / hardened steel (heavy use) |
| Handle material | Wood, plastic or stainless steel (by model) |
| Packing | Single pin / set (several diameters) |
| Stencil thickness | 0.08–0.15 mm (80–150 μm, mainstream SMT stencils) |
| Typical apertures | QFN 0.4–0.5 mm pitch, BGA 0.4 mm pitch, 0201 / 01005 parts |
| P/N (currently supplied) | CUW-15 (LAMOST part number) |
Use cases
1. Recovering from a print defect inline. When SPI finds insufficient paste on a pad, the matching aperture may be clogged. The operator picks the right pin diameter, inserts it from the paste side of the stencil, pushes it through to the bottom, and clears the blockage so the next board prints normally. Compared with taking the stencil off for cleaning, this saves 30–60 minutes of downtime.
2. Clearing fine-pitch QFN / BGA apertures. Apertures for fine-pitch parts such as QFN 0.4 mm pitch and BGA 0.4 mm pitch are only 0.15–0.25 mm wide, and a wiper often cannot clear deep blockages. Fine 0.15 / 0.20 mm pins handle these points; use a light touch to avoid enlarging the aperture and keep the stencil accurate.
3. Clearing leftover paste after changeover. When switching PCB models, paste left from the last batch may clog apertures used by the new model. After the test print, use a pin on the defective points instead of taking the whole stencil off, to save changeover time.
4. Stencil check before restarting after a long holiday. After a long stop, leftover paste dries and hardens on the stencil, raising the risk of a bad first board. We suggest checking suspect apertures one by one with a pin (especially those for fine-pitch parts in the last batch before the holiday); combined with ultrasonic cleaning this works even better and lowers first-board defects.
Selection guide
| Aperture size | Suggested pin diameter | Typical parts |
|---|---|---|
| 0.15–0.25 mm | 0.15 / 0.20 mm | QFN 0.4 mm pitch, 0201 / 01005 |
| 0.25–0.35 mm | 0.25 / 0.30 mm | QFN 0.5 mm pitch, BGA 0.4 mm pitch |
| 0.35–0.5 mm | 0.30 / 0.40 mm | QFN 0.65 mm pitch, SOIC |
| 0.5–0.8 mm | 0.50 / 0.65 mm | Standard 0805 / 1206 parts |
| 0.8–1.0 mm | 0.80 / 1.0 mm | Large capacitors, connectors |
| Suggested spares | 1–2 each of 0.15 / 0.20 / 0.30 / 0.40 / 0.50 mm | Covers mainstream SMT aperture sizes |
Why apertures clog, and how pins help
| Cause | Description | Prevention |
|---|---|---|
| Paste viscosity | Flux evaporates, paste lumps | Replace regularly, control the environment |
| Print parameters | Speed too fast / pressure too low | Adjust squeegee pressure and speed |
| Temperature and humidity | Heat speeds oxidation, low humidity speeds drying | Cleanroom 22–25 °C, RH 40–60% |
| Holiday stops | Paste lumps after a few hours at rest | Clean the stencil before stopping |
| Fine-pitch apertures | QFN / BGA openings only 0.15–0.25 mm | Keep small-diameter pins ready |
How it works: a steel pin of the matching diameter is pushed through the stencil from the top (paste side) to the bottom (PCB side), physically pushing the blockage out. It is more direct than a wiper and faster than ultrasonic cleaning.
Choosing the pin diameter: the pin should be slightly smaller than or equal to the smallest aperture opening. Too large enlarges the aperture; too small cannot push the blockage out.
Three cleaning methods compared
| Method | Time | Depth | Downtime needed | Use |
|---|---|---|---|---|
| Cleaning pin | Seconds | Deep, single point | No | Sudden inline blockage |
| Stencil wiper | Minutes | Shallow | No (built in) | Routine prevention |
| Ultrasonic cleaning | 30–60 minutes | Full, deep | Yes | Daily / weekly deep cleaning |
In practice: wiper for routine prevention + pins for emergencies + ultrasonic for daily / weekly deep cleaning. Each SMT line should keep 2–3 pins in the main diameters.
Use notes: avoid enlarging apertures
- Insert from the paste side: push from the top (paste side) to the bottom, not the other way. Most lumps are on the paste side, so push from the top down.
- Push gently: push the pin; do not twist or lever. Twisting wears the aperture walls.
- Check pins regularly: check every 50–100 uses for bending or breakage; a bent pin will not hit the right spot.
- Same aperture clogs 3 times or more: this is a systematic problem (paste viscosity, squeegee pressure, print speed) and the pin only treats the symptom. Ask an engineer to review the print parameters.
※ Pin sizes, aperture matches and use intervals here are general guidance and vary case by case. Please confirm the selection against your stencil spec and print parameters.
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