An electronic shelf label is a small circuit board, an e-paper display, a coin-cell battery and a sealed housing. This page follows a label through the SMT and assembly lines at our partner factories in Guangzhou, Foshan and Shenzhen, and explains what is checked at each step.
Incoming materials→Paste printing→SPI→Placement→Reflow→AOI / X-ray→Depaneling→Assembly→Sealing→Test
1. Incoming materials
Components, displays, batteries and housings are checked on arrival against the bill of materials and sampling plans. Reels go into controlled storage; at the Guangzhou and Foshan sites, intelligent racks and an X-ray component counter keep track of every reel, and moisture-sensitive parts are kept in dry cabinets.
Reel counting and feeders ready for placement.
2. Solder-paste printing and SPI
Automatic printers apply solder paste through a stencil. 3D solder-paste inspection (SPI) then measures the volume, height and position of every deposit before any component is placed; in Guangzhou the SPI results feed back to the printer so drift is corrected automatically.
3. Placement and reflow
High-speed placement machines fit the chips, passives and antenna components, and the boards pass through multi-zone reflow ovens with monitored temperature profiles. Together the three sites run more than 15 SMT lines: 4 in Guangzhou, 8 in Foshan and 3 in Shenzhen.
Placement machines and a reflow oven at our partner factories.
4. AOI and X-ray
Automated optical inspection (AOI) checks every board for missing, shifted or reversed parts and solder defects. Joints that cannot be seen, such as those under QFN packages, are checked by X-ray. A first-article inspection system verifies the first board of each run against the bill of materials before the batch continues.
AOI in Guangzhou and X-ray inspection in Foshan.
5. Depaneling and board test
Boards are cut from the panel by an automatic depaneling machine and given a functional test: power, radio and display interface. Boards that fail are separated and analysed, not reworked blindly.
6. Assembly, sealing and pressure-holding
The display, board and battery are fitted into the housing. The housing is then sealed by an automatic dispensing machine and held under pressure while the adhesive sets, which keeps the front flat and the seal even. In Guangzhou this is done on dispensing machines and pressure-holding fixtures that we bought for our own labels; the same process runs on the assembly lines in Foshan and Shenzhen.
Housing sealing and pressure-holding.
7. Final test and packing
Every finished label is powered, paired over the air and shown a test image, then packed in trays. Test methods and inspection are described on testing and quality.
Equipment at a glance
| Step | Equipment at our partner factories |
|---|
| Printing | Automatic stencil printers |
| Paste inspection | 3D SPI |
| Placement | High-speed and multi-function placement machines (Hitachi, Hanwha, Samsung, Yamaha and others) |
| Reflow | Multi-zone lead-free reflow ovens with profile monitoring |
| Inspection | AOI, X-ray, first-article inspection systems |
| Assembly | Automatic depaneling, dispensing machines, pressure-holding fixtures, screw and welding machines |
| Traceability | MES, WMS, serial-number tracking |
See partner factories for what each site has, and how AiEInkSmart labels are made for the full picture.
Need a custom housing or a sample run? Samples and small batches are built on the Guangzhou line. Send us your requirements, or start with an
ESL demo kit.
