Chapter 166: Industrial Grade

The rolling shutter of the electronics market was half-drawn, the sound of metal scraping against its track echoing through the aisle. Lin Chen squeezed in sideways. The numbness in his left foot was magnified on the three concrete steps, forcing him to shift all his weight onto his right leg. His knee trembled slightly, the sole of his shoe leaving a half-circle of gray scuff marks on the terrazzo floor. The air inside was thick with the mingled smells of rosin, solder paste, and old cardboard. Overhead, fluorescent tubes flickered intermittently, casting a cold glare on the components lining the shelves. He lowered his head to check the list on his phone’s memo app: industrial-grade silicone sealing strips, 4010 aluminum heatsinks, 1000μF solid capacitors, industrial TF cards, polyurethane conformal coating, thermal grease. Budget: eight hundred. No going over.

He found a stall specializing in industrial control accessories. The owner was a middle-aged man wearing reading glasses, currently probing an old PLC board with a multimeter. Wire strippers and heat-shrink tubing were scattered across the desk. Lin Chen handed over the list, his voice low. “Need heat-resistant ones. High dust, high humidity environment.” The boss glanced at it, pulled a few rolls of gray-black sealing strips from the bottom shelf, and tossed down two finned heatsinks. “Silicone strips are three yuan a meter. Heatsinks are eight a piece. The conformal coating comes in cans, forty-five. Your order’s small, so no free shipping. Self-pickup.” Lin Chen didn’t haggle. He scanned the QR code and paid immediately. He knew the few yuan saved by bargaining wouldn’t cover the time cost. Delivery was due Wednesday afternoon. The margin for error was zero. He asked for an extra roll of insulating tape and two zip ties; the boss casually tossed them into a plastic bag.

Back in the dorm, he cleared his desk and laid down an anti-static mat. He turned the desk lamp to its brightest setting, focusing the light squarely on the center of the workspace. With his left foot completely numb, he simply took off his shoe, propped it on a nearby plastic stool, and relied on his right leg and core muscles to maintain his posture. He started with the circuit boards. Using anhydrous alcohol wipes, he cleaned the flux residue around the solder joints and waited for it to evaporate completely before applying the conformal coating. The coating had to be fully covered, especially around the pin headers and capacitor leads. He carefully controlled the force in his wrist, applying two thin coats to prevent pooling. The coating would take two hours to dry. He used the waiting time to cut the sealing strips, slowly pressing them into the casing grooves with a utility knife. The cut had to be perfectly even; otherwise, dust would seep through the gaps. By 3:30 PM, the coating had cured. He mounted the heatsinks, applied thermal grease, and secured them with a Phillips screwdriver. Two boards, the same repetitive motions, but he kept the torque on every screw within a strictly consistent range. Over-tightening would warp the casing and break the seal.

At 7:00 PM, assembly was complete. He opened a terminal and ran a simulated load script. The CPU temperature began to climb. Forty-two degrees Celsius was the norm on the factory floor. He aimed a hairdryer at the board while an old fan created turbulent airflow. The temperature stabilized at sixty-nine degrees. The heatsink was hot to the touch, but the core chip did not trigger thermal throttling. He sprinkled a handful of talcum powder around the board to simulate dust settling. The powder landed on the conformal coating but did not adhere to the interfaces. The sealing strips fit seamlessly. The log window scrolled smoothly: [INFO] Temp: 69°C. Dust ingress: 0%. CRC check: OK. Local cache: active. He leaned back in his chair and let out a long breath. The muscles in his right leg began to cramp from hours of compensating. He reached down to rub them, his fingers brushing against his left ankle. The skin was ice-cold, like a piece of wood that didn’t belong to his body. He picked up his mistake notebook from the desk, turned to a fresh page, and wrote: 19:40 Conformal coating cure time insufficient; slight bubbling at the edges. Next time, extend resting period or switch to vacuum degassing. Heatsink contact surface needs to be sanded flat; thermal grease application must be even. Script heartbeat interval adjusted to 5s to reduce weak-network load.

His remaining balance was just over twenty-three thousand. Eight hundred had been spent, exchanged for two boards tough enough to be shoved into the mud. He ran the numbers for Wednesday’s train ticket and accommodation, plus his contingency fund. It was enough. He packed the boards into a shockproof foam box and slapped on a label: Phase II Line - Node A/B. Inside the box, he also tucked two spare rolls of sealing strips, a tube of conformal coating, a roll of insulating tape, and a set of hex keys. If anything went wrong on-site, he could make repairs right there. He double-checked the script’s deployment package, confirming that all dependencies were bundled and the offline installation script was flawless. The resume-on-disconnect logic was hardcoded, and the local log rotation strategy had been adjusted so it wouldn’t overflow the TF card.

His phone screen lit up at 9:20 PM. It wasn’t Old Zhao. It was Professor Zhou. Factory just issued a temporary notice: Phase II line debugging moved up to Tuesday afternoon. Wednesday’s trial installation is canceled; we’re going straight to live deployment. Arrive Monday night, bring all your tools. The workshop director’s surname is Wu. He’s got a hard temper. Follow his rules. There’s no debugging time on-site. It has to run the moment you power it up. Lin Chen stared at the screen, his fingers hovering over the keyboard. One day early. That meant the on-site deployment window was compressed to four hours. He would need to reroute his plans, contact the factory network administrator in advance to open the necessary ports, and complete the environment adaptation on Monday night. The workshop had no air conditioning, high dust concentration, and the network would likely be an isolated intranet. USB transfer would be the only deployment method. He typed his reply: Received. Arriving Monday night. Deployment package already bundled for offline use. On-site only requires plugging in and powering on. He hit send. He shut down his computer and moved the shockproof box to the corner. The wind outside had grown colder. The shadows of the plane trees cast against the wall looked like a taut net. He lay down. His left foot was still numb, but his breathing was steady. Tomorrow, he still needed to go to the hardware store for insulating sleeves and grounding wires. The road was still long, but the boards could already breathe. The next step was to throw them into the real workshop and see if they could survive their first night shift under Director Wu’s rules.