In the SMT workshop of Changhong Precision Electronic Technology Co., Ltd., a subsidiary of Changhong Holding Group, fully automated production lines are operating in an orderly manner. Micro-components are accurately placed by nozzles, and flexible-rigid PCBs enter the reflow oven for simultaneous welding, with the first-pass yield displayed on the screen stably maintaining above 95%. This seemingly ordinary scene is underpinned by the enterprise’s 33-year leap to overcome the pain points of SMT technology and transform from "manual operation" to "lean manufacturing".
Previously, the welding of flexible-rigid PCBs was widely recognized as a "troublesome task" in the industry. In traditional processes, after SMT completion, manual soldering of flexible and rigid PCBs with electric soldering irons was required. Skilled workers had a limited daily soldering output; issues such as cold soldering and tin bead short circuits occurred frequently, leading to a rework rate of up to 20%. The scrap loss of flexible PCBs also drove up production costs. To solve this problem, the improvement team worked alongside the production line for 37 consecutive hours, conducted repeated tests on 10 types of materials beside the reflow oven at a high temperature of 50°C, and manually polished counterweights. Ultimately, they fixed the flexible PCBs with magnetic materials and metal pressing blocks, enabling the simultaneous reflow welding of flexible-rigid PCBs and completely resolving the problems of flexible PCB deformation and displacement.
The team has also broken through technical bottlenecks in the field of medical electronics welding. By developing an integrated jig, it realized the simultaneous reflow welding of heat-dissipating copper blocks and power amplifier devices. Spring pressure columns precisely control the pressure, reducing the welding void rate to below 10%, increasing the first-pass yield from 90% to 98.55%, and raising equipment utilization by 24% at the same time. From the "double-sided simultaneous welding" of PCIE connectors to the "low-temperature reflow upgrade" of single-sided PCBs, every technological breakthrough stems from repeated trial and error and perseverance on the front line of the workshop—an effort that also earned Changhong Precision a place on the list of Sichuan Province’s first batch of advanced-level smart factories.
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