Hello everyone, I am A-Zhe, a process engineer at a company that produces high-performance copper-clad laminates. Today, I want to share with you a tough battle our team fought last year— how we turned a nearly invisible “small pit“ on our product, which was costing us hundreds of thousands each month, into a “golden signboard“ that earned us the trust of our clients.
1. Painful Scene: Customer Complaints Pile Up, but We Can’t Find the “Perpetrator“
Our main product— a high-performance copper-clad laminate (which serves as the “framework“ for all electronic products), suddenly faced a wave of complaints from several major clients. The issue was very specific: the surface of the board had fine dents..
Don’t underestimate these small dents! At the client’s end, they could lead to subsequent soldering short circuits or open circuits, directly causing the entire mainboard to be scrapped. Worse still, our quality ranking among8 suppliers dropped to fourth. Our sales colleagues were anxious: “If this continues, next year’s big orders will be gone!“
Internally, the situation was even more dire. The quality control department was picking out dented boards every day, leading to a monthly scrap cost of up to 130,000 yuan. The production, process, and equipment departments held countless meetings, with some suggesting that the steel plates were not clean, others saying the prepreg was problematic, and some suspecting uneven pressure from the press… but after trying various solutions, the problem persisted. The entire team felt like they were groping in the dark, unable to exert their strength.
2. Root Cause: The “Real Culprit“ Was Hidden in the Air
The turning point came when the company invited a lean improvement coach. Instead of letting us continue to “guess“, he guided us to do something that seemed “foolish“ but was extremely effective—setting up sticky dust paper on-site to “catch the thief“.
We placed sticky dust paper at every key position on the production line, and after 12 hours, we collected and analyzed the results. The findings were shocking: 93% of the foreign objects were actually kraft paper fibers!
Kraft paper? We do use it as a cushion during lamination, but it is clearly underneath the copper foil, how did it end up on top?
The coach guided us to map out the entire workflow and simulate the airflow. The truth finally surfaced: on the assembly table, the edge of the kraft paper was too close to the copper foil (only 1 cm), and the crane’s action when placing the board was too forceful, pushing the kraft paper out of its gap. The airflow in the workshop acted like an invisible hand, blowing these loose fibers up, and due to resistance “taking a turn“, they landed precisely on the mirror-like surface of the copper foil!
At that moment, we realized: the problem was not with the material itself, but with the “microenvironment“ design of the assembly process..
3. Coach’s Guidance: Using Skill to Solve Big Problems
Having identified the root cause, the next step was to figure out how to “fill the pit“. Under the guidance of the lean improvement coach, we identified four key points and were encouraged to validate them in a low-cost, high-efficiency manner:
- 1. Stabilize the Copper Foil: If the copper foil itself is warped, it is more likely to trap fibers. We installed a simple leveling roller before cutting to ensure the copper foil lays flat.
- 2. Increase the Distance: This is the most critical step! We placed a layer of smooth Teflon paper between the kraft paper and the copper foil, increasing the edge distance from 1 cm to 20 cm. This way, the wind can no longer reach the copper foil.
- 3. Control the Source: We held a meeting with the kraft paper supplier to establish strict edge inspection standards, directly rejecting any with severe fraying. Additionally, we changed the longitudinal glue application on the production line, which easily carried fibers, to a gentler transverse application.
- 4. Optimize Actions: We adjusted the position of the crane sensor to lower it, making the action of placing the steel plate gentler to avoid compressing the kraft paper and creating gaps.
Throughout the process, the coach repeatedly emphasized: “Don’t aim for perfection in one go; start with small-scale tests, let the data speak.“
4. Improvement Results: A Stunning Transformation from “Chaser“ to “Leader“.
In just a few months, the results were immediate:
✅ The dent defect rate plummeted 78%, far exceeding our 60% target!
✅ It is estimated that we saved nearly 1.1 million yuan in scrap costs annually.
✅ What makes us most proud is, in the supplier quality ranking from our clients, we jumped from fourth place to first place! The sales director specifically sent a message to thank us: “You really saved the big order this time!“
More importantly, this experience completely changed our way of working. We no longer rely on experience to “make guesses“, but have learned to trace back to the root cause using data and logic. After the project ended, we documented all successful practices into standard operating procedures and trained over a hundred frontline employees.
Now, every time I see a flawless circuit board coming off the line, I think back to those days of “filling the pit“. It made me realize that the competitiveness of the manufacturing industry often lies in the meticulous attention to these “small defects“..
Improvement is endless, and we are always on the road.
— A-Zhe, a process engineer who firmly believes that details determine success or failure.
Have you encountered similar “difficult problems“? Feel free to share your story in the comments!
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