RBCT Chapter 86 Wen Piao
Chapter 86 Wen Piao
Late October 2019.
The first heavy snowfall in the north came two weeks early.
The first batch of flight data from the MicroSense collaboration returned to Shenzhen on November 25th. This batch consisted of 180 F4 prototypes equipped with MicroSense IMUs, representing 5% of Hongyuan's production capacity after the October signing ceremony. These were sent to three northern test bases for winter flight verification—Harbin, Urumqi, and Hohhot.
The data doesn't look good.
In an environment of -15 degrees Celsius, the temperature drift of the micro-sensing IMU was nearly five times higher than that of the Bosch BMI088. Specifically, this was reflected in the F4—the positioning deviation of the F4 remained stable within six centimeters in a normal temperature environment, while the positioning deviation of the 180 units equipped with the micro-sensing IMU jumped to 35 centimeters in an environment of -15 degrees Celsius.
Thirty-five centimeters is barely acceptable for consumer-grade drones. For industrial-grade flight controllers—it's useless.
When Liu Yu walked into Su Chen's office with the test report, Su Chen had already looked at the data on the screen three times.
"Mr. Su, the division of responsibility for this issue isn't clearly stipulated in our cooperation agreement. Did we fail to adequately consider low-temperature scenarios when selecting the northern base—or does the Microsensor's IMU itself not meet low-temperature specifications?"
"I'll handle this," Su Chen said. "I'm flying to Wuxi tomorrow."
He wrote a line in his notebook: "Low temperature drift. A problem with the precision of temperature control in deep hardening processes."
The next day at noon, Su Chen arrived at MicroSensing Semiconductor. Zhao Jiancheng personally came downstairs to the front desk to greet him, and without exchanging pleasantries, took him directly to the conference room on the third floor.
There were eight people in the meeting room. Zhao Jiancheng first gave an introduction.
"This is Mr. Huang Zhihua, our chief process engineer at Microsensing. He is responsible for the process debugging and yield management of the entire production line. He is the most senior person in our Microsensing technical team—he joined the company two years before me."
Su Chen extended his hand. Huang Zhihua did not reach out. He simply nodded slightly.
Su Chen withdrew his hand. He could roughly tell that this person had feelings towards him.
Zhao Jiancheng awkwardly tried to smooth things over: "Engineer Huang spends most of his time in cleanrooms and isn't used to business pleasantries. Please don't mind, Mr. Su."
Su Chen waved his hand, not responding to those words.
Next, Zhao Jiancheng introduced several other core members. One of them caught Su Chen's attention—Mr. Lin Shiming, 72 years old, a former senior process engineer at Bosch's Munich headquarters. After retiring, he was invited by Zhao Jiancheng to be a consultant for Microsensor, working in Wuxi for four months every year. Su Chen could feel from Lin Shiming's handshake that it was a hand that had truly worked on the front lines for decades. Dry, firm, and strong, with large knuckles.
After the introduction, Zhao Jiancheng got straight to the point.
"Mr. Su, we received the test data yesterday. Mr. Huang and I have already discussed the root cause of the problem. The core issue is indeed the temperature control accuracy of the deep hardening process. Our current equipment can achieve an accuracy of ±0.3 degrees Celsius within the normal temperature range. However, in the low-temperature range—specifically, between -20 and -15 degrees Celsius—the temperature control accuracy drops to ±2.1 degrees Celsius. This error will be amplified into a significant temperature drift in MEMS structures."
"This is a technical issue," Huang Zhihua added coldly from the side. "It's not something an outsider can solve with a few words."
Su Chen didn't respond to him. He just looked at Zhao Jiancheng.
"I have a question. What is the overall yield rate of MicroSense's drone-grade IMU production line?"
Zhao Jiancheng remained silent for two seconds.
"Seven percent."
The sound of the air conditioner in the conference room suddenly became very clear.
"Seven percent," Zhao Jiancheng repeated. "Only one out of every fourteen produced can leave the factory. This production line is currently operating at a complete loss. It's being sustained by the company's other product lines."
He looked up at Su Chen.
"Mr. Su, I didn't dare tell you this figure in the previous agreement. I was afraid you would leave immediately after hearing it. But since you've come in person today—I don't want to lie to you."
Su Chen remained silent.
He knew perfectly well why the microsensor was stuck here. Bosch's temperature control precision in deep hardening processes is ±0.05 degrees Celsius. This precision is the result of decades of equipment iteration and parameter tuning. Microsensors lack this level of precision. ST and TDK also cannot reach Bosch's level; their precision is around ±0.1 degrees Celsius. Microsensors' ±0.3 degrees Celsius is sufficient within the normal temperature range, but it will fail in the low-temperature range.
This isn't a design problem. It's a problem of equipment, experience, and time.
Su Chen moved the chair forward a little.
"Mr. Zhao, what if I could help you solve the low-temperature drift problem?"
Everyone in the conference room was stunned.
Huang Zhihua was the first to react. He gave a cold laugh.