【103】Guarding China's 5G signals at a thickness of 0.09 millimeters

【103】Guarding China's 5G signals at a thickness of 0.09 millimeters

A crucial meeting of Huawei HiSilicon was held at 11 p.m. On the video, the head of the chip packaging department opened the three-dimensional drawing, showing a complex plastic part with a structure like a maze rotating and rotating: "This is the sealing cover of the 5G millimeter-wave antenna module. The thinnest part of the wall is 0.09 millimeters, but 32 electromagnetic shielding ribs with a height difference of 0.15 millimeters need to be integrated on it." He paused for a moment, and the screen cut to an electron microscope photo, "Did you see the golden coating at the top of the ribs? Any slight burr or burr on the injection process would cause the coating to break at the micrometer level - and this means a 30% decline in antenna performance."

In the meeting room, only the hum of the projector fan could be heard. What is 0.09 millimeters? The thickness of an A4 paper is 0.1 millimeters. We need to make precise ribs thinner than a hairline on a plastic with a thickness close to that of a sheet of paper, and produce 500,000 pieces continuously without any flaws. What's even more desperate is the schedule - Huawei gave us one-third of the time for a regular project because of the US sanctions, and they had to complete the domestic substitution before the chip supply was cut off.

I will always remember the arguments at the scheme review meeting. Mold engineer Old Qian slapped the table and said: "0.09 millimeter wall thickness with 0.15 millimeter ribs - this is like building the Great Wall on cling film! According to the textbook, this is fundamentally impossible to form!" But young CAE engineer Young Sun pulled out simulation data: "If using ultra-high-speed injection, allowing the melt to fill the rib area within 0.01 seconds and coordinating 1000 Hertz of mold cavity pressure closed-loop control, theoretically it is feasible." The distance from theory to practice took us sixty days to measure.

When the first set of molds was tested, the burrs at the top of the ribs were as fine as dandelion fluff, but after gold plating, they became a fatal defect. The team tried eleven sets of process parameters, and the burrs only dropped from 0.002 millimeters to 0.001 millimeters - for electromagnetic waves, this is still an insurmountable gap. The turning point came on a rainy night. The technical consultant of the material supplier casually said: "Have you tried making a diamond-like coating on the mold surface? That stuff is harder than steel and has a friction coefficient nearly zero." Three days later, when the coated molds were re-molded together, the burrs disappeared. At that moment, several men in the workshop hugged and wept in the workshop.

However, the real disaster struck on the eve of mass production. At 2 a.m., the automated production line suddenly alerted - the mechanical hand broke three ribs when picking up the parts. We retrieved the slow-motion video to discover that the thin wall of 0.09 millimeters would have a slight tremor of 0.3 seconds after ejection, while the movement trajectory of the mechanical hand was rigid. That dawn, the electrical engineer came up with a romantic solution: Let the mechanical hand imitate the hovering action of bees collecting nectar, performing a 0.1-second resonance matching before contacting the plastic part. This algorithm derived from the flying action of insects ultimately saved the entire project.

Last week, Huawei sent the first batch of 100,000 product test reports. In the "million defect rate" column, the number was 0. Along with the report, there was also a thank-you letter, which ended with: "In the darkest hour of US technology blockade, it is such enterprises that have supported the millimeter-wave sky for China's chips."

Now, these 0.09 millimeter plastic parts are being encapsulated on the 5G base station chips independently developed by China. When you smoothly download high-definition videos at the airport, you may not know that behind that smoothness there is a group of Chinese engineers who fought for 60 days for 0.001 millimeter burrs. This story is small, small to the point of only concerning fractions of a millimeter; this story is big, big enough to relate to the communication future of a country.

Building China's 5G defense line at the limit thickness of 0.09 millimeters - Golden Eagle Precision Injection Molding puts the unparalleled armor on domestic chips.