Mass production of 0.15mm ultra-thin Type-C housing.

In 2024, a leading global consumer electronics brand launched an R&D project for a new generation of ultra-thin laptops. To further reduce the chassis thickness while maintaining interface strength, the wall thickness of its Type-C power and data connector housing had to be reduced to 0.15mm. This specification far exceeds the industry standard of 0.25-0.30mm. The brand's original process, traditional precision stamping combined with brazing, frequently encountered issues such as cracking, burrs, and insufficient weld strength when attempting wall thicknesses below 0.20mm, causing the yield rate to drop to below 80%, which could not meet the delivery requirements for orders in the millions.

After receiving the technical requirements, Fangchi MIM formed a dedicated task force comprising teams from the R&D Center's Materials Group, Mold Group, and Injection Process Group. The first challenge was the feedstock. Commercially available standard 316L stainless steel feedstock exhibited insufficient flowability for wall thicknesses below 0.20mm, making it prone to short shots or weld lines. The team conducted 27 sets of orthogonal formulation experiments in the lab, ultimately increasing the paraffin wax ratio in the binder system from the conventional 45% to 52% and adding a small amount of stearic acid as a surfactant. This increased the feedstock's melt flow index at injection temperature by approximately 35%. Under a cavity pressure of 120MPa, the new feedstock could successfully fill thin-wall areas as thin as 0.15mm, with a uniform flow front temperature distribution and no cold material marks.

The second challenge was the mold. To achieve a dimensional tolerance of ±0.01mm on a 0.15mm wall thickness, the mold cavity had to be manufactured using high-speed milling combined with mirror EDM to ensure a cavity surface roughness of Ra ≤ 0.1μm. The mold was also designed with an eight-point sequential valve hot runner system. Simulation analysis determined the gate location at the midpoint of the housing's long side, allowing the melt to fill symmetrically from the center toward both ends, avoiding warpage caused by unbalanced flow. During the first mold trial, the parts still exhibited localized incomplete filling. The team adjusted the mold temperature to 110°C and increased the injection speed from 80mm/s to 120mm/s, finally obtaining fully filled samples.

The third critical point was precise control of the sintering shrinkage rate. Thin-wall parts of 0.15mm are extremely sensitive to the temperature uniformity of the sintering furnace. Fangchi technicians conducted multi-point furnace temperature tests on nine sintering furnaces, fixing parts from the same batch in the central zone of the same furnace chamber. A mixed atmosphere of nitrogen and hydrogen was used for protection, controlling the carbon content fluctuation on the part surface after debinding to within ±0.02%. After three consecutive trial production runs totaling 120,000 parts, the shrinkage compensation coefficients for the green part dimensions were finalized: 1.175 in the length direction, 1.168 in the width direction, and 1.182 in the thickness direction. After batch sintering, the product's dimensional CPK value reached above 1.33.

During the mass production phase, Fangchi dedicated 6 out of its 24 injection molding machines to a dedicated production line for this housing. A fully automated CCD dimensional inspection system was deployed, capable of inspecting 700 parts per hour and simultaneously measuring 12 dimensions, including housing length, width, wall thickness, and latch position. Inspection data is uploaded to the MES system in real time. If a dimensional drift trend is detected, the system automatically triggers an alarm and prompts the operator to fine-tune the holding pressure or mold temperature. After a three-month ramp-up, the daily production capacity for this product stabilized at 900,000 units, with an overall yield rate exceeding 98.5%.

To date, Fangchi has delivered over 120 million ultra-thin Type-C housings to this brand, widely used in its flagship laptops, tablets, and some high-end smartphones. The customer's procurement department commented: 'Fangchi is the only supplier capable of stable mass production at a 0.15mm wall thickness, with yield rates and delivery schedules far exceeding those of other candidate vendors.' This case has further solidified Fangchi's industry-leading position in the field of ultra-thin MIM parts for consumer electronics.