The medical device customer called us in August. They had just received FDA 510(k) clearance for a new portable patient monitor, and they needed a silicone keypad supplier that could ramp from 5,000 units per month to 25,000 units per month in 90 days. Our existing cleanroom could handle 15,000 units per month. We were 10,000 units short.
We broke ground on the cleanroom expansion two weeks later. The project took 45 days from design to validation, and we shipped the first 25,000-unit batch on October 15. The customer's quality manager walked through the expanded room last week and said, "This is cleaner than our own production floor."
We have now expanded our Class 100,000 cleanroom by 40%, from 180 square meters to 252 square meters. The new space adds two silicone compression molding presses, a dedicated ESD assembly line, and a separate packaging area for sterile-ready components.
What a medical cleanroom actually requires
A lot of customers ask us why we need a cleanroom for silicone buttons. Silicone rubber does not rust, and it does not outgas like some plastics. The issue is not the silicone itself, but what gets on it during production. A single dust particle on a silicone button that goes into an infusion pump can cause a visual defect that the customer's inspector will reject. A single fiber from a work uniform can get trapped under the silicone button and cause a tactile feel issue after assembly.
Our cleanroom is Class 100,000, which means no more than 100,000 particles of 0.5 microns or larger per cubic foot of air. We maintain this with HEPA filters that recirculate the air 20 times per hour. The temperature is held at 23C ±2C, and the humidity at 45% ±10%. Both are monitored continuously, and the data is logged to our quality management system.
Medical-grade silicone button assembly line in our Class 100,000 cleanroom.
Everyone who enters the cleanroom goes through an airlock. We wear smocks, hair covers, beard covers, shoe covers, and nitrile gloves. We wash our hands before putting on the gloves. We cannot bring phones, paper notebooks, or pens into the room. We use a computer terminal mounted on the wall for process data.
What the expansion added
The original cleanroom had one 80-ton compression molding press and one assembly line. The expansion adds:
Two new 60-ton compression molding presses - these run platinum-cured silicone, which is required for medical applications because it does not contain peroxide byproducts. The presses have closed-loop temperature control, holding the mold at 175C ±5C within a 0.5C tolerance.
A dedicated ESD assembly line - this line assembles the silicone buttons onto the dome sheet arrays. The workbenches have ESD mats, wrist strap points, and ionizing air blowers to remove static. We measure the surface resistance of every workbench at the start of each shift.
A sterile-ready packaging area - this is a separate room within the cleanroom, where we bag the assembled keypads in anti-static bags with desiccant. The bags are heat-sealed, labeled with the lot number, and dated. We also provide a certificate of conformity with every shipment.
Four-legged stainless steel domes used in medical-grade silicone keypads.
How we validate a new cleanroom
We did not just build the room and start production. We ran a 14-day validation protocol before we allowed any customer production to run in the new space.
Day 1-3: We measured particle counts, temperature, and humidity at 12 points in the room, twice per day. All readings had to stay within spec for 72 hours straight.
Day 4-7: We ran a "dummy production" run. We used scrap silicone material to run the new presses through 100 cycles, measuring the flash, the part dimensions, and the force required to demold. We had to demonstrate that the new presses produced parts within the same tolerance as the old presses.
Day 8-14: We ran a full production validation. We produced 5,000 keypad assemblies for our existing medical customer, and we inspected every part. The acceptance rate was 99.6%, which matched our historical average. Only after this did we release the new space for customer production.
What this means for our customers
If you are a medical device OEM looking for a silicone keypad supplier with cleanroom capacity, we can now support programs from 5,000 to 50,000 units per month. We also have the capacity to support membrane switch panels and FPC button assemblies for medical devices, all produced in the same cleanroom.
We are also building a Class 10,000 cleanroom next year, which will allow us to produce components for implantable medical devices. That project should be complete by Q3 2027.
- John Smith, Senior Application Engineer, Shanyo
