Application Scenarios
In a PVD sputtering chamber, argon gas is introduced at controlled flow rates while the pump maintains process pressure at a setpoint. A thermal conductivity gauge would read differently as the gas composition shifts between argon and residual outgassing species, causing pressure control drift and inconsistent film properties. The MKS 902-1112 solves this by measuring absolute pressure directly through a piezoresistive silicon sensor—its reading depends only on the force exerted on the diaphragm, not on which gas molecules are doing the pushing. When the chamber undergoes rapid venting for substrate transfer, the solid-state sensor withstands the air inrush without damage, a failure mode that disables many competing sensor technologies. For facilities running recipe-driven processes, the RS-485 digital interface allows the control system to poll pressure values at 0.1 Torr resolution, providing tighter feedback than a 10 mV/Torr analog signal alone.
Parameter
| Parameter | Value / Description |
|---|---|
| Product Model | MKS 902-1112 |
| Manufacturer | MKS Instruments (USA) |
| Product Category | Piezo Vacuum Transducer / Absolute Pressure Sensor |
| Series | 902 / PVD21 |
| Sensor Technology | MEMS Piezoresistive (Silicon) |
| Measurement Range | 0.1 to 1000 Torr (Full Scale, Absolute) |
| Accuracy (100–1000 Torr) | ±1% of Reading |
| Repeatability (100–1000 Torr) | ±0.3% of Reading |
| Analog Output | 0–10 VDC (Linear, 10 mV/Torr) |
| Digital Communication | RS-485 (Model 902-1112) |
| Supply Voltage | 9–30 VDC |
| Power Consumption | < 1.2 W Maximum |
| Pressure Connection | NW16 ISO-KF (KF16) |
| Exposed Materials | 316 Stainless Steel |
| Operating Temperature | 0°C to 50°C |
| Maximum Bakeout (Non-operating) | 85°C to 100°C |
| Overpressure Limit | 1500 Torr |
| Weight | Approx. 0.17 kg (with KF16 flange) |
Technical Principles and Innovative Values
Innovation Point 1 – Gas-Type Independence Eliminates Calibration Drift: Unlike Pirani or thermocouple gauges whose readings vary with thermal conductivity of the gas being measured, the MKS 902-1112 responds only to mechanical deflection of its silicon piezoresistive element. In processes where gas composition changes—sputtering with reactive gases, freeze-drying where water vapor dominates then diminishes—the transducer maintains accuracy without recalibration for each gas species.
Innovation Point 2 – Solid-State Sensor Survives Air Inrush and Vibration: The silicon piezoresistive sensor element has no filaments, no moving mechanical parts, and no fragile membrane assembly. Rapid venting that would rupture a hot cathode gauge or degrade a thermal conductivity sensor does not affect the MKS 902-1112. Its robust construction also tolerates the mechanical vibrations present on roughing pump lines and mobile vacuum carts.
Innovation Point 3 – Dual Analog and Digital Output in One Compact Housing: The MKS 902-1112 provides both a 0–10 VDC analog signal and an RS-485 digital interface from the same device. The analog output integrates with legacy PLCs and chart recorders, while the digital channel enables reading the transducer’s 0.1 Torr resolution digital value and accessing diagnostic parameters. This dual-interface design eliminates the cost and panel space of separate analog and digital transmitters.
Innovation Point 4 – Compact Integrated Electronics Reduce System Footprint: By integrating signal conditioning, analog output drivers, and digital communication circuits directly into the transducer housing, the MKS 902-1112 eliminates the external signal conditioner or display controller that older vacuum gauge designs required. The result is a single compact device that mounts directly on the vacuum chamber port and connects straight to the control system.
