Description:

The 628A11TBE​ is a heated absolute capacitance manometer (pressure transducer) from MKS Instruments, part of the Baratron® Type 628A family of temperature-controlled vacuum measurement instruments. It measures absolute pressure in vacuum and low-pressure process environments and converts it into a linear 0 to +10 VDC signal for a controller, PLC, DCS or readout.Decoding the order number from the MKS model-code structure (62XA–XXX–Y–Z): 628A is the type (sensor temperature regulated at 100 °C), 11T is the full-scale range code for 10 Torr, B selects the Swagelok 8-VCR female​ process fitting, and E specifies ±0.25 % of reading​ accuracy. The electrical connection on the Type 628 is a 15-pin Type “D” connector.What defines the 628A11TBE​ against ordinary pressure transmitters is the heated sensor. The sensing head is actively regulated at 100 °C, roughly double the 45 °C used on the 627 series, specifically so that condensable process byproducts do not deposit on the diaphragm and so that ambient temperature swings do not move the zero. Combined with an all-Inconel wetted surface and a single-sided dual-electrode capacitance sensor, the 628A11TBE​ is built for processes where the gas is corrosive, dirty or prone to polymerising — conditions that destroy ordinary sensors within weeks.Buyers should be aware of two practical points. First, several reseller listings describe this part with specifications it does not have (4–20 mA output, psi ranges, IP65, −40 °C ratings); those do not match MKS documentation and should be disregarded. Second, the 628A is a legacy product — the RoHS-compliant successors are the 628D​ and 628H, which MKS states are interchangeable with earlier Type 128, 628A and 628B manometers.

Application Scenarios:

A semiconductor fab runs a plasma etch tool with a chamber base pressure around a few mTorr and process pressure in the 5–50 mTorr to low-Torr window. The process chemistry produces condensable fluorine and polymer byproducts that happily coat anything cooler than the chamber walls. An unheated or 45 °C gauge slowly accumulates that film on its diaphragm, and the symptom is not a hard failure — it is a zero that drifts a little more every week, so that recipes that once produced good etch depth quietly start producing scrap. Fitting a 628A11TBE​ addresses this at the physical level: because the 628A11TBE​ holds its sensor at 100 °C, the byproducts stay in the vapour phase and do not condense on the measuring element, so the zero stays where it was set.The same logic applies in a PECVD or ALD tool, where precursor gases are deliberately reactive and any cold spot becomes a deposition site. Here the pain point is not just drift but tool availability: every time a gauge drifts out of tolerance the chamber must be vented, the gauge pulled and re-calibrated, and the process re-qualified. Keeping a 628A11TBE​ on the shelf — and, more importantly, keeping an accurate spare so the swap does not require a recipe re-qualification — converts a multi-shift outage into a scheduled maintenance item.Across both scenarios the value of the 628A11TBE​ is that it measures total pressure directly and independently of gas composition. Whether the chamber holds nitrogen, argon, silane or a fluorine mix, the reading depends on pressure alone, so one sensor covers an entire recipe portfolio without gas-specific correction factors.

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Technical Principles and Innovative Values:

• Innovation Point 1 — 100 °C thermal regulation rather than compensation alone: Most “temperature compensated” instruments correct for temperature arithmetically. The 628A11TBE​ instead holds the sensor at a fixed 100 °C, so ambient variation never reaches the diaphragm in the first place. The higher setpoint compared with the 45 °C 627 series is a deliberate contamination strategy: process byproducts that would condense at 45 °C remain vapour at 100 °C, which is why the 628A11TBE​ is specified for the harshest chemistries.
• Innovation Point 2 — Measurement independent of gas composition: Because the sensor measures the physical force on a diaphragm rather than a gas-dependent property such as thermal conductivity, the 628A11TBE​ reads total absolute pressure identically for nitrogen, argon, oxygen or reactive process gases. There is no gas correction table, no per-recipe calibration factor, and no error introduced when a chamber switches chemistry between steps.
• Innovation Point 3 — Single-sided dual-electrode Inconel sensor with a fixed-frequency bridge: This mechanical and electrical architecture is what allows the 628A11TBE​ to survive 45 psia overpressure — more than three times atmospheric — with minimal or no shift in output. In practice that means an accidental vent to atmosphere during maintenance does not automatically mean a new transducer, which is a real and recurring cost in vacuum plants.
• Innovation Point 4 — Percent-of-reading accuracy where it matters: Accuracy is stated as a percentage of reading, not of full scale. At the bottom of the range, where vacuum processes actually run, that distinction is substantial — a full-scale specification would make low-pressure readings nearly meaningless, whereas the 628A11TBE​ holds 0.25 % of the actual value down through four decades.
• Innovation Point 5 — Low-impedance bridge conditioning plus full RFI and surge protection: The signal conditioner is paired with a metal enclosure, surge and ESD suppression networks and RFI filtering on every input and output. Plasma chambers are electrically hostile environments, and the 628A11TBE​ is designed on the assumption that RF energy from the plasma source is present rather than hoping it is not.
• Innovation Point 6 — Interchangeability that protects the installed base: MKS documents the successor 628D and 628H as interchangeable with earlier Type 128, 628A and 628B manometers, and the 15-pin “D” interface and ±15 V / 0–10 V signal standard are shared across the 600 series. That means a legacy tool can be migrated one gauge at a time rather than through a full instrument redesign.