Product details
UFC-1661e at a Glance
- UFC-1661e is a digital mass flow controller from UNIT Instruments.
- It comes from the 1660/1661e Series with enhanced MultiFlo tech.
- It runs 30 to 30,000 sccm in N2 terms.
- MultiFlo lets you set full scale from 33% to 100%.
- One tool can serve many gas and range jobs.
- The unit answers in under 1 second per SEMI E17.
- Metal seals protect high-purity corrosive gas lines.
- This is the current model. Product pages were verified in November 2026.
Key Specs
- Brand: UNIT Instruments
- Model: UFC-1661e
- Series: 1660/1661e Series
- Type: Enhanced MultiFlo digital mass flow controller
- Flow range: 30 to 30,000 sccm, N2 equivalent
- Accuracy: +/-1.0% of setpoint (35% to 100% FS)
- Low-range accuracy: +/-0.35% FS (10% to 34% FS)
- Calibration: 32-point table per gas, 3-sigma guarantee
- Repeatability: +/-0.15% FS
- Response: under 1 second settling, tunable up to 20 seconds
- Gas type: unlimited process gases via MultiFlo
- Factory gas: N2 baseline calibration
- Inlet pressure: 20 to 60 psia with atmospheric exhaust
- Proof pressure: 140 psig
- Burst pressure: 500 psig
- Differential: 7 to 45 psid, range dependent
- Wetted parts: 316L stainless steel and 7Mo (SEMI F20)
- Surface finish: 10 or 16 micro-inch Ra (SEMI F19)
- Seals: metal C-seal or W-seal
- Seat: Kel-F or metal
- Temperature: 0 to 50 degrees C (32 to 122 degrees F)
- Turndown: 2% to 100% FS
- Linearity: +/-0.5% FS
- Zero stability: 0.6% FS per year or less
- Auto zero: standard on digital models
- Temperature effect: zero 0.05% FS per degree C, span 0.1% FS per degree C
- Pressure effect: 0.007% of reading per psi (N2)
- Size: about 137 x 127 x 38 mm
- Footprint: 1.5 inch
- Length: 124 mm with 1/4 VCR
- Weight: 1.2 kg (2.65 lb)
- Power: +/-15 VDC or 11 to 25 VDC, 160 mA max
- Valve: proportional electromagnetic, Unit 132 type
- Valve modes: normally closed or normally open
- Leak rate: 1 x 10^-10 atm-cc/sec He
- Heat: none, standard unheated version
Signal and Control Detail
- Dual connector design: analog plus RS-485 daisy-chain.
- Analog choices: 9-pin D-sub or 20-pin card edge.
- RS-485 uses a modular jack for multi-unit chains.
- Auto zero trims drift on its own.
- Response time is programmable from under 1 second.
- Slow ramps up to 20 seconds cut pressure spikes.
Fit, Setup and Service
- Mount on a clean, level gas panel.
- Use 1/4 VCR lines for a 124 mm overall length.
- Keep inlet at 20 to 60 psia with atmospheric exhaust.
- Do not exceed 140 psig proof pressure.
- Set full scale from 33% to 100% on site.
- Change gas type and range without a factory trip.
- Metal seals suit reactive and corrosive gas service.
- Check zero once a year. Auto zero handles small drift.
- Pick the 20-pin card edge for rack-based tools.
Compatibility and Certification
- CE certified for the European market.
- Meets SEMI E12, E16, E17, E27 and E56.
- Calibration is NIST-traceable.
- Wetted parts meet SEMI F20 and F19.
- Works with common analog and RS-485 host systems.
Best-Fit Equipment and Scenarios
- Plasma etch chambers that need fast, stable gas flow.
- CVD and EPI tools with many gas recipes.
- Diffusion furnaces and sputtering lines.
- High-purity corrosive and reactive gas delivery skids.
- Labs that swap gases and ranges often.
- Rack-based systems with 20-pin card edge wiring.
FAQ
- Q: Can one unit cover several flow sizes?
A: Yes. MultiFlo sets full scale from 33% to 100%. You pick the range on site. - Q: Do I need to send it back to change gas?
A: No. You can set gas and range in the field. This saves shipping time. - Q: What helps most with corrosive gas service?
A: Choose the metal C-seal or W-seal option. Keep lines dry and clean. - Q: How do I wire it into a large tool?
A: Use the RS-485 modular jack for daisy chains. Use the analog port for setpoint and readback. - Q: From field experience, what causes slow settling?
A: Long ramp settings are a common cause. Shorten the ramp when speed matters. Also check inlet pressure stays in the 20 to 60 psia window.
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