VPI Andrew Li
2025年2月11日
In high vacuum sputtering coating equipment (VPI 650MH series sputtering coater), controlling gas flow is crucial for the stability of the sputtering process. Common gas flow control devices include Electromagnetic Flow Valve (Em) and Mass Flow Controller (MFC). They have different working principles and application scenarios, so how should you choose?
Electromagnetic Flow Valve: Relatively Simple Structure, Suitable for On/Off Control
Working Principle
An electromagnetic flow valve is a device that controls valve switching based on an electromagnet, working similarly to an electromagnetic relay:
When the solenoid coil is energized, the electromagnet generates a magnetic field, driving the valve core to open, allowing gas flow.
When the solenoid coil is de-energized, the magnetic field disappears, and a spring or air pressure pushes the valve core to close, stopping the gas flow.
It can also use PWM (Pulse Width Modulation) to achieve simple flow adjustment, but the control precision is low.
Advantages
✅ Simple structure, low cost✅ Suitable for fast switching control✅ Easy maintenance, long service life
Disadvantages
❌ Cannot precisely regulate gas flow, only suitable for on/off control❌ Poor flow stability, greatly affected by environmental temperature and pressure changes
Application Scenarios
Gas circuit systems requiring simple on/off control
Rough gas control into the vacuum chamber during pre-vacuum extraction
Applications where flow precision is not critical, such as general gas transport
Gas Mass Flow Controller (MFC): High-Precision Flow Control
Working Principle
MFC uses thermal mass flow sensors or differential pressure measurement technology, combined with electronic feedback control, to achieve precise regulation of gas mass flow (rather than volumetric flow):
The sensor continuously detects gas flow and transmits data to the control system.
The control system compares the set value and adjusts the flow through a proportional valve to keep it stable.
Since mass flow measurement is used, it is not affected by temperature and pressure changes.
Advantages
✅ High precision (typically ±1% of the set value or better)✅ Enables stable gas flow control✅ Flexible adjustment, suitable for various process gases✅ Less affected by environmental changes, ensuring long-term stable flow
Disadvantages
❌ Higher cost❌ Requires periodic calibration to ensure accuracy
Application Scenarios
High vacuum sputtering coating processes, precise control of process gas flow (e.g., argon, oxygen, nitrogen)
Semiconductor manufacturing, used for vapor deposition (PVD)
Gas analysis instruments, applications requiring strict gas flow control
Chemical and bioengineering, precise control of reaction gas flow
How to Choose?
Requirement | Choose Electromagnetic Flow Valve | Choose Gas Mass Flow Controller (MFC) |
Simple on/off control needed | ✅ Suitable | ❌ Not suitable |
Precise gas flow control needed | ❌ Not suitable | ✅ Suitable |
Affected by temperature, pressure changes | ✅ Highly affected | ❌ Minimally affected |
Suitable for high vacuum coating processes | ❌ Not suitable | ✅ Suitable |
Limited budget | ✅ Low cost | ❌ High cost |
How to Choose for High Vacuum Sputtering Coating Equipment?
If only gas switching is needed, such as vacuum chamber exhaust control or rough gas intake regulation, an Electromagnetic Flow Valve (Em) can be chosen.
If precise gas flow regulation is required, ensuring uniformity and stability in the coating process, an MFC (Mass Flow Controller) is essential.
In high vacuum sputtering coating equipment, MFC is sometimes indispensable, as precise gas flow control directly affects coating quality and repeatability. If you are selecting or upgrading coating equipment, consult VPI's technical engineers for the best solution tailored to your experiments.