What pulse-current test asks of a switch
When an ATE system tests power discretes such as MOSFETs, it needs a switch that carries a high pulse current without distorting the pulse shape. The current pulse does two jobs: it confirms the DUT survives the current or surge without degradation, and it exposes a weak die-to-substrate bond, which shows up under pulse stress. Because each device runs several tests at different voltages and currents, the same switch also has to isolate the test resources from one another and keep working across billions of cycles.
Why the standard alternatives miss a requirement
- Electromagnetic relays carry current but their pivoting mechanics wear out near one million operations, well short of production ATE duty.
- Semiconductor switches rarely combine the needed current and voltage in one die, forcing stacked topologies or compromised isolation.
Reed relays built around one or more sealed capsules combine long-life contacts with the voltage and pulse-current headroom this test needs.
HGFR and HVFR for pulse duty
The HGFR and HVFR series both switch low-level signals billions of times and carry high-current pulses on the same channel, which suits systems that mix precision measurement and pulse stress. They carry 3 A continuously and a 5 A pulse for up to 5 ms without distorting the leading or trailing edge. For larger pulses the timing rule is to energize the coil and wait at least 5 ms before applying current so the blade is settled. Clean edges matter because the pulse is what reveals die and bond integrity; a distorted edge masks the very defect the test looks for.
HGFR: high-insulation mercury wetted relay
- Dielectric withstand to 3.5 kVDC
- Continuous make current to 3 A
- Low contact resistance on long-life sealed contacts
- Insulation resistance 10 TΩ and above
HVFR: high-voltage, high-insulation dry reed relay
- Switching voltage to 1 kV (2 kV momentary)
- 1 A switching; pulse current 5 A / 10 A / 20 A
- Dielectric withstand 3 kV and above; insulation 10 TΩ and above
- Switching within 1.2 ms; life above one billion operations
Why the contact preserves the pulse
The pulse fidelity comes from the contact interface. Sealed in inert gas (HVFR) or mercury-wetted (HGFR), the contact stays free of the oxide and contamination films that build on an open mechanical contact; a clean, low-resistance path carries the pulse without the ringing, voltage drop and edge rounding a degraded contact introduces. Choose HGFR where bounce-free mercury contacts help with the most demanding pulse edges, and HVFR where a dry, high-voltage contact is preferred and the pulse-current ladder (5/10/20 A) matches the DUT.
About SHR AUTOSENSOR
SHR AUTOSENSOR TECH LIMITED (SHR AUTOSENSOR) manufactures high-voltage reed relays, mercury wetted relays and high-voltage DC contactors. Contact: [email protected] | +86 13761571029 | www.reed-relay.com