Bare Alloy Current Sense Resistor

The Bare Alloy Current Sense Resistor from RST Electric represents the state-of-the-art in precision current sensing technology. Designed for applications where board space is at a premium and measurement accuracy is paramount, this Surface Mount Shunt utilizes an advanced electron beam welding process to join a high-stability alloy resistance element with pure copper electrodes. This all-metal construction eliminates the parasitic inductance and thermal EMF common in conventional thick-film or wirewound shunts, enabling fast, accurate current detection in high-frequency circuits.

Core Material

The core of this Low Ohm Resistor is a precision alloy element available in three material options: Manganin (CuMn) for low TCR applications, Karma (NiCr) for superior stability, and FeCrAl (Iron-Chromium-Aluminum) for high-temperature environments. The element is electron beam welded to pure copper terminations, creating a monolithic structure with minimal contact resistance and exceptional mechanical strength. The result is a resistor capable of withstanding high surge currents, thermal cycling, and long-term aging without drift.

The WSN series is available in four standard surface-mount footprints:

● 2512 (6.4×3.2mm) – 3W rating, ideal for compact power stages

● 3920 (10×5.2mm) – 5W rating, optimized for automotive and industrial applications

● 5930 (15×7.2mm) – 7W rating, for high-current bus bars and battery packs

● 2726 (6.95×6.6mm) – 5W rating, unique low-profile square format for dense layouts

Resistance values span from an industry-leading 0.1mΩ up to 5mΩ, with tolerances as tight as ±0.5% and TCR as low as ±100 ppm/°C (Manganin). Each unit undergoes rigorous reliability testing per AEC-Q200 standards, including temperature cycling, high-temperature storage, load life, and humid heat exposure.

As a trusted Bare Alloy Current Sense Resistor manufacturer in China, RST Electric combines over 10 years of precision resistor engineering with advanced manufacturing techniques to deliver components that meet the most demanding requirements of automotive, industrial, and renewable energy applications.

Technical Specification

Product Features

1.Electron Beam Welded Construction – Monolithic alloy-to-copper weld eliminates contact resistance and ensures exceptional mechanical strength and long-term stability.

2.Ultra-Low Resistance Down to 0.1mΩ – Enables accurate measurement of hundreds of amperes with minimal power loss and voltage drop .

3.Extremely Low Inductance (0.5nH – 5nH) – Near-zero parasitic inductance allows use in high-frequency switching circuits (up to several MHz) without signal distortion.

4.Very Low Thermoelectric EMF (<1µV/°C) – Minimizes measurement errors caused by temperature gradients across the resistor, critical for precision current sensing.

5.Multiple Alloy Options – Choose Manganin (low TCR), Karma (high stability), or FeCrAl (high-temperature) to optimize performance for specific applications.

6.Industry-Standard SMD Footprints – Available in 2512, 3920, 5930, and 2726 sizes, compatible with automated assembly processes.

7.High Power Density – Up to 7W in a compact 5930 package, ideal for space-constrained power modules and battery packs.

8.Precision Tolerances – ±0.5% available for high-accuracy current measurement in automotive BMS and industrial drives.

9.All-Metal Structure – No ceramic substrate or thick-film materials ensures superior pulse handling and thermal conductivity.

Product Applications

Drawing and dimensions

Package and shipment

RST Electric ensures safe delivery of every Bare Alloy Current Sense Resistor:

● Tape & Reel Packaging: All WSN series resistors are supplied on 7-inch or 13-inch reels (quantity per reel: 4000 for 2512, 2000 for 3920/5930, 1000 for 2726), compatible with automated pick-and-place assembly.

● Bulk Packaging: Available upon request for prototyping or small-volume production.

● Moisture Sensitivity: These resistors are classified as MSL 1 (unlimited shelf life) and do not require special handling for moisture.

● Documentation: Packing lists, inspection certificates, and material declarations included with each shipment.

● Freight Options: Express courier (DHL/FedEx/UPS) for small quantities, air freight for medium volumes, sea freight for bulk orders.

FAQ

1.Q: What are the advantages of choosing RST Electric?

A: We have been deeply involved in the Bare Alloy Current Sense Resistor field for over 10 years. We are a certified manufacturer with full control over alloy selection, electron beam welding and testing processes. There are no intermediate steps. The factory supplies products directly at a high cost-effective price. We have an ISO 9001-certified production base and dedicated production lines. Each product undergoes 100% electrical testing, and samples pass the AEC-Q200 automotive-grade reliability tests. The quality is stable and controllable, and it can precisely adapt to demanding scenarios such as automotive and industrial applications.

2. Q: What customization services does your company offer?

A: We provide comprehensive customization services across multiple dimensions: The package size supports standard specifications such as 2512 and 3920, as well as custom sizes; the resistance range is from 0.1mΩ to 5mΩ, and special resistance values can be customized; the tolerance can be as low as ±0.1%, suitable for different precision requirements; the material can be manganese copper, Kama, etc., or customized alloys; at the same time, the TCR option of ±100 to ±750ppm/°C is supported, and the terminal coating can be selected as pure tin, tin-lead or gold plating as per demand.

3. Q: What are the quality guarantees?

A: Each Bare Alloy Current Sense Resistor we produce undergoes 100% electrical testing, with a focus on checking core parameters such as resistance value and tolerance. Samples are also tested according to the AEC-Q200 standard, including temperature cycling, load life, high-temperature storage, and humidity testing, which fully meet the performance requirements for automotive applications. We have an ISO 9001 certification production system, and a professional engineering team dedicated to automotive-grade current detection solutions, ensuring the long-term stability and reliability of the products.

4. Q: What are the delivery time, shipping methods and after-sales guarantees?

A: The delivery time is flexible. For standard-sized products, it takes 10-15 working days; for customized products, it takes 15-25 working days. The shipping method can be chosen based on the purchase quantity. For small batches, international courier services like DHL can be used; for medium batches, air freight can be adopted; for large batches, sea freight can be used. After-sales provide a 12-month warranty. Remote fault diagnosis and delivery of spare parts are available. Complete documents such as test reports and material certificates can be provided with the goods. At the same time, product integration technical support is provided throughout the process to ensure a worry-free purchase experience.