WALTER Alloy Resistors: HFCL-3618 Series Current Sensing Resistors Product Details
Date：2025-12-19
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The HFCL-3618 series current sensor resistor is a high-performance electronic component manufactured with advanced cermet technology, belonging to the category of four-terminal, side-electrode-free, long-electrode current sensor resistors. Made of MnCu alloy as the core resistive material, this product features precise resistance control, excellent temperature stability, and reliable structural design. It is widely applied in various electronic devices and industrial scenarios requiring high-precision current detection, providing critical support for the safe and stable operation of circuit systems.
Core Specifications
Resistance Range
The resistance range covers 1mΩ~25mΩ. For the 1mΩ~4mΩ range, the resistance tolerance is ±1% (Grade F), while the 5mΩ~25mΩ range offers two precision options: ±0.5% (Grade D) and ±1% (Grade F), which can be flexibly adapted to the precision requirements of different application scenarios. Custom non-standard resistance values are also available upon customer request to further expand the application scope.
Power and Temperature Characteristics
The rated power is 3.0W, enabling continuous full-load stable operation at an ambient temperature of 70℃. The product boasts an excellent Temperature Coefficient of Resistance (TCR): ±100ppm for the 1mΩ~4mΩ range and an optimized ±50ppm for the 5mΩ~25mΩ range, ensuring minimal resistance change within a wide operating temperature range. It operates reliably within a broad temperature range of -55℃~155℃. When the ambient temperature exceeds 70℃, the load can be reasonably adjusted according to the standard power derating curve to maintain stable performance.
Physical Dimensions
The product features precise and controllable physical dimensions with the following parameters: Length (L) 9.00±0.30mm, Width (w) 4.50±0.30mm, Thickness (T) 0.60±0.20mm. The electrode-related dimensions are A=0.65±0.20mm, B=0.90±0.20mm, C=0.75±0.20mm, and D=7.25±0.30mm. The standardized dimension design facilitates automated assembly and circuit board layout.
Structure and Materials
The product adopts a multi-layer composite structure, with each component selected from high-quality materials to ensure overall performance and reliability:
1. Substrate: Made of alumina ceramic, it offers excellent insulation, thermal conductivity, and mechanical strength, providing stable support for the resistive element;
2. Adhesion Layer: Epoxy resin is used to achieve firm bonding between the substrate and the resistive element, ensuring structural stability;
3. Resistive Element: High-purity Cu-alloy is adopted, featuring low resistance, high conductivity, and excellent temperature stability, serving as the core component for high-precision current detection;
4. Terminal Electrode: A multi-layer composite structure of Sn, Ni, and Cu, providing good solderability and oxidation resistance to ensure firm welding and excellent electrical conductivity;
5. Protective Coating: Green flame-retardant epoxy resin that meets UL-94-V0 standards, effectively isolating the internal structure from external environmental erosion;
6. Marking Coating: Black flame-retardant epoxy resin that also complies with UL-94-V0 requirements, clearly marking product information with high wear resistance.
Reliability and Environmental Characteristics
Reliability Tests
The product has passed rigorous reliability tests, with all performance indicators complying with IEC60115-1 standards:
• Short Time Over Load Test: Under an ambient temperature of 25±2℃, applying 2.5 times the rated power for 5 seconds, the resistance change does not exceed ±(1.0%+0.5mΩ);
• High/Low Temperature Tests: Excellent resistance stability after 1000 hours of storage at -55±2℃ (low temperature) and 1000 hours of exposure at 170±2℃ (high temperature);
• Moisture Load Life Test: Under 60±2℃ and 95% relative humidity, with a cycle of 90 minutes on and 30 minutes off for 1000 hours, the resistance change does not exceed ±(2.0%+0.5mΩ);
• Thermal Shock Test: 100 cycles of -55℃ (30min) → Room Temperature (3min) → 155℃ (30min) → Room Temperature (3min) without performance degradation;
• Resistance to Solder Heat and Solderability: Capable of withstanding 3±0.5 seconds of dip soldering in a solder bath at 245±5℃ and 20±1 seconds of reflow soldering at 275±5℃, with solder coverage exceeding 95% and resistance change meeting standards after soldering;
• Mechanical Performance: Passed 5 mechanical shock tests with 100G acceleration and 11ms duration, as well as substrate bending tests with a fulcrum spacing of 90mm and a bending width of 2mm, with no significant resistance change.
Environmental Adaptability
It offers flexible storage conditions: 2 years of storage in an airtight environment with a temperature of 10℃~40℃ and relative humidity ≤75%; maximum 30 days of storage in a non-condensing environment with a temperature of 10℃~60℃ and relative humidity of 95%, facilitating inventory management and long-term use.
Soldering and Packaging
Soldering Specifications
Recommended soldering methods include infrared, vapor phase, and hot air. Reflow soldering must follow the standard temperature profile with a peak temperature not exceeding 275±5℃. For iron soldering (hot air equipment), the temperature should be controlled at 350℃ with a soldering time of 3~5 seconds to avoid product function damage due to overheating. The recommended solder pad dimensions are P=2.80mm, W=7.80mm, D=1.40mm, V=1.10mm, and E=0.55mm, suitable for specific stable current scenarios to ensure soldering quality and electrical conductivity.
Packaging Specifications
The product is supplied in reel packaging, with 2000pcs per reel and a single reel weight of 440±50g. The reel specifications are A=178±5mm, N=60±2mm, and W1=17±1mm. The peeling strength of the seal tape is 0.1~1.0N (10~100gf), meeting the requirements of automated surface mount production lines while ensuring product integrity during transportation and storage.
Lot Acceptance Tests
Each batch of products undergoes strict outgoing inspection, with a maximum batch quantity of 500Kpcs. The inspection items include:
1. Visual Inspection: Using a magnifying glass to ensure no obvious contamination, uncleanness, marking errors, or damage;
2. Dimension Measurement: Using calibrated calipers, micrometers, and other professional measuring tools to verify that product dimensions meet specifications;
3. Resistance (Ro) Test: Measuring resistance using the 4-wire method at 25℃ to ensure it falls within the specified range;
4. TCR Test: Measuring resistance at 25℃ and 125℃ via the 4-wire method, then calculating the TCR value using the standard formula to ensure compliance with temperature coefficient requirements;
5. Insulation Resistance (Ri) Test: Using a high ohm meter to measure the insulation resistance between the protective coating and the resistive element, ensuring it is not less than 100MΩ.
Conclusion
The HFCL-3618 series current sensor resistor stands out with its high precision, high reliability, and wide environmental adaptability. Through scientific structural design, high-quality material selection, and strict quality control, it can accurately meet the core current detection needs of various electronic devices. Whether in industrial control, power management, automotive electronics, or consumer electronics, this product delivers stable performance to provide precise current monitoring support for circuit systems, making it an ideal choice for enhancing overall device reliability and operational efficiency. In the future, we will continue to optimize product performance and iterate upgrades based on market demands, providing customers with more competitive current sensing solutions.
