As electronics technology continues to advance, small size and high-performance inductors are being more widely used in various electronic devices. Among them, the bottom-electrode molded power inductor, with its compact structure, high reliability, and excellent performance, has become a preferred component for high-density, high-frequency electronic systems. Its comprehensive performance is superior to that of traditional wire-wound inductors, especially in applications pursuing miniaturization, high reliability, and low EMI. This article will elaborate on the advantages and product selection of bottom-electrode molded inductors, aiming to provide a reference for power design engineers.
1- Advantages of Bottom-Electrode Molded Inductors
Molded inductors come in two types: one using L-type electrodes and the other using bottom electrodes. The bottom-electrode molded power inductor utilizes a new molding process, characterized by encapsulating the coil and magnetic core into a single unit and placing the electrodes on the bottom, thereby achieving higher integration and performance optimization.
Figure 1. Bottom-electrode molded power inductor structure
The advantages of bottom-electrode molded power inductor are mainly reflected in the following aspects:
◾ Miniaturization and High-Density Integration: It can reduce the PCB footprint and increase mounting density. Compared to traditional wire-wound inductors, bottom-electrode molded power inductors have a smaller volume, making them particularly suitable for space-constrained portable devices and high-density power modules.
◾ Low DC Resistance (DCR): By optimizing the coil winding method and electrode design, the inductor can achieve a lower DCR, thereby reducing power loss and improving conversion efficiency (especially outstanding in low-voltage, high-current scenarios).
◾ High Reliability: The end of the coil is bent and pressure-molded with the T-core powder to form a solid bottom electrode. This increases solder pad strength and eliminates the need for additional welded terminals, removing the risk of open circuits and enhancing product reliability.
As an innovative molded power inductor technology, the bottom-electrode type offers significant advantages in product structure, electrical performance, and application. It is widely used in fields such as automotive DC-DC converters, ADAS systems, power modules, high-frequency switching power supplies, motor drives, photovoltaic inverters, and communication equipment.
2- Selection Guide for Bottom-Electrode Molded Power Inductors
Codaca has developed inductors with different material characteristics to suit various customer applications. To help customers select the most suitable power inductor, below are representative models of Codaca's industrial-grade bottom-electrode molded inductors—CSEG, CSEC, CSEB, and CSEB-H—with a comparison of their electrical characteristics.
2.1 CSEG: Ultra-Low DCR, Lowest Loss in Low-Frequency Range
◾ Magnetic Shielding Structure: Strong resistance to electromagnetic interference (EMI).
◾ Molded Construction: Ultra-low acoustic noise.
◾ Soft Saturation Characteristics: Withstands high peak currents.
◾ Ultra-Low DCR: Highest Irms (temperature-rise current).
◾ Achieves the lowest power loss in the low-frequency range (below 700 kHz).
◾ Slim Design: Saves space, suitable for high-density mounting.
◾ Operating Temperature: -40°C to +125°C (including coil self-heating).
2.2 CSEC: High Saturation Current, Lowest Loss in High-Frequency Range
◾ Magnetic Shielding Structure: Strong resistance to EMI.
◾ Molded Construction: Ultra-low acoustic noise.
◾ Ultra-High Isat (Saturation Current).
◾ Soft Saturation Characteristics: Withstands higher peak currents.
◾ Achieves the lowest power loss in the high-frequency range (700 kHz to 3 MHz).
◾ Slim Design: Saves space, suitable for high-density mounting.
◾ Operating Temperature: -40°C to +125°C (including coil self-heating).
2.3 CSEB: Extensive Range of Product Sizes and Models
◾ Magnetic Shielding Structure: Strong resistance to EMI.
◾ Molded Construction: Ultra-low acoustic noise.
◾ Wide range of sizes and inductance values (max size 1510).
◾ Soft Saturation Characteristics: Withstands high peak currents.
◾ Slim Design: Saves space, suitable for high-density mounting.
◾ Standard product is AEC-Q200 compliant.
◾ Operating Temperature: -40°C to +125°C (including coil self-heating).
2.4 CSEB-H: Low DCR and High Temperature-Rise Current
◾ Magnetic Shielding Structure: Strong resistance to EMI.
◾ Molded Construction: Ultra-low acoustic noise.
◾ Low DCR.
◾ High Irms (Temperature-Rise Current).
◾ Soft Saturation Characteristics: Withstands high peak currents.
◾ Slim Design: Saves space, suitable for high-density mounting.
◾ Standard product is AEC-Q200 compliant.
◾ Operating Temperature: -40°C to +125°C (including coil self-heating).
2.5 Performance Parameter Comparison
The four series of high-performance molded power inductors mentioned above are independently developed and designed by Codaca. All series feature high reliability and a magnetic shielding structure, but each series has its unique performance advantages.
Table 1. Performance Summary of Various Molded Inductor Specifications
The easiest selection method is to use the "Power Inductor Finder" and "Power Inductor Loss Comparison" tools on the Codaca official website. The system will present the performance of each based on your entered operating conditions (current, ripple, temperature, operating frequency, etc).
◾ Isat Saturation Current Comparison
Taking an inductance value of 4.7 μH as an example, products of the same size but different series are compared.
Compared with CSEG, CSEB-H, and CSEB, the CSEC series offers higher saturation current capability, making it the ideal choice for applications that require high peak current tolerance.
Figure 2. Inductance vs. Saturation Current Curve Comparison for Various Molded Inductor Specifications
◾ Irms (Temperature-Rise Current) Comparison
Taking a 4.7µH inductance value as an example, we compare products of the same size from different series.
Table 2. Characteristic Parameter Comparison Table for Various Molded Inductor Specifications
From the comparison table above, in addition to its ultra-low DCR, the CSEG series has a temperature-rise current that is about 40% higher than that of the CSEC, CSEB-H, and CSEB series, allowing it to operate at a lower temperature under the same working conditions.
Figure 3. Comparison of temperature-rise current curves for various specifications of integrated molded inductors
◾ Power Loss Comparison
Taking a 4.7µH inductance value as an example, the loss characteristics of each series were tested using a standard loop test.
Test Conditions: Current = 10.5A, Ripple = 40%, Frequency Range = 100-3000 kHz, B = 3mT.
Figure 4. Power Loss Comparison of Various Molded Inductor Models
Based on the curve analysis above, the CSEG series has the lowest total loss below 700 kHz. The CSEC series has the lowest loss above 700 kHz. The CSEB and CSEB-H series have moderate losses.
3- Additional Product Series
The above comparison focuses on the main characteristics of industrial-grade bottom-electrode molded inductors. For automotive electronics applications, Codaca has developed several corresponding automotive-grade molded inductor product models, such as the VSEB and VSEB-H series.
Figure 5. Codaca Automotive-Grade Molded Inductors (highlighted in red circle)
Codaca's automotive-grade bottom-electrode molded power inductors use a low-loss alloy powder core material and improved molded process, featuring low loss, high efficiency, and a wide application frequency range. Their compact design saves space and is suitable for high-density mounting. All products comply with the AEC-Q200 standard. The operating temperature range can extend from -55°C to +165°C (including coil self-heating), adapting to the complex application environments of automotive electronics.