With the development of miniaturization of electronic products, the volume of small inductors has been reduced to the physical limit. In view of this, Michael Pocsatko, president and CEO of EPCOS Greater China, believes that the development direction of inductors in the future is integration. Inductors will be combined with other discrete devices into complex modules to provide customers with complete systems that are easy to use. However, currently, miniaturization of discrete devices is still the main focus, and there is still some distance to achieve integration.

In order to comply with the future development direction, major manufacturers continuously improve the manufacturing process of inductors, expand production capacity, and meet the growing market demand. According to TDK's mid fiscal year 2006 joint results, TDK's inductor sales increased by 27% year-on-year, driving the overall growth of TDK's business. And this growth has been confirmed in the sales performance of TDK distributors. Fang Xingliang, General Manager of Shenzhen Tianweihua Electronics Co., Ltd., said, "Driven by market demand, our sales of TDK small inductors increased by 30% in 2006

It is understood that small inductors are widely used in fields such as mobile phones, digital set-top boxes, Bluetooth earphones, LCD TVs, automotive electronics, industrial control, and have huge market potential. In terms of chip inductors alone, the market demand in 2007 will reach over 300 billion units, with a value of approximately 30 billion yuan.

Meanwhile, industry insiders have pointed out that after experiencing the impact of RoHS environmental directives and rising raw material prices, the price of small inductors has stabilized, leading to a continuous increase in demand for small inductors in the market and an expanding production and sales gap. In order to meet the growing market demand, major inductor manufacturers have launched various new products for different market applications.

Small inductors for different applications:

With the continuous segmentation of the market, various small inductors targeting specific application areas have emerged. In data systems and industrial electronic applications, the increasing demand for load point power supplies has brought development opportunities for high-power and small-sized inductors. For this reason, EPCOS has launched the HPI series of high-power inductors for the load point power supply market. While significantly improving the current carrying capacity, the size is only 12 × 12mm。

EPCOS's HPI series inductors are aimed at the DC/DC converter market, including load point converters and voltage regulator modules (VRMs). In these circuits, HPI acts as an output inductor, and its performance directly affects the total output of the converter. Therefore, optimizing the size and electrical characteristics of the inductor can ensure that the converter meets the requirements in various applications.

Pocsatko emphasized that "HPI can completely replace spiral power inductors because it uses a spiral coil internally, which means a flat rectangular copper wire is wound vertically to form a spiral." Unlike ordinary coils wound with circular copper wire, spiral coils can make more use of the copper coil in the core window of the inductor, making the gap factor of the copper coil close to 1. In this way, while improving the utilization rate of copper coils, the ohmic resistance of the coil is reduced, and efficiency is improved. In addition, the size of inductive devices can also be made smaller, with the same or higher current carrying capacity, which saves space for circuit board use.

It is understood that most manufacturers use various core shapes and materials in inductors for the DC/DC converter market, but the EPCOS HPI series inductors use a ferrite core material. Although other materials allow higher saturation currents, the magnetic core loss of ferrite materials is significantly reduced. DC/DC converters usually have ripple currents, and when the output inductance faces severe ripple currents, the advantages of ferrite materials are more prominent. The cost of ferrite materials is also lower than other materials, and the magnetic core can have a special inductance value by precisely adjusting the gap.

Michael Pocsatko also pointed out that another advantage of the HPI series inductors is the use of self leads as the contact between the coil and the circuit board. These leads are rolled under the coil holder, minimizing the circuit board space required for inductance. At the bottom of the outer surface, a specially designed insulator fixes these leads and insulates them from the magnetic core. Due to the high value of space in such applications, HPI inductors have significant advantages compared to similar products.

At present, the HPI series inductors have 2 packaging heights and 8 standard inductance values. The inductance values can also be customized by adjusting the gap. The HPI series inductance can provide excellent electrical performance, and the packaging greatly reduces the circuit board space required for the inductance, allowing circuit designers to optimize power density and greatly reduce the number of phases in the load point power supply. The inductance value of the HPI series inductor is 0.5-3.92 μ H. The current carrying capacity is 12-30A.

In addition to small inductors for industrial applications, many manufacturers have launched products for the consumer electronics market. Cooper's newly launched inductors SD3112, SD3114, and SD3118, with a shape of 3.1 × 3.1mm, compliant with RoHS directive requirements, with high power density to area ratio, suitable for portable devices such as mobile phones, digital cameras, small LCD displays, and PDAs. Among them, SD3112 provides high output, and the variation range of inductance value is from 1 μ H/1.65A to 220 μ H/0.113A。 The slightly higher SD3114 (1.4mm) and SD3118 (1.8mm) provide higher rated current. It is understood that SD3112, SD3114, and SD3118 have a ferrite shielding structure, which has the advantage of strong EMI suppression ability, and this structure is convenient for automatic pickup and playback machines to identify devices and determine their installation direction appropriately. This series of products is packaged in rolls (4100 per roll), priced at 19 cents for bulk supply, with a delivery time of 4 weeks.

In addition, Vishay has also launched new ultra-thin, high current chip inductors IHLP-4040DZ-01 and IHLP-4040DZ-11, with high maximum frequency and low inductance values. The maximum frequency of IHLP-4040DZ-11 is 1.0MHz, while the maximum frequency of IHLP-4040DZ-01 is 5.0MHz. The inductance values of both devices are as low as 0.19 μ H。 The IHLP series products are packaged in DCR, with a size of 10.3 × 11.5mm, with a thickness of 4.0mm and a standard occupying area of 4040. These two products can handle high instantaneous current peaks without hard saturation, and provide higher rated current while providing lower DCR values; And it adopts a 100% lead-free composite structure packaging that complies with RoHS standards and has a protective layer, reducing buzzing noise to ultra-low levels; It has the characteristics of heat shock resistance, moisture resistance, mechanical shock resistance and vibration resistance. In applications such as mobile phones, PCs, PMP, GPS, automotive electronics, load point converters, distributed power systems, and FPGA, the IHLP series products are small, high-performance, and low-power solutions.

Market prospects for small inductors:

The market demand for small inductors is constantly growing, coupled with the increasing added value of inductor manufacturers' products, which provide growth space for small inductors. Therefore, in the spot market, the market share of small inductance products is showing an upward trend.

Fang Xingliang: The SMD inductors of models 0401 and 0201 are very popular.

According to Fang Xingliang from Tianweihua, the 0401 and 0201 SMD inductors are highly popular among customers in major electronic markets in Shenzhen, with orders from manufacturers such as Bluetooth earphones and digital set-top boxes growing rapidly. For example, the TDK MLK1005S3N9S, MLF1608A100KT and other models of stacked inductors sold by Tianweihua are widely used in high-frequency environments and have good market sales; The TDK HHM1517 and HHM1520, which are applied to bandpass filters such as Bluetooth headphones and wireless network cards, as well as balanced/unbalanced transformers, also have broad market prospects.

Pocsatko also stated, "In the Chinese market, we maintained a growth rate of nearly 30% in 2006, with product lines such as inductors contributing to performance growth." However, he also pointed out that small inductors face challenges as raw material prices rise. For example, in the past year, the cost of producing small inductors in some regions has increased by 100%. In order to reduce costs, EPCOS has implemented a strategy of localizing new product production and established six production plants in China, becoming the second largest electronic component manufacturer in the Chinese market and establishing EPCOS's position in the Chinese market.

Local Chinese manufacturers have advantages in controlling production costs. For example, Guangdong Zhaoqing Yingda Inductor Device Co., Ltd. reduces production costs by controlling the preparation process of raw materials and powders. Zhaoqing Yingda has the ability to produce its own ferrite powder, and electronic paste can also be purchased through other companies within the headquarters, greatly saving costs. Moreover, even if customers have special requirements for the frequency characteristics of inductors, Zhaoqing Yingda can still meet customer requirements through the research and development of raw materials. At the same time, the control of product quality and parameters can also be traced back to the raw materials and initial chemical raw materials. Once problems arise, product quality and parameters can be controlled by changing the raw materials and chemical raw materials. These are advantages that manufacturers that rely on imported materials for production do not have.

In addition to the increase in raw material prices, the RoHS directive has also brought cost pressure to small inductor manufacturers. But with the efforts of major manufacturers, the impact of environmental directives such as RoHS is gradually being addressed and is no longer the main factor affecting the development of small inductors.

However, with the development of the market, the miniaturization of inductance devices has reached its limit. How to further reduce the volume of inductors without increasing costs is a common concern for many inductance manufacturers. Many inductance manufacturers believe that integration is the future development trend of small inductance devices. Integrating inductors and other devices into a complex module and combining them into a complete system can reduce both volume and cost. But it will still take time for small inductors to achieve integration.