The Metal Powder Composite Choke Coil is a choke coil in which the conventional ferrite has been replaced with metal. As metal materials have a higher saturation magnetic flux density (*1) than ferrite, many magnetic fluxes can be produced. Therefore, in comparing the two using the same size cores, metal is able to deliver the required performance even when a larger current is applied. However, as the current flows out as it is with metal, an eddy current is created when an alternate voltage is applied, causing a large loss. This loss not only shortens the battery life, but at the same time converts into a large volume of heat. Moreover, if a fan is used to lower the temperature, the power consumed will further shorten the battery life, in addition to deteriorating AV performance due to the noise caused by the fan. As the temperature of recent CPUs is particularly high when they are operating, the problem of how they can be cooled down has become a major issue. As using a device that produces an even larger amount of heat in such a place was inconceivable, it was decided that the practical long-term application of metal-core choke coils would be difficult. However, through applying the manufacturing method for a traditional sendust core, and using a fine, highly efficient material powder while taking advantage of the high saturation magnetic flux density that is available only with metal, we at NEC TOKIN Corporation have successfully produced Metal Powder Composite Choke Coils. These coils exhibit excellent properties with low loss. In addition, by molding the metal powder materials into a single piece, this structure reduces the conventional whining sound. Of the Metal Powder Composite Choke Coils, the MPC Series is most suited for the high operating frequencies around CPUs due to the especially large current applied. Through making structural adjustments such as in the material chosen and by forming the copper wire into flat wire, a low-loss performance that is uniquely high is achieved. Also, when direct current (DC) is applied through a choke coil, inductance is lowered resulting in even more current passing through, thereby causing a phenomenon known as “DC superposition.” When this phenomenon occurs more frequently, circuits become unstable thus increasing loss. In a worst-case scenario, DC superposition can result in destruction of IC circuits. The superior nature of the MPC Series gives the ultimate level of control of this phenomenon. Meanwhile, within choke coils for logic circuits where mid-level current are applied, ferrite continues to be popular mainly because of cost demands. However, from the perspective of loss reduction on the overall PC, strategies specific to the CPU periphery are reaching their limits. There are now calls for highly efficient components in other areas. NEC TOKIN offers the MPLC Series for these applications. The difference between this series and the MPC Series is that by forming the copper wire into a round wire, this series responds to applications that require higher inductance. Of course, the high-efficiency, excellent DC superposition characteristics and non-existent whining sound are all due to the nature of the metal powder composite. By using a highly efficient metal core, choke coil characteristics can be improved by almost twice compared to those of traditional ferrite cores. For this reason, a choke coil with the same performance as that of a traditional choke coil can be made in almost half the volume. In addition, for a coil with the same-sized profile, the core can be thinned and instead, the diameter of the wire to be wound can be increased. As a result, electric resistance is reduced, loss is dramatically decreased and a choke coil that produces less heat can be realized. *1 Saturation Magnetic Flux Density: The upper limit of magnetic flux density that limits the strength of magnetization of a material. Magnet Bias Even when it comes to traditional ferrite core choke coils, NEC TOKIN holds technology that can be found nowhere else. This method is called “magnet bias” (MB·PI Series BIASCHOKE®). The upper limit of magnetic fluxes generated in a core when a current is applied to a coil can not be changed as long as ferrite is used. Now, what would happen if magnetic fluxes in the opposite direction were made beforehand using a strong magnet? For example, supposing a certain core allows up to ten magnetic fluxes to be generated, and using a magnet, three magnetic fluxes in the minus direction of the fluxes are made. The result: a current that is only able to make up to thirteen magnetic fluxes can be applied to the core. Although, this extremely interesting idea has actually existed for about 30 years, it was never realized because a strong magnet was required to make magnetic fluxes in the opposite direction. A particular problem was the 230- to 240-degree heat that was added to a board as it was passed through the reflow oven during the mounting process. Due to this heat, an element that could function at normal temperatures became useless as the magnetic force became weakened during the device mounting process. However, NEC TOKIN utilized their experience from handling magnetic materials over many years, and solved this issue by realizing the magnet-bias method choke coil. With its superior nature, this fills the gap between the common ferrite core and metal.