SMDs Evolve to Suit Latest Technology Requirements
Developments in technologies for miniaturizing surface mount devices (SMD) abound. Moreover, requirements are becoming even stricter for ultra-small thin chips related to smartphones, modules, and Internet of Things (IoT) devices. High-reliability chips for cars or industrial equipment, demand for which is growing, have been downsized dramatically. SMDs are continuing to evolve in line with the technological trends in growth fields.
Photo 1: Wide variety of automotive power inductors capable of operating at 150°C.
Downsizing, Thinning Technologies
Trends in main chip components, such as multi-layer ceramic capacitors (MLCC), resistors, and inductors, have shifted towards miniaturization; nowadays, the 1005-size accounts for the largest proportion. However, since the mounting density of components in smartphones, wearable computers, and various modules is further increasing, the market for 0603- and 0402-size components is expanding rapidly. According to a report by Japan Electronics and Information Technology Industries Association (JEITA), 0603-size components will constitute the largest proportion around 2018, surpassing1005-size components.
For modules, the component embedding technology is becoming widely used as a miniaturization technology. A component embedding substrate is a multilayer substrate where components, such as ICs, resistors, and capacitors are incorporated in its internal layer and also are mounted on its surface to reduce the substrate area.
Components intended for incorporation into substrates need thinning. The thickness of MLCCs has been reduced from 0.14 to 0.11mm and further to 0.09mm. Also, thin chip resistors with a thickness of 0.14mm or 0.13mm have been developed.
Trends in Chip Inductors
The development of new chip inductor products suitable for principal applications, such as power supply circuits, noise suppression, and high-frequency circuits, is underway.
Many power inductors are wire-wound ferrite power inductors, in which a nickel-zinc (Ni-Zn) ferrite core is wound with copper wire. Multilayer (thin-film) inductors and wire-wound and multilayer metal inductors are also available. In smartphones, the usage rate of metal inductors has risen because they are capable of operating at high currents. They have been miniaturized to 1608-size. Some metal inductors that operate at a high temperature of 150°C have been developed and are available for in-car use. Wire-wound ferrite inductors that operate at 150°C have also been developed for this purpose.
Generally, signal inductors are used as filters in combination with capacitors. These inductors need to be small and have high quality factor, high inductance accuracy, high self-resonant frequency, and high allowable current. In near field communication (NFC), LC filters are used for noise suppression.
Filtering inductors are available in wire-wound, multilayer, and thin-film types. The multilayer type has been miniaturized to the 0402-size. Such inductors of 0201-size have been newly developed as next-generation chips. High-frequency inductors are available for use as resonators, impedance matching, and chokes for high-frequency circuits. Among them, wire-wound inductors are more effective in meeting requirements for quality factor or allowable current. Multilayer inductors have a wide inductance range and are suitable for miniaturization. Also, thin-film inductors are suitable for inductance accuracy and miniaturization.