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OCTOBER 2018 I DESIGN007 MAGAZINE 59 Table 5: Thin-film inductor. (t) may be an issue. The example shown in Table 4 represents two multilayer inductors that can be considered for embedding in the circuit structure. Although the excessive thickness of the 0603 inductor may make it impractical for embed- ding, the 0.35-mm profile of the 0402 device outline should be acceptable for embedding, even though the greater component thickness will also require a cavity in the circuit struc- ture typical of that illustrated for the resistor and capacitor components. The five multilayer thin-film inductor devices shown in Table 5 represent outline variations characteristic of the resistor and capacitor families. They are said to be excellent for high-frequency applications, have a low DC resistance, high Q, and are fur - nished with terminal plating most suitable for solder or conductive polymer attachment. The value range for the 0402 inductor is lim- ited. More values may be offered for the larger outline inductors, but the excessive height of the other four inductors listed in the table will eliminate them for embedded component applications without increasing cavity size. Embedded Component Assembly The terminal plating alloy specified must be selected to be compatible with the specific joining method employed. While the tin-plated terminals are more common and compatible with solder or conductive polymer attachment, some discrete passive components can be sup- plied with copper or gold terminal plating. The copper-plated terminals will be specified when direct microvia termination is required. Alternative component termination methodol- ogies and PCB surface plating variations will be discussed further in Part 5 of this series. DESIGN007 Vern Solberg is an independent technical consultant specializing in surface mount technology, microelec- tronics design, and manufacturing technology. To read past columns or contact Solberg, click here.

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