Electronic Design

Components: Introduction/Passive & Electromechanical

Smaller Component Packaging On The Way
The mantra in component development continues to be smaller, smaller, smaller. In the coming year, expect much of the news in passive-component development to focus on packaging. Vendors will address the need for smaller parts by migrating discrete components into case sizes as small as the 0201 and by integrating passives within BGA-style packages.

Manufacturers will continue to integrate passives using thick-film techniques and modular technologies such as low-temperature cofired ceramics (LTCCs). Because LTCCs allow passives to be integrated with semiconductors, they apply this technology to create compact RF functional blocks like LC filters and even complete Bluetooth radio modules.

Reductions in discrete package size and integration of passives will shrink component footprints and reduce component heights to satisfy space constraints in portable applications. In many cases, device integration will be accomplished with performance in mind, reducing lead and trace lengths and their performance-limiting parasitics.

For power-handling components like resistors, size reduction amounts to raising the current-handling ability of a given device. That typically requires improvements in material composition and packaging to dissipate more heat in a small area—the same challenge faced by power semiconductors and high-speed processors. Among power resistors, thick film is one approach that promises to improve power density through the development of affordable surge inks, more precise screening techniques, and better packaging.

Material selection and packaging also drive developments among capacitors. In the coming year, component development will seek to reduce device size by exploiting existing chemistries, such as electrolytics, film, and ceramics, while lowering equivalent series resistance (ESR) and improving reliability.

Meanwhile, development of electric double-layer capacitors—commonly referred to as ultracapacitors or supercapacitors—will continue as vendors attempt to improve their ability to supply high peak currents in applications such as electric and hybrid vehicles. Vendors will try to raise the working voltage ratings of ultracapacitors so designers can achieve their required voltage ratings with fewer devices. Concurrently, vendors will strive to make these energy storage components more affordable.

For magnetic components, size reduction is the goal for RF and power devices. In the power area, two trends seem to be pulling inductor development in opposite directions. Vendors are striving to provide smaller parts with higher current ratings at relatively low inductance for use in dc-dc converters like those used to power microprocessors in notebook applications. However, the expectation of rising efficiency among microprocessors, monitors, and other functions is raising the demand for surface-mount inductors with somewhat lower current ratings but higher inductance. Furthermore, high di/dt requirements necessitate better high-frequency performance from power inductors.

Naturally, improving high-frequency performance also is the primary goal in other areas of component development. Oscillators are one such example. The need to generate higher frequencies with lower phase noise and reduced jitter should push new oscillator designs to inverted mesa or surface acoustic-wave (SAW) technologies.

LEDs make up another component category that's chasing higher performance. The development efforts here are geared toward increasing device brightness in all colors, especially blue and white, to permit continued replacement of other lamps (particularly incandescents) in lighting applications and to foster development of LED-based displays. With life expectancies routinely quoted at 100,000 hours, LEDs already have the reliability to supplant incandescents. Development must now focus on improving performance to the point where LEDs are cost-competitive bulb replacements.

Cost reduction also is a key incentive for component shrinks and integration. Smaller parts use less material per device and less pc-board real estate, which lowers board costs. At the same time, component integration reduces the number of parts that must be placed on a pc board, reducing assembly time. With fewer board-level interconnects, reliability rises, also lowering costs. The continued migration of power components to surface-mount packaging is yet another way to reduce assembly costs by eliminating manual insertion of the few non-SMT components on a board.

Given the negative economic forecasts for the electronics industry, cost issues should be more critical than ever in 2002. Price pressures will force designers to pinch pennies on many new designs. So while smaller size and better performance are general industry trends for all component development, many high-volume applications will shy away from cutting-edge component technologies in favor of more established component and package styles that offer commodity pricing.

In some cases, the need to reduce cost may even result in the elimination of passives. Circuit protection is one area where designers rely on the ruggedness of their ICs to eliminate passive components in certain instances.

Replacing passives isn't exactly a recent development, though. Semiconductor components have sought to replace passive components since the earliest days of the integrated circuit. That trend goes on in many areas. Among resistive components, digitally controlled potentiometers keep making inroads against electromechanical trimmers. In the capacitor area, voltage regulators and dc-dc converters hope to reduce demands for external capacitance either by integrating capacitors on-chip or by achieving faster, more stable performance.

Because of their faster operation, longer life, and higher reliability, solid-state switches and relays continue to replace electromechanical types. Yet for some applications, solid-state performance is still inadequate. So, semiconductor manufacturers are working to develop devices with lower on-resistance, higher current ratings, and lower capacitance. These improvements will help switch and relay ICs to find many new uses. Nevertheless, the development of electromechanical switches and relays should also continue unabated as vendors spin endless variations of switch and relay packaging to suit just about every application.

With demands for lead-free assembly coming from Europe and Japan, the introduction of lead-free components should continue. As component makers adapt their new designs to the leadless solder systems, they will switch to lead-free terminations. They also will move toward high-temperature plastics and other packaging materials that can withstand the processing temperatures associated with lead-free board assembly.

In sensor developments, the key factors are greater levels of integration and a drive to commercialize sensors into more applications. Much of this is driven by microelectromechanical systems (MEMS) technology. MEMS developments could soon merge sensors and actuators with all of the necessary analog and digital functions to create complete closed-loop control circuits on a single chip. That level of integration could have a profound impact on many fields.

See associated timeline.

Electric double-layer capacitors (EDLCs) will continue to offer high capacitance, low ESR, and high energy storage, but at higher voltages. For example, Ness (www.ness.co.kr) plans to extend its continuous working voltage ratings from 2.7 to 3 V.

New high-capacitance technologies such as Ness' Pseudocapacitor also are in the works. A hybrid of EDLC and battery technology, this capacitor will use metal oxide rather than activated carbon for the electrode material and rely on battery-like electrochemical reaction. It's expected to beat EDLCs and batteries for power density while offering more than 1400 F at 2 V. With its inexpensive electrode materials, the Pseudocapacitor could provide high capacitance at relatively low cost once in high-volume production.

Although the shortage of tantalums seems to have passed, designers will keep seeking their replacements among ceramics and aluminum organic polymer types. The latter devices should increase in popularity as more vendors introduce these parts, which can be more readily manufactured in values as high as several hundred microfarads.

Look for SMT power inductors to sacrifice some current handling for smaller size. For example, BI Technologies' (www.bitechnologies.com) HM73 is a pressed-and-fired, 40-A 0.5-mH device that measures 15 by 13 by 6.5 mm. The company plans to spin off a size-reduced variation with similar inductance, but about half the current rating.

Planar transformers and inductors will become more readily available as off-the-shelf, standard components from companies like Pulse (www.pulseeng.com), which plans to offer these components in power ratings up to 200 W.

Among electromechanical signal relays, demand for broadband operation will foster development of devices operating well into the gigahertz range.

Solid-state relays (SSRs) will continue making inroads against reed relays in automatic test equipment systems as IC relays achieve ratings better than 5 pF-Ω.

Chip resistors will continue to migrate into 0402 and 0201 case sizes at the expense of 0603 and larger sizes. Migration to 0201 may depend on manufacturers' ability to master pick-and-place routines for these miniscule parts.

As digital design techniques proliferate, designers will rely less on electromechanical trimmers and more on incremental encoders and digital-controlled potentiometers (DCPs). Improvements in these digital components will expand their potential use. For example, Xicor (www.xicor.com) expects to introduce DCPs with greater than 10-bit resolution and voltage ranges beyond 5 V—possibly up to ±30 V. There are also plans to develop more application-specific DCPs.

Electromechanical dc relays will be pushed to handle hundreds of volts and hundreds of amps in hybrid electric vehicles and fuel cells. That level of performance is usually associated with industrial applications. But vendors will be forced to find innovative ways to attain pricing that's suitable for high-volume applications.

See associated timeline.

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