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A popular industry aphorism states, "There are three ideals sought by component designers: high performance, low cost and small size. Pick two." But that doesn't stop designers from shooting for the stars, and manufacturers of capacitors are among those striving to come up with technologies that will come as close as possible to realizing all three goals.

The quest has resulted in the emergence of new variations on standard types of capacitors, as designers seek to shore up the weaknesses of one type to match the strengths of - and thereby compete with - another.

Rubycon America Inc. (Gurnee, Ill.), for example, has developed an ethylene glycol-based electrolyte to create two families of aluminum-electrolytic (AE) capacitors that the company states offer the performance advantages of organic-semiconductor-based capacitors at a cost that's one-third lower.

The ZA series has impedance characteristics as low as one-third that of conventional low-impedance aluminum capacitors at 100 kHz, 20 degrees C. The series is suited for use in many applications in which solid electrolytic capacitor technology has been the preferred choice, according to Rubycon.

The caps have rated voltages of 6.3 to 35 V, a capacitance range of 4.7 to 1,000 microfarads, an operating-temperature range of -40 to +105 degrees C, and a load life of 1,000 to 2,000 hours at +105 degrees C.

Case sizes are available from 4 x 7 mm to 10 x 16 mm. Typical applications include dc/dc converters, boards and noise filters for digital equipment.

The ZL series is claimed to reduced impedance characteristics as much as 40 percent compared with conventional AE low-impedance capacitors. Rubycon states that the series also has a long life and a high ripple current. Case sizes range from 5 x 11 mm to 16 x 25 mm. Rated voltages are 6.3 to 50 V, with a capacitance range of 22 to 6,800 microfarads, operating-temperature range of -40 degrees C to +105 degrees C and load life of 2,000 to 5,000 hours at +105 degrees C.

Applications for the ZL series include output-filtering circuits for switching power supplies, dc/dc converters and boards. Pricing is typically 6 cents each in 1,000-piece lots. The parts are available from stock for immediate delivery.

Electronics Concepts Inc. (Eatontown, N.J.) states that its ECR subminiature metallized polycarbonate capacitors, based on its patented metallization process, offer the size advantages of ceramic CK05 capacitors but none of the ceramic caps' negative characteristics, such as piezoelectric effects. The parts are further claimed to be neither frequency- nor voltage-sensitive. On average, the ECR capacitors have a 20-year life expectancy.

The company also claims that the ECRs outperform other types of film dielectric capacitors, making them suited for applications that emphasize performance in relation to size. Such applications include avionic instrumentation and signal-processing equipment. The caps are said to meet MIL-PRF-55514/8 (CFR12/CFR26) and MIL-STD-202 standards.

ECR capacitors come in sizes from 0.09 x 0.19 x 0.19 inch to 0.195 x 0.395 x 0.395 inch. The operating-temperature range is -55 degrees C to +125 degrees C without derating; the dissipation factor does not exceed 0.3 percent over the full temperature range. Capacitance tolerance is plus/minus 1 percent standard, with plus/minus 2, plus/minus 5 and plus/minus 10 percent available. Available voltages are 50, 75, 100, 150, 200 and 250 V.

Pricing ranges from $1.10 to $1.80. The capacitors ship from stock.

Taiyo Yuden (San Jose, Calif.) has developed a nickel-based multilayer ceramic capacitor that it says costs less and has higher capacitance than aluminum electrolytic or tantalum (Ta) capacitors. The nickel-based MLCCs are claimed to have significantly lower equivalent series resistance (ESR) and a smaller case size and lower profile than AE and Ta capacitors with similar capacitance and rated voltage, and the MLCCs' lack of polarity is said to enable simpler, more efficient mounting.

Because of the lower ESR, the MLCCs also have lower power loss and heat generation, and their impedance is lower at higher frequencies.

The MLCCs are intended for use in high-performance applications such as CPUs, ICs and cellular phones. They are are available from 0.1 microfarads to 100 microfarads.

Taiyo Yuden claims to have achieved the performance advances by using high-precision multilayering techniques and advanced process technology. The Y5V dielectric MLCCs are also said to exhibit good impedance stability over a wide temperature range-an important factor for reliable operation in bypass applications.

Pricing ranges from 1 cent to $1.50 each in OEM quantities. Delivery time is stock to four weeks.

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