Like their counterparts in film capacitors, suppliers of aluminum electrolytic capacitors are moving in a big way to surface-mount packaging technology. It's a move that vendors say will improve voltage ratings, equivalent series resistance (ESR), capacitance range and the operating-temperature performance of aluminum electrolytics.
The transition to surface mount for aluminum electrolytic caps has heated up tremendously, said Rich Schuster, president of NIC Components Corp. (Melville, N.Y.). The market had been slow to accept surface-mount technology because of the high capacitance values and higher voltages involved with aluminum electrolytics, Schuster acknowledged. But, he added, it's only natural that OEMs want to switch all of their devices over to surface mount when possible to eliminate a soldering process.
Walter Bonomo, regional product manager for BC Components (Chicago), noted that surface-mountable devices allow more miniaturization, which translates into more capacitance or a higher voltage in the same size package.
A key reason why the electronics industry has not shifted as fast to surface-mount technology for aluminum electrolytic caps as it did for tantalum and ceramic capacitors is cost. Engineers can expect to pay 30 to 50 percent more for a surface-mount device (SMD) compared with a leaded part.
When SMD versions of aluminum electrolytic capacitors were first brought to the marketplace several years ago, the most compelling issue was survivability. The question was: Could the electrochemical device withstand the high temperatures and surface-mount processing? Today, with changes in processing and in the electrolyte, that's not an issue anymore, said Mike Shade, vice president of operations for Illinois Capacitor Inc. (Lincolnwood, Ill.). If an engineer can design a board with 100 percent surface-mountable devices, then he'll use the SMD aluminum electrolytic capacitor. But if he still has other devices that are through-hole, then he'll stick with them because it's a cost saving, he said.
On the technical side, the only drawback to using aluminum electrolytic capacitors is that they still have a relatively high profile compared with tantalum and ceramic caps. For that reason they aren't used in cell phones, PDAs or portable wireless products, said Schuster of NIC Components.
Another more recent challenge that engineers face is availability. Since interest in surface-mount aluminum electrolytic capacitors has started to pick up, manufacturers have limited production capacity. They are only just now gearing up production to meet demand. This has resulted in lead times as far out as 20 weeks. For instance, lead times for leaded aluminum electrolytics at Tecate Industries Inc. (Poway, Calif.) average six to eight weeks, compared with 20 weeks for some SMDs. A similar scenario is being played out at other major aluminum electrolytic cap makers.
Demand is up due to a shortage of tantalum devices, said Tim Martinez, vice president of marketing at Tecate. Design engineers are looking at surface-mount electrolytics, particularly low-ESR versions, to try to fill the gap, but they're not drop-in replacements, he added. One result is that cap makers are combining surface-mount technology with low-ESR requirements to meet current demand.
Indeed, there's a big push in surface-mount not just for standard parts but for low-ESR versions to achieve a kind of balance between the case size and ESR rating, Shade said.
Over the past year, Illinois Capacitor has introduced several surface-mount products, including two low-ESR lines: the AXZ and the low-profile GAZ series. The cap maker has also expanded its standard offerings to include additional case sizes, values and temperature ranges.
The introduction of sub-$1,000 and sub-$500 personal computers is expanding the market for low-impedance (low-ESR) devices, said Derrick Fitzpatrick, quality systems manager for United Chemi-Con Inc. (Rosemont, Ill.). For this application, United Chemi-Con offers its new low-impedance, surface-mount aluminum electrolytic MVY series.
Cap makers are also developing leaded aluminum electrolytic devices that enhance performance for extended life and high ripple current. BC Components, for example, produces a snap-in 198 PHR-SI series that combines longer life and very high ripple current for motor controls. The devices have a capacitance range of 56 microfarads to 820 degrees at 400 V and 450 V, and handle very high ripple currents. The lower the ESR, the higher the ripple current it can handle, BC's Bonomo said.
While the computer, power supply and telecommunications industries have been driving the need for low-ESR/low-impedance devices, the automotive industry has pressured aluminum electrolytic capacitor makers for devices that can withstand higher temperatures.
"In the past, all of the electronic components and systems could be contained in the passenger compartment, but it makes maintenance more difficult and there are space constraints," Bonomo said. "Instead, everything is going under the hood, which is driving the need for longer life, higher reliability and higher temperature."
Earlier this year, BC Components introduced two new surface-mount lines: the 140CLH, with a high operating temperature of up to 125 degrees C and a capacitance range of 0.47 degrees to 680 degrees at 6.3 V to 63 V; and the 150CLZ device, which comes with more capacitance in the same size package and can handle a higher ripple current. The capacitance range is 47 degrees to 1,000 degrees in a 6.3- to 63-V range with an operating temperature range of up to 105 degrees C.
United Chemi-Con also offers two new high temperature product lines. The MVH series of aluminum electrolytics are rated at 125 degrees , and the new U787D high- temperature aluminum electrolytic ranges to 150 degrees for automotive applications. United Chemi-Con's Web site, www.chemi-con.com, is loaded with technical notes on understanding aluminum electrolytic capacitors, including topics on applying voltages and restrictions of operating environments.
For many space-constrained applications, packing more capacitance or higher voltages in the same size package is a growing requirement. In response, cap makers are developing products with a wider capacitance range and higher voltage ratings. For example, Tecate's new MXMH series of surface-mount aluminum electrolytic capacitors comes in a capacitance range of 3.3 degrees to 10 degrees at 200 V or 400 V. The polarized surface-mount MXLL offers an extended life. The new Tecate MXMS series boast a 2,000-hour life cycle, a capacitance range of 4.7 degrees to 150 degrees and a small case size of 4 x 5.5 mm to 6.3 x 5.5 mm.
This month, Jaro Components Inc. (Boca Raton, Fla.) is launching a series of surface-mount aluminum electrolytic capacitors that feature 5,000 hours of performance at 105 degrees C. The ACHE series is available in sizes from 4 x 5.8 mm to 6.3 x 5.8 mm. The operating temperature ranges from -40 degrees C to 105 degrees C. The voltages range from 16 Vdc to 50 Vdc, with a nominal capacitance range of 0.47 degrees to 47 degrees . The capacitance tolerance is plus/minus 20 percent.
NIC can supply surface-mount aluminum electrolytic capacitors with a capacitance range of up to 100 degrees F. They are also available in low-ESR, low-leakage and extended-temperature ranges of up to 125 degrees C. The company says it has achieved higher performance ratings because of higher magnification foil and better production techniques.
NIC also offers its surface-mount product in 4-mm-high profiles. "We're getting much better volumetric efficiency so that we're able to put more capacitance into small packages," Schuster said.
Most recently, NIC has introduced a larger aluminum electrolytic in a surface-mount configuration that offers a capacitance range as high as 6,800 degrees , and a high-voltage surface-mount aluminum electrolytic with voltage ratings up to 450 Vdc, which can replace large-can, radial-leaded and possibly snap-in types.
Although a latecomer to the surface-mount party, Illinois Capacitor jumped ahead of the competition by rolling out a 1 degrees , 50-V device in a 3-mm can, significantly smaller than the 4-mm can offered by many competitors. It also offers a 1 degrees at 63-V device in a 4-mm-diameter can size.
"The higher voltage rating provides the user with longer life and better reliability even if he doesn't need the higher voltage," Shade said. "Surface-mount used to be strictly all low voltage, but we're taking our surface-mount devices up to 400 volts."
Some suppliers-including BC Components, NIC and United Chemi-Con-are moving to polymer or solid-aluminum capacitors, which allows them to achieve lower ESR ratings as well as a smaller footprint. They are very popular for next-generation microprocessors, Schuster said, because they feature much longer life and better performance. Although they have been available for about four or five years, they've really taken off in the past two years, Schuster said. "The only drawback is limited production, but we're expanding production and coming out with a couple of new series over the next 30 to 60 days."
The new radial-leaded and surface-mount solid-alumi-num capacitors will feature low ESR, very low impedance and very high ripple current. "This will be the first time that we offer the technology in a radial-leaded configuration, which will allow for a wider range of capacitance and lower loss," Schuster said.
United Chemi-Con's SMD polymer electrolyte PX series offers low impedance (25 m ohms ESR), low voltage (4 V to 25 V), and a capacitance range of 6.8 degrees to 680 degrees for dc/dc converters and power supplies. They are available in a vertical-mount-style chip package.
BC Components has expanded its solid-aluminum cap line with its SMD HiTMP series that carries a high-temperature rating of up to 275 degrees . It is specified for 300,000 hours at 40 degrees and 20,000 hours at 125 degrees . Samples are available now. The company expects to go into mass production by the end of the year.
Innovation with older technologies is not lost on some aluminum electrolytic cap makers. They have beefed up their older axial-leaded aluminum electrolytic lines by offering a higher temperature range and low ESR/impedance. Axial-leaded devices offer low mounting heights that are desirable in automotive applications.
BC Components' new 120 ATC line of axial-leaded devices combines several improvements, such as high ripple current, high vibration resistance and high temperature. Key features include a high-temperature range of up to 125 degrees , long life and low ESR. The line targets auto and other high-temperature and long-life applications.
Illinois Capacitor also expanded its line of standard axial-leaded aluminum electrolytic capacitors. The most recent addition, the TMA series, boasts an extended temperature range of up to 105 degrees . The full operating temperature range is -40 degrees to 105 degrees . "It's for engineers who are working with low-profile designs. It gives them an option of laying the device down," he said.
"The market for axial-leaded devices has been declining for a while," Bonomo said, "but it has been growing lately for specific applications such as automotive applications."
COMPANY CONTACTS
BC Components
(847) 296-9988
www.bccomponents.com
EETInfo No. 618
Illinois Capacitor Inc.
(847) 675-1760
www.illcap.com
EETInfo No. 619
JARO Components Inc.
(561) 241-6700
www.jaro1.com
EETInfo No. 620
NIC Components Corp.
(516) 396-7500
www.niccomp.com
EETInfo No. 621
Tecate Industries Inc.
(858) 513-2300
www.tecategroup.com
EETInfo No. 622
United Chemi-Con Inc.
(847) 675-2000
www.chemi-con.com
EETInfo No. 623
