Aluminium organic
Kemet has introduced its A700 series, an aluminium organic capacitor low ESR surface mount aluminium capacitor with polymer cathode. The AO-CAP has a structure that uses aluminium as the anode material, aluminium oxide as the dielectric and a conductive, organic polymer for its counter-electrode material.
According to the company the AO-CAP offers several advantages over standard wet electrolytic aluminiums: it is truly surface-mountable and robust to the SMT process; it also does not exhibit the dry-out related failure mode that limits the useful lifetime of standard aluminiums; the use of an organic polymer ensures that the AO-CAP exhibits a benign failure mode; the polymer also results in extremely low ESR levels, and achieves high capacitance retention at high operating frequencies, which leads to optimum performance at higher frequencies.
The AO A700 series which has a strong epoxy body which protects against cracks (flex), is an ideal alternative to high-capacitance ceramics as well as existing aluminium organic capacitors found in the industry. The AO-CAP can also help reduce component counts, which permits the designer to save on board space as well as offer a more cost-effective alternative to high-cost high-capacitance ceramics.
The new capacitor is introduced as a totally lead-free device and has a maximum operating temperature of 125°. The AO-CAP demonstrates excellent surge current performance and long term reliability, and as a result of this, there is no recommended de-rating of application voltage to reduce failure rate, says Kemet. The maximum recommended application voltage is the rated voltage up to 85°C. Beyond 85°C, the industry standard voltage de-rating with temperature still applies: 80% of rated voltage at 105°C and 67% of rated voltage at 125°C.
Packages are the familiar tantalum V, D and X which have the same footprint and heights of 1,9, 2,8 and 4 mm respectively.
Tantalum organic
The new T520 series Kemet organic capacitor, the KO, is a tantalum capacitor with Ta anode and regular Ta2O5 dielectric. However, a conductive, organic, polymer replaces the MnO2 cathode. This results in very low ESR (up to 50% less than equivalent standard Ta types) and improved capacitance retention at high frequency, according to the manufacturer. The KO cap also exhibits a benign failure mode, which eliminates the ignition failures that can occur in standard tantalum types. Removal of the MnO2 eliminates the source of oxygen that can fuel the ignition if the capacitor fails short in a circuit that allows high fault current.
The new T520 series captures the best features of multilayer ceramic caps (low ESR and high frequency capacitance retention), aluminium electrolytics (benign failure mode) and proven solid tantalum technology (volumetric efficiency, surface mount capability, and no wearout mechanism). The KO Cap can reduce component counts, eliminate through-hole assembly by replacing cumbersome leaded aluminium capacitors and offer a more cost-effective solution to high-cost high-cap ceramic capacitors. These benefits allow the designer to save both board space and money.
Available in V, D and X packages the T520 ranges up to 470 µF at 6,3 V and 330 µF at 10 V. Higher working voltages are expected soon.
0805 footprint
Kemet has introduced the 'R' case tantalum chip. This EIA designation is size code 2012-12, meaning that the part is nominally 2,0 mm long by 1,2 mm wide and 1,2 mm maximum height. This part is also called the '0805 tantalum'. The R case is available in both T491 and T494 low ESR versions. This part becomes the smallest tantalum chip capacitor, and offers designers the opportunity to save board real estate in a stable dielectric. There is no X7R ceramic offering that gives this much CV in the 0805 package.
The target applications for the new R case part are in miniaturised products. Values immediately available in R case size include 10 µF 4 V, 10 µF 6 V, 4,7 µF 10 V and 2,2 µF 16 V.
High capacitance ceramic chips
During 2001 Kemet will add a series of high value chip ceramic capacitors to its range: 10 µF 10 V in 1210 X5R, available now; 22 µF 10 V in 1210 Y5V in May; 10 µF 10 V in 1206 Y5V in June; 10 µF 6,3 V in 1206 Y5V in August; 22 µF 6,3 V in 1206 Y5V in August; 22 µF 6,3 V in 1210 X5R in September. Extensions to 47 µF are under development as are 0402 sizes to 0,1 µF at 10 V.
For further information contact Insight Memec, (021) 674 4124.
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