HXW Series have been developed for applications such as power supplies or adapters, and LXW Series has been developed for LED lights or other devices where higher reliability is essential. In order to realize miniaturization while maintaining the characteristics of conventional devices, both series have maintained the equivalent rated ripple current as prior series while achieving a reduction of approximately 20%. These series have abundant size options with thin profiles with diameters as small as 10mm and lengths to 60mm. We also offer < 30mm lengths which is popular for 1U server power supplies as well as 90 degree lead forming to horizontally mount the capacitor for a low profile height. With respect to low temperature operation, all products including our 500V rated can be used in the temperature region as low as -40ºC and, as a result of that, these series become usable in a broader application range. Table 1 gives an outline of HXW Series and LXW Series.

Table 1: Outline of HXW Series and LXW Series

　This article introduces 3 key points such as Miniaturization, Low Temperature Characteristics and Life Prolongation which were focused as essential technical elements in R&D of HXW and LXW series.

(1) Miniaturization
    AE capacitors are polarized electrolytic capacitors whose aluminum oxide layer formed on the surface of anode foil acts as dielectric and stores electricity. Etched surface of anode foil having microscopic pits enlarge the surface area of the anode foil. Etched and enlarged surface area enables AE capacitors to achieve significantly high capacitance compared with other capacitor types.

    Capacitance of AE capacitors increases proportionally to the surface area of anode foil. For this reason, it is effective to further enlarge the surface area by increasing the etch pit density. However, with higher etch pit density, this causes elution of the aluminum which results in a loss of the material strength of the anode foil. As AE capacitors are being manufactured by cutting and winding of the anode foil, it is difficult in nature to cut and wind low strength anode foil when developing smaller-sized capacitors.

    Rubycon has been developing in house our own manufacturing equipment and other process control in order to manufacture capacitors under optimal conditions helping to better match the characteristics/specifications of the products and material. Rubycon continues its long-standing research and development of cutting & winding technologies of large-capacitance aluminum. In the development of our HXW and LXW Series, Rubycon has successfully enabled to cut & wind the large-capacitance and lower-strength anode foil with high precision in order to commercialize the smallest-sized capacitors. Likewise, Rubycon has successfully developed higher-strength anode foils maintaining higher-capacitance versus conventional types. As a result of its diligent R&D in both products and material, Rubycon has succeeded in developing and marketing our HXW and LXW series which are the smallest in size without compromising the reliability.

(2) Low Temperature Characteristics Improvement
    Electronic devices or power supplies are also considered for outdoor installations. In the colder seasons having a low temperature guarantee is necessary. Temperatures of -30ºC or lower are generally required. The challenge of an AE capacitor at such temperatures involves the electrolyte employed. Generally speaking, the electrolyte used inside can have a tendency to change from a liquid to solid state which can cause wide variance in ESR and capacitance characteristics. To meet such lower temperature stability without relying on the capacitor self heating, we have developed specialized electrolytes that are more stable and have a lower freezing point.
A while back, Rubycon upgraded our 450V, QXW series which can be used as low as -40ºC. Rubycon has applied this electrolytic solution to our HXW and LXW series which also can operate as low as -40ºC also including our 500 volt options.

    Figure 3 is a graph comparing the capacitance change rate of the two series at low temperatures. Our conventional BXC series exhibits a rapid drop of its capacitance at -15ºC and our LXW series using a newly developed electrolytic solution has an electric resistance value which is more stable in a low temperature environment- even as low as -30ºC.

Figure 3: Capacitance Change Rate in a low temperature (500WV,Φ18)

(3) Life Prolongation

    Capacitors used for power supplies of LED lights for example require stable and long-life characteristics. AE capacitors use electrolytic solution inside, which diffuses gradually through the seal material to finally reach an open (safe) end of life when the electrolyte eventually dries up. For that reason, it is indispensable to slow the diffusion of the solution as well as to reduce the deterioration of the solution itself.

    Rubycon has accumulated its know-how of electrolytic solutions development over 50 years and has a number of achievement records in the field of long-life characteristic improvement of capacitors for LED lights for example. Electrolytic solution of our LXW series have been developed with the objective of lower resistance value and higher stability of electric characteristics of the solution in the environment of longer time of use in a higher temperature. Figure 4 exhibits high temperature load test results (Rated Ripple Voltage Superimposed) of our LXW series at a temperature of 105ºC.Even after an interval of 12,000hrs it can be seen that there is not much difference in electric characteristics, which results in performance stability.

    Our LXW series demonstrates excellent electric characteristics in low temperature environments as well as long-term reliability in a high temperature environment and thus the LXW Series is a remarkable invention for a broad range of environments.

Figure 4: High Temperature Loaded Test Results of LXW Series at 105ºC(450V 220µF Φ18×50L)

AE capacitors are capacitors which combine such characteristics as high voltage resistance, high capacitance and safe performance which are required for input smoothing capacitors of power source input circuits / devices. AE capacitors are relatively small in size and low in cost compared with other types of capacitors of the same capacitance and, for this reason, AE capacitors are broadly used for various power source input circuits / devices.

source：http://www.rubycon.com/