Suntan Blog

For all capacitor technologies that do not have the ability to recover after a partial breakdown, the current flow is continuous.

However metallized film capacitors have the property to recover after an instantaneous breakdown (partial breakdown) due to the fact that the metallized electrodes (capacitor plates) act as a fuse. For fusing a small current is needed, but is not continuous. This effect is defined as “self healing” and not as breakdown.

Therefore in testing these capacitors on a proof voltage, it is always possible that the capacitors have the self healing effect, taking temporarily a peak current, but are completely isolated again after this phenomenon is stopped. To take this in account for qualifying capacitors, in all IEC standards of metallized film capacitors a breakdown is defined only when it is “permanent”.

Therefore a note is added for explanation.

Requirement: There shall be no permanent breakdown or flashover during the test.

Note: The occurrence of self-healing breakdowns during the application of the test voltages is allowed.

To detect if the behavior is a self healing or permanent breakdown, it is recommended to measure the remaining charging current only after one minute of charging and to neglect the small current peaks (arcing) before that time. Modern “high pot” test equipments have the function to allow arcing currents before the final permanent breakdown current.

The Electric Double Layer Capacitors developed by Suntan are storage capacitors with highest capacitance values in the Farad range. They are among others suited to serve as batteries, can deliver considerably higher currents for a short time, however, and are maintenance free.

The construction of a Double Layer Capacitor can be described as a plate capacitor where the most important topic is to obtain electrodes with an extremely large surface. For this purpose activated carbon is ideally suited, as it allows to obtain capacitance values of up to 100F/g of the active mass of the electrode.

The electrolyte, the conductive liquid between the electrodes, is a conducting salt dissolved in an aqueous or organic solvent which permits to apply voltages of 2 V (in special cases 3 V).

The actual double layer consists from ions which attach to the electrodes - negative ions to the positive electrode and positive ions to the negative electrode - as soon as a voltage is applied to the cell and thus create a dielectric of a few Angstrom only. According to the formula for the capacitor from the dielectric constant of the double layer (approx. 10) and the extremely thin dielectric you get an very high capacitance value.

A well constructed multilayer ceramic capacitor chip is extremely reliable and, for all practical purposes, has no wearout mechanism when used within the maximum voltage and temperature ratings. Most failures occur as a result of mechanical or thermal damage during mounting on the board, or during subsequent testing.

Capacitor failure may also be induced by sustained operation at voltages that exceed the rated DC voltage, voltage spikes or transients that exceed the dielectric's voltage capability, sustained operation at temperatures above the maximum rated temperature, internal defects, or excessive temperature rise due to power dissipation.

As with any practical device, multilayer ceramic capacitors also possess an inherent, although low, failure rate when operated within rated conditions.The primary failure mode is by short-circuit or low insulation.

resistance, resulting from cracks or from dielectric breakdown at a defect site. Suntan monitors reliability with a periodic sampling program for selected values.

Aluminum Electrolytic Capacitors include axial, snap-in and screw-terminal types. These capacitors offer very long life in applications requiring high ripple currents and temperatures up to 150°C. Other models have rated voltages as high as 550 VDC.

In addition to those products shown in the datasheets, KEMET can optimize the construction to offer application-specific balance between required life, temperature, ripple current, physical size, and cost.

Motor start capacitors are also offered.

A high performance electrolytic capacitor designed for automotive applications with high vibrations and high ambient temperatures.

An electrolytic capacitor with outstanding electrical performance. It is polarized with the negative pole connected to the case. The outer case has a plastic cover.

The low ESR is a result of a low resistive electrolyte/paper system. Together with the TDC thermal concept, this range has very high ripple current capability. The capacitor is suitable for both mobile and aircraft applications, with operation up to 105°C.

1. Aluminum electrolytic capacitors have a bi-polar structure. This is marked on the body of the capacitor. A capacitor must not be mounted with reversed polarity. The application of an AC or reverse voltage may cause a short circuit or damage the capacitor. Bi-polar capacitors must not be used in AC applications, where the polarity may be reversed in the circuits or is unknown.

2. The DC voltage applied to the capacitor terminal must not exceed its rated operating voltage, as this will result in a rapid increase of the leakage current and may damage the capacitor. It is recommended to operate the capacitor at 70 – 80% of its rated voltage to optimize its service life.

3. The ripple current applied to the capacitor must be within the permitted range. An excessive ripple current leads to impaired electrical properties and may damage the capacitor. Note that the sum of the peak values of the ripple voltage and the DC operating voltage must not exceed the rated DC voltage.

4. Capacitors must be used within their permitted range of operating temperature. Operation at room temperature optimizes their service life.

5. Capacitors with case diameter 8 mm are equipped with a safety vent. In capacitors fitted with a lead or soldering lug, the safety vent is usually located at the base of the case. It needs sufficient space around it to operate optimally. The following dimensions are recommended: for case diameter d = 8 to 16 mm, more than 2 mm; for d = 18 to 35 mm, more than 3 mm; and for d = 42 mm or more, more than 5 mm.

6. Capacitors should not be mounted with the safety vent face down on the board. Do not locate any wire or copper trace near the safety vent. Do not reverse the voltage, as this may result in excess pressure and the leakage of electrolyte.

7. Gas is released through the safety vent when the pressure inside the capacitor is too high. A gaseous liquid around the safety vent does not indicate a leakage of electrolyte.

8. The capacitor should be stored under conditions of normal temperature and in a non-acid, non-alkali environment of normal humidity. Exposure to high temperatures, for example under direct sunlight, will reduce its operating life. If the capacitor is stored in an environment containing acids or alkalis, the solder ability of the leads may be affected.

9. Containing acids or alkalis, the solder ability of the leads may be affected. The leakage current of an aluminum electrolytic capacitor may increase after a long period of storage. After such storage, the capacitor must be aged by applying the rated operating voltage for 6 – 8 hours before use.

Long life, with little degradation over hundreds of thousands of charge cycles. Due to the capacitor's high number of charge-discharge cycles (millions or more compared to 200 to 1000 for most commercially available rechargeable batteries) it will last for the entire lifetime of most devices, which makes the device environmentally friendly. Rechargeable batteries wear out typically over a few years, and their highly reactive chemical electrolytes present a disposal and safety hazard. Battery lifetime can be optimised by only charging under favorable conditions, at an ideal rate and, for some chemistries, as infrequently as possible. Electric Double Layer Capacitor can help in conjunction with batteries by acting as a charge conditioner, storing energy from other sources for load balancing purposes and then using any excess energy to charge the batteries at a suitable time.
Low cost per cycle
Good reversibility
Very high rates of charge and discharge.
Extremely low internal resistance (ESR) and consequent high cycle efficiency (95% or more) and extremely low heating levels
High output power
High specific power. According to ITS (Institute of Transportation Studies, Davis, California) test results, the specific power of electric double-layer capacitors can exceed 6 kW/kg at 95% efficiency
Improved safety, no corrosive electrolyte and low toxicity of materials.
Simple charge methods—no full-charge detection is needed; no danger of overcharging.

1. Do not use the trimmer capacitor under atmosphere of RTV silicone rubber (Room Temperature Vulcanizing Silicone Rubber) except Acetone liberating silicone sealant.

2. Before using trimmer capacitor, please store under the condition of -10 to +40 degrees C and 30% to 85%RH.

3. Do not store in or near corrosive gasses.

4. Use within 6 months of delivery.

5. Do not store under direct sunlight.

6. Do not use the trimmer capacitor under the conditions listed below.

(1) Corrosive gasses atmosphere (ex. Chlorine gas, Hydrogen sulfide gas, Ammonia gas, Sulfuric acid gas, Nitric oxide gas, etc.)

(2) In liquid (ex. water, oil, medical liquid,organic solvent, etc.)

(3) Dusty / dirty atmosphere

(4) Direct sunlight

(5) Static voltage nor electric/magnetic fields

(6) Direct sea breeze

(7) Other variations of the above

Electric Double Layer Capacitor do not have a conventional dielectric. Rather than two separate plates separated by an intervening substance, these capacitors use "plates" that are in fact two layers of the same substrate, and their electrical properties, the so-called "electrical double layer", result in the effective separation of charge despite the vanishingly thin (on the order of nanometers) physical separation of the layers. The lack of need for a bulky layer of dielectric permits the packing of plates with much larger surface area into a given size, resulting in high capacitances in practical-sized packages.

In an electrical double layer, each layer by itself is quite conductive, but the physics at the interface where the layers are effectively in contact means that no significant current can flow between the layers. However, the double layer can withstand only a low voltage, which means that electric double-layer capacitors rated for higher voltages must be made of matched series-connected individual Electric Double Layer Capacitor, much like series-connected cells in higher-voltage batteries.

Electric Double Layer Capacitor have much higher power density than batteries. Power density combines the energy density with the speed that the energy can be delivered to the load. Batteries, which are based on the movement of charge carriers in a liquid electrolyte, have relatively slow charge and discharge times. Capacitors, on the other hand, can be charged or discharged at a rate that is typically limited by current heating of the electrodes. So while existing Electric Double Layer Capacitor have energy densities that are perhaps 1/10th that of a conventional battery, their power density is generally 10 to 100 times as great (see diagram, right).

Mica capacitors are currently used in some low power RF designs, and pulse (snubber) applications, but advances in ceramic capacitor performance have slowly eroded mica’s traditional edge in these areas over the years. Perhaps more importantly, mica capacitors tend to be bulky—a result of the relatively low dielectric constant. For example, a 300 pF dipped mica capacitor may be as much as 16 times larger (in volume) than a good 300 pF MLC (NPO) capacitor. This low volumetric efficiency is a serious drawback in many applications such as portable electronic equipment. Some chip mica capacitors are available, but they tend to be expensive. Mica capacitors are still indispensable in high-power RF transmitter applications. In the latter case special rectangular, cylindrical, and button-style cases are used. Another niche is high-voltage applications that are a result of mica’s high dielectric breakdown and corona resistance.

Suntan Silver Mica Capacitors are available with values that range from 1–22,000 pF, voltages are in the range 50–1000V for standard dipped mica capacitors. Mica capacitors exhibit very little voltage dependence, have high Q or conversely small power factors that are quite independent of frequency. With all these advantage, our mica capacitors are ideal for high requence and RF applications.