Suntan Blog

A thermocouple must be attached to the capacitor body as in:

The temperature is measured in unloaded (Tamb) and maximum loaded condition (TC).
The temperature rise is given by ΔT = TC - Tamb.
To avoid radiation or convection, the capacitor should be tested in a wind-free box.

Capacitance is the ability to store electric charge. In its simplest form a capacitor consists of two parallel plates or electrodes that are separated from each other by an insulating dielectric. It is found that when a battery or any other voltage source is connected to the two plates as shown a current flows for a short time as it charges up. It is found that one plate of the capacitor receives an excess of electrons, while the other has too few. In this way the capacitor plate or electrode with the excess of electrons becomes negatively charged, while the capacitor electrode becomes positively charged.

If the battery is removed the capacitor will retain its charge. However if a resistor is placed across the plates, a current will flow in the resistor until the capacitor becomes discharged.

Safety

The Gold Capacitor should be distant from fire , high temperature or high humidity environment.

Do not compress, crush, throw down or heat the Gold Capacitor. In addition, do not take the Gold Capacitor apart.
Do not throw the Gold Capacitor in any liquid.

Precautions in use

Do not apply voltage higher than rated voltage. Over the rated voltage will cause the Gold Capacitor to explode.

Since the Gold Capacitor is polarized; do not apply a reverse voltage.
Reversing charge the Gold Capacitor will decrease the capacitance and cause ill effects in circuit.

The Gold Capacitor is not suited to AC circuit. It can not perform rectification and filter function.

Reduce the time during soldering operation. The recommend soldering conditions is: temperature below 250, the longest operating time should be less than 5 sec.

Do not bend the lead terminal too frequently to split.

The reason for the continued use of silver mica capacitors is the fact that they can offer very high levels of performance, better in many areas than any other type of capacitor. However in many applications, other more modern technologies provide levels of performance that meets the needs for that particular requirement.

The particular properties of the silver mica capacitor are summarised below.

• High accuracy: Silver mica capacitors can be obtained with tolerance figures of +/- 1%. This is much better than virtually every other form of capacitor available today.
• Temperature co-efficient: The temperature co-efficient of silver mica capacitors is much better than most other types of capacitor. The temperature coefficient is positive and is normally in the region 35 to 75 ppm / C, with +50 ppm / C being an average value
• Value range: Values for silver mica capacitors are normally in the range between a few picofarads up to two or possibly three thousand picofarads.
• Low capacitance variation with voltage: Silver mica capacitors exhibit very little voltage dependence.
• High Q: Silver mica capacitors have very high levels of Q and conversely small power factors. These are both almost independent of frequency.

Although silver mica capacitors have a high tolerance and low temperature co-efficient they are known to jump in value on occasions.

A metal oxide varistor, or MOV, is a voltage dependent, nonlinear device that provides excellent transient voltage suppression. When exposed to high transient voltage, the metal oxide varistor clamps voltage to a safe level. A metal oxide varistor absorbs potentially destructive energy and dissipates it as heat, thus protecting vulnerable circuit components and preventing system damage.

Varistors are non-linear, voltage-dependent resistors whose value of resistance decreases with increasing voltage. Varistors are mainly used for over-voltage protection. Varistors are utilized in low-voltage electronic equipment for absorbing high-voltage pulsative noise while bypass capacitors are utilized for removing low-voltage and high-frequency alternating noise.

An advanced device having both the functions is a ceramic capacitor with varistor performance. Varistors are commonly made by sintering particulate metal oxides, with or without minor amounts of other inorganic materials, as in disk or rod form. Metal oxide varistors (MOV) are semiconductor devices that are fabricated using technology from the ceramic capacitor industry. Zinc oxide varistors are ceramic semiconductor devices based on zinc oxide. Varistors are produced by a ceramic sintering process which gives rise to a structure consisting of conductive zinc oxide grains surrounded by electrically insulating barriers. These barriers are attributed to trap states at grain boundaries induced by additive elements such as bismuth, cobalt, praseodymium, manganese and so forth. A monolithic chip varistor is generally provided with a varistor body including a plurality of varistor layers composed of a zinc oxide-based ceramic material and at least one pair of internal electrodes opposed to each other with one of the varistor layers there between , and a pair of external electrodes.

Suntan metal oxide varistor devices are made primarily of zinc oxide with small amounts of bismuth, cobalt, manganese, and other metal oxides. They can be connected in parallel for increased energy-handling capabilities. MOVs can also be connected in series to provide higher voltage ratings or to provide voltage rating between the standard increments.

Variable Electrical parameters are those that the Design Engineer must specify when selecting a Quartz Crystal device for any particular application.

a. Package Type: Will the package be Through Hole or Surface Mount, and are there size constraints with either.

b. Frequency

c. Load Capacitance: The specified Load Capacitance is dependent on the Resonance Mode required in the application . For Series resonance, no Load Capacitance is required. For Parallel Resonance, the Load Capacitance specified by the Design Engineer will be used to calibrate the Quartz Crystal thereby effecting the major operating characteristics of the device, including initial Frequency Tolerance.

d. Frequency Tolerance: At 25 degree Celsius, an amount of initial frequency deviation acceptable for the application is required. Tighter specifications of Frequency Tolerance lower yield in Quartz Crystal Blank production thereby serving to increase production costs.

e. Stability: Over the Operating Temperature Range, an amount of total deviation acceptable for the application. Tighter specifications of Stability lower yield in Quartz Crystal Blank production thereby serving to increase production costs.

f. Operating Temperature: Standard Operating Temperature ranges are generally considered as -20-+70 degrees Celsius (considered "commercial" Operating Temperature), and -40-+85 degrees Celsius (considered "Industrial" Operating Temperature) Other Operating temperature ranges are available and should be specified .

(1) Ceramic Trimmer Capacitor series can be soldered by flow soldering method and soldering iron. Do not use reflow soldering method.

(2) Soldering condition If the soldering conditions are not suitable, e.g., excessive time and/or excessive temperature, the trimmer capacitor may deviate from the specified characteristics.

(3) The dimension of mounting hole should be Murata's standard mounting hole used at flow soldering. The amount of solder is critical. Insufficient amounts of solder can lead to insufficient soldering strength on PCB. Excessive amounts of solder may cause bridging between the terminals or contact failure due to flux wicking up.

(4) When using soldering iron, the string solder should be applied to the lower part of the terminal only. Do not apply flux except to the terminals. Excessive amounts of solder and/or applying solder to the upper part of the terminal may cause fixed rotor or the contact failure due to flux invasion into the movable part and/or the contact point. The soldering iron should not come in contact with the plastic case of the trimmer capacitor. If such contact does occur, the trimmer capacitor may be damaged.

(5) Our recommended chlorine content of string solder is 0.5wt% max.

(6) Do not use water-soluble flux (for water cleaning). To prevent the deterioration of trimmer capacitor characteristics, apply flux only to terminals.

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.