GLOSSARY
CRYSTAL RESONATORS
2520 size This indicates the outside dimensions of the product. 2520 size indicates a product sized 2.5 by 2.0 in mm, and 3225 size indicates a product sized 3.2 by 2.5 in mm.
Affected layer Micro cracks on layers of crystal blanks, which is caused by the lapping or cutting process.
Aging The frequency change of the crystal operated at specific conditions for a certain period of time.
Amount of aging The amount of characteristical changes of a crystal resonator over time.
AT-cut A crystal cut, which the orientation of a synthetic quartz bar is set up at 35°15′from the Z axis and its temperature characteristics show a cubic curve. The mode of vibration is thickness-shear.
Autoclave A sealed vessel made from special iron, that withstands high pressure and heat. The largest size is 14 m.
Base-plating A process of applying coatings of metal layers on the surface of crystal wafers. There are two main methods: vacuum deposition and sputtering. The vacuum deposition melts metals in the chambers under a vacuum state. The sputtering method occurs by bombarding the surface of the sputtering target with gaseous ions.
BT-cut A crystal cut, which the orientation of a synthetic quartz bar is set up at -49° from the Z axis and its temperature characteristics show a turnover curve. The mode of vibration is thickness-shear.
Bypass Capacitor A component required to lower the impedance of the power-supply system inserted between the power-supply pin and ground pin of the IC. Mount as closely as possible to the IC, using a bypass capacitor with a capacitance suitable for the oscillation frequency. (Example) kHz range 10μF to 100μF MHz range: 0.01μF to 0.1μF
Cap (Lid) A ceramic or a metal cover, which protects the crystal blank bonded on the package.
Chemical processing A process in which the crystal blank is polished and processed with chemical solutions instead of machines.
Conductive adhesive agent An adhesive agent which becomes electrically conductive when cured. It is used to electrically connect the crystal wafer onto the package.
Control Resistance Insertion is preferable to limit the current running to the crystal resonator and to reduce the influence of IC output impedance and load on the oscillation loop.
Convexing (Beveling) The process of contouring the sides of the crystal elements to concentrate the vibration energy to its center. It is called convexing if there is no flatness in the center, and it is called beveling if there is flatness in the center.
Crystal Resonators with Suppressed Fundamental Mode The crystals with suppressed fundamental mode are designed to suppress the fundamental oscillation of third overtone resonators to ensure proper overtone oscillation. These crystals enable the oscillation of overtone frequencies on a circuit without using a tuning coil. This has the beneficial effects of reducing the number of components in the circuit, reducing the need for trimming and miniaturization.
Cylindrical type Crystal resonators in cylindrical constructions, which are generally in kHz frequency range.
Drive Level Loading condition of crystal resonator, which is determined by electric current or power applied to the crystal blank. Electric power P is determined by the following equation: P=I2×R1, where I represents electric current and R1 represents series resistance.
Equivalent Circuit The electrical equivalent circuit of a crystal resonator operating at its mechanical resonant frequency.
Feedback Resistance The feedback resistance for DC bias is one of the constants that determine the cut-off characteristics in the lower range of frequency. Generally, a resistance of 10 MΩ is used for oscillation in the kHz range, and a resistance of 1 MΩ is used for oscillation in the MHz range. However, if it is for overtone oscillation, a resistance of 1 kΩ may be used.
Formed-lead (SMD) type Crystal resonators with formed leads (terminals).
Frequency The number of recurrences of a periodic phenomenon (like radio wave or acoustic wave) per one second, often measured in Hertz (Hz).
Frequency Characteristics over Temperature (Crystal Resonators) Allowable deviation of frequency at room temperature, in parts per million(×10-6). This is the maximum value within the operating temperature range.
Frequency Tolerance (Crystal Resonators) Allowable deviation from nominal at room temperature (25 deg.C), indicated in parts per million(×10-6).
Fundamental Crystal Resonators Crystal resonator designed to oscillate in the lowest-order (fundamental) oscillation mode.
Hertz The basic unit of frequency. Number of vibrations (cycles) per second.
Inverse Piezoelectric Effect The phenomenon of a piezoelectric material where certain crystals deform when they are exposed to electrical field. Lippmann predicted its presence, and P. Curie and J. Curie proved it.
kHz Band Crystal Resonators(Tuning Fork Crystal Resonators) A resonator with low power consumption and a tuning fork shaped crystal blank. Common application includes watches and mobile phones.
Lapping Lapping or polishing process of a crystal element to precisely smoothen its surface to the required frequency.
Lasca Natural quartz, used as a raw material for growing synthetic quartz.
Length-width flexure vibration A vibration mode where the frequency is determined by the dimensions of the crystal element.
Load Capacitance The effective external capacitance that determines the resonance frequency of a crystal resonator. When this capacitance is small, the crystal resonator is vulnerable to changes in the circuit characteristics, thus deteriorating the frequency stability.
Lumbered quartz bar processing A process which grinds the reference surfaces (crystallographic axis) of synthetic quartz bars.
Maximum Drive Level The maximum electric current applied to an operating crystal.
Mechanical processing A process in which a crystal blank is adjusted to the right shape and size by using cut wares and machine tools. Lapping is also a kind of mechanical processing.
Metal-jacket (SMD) type Crystal resonators attached with an additional metal clip to make it available for surface-mounting.
MHz Band Crystal Resonators A resonator using thickness-sheer mode and has high stability during temperature variations. There are many packages and sizes available for various applications.
Motional capacitance The capacitance in the motional arm of the equivalent circuit.
Natural Quartz A mineral composed of silicon and oxygen, which has well-grown crystal faces. Amethyst and citrine is also a kind of natural quartz used for jewelry.
Negative Resistance The resistance value which indicates the oscillation allowance of an oscillator circuit. It is expressed in a negative value.
Nominal Frequency The specified center frequency of the crystal.
Operating Temperature Range Temperature range over which the crystal resonator can be operated within allowable deviation range.
Oscillation Allowance The degree in ratio which indicates the oscillation allowance of an oscillator circuit. It is the same as the negative resistance.
Overtone Crystal Resonators Crystal resonator designed to oscillate in the overtone oscillation mode (third, fifth, and seventh).
Overtone Order Desired order of vibration mode, (odd) integer multiples of the fundamental mode.
Package A ceramic or a metal container for bonding crystal blank. The container also protects the crystal blank.
Piezoelectric Effect The phenomenon of a piezoelectric material where certain crystals generate a voltage in response to applied mechanical stress. This was discovered by P. Curie and J. Curie in 1880.
Piezoelectric Element An element having the properties of converting a mechanical strain (like vibration or pressure) to a charge; conversely, converts a charge to a mechanical strain.
Plastic-encapsulated (SMD) type Crystal resonators encapsulated with resin.
Pullability A measure of the frequency change for a given change of load capacitance.
Q-factor A value which indicates the sharpness of the peak resonance. A crystal has a small loss of vibration energy and high purity.
Reference temperature The temperature at which certain crystal measurements are made.
Reflow A soldering method which melts the solder paste being applied to the connection pads of the PCB (Printed Circuit Board) to mount electric components.
Reflow Temperature Profile Specific conditions indicating the required time and temperature of the reflow oven, for mounting electric components to the PCB by reflow soldering.
Sealing A process in which the package is tightly closed to be leak proof. This process is done under nitrogen gas atmosphere or vacuum state for the prevention of frequency stability degradation over time. There are two methods: seam-welding and glass-sealing.
Seed Quartz A highly pure crystal stick or a plate used as a crystal nucleus for growing synthetic quartz bars. This crystal stick/plate serves as the seed for the recrystallization process.
Series Resistance The resistance of the crystal at the series resonance frequency, also called the equivalent series resistance (ESR).
Shunt capacitance The shunt capacitance in parallel with the motional arm of the equivalent circuit.
SMD type Abbreviation of Surface Mounted Device. It is a generic term used to identify packages which can be mounted to the PCBs.
Storage Temperature Range Temperature range, which crystal resonator should be stored at without any deterioration or damage.
Synthetic quartz A synthetic quartz bar grown by the hydrothermal crystallization method, which is used as the material for crystal devices. This high quality synthetic quartz contains practically no impurities and its shape is suitable for processing.
Thickness shear vibration One of the vibration modes of crystal resonators where the frequency is inversely proportional to its thickness. In this vibration mode, the top and the bottom surface of the crystal blank's thickness direction moves in opposite direction from each other. This mode is called the AT-cut.
Turnover Temperature The temperature at the peak of the parabolic curve that a crystal in kHz shows with temperature. It is expected that the crystal will have a steady oscillation if the peak temperature is within the working temperature range.
Two Dimensional Temperature Constant The temperature co-efficient of a parabolic curve shown in frequency vs. temperature.
Vibration Mode One factor which determines the mechanical vibration behavior of a crystal blank is cutting angle. Examples of such vibration behaviors are thickness-sheer mode and flexure mode.