JP2005217687A - Temperature compensated crystal oscillator - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a temperature compensation type crystal oscillator which is easily handled and excellent in productivity. <P>SOLUTION: The temperature compensation type crystal oscillator is configured in such a way that a rectangular container body housing a crystal vibration element in the inside is fixed on a supporting base, and that an IC element for outputting an oscillation signal corresponding to the oscillation frequency of the crystal vibration element while correcting the oscillation signal on the basis of temperature compensation data, and a plurality of packaging legs disposed along the external periphery of the supporting base, are attached on the bottom surface of the supporting base. On the external peripheral region of the bottom surface of the supporting base, a writing control terminal consisting of a metallic post for writing temperature compensation data into the IC element is attached between adjacent packaging legs so as to be spaced from the packaging legs, the distance in side face between the writing control terminal and the packaging legs is set so as to be gradually wide from the outward to the inward, and a part of a resin material for covering the IC element is allowed to flow into the gap between the packaging legs and the writing control terminal. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a temperature-compensated crystal oscillator used as a timing device for communication equipment and electronic equipment.

  Conventionally, crystal oscillators have been used as timing devices for portable communication devices and the like.

  As such a conventional crystal oscillator, for example, as shown in FIG. 4, a container body 23 in which a crystal resonator element 24 is accommodated is provided, a recess 25 is provided in the central area of the lower surface, and a plurality of external terminals 22 are provided on the upper surface. There is known a structure in which an IC element 26 that is attached to the mounting base 21 and that outputs an oscillation signal based on the oscillation frequency of the crystal vibration element 24 is accommodated in the region of the recess 25 ( For example, see Patent Document 1.)

  The container body 23 and the mounting base 21 are usually made of a ceramic material such as alumina ceramic, and a wiring pattern is formed on the inside and the surface thereof. By adopting a conventionally known green sheet laminating method or the like, It has been produced. A plurality of bonding electrodes are provided at corresponding positions on the lower surface of the container body 23 and the upper surface of the mounting base 21, and these bonding electrodes are bonded to each other with a conductive bonding material. As a result, the container body 23 was fixed to the upper surface of the mounting base 21.

In addition, a temperature compensation circuit for correcting the oscillation output of the crystal oscillator based on the temperature compensation data created according to the temperature characteristics of the crystal resonator element 24 is provided inside the IC element 26. In order to store such temperature compensation data in the memory in the IC element 26, a write control terminal 27 is provided on the outer surface of the mounting substrate 21, and after assembling the crystal oscillator, the write control terminal 27 is connected to the write control terminal 27. The temperature compensation data is stored in the memory in the IC element 26 by applying the temperature compensation data to the IC element 26 by applying the probe needle of the temperature compensation data writing device.
JP 2000-77943 A

  However, in the above-described conventional temperature-compensated crystal oscillator, since the write control terminal 27 for writing temperature compensation data is provided on the outer surface of the mounting substrate 21, it is used for manufacturing the mounting substrate 21. It is necessary to attach the film-like write control terminal 27 by making a through hole in a ceramic mother board, applying a conductive paste on the inner surface and baking it, or applying metal plating. Such a complicated processing process is indispensable, so that the productivity of the temperature compensated crystal oscillator is remarkably lowered.

  Therefore, in order to eliminate the above-described drawbacks, it is conceivable to arrange the write control terminal 27 on the lower surface of the mounting substrate 21.

  However, when the write control terminal 27 is arranged on the lower surface of the mounting base 21, a stray capacitance is generated between the wiring of the mother board (not shown) on which the temperature compensated crystal oscillator is mounted and the write control terminal 27. In such a case, the electrical characteristics of the communication equipment and electronic equipment in which the temperature compensated crystal oscillator is incorporated may be greatly affected, and the temperature compensated crystal oscillator may be soldered on the motherboard. , There is a risk that a part of the melted solder comes into contact with the write control terminal 27 to cause a short circuit, and there is a disadvantage that the temperature-compensated crystal oscillator is not easy to handle.

  The present invention has been devised in view of the above drawbacks, and an object thereof is to provide a temperature compensated crystal oscillator that is easy to handle and excellent in productivity.

  The temperature-compensated crystal oscillator according to the present invention fixes a rectangular container housing a crystal resonator element inside on a support base, and supports the oscillation frequency of the crystal resonator element on the lower surface of the support base. An IC element that outputs the oscillation signal while correcting the oscillation signal based on temperature compensation data, and a plurality of mounting legs arranged along the outer periphery of the support base are attached to the support element. A write control terminal composed of a metal post for writing temperature compensation data to the IC element is attached between the adjacent mounting legs at the outer peripheral area of the lower surface of the substrate, spaced apart from the mounting legs, and the writing is performed. The distance between the side surfaces of the control terminal and the mounting leg is set so as to gradually increase from the outside to the inside, and the IC element is covered in the gap between the mounting leg and the writing control terminal. Part of the resin material was allowed to flow And it is characterized in and.

  The temperature-compensated crystal oscillator of the present invention fixes a rectangular container body containing a crystal resonator element on a support base, and has an oscillation frequency of the crystal resonator element on the lower surface of the support base. An IC element that outputs a corresponding oscillation signal while correcting it based on temperature compensation data, and a plurality of mounting legs arranged along the outer periphery of the support base are attached, A plurality of write control terminals made of metal posts for writing temperature compensation data to the IC element are attached to the IC element in the outer peripheral area of the lower surface of the support base, spaced apart from the mounting legs. The interval between the side surfaces of the adjacent write control terminals is set so as to gradually increase from the outside toward the inside, and the gap between the adjacent write control terminals is made of a resin material that covers the IC element. A part of it The one in which the features.

  In the temperature compensated crystal oscillator of the present invention, a write control terminal for writing temperature compensation data to the IC element is formed by a metal post, and the write control terminal is attached to the lower surface of the support base. As a result, when assembling the temperature compensated crystal oscillator, the temperature compensated crystal oscillator can be manufactured simply by attaching the write control terminal made of a metal post to a predetermined position on the lower surface of the support base. Thus, no complicated processing process is required as in the case of forming the write control terminal of the conventional temperature compensated crystal oscillator. Therefore, the manufacturing process of the temperature compensated crystal oscillator is simplified, and the productivity can be greatly improved.

  Also, in this case, when stray capacitance is generated between the wiring of the motherboard on which the temperature compensated crystal oscillator is mounted and the write control terminal, or when the temperature compensated crystal oscillator is mounted on the motherboard by soldering or the like, There is also an advantage that the temperature compensated crystal oscillator can be handled easily without a part of the melted solder coming into contact with the write control terminal and causing a short circuit.

  Further, the distance between the side surfaces of the write control terminal and the mounting leg is set so as to gradually increase from the outside toward the inside, and the IC is provided in the gap between the mounting leg and the write control terminal. Since a part of the resin material covering the element is allowed to flow, the resin material can easily and quickly flow between the write control terminal and the mounting leg portion. It is possible to reinforce the attachment strength of the legs and the like to the support base, and it is possible to maintain high mechanical strength and reliability of the temperature compensated crystal oscillator.

  According to the temperature-compensated crystal oscillator of the present invention, a plurality of the write control terminals are arranged close to each other between the adjacent mounting legs, and the interval between the side surfaces of the adjacent write control terminals is outside. By setting so as to gradually widen from one side to the inside, it becomes possible to allow the resin material to flow easily and quickly between the side surfaces of the adjacent write control terminals, and to support the adjacent write control terminals. Therefore, the mechanical strength of the temperature compensated crystal oscillator can be kept high.

  Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

  1 is an exploded perspective view of a temperature compensated crystal oscillator according to an embodiment of the present invention, FIG. 2 is a cross-sectional view of the temperature compensated crystal oscillator of FIG. 1, and the temperature compensated crystal oscillator shown in these figures is The rectangular container body 1 containing the crystal resonator element 5 inside is fixed on the support base 6, and the IC element 7 and a plurality of mounting legs 12 are mounted on the lower surface of the support base 6. It has a worn structure.

  The container body 1 is made of, for example, a substrate 2 made of a ceramic material such as glass-ceramic or alumina ceramic, a seal ring 3 made of a metal such as 42 alloy, Kovar, or phosphor bronze, and a metal similar to the seal ring 3. The container body 1 is formed by attaching the seal ring 3 to the upper surface of the substrate 2 and placing and fixing the lid body 4 on the upper surface of the substrate 2, and is positioned inside the seal ring 3. A crystal resonator element 5 is mounted on the upper surface of the substrate 2 to be operated.

  The container body 1 is for hermetically sealing the quartz resonator element 5 in its interior, specifically, in a space surrounded by the upper surface of the substrate 2, the inner surface of the seal ring 3, and the lower surface of the lid body 4. A pair of mounting pads connected to the vibration electrode of the crystal resonator element 5 is provided on the upper surface of the substrate 2, and a plurality of pads connected to bonding electrodes of the support base 6 described later are provided on the lower surface of the substrate 2. Bonding electrodes are provided, and these mounting pads and bonding electrodes are electrically connected to each other through wiring patterns on the substrate surface, via-hole conductors embedded in the substrate, internal wirings, etc. ing.

  When the substrate 2 of the container body 1 is made of alumina ceramic, a conductive paste serving as a wiring pattern is applied to the surface of a ceramic green sheet obtained by adding and mixing an appropriate organic solvent to a predetermined ceramic material powder. It is manufactured by applying conventionally known screen printing or the like, laminating a plurality of these, press-molding, and firing at a high temperature.

  The seal ring 3 and the lid body 4 of the container body 1 are manufactured by forming a metal such as 42 alloy into a predetermined shape by using a conventionally known metal processing method, and the obtained seal ring 3 is attached to the substrate 2. After brazing the conductor layer previously deposited on the upper surface, and subsequently mounting and fixing the crystal vibrating element 5 on the upper surface of the substrate 2 using a conductive adhesive, a well-known conventional technique is applied to the upper surface of the seal ring 3. The container body 1 is assembled by joining the lid body 4 by resistance welding or the like. In this way, when the seal ring 3 and the lid 4 are joined by resistance welding, a Ni plating layer, an Au plating layer, or the like is previously deposited on the surfaces of the seal ring 3 and the lid 4.

  On the other hand, the quartz crystal vibrating element 5 accommodated in the container body 1 is formed by attaching and forming a pair of vibrating electrodes on both main surfaces of a crystal piece cut along a predetermined crystal axis, and a variable voltage from the outside. Is applied to the quartz crystal piece via a pair of vibrating electrodes, thickness shear vibration is caused at a predetermined oscillation frequency.

  The quartz vibrating element 5 is mounted on the upper surface of the substrate 2 by electrically connecting a pair of vibrating electrodes to a corresponding mounting pad on the upper surface of the substrate via a conductive adhesive, whereby the quartz vibrating element 5 and the container are mounted. The electrical connection with the body 1 and the mechanical connection are made simultaneously.

  If the lid 4 of the container body 1 is connected to the ground mounting legs 12 on the lower surface of the support base, which will be described later, via the wiring pattern of the container body 1 and the support base 6 or the like, the lid body will be used when used. Since the shield function is imparted by grounding 4, the crystal resonator element 5 and the IC element 7 to be described later can be protected better than unnecessary electrical action from the outside. Therefore, the lid body 4 of the container body 1 is preferably connected to the ground mounting legs 12 via the container body 1, the wiring pattern of the support base 6, or the like.

  The support base 6 on which the container 1 is placed and fixed has a substantially rectangular shape, and includes a plurality of mounting legs 12 and a plurality of write control terminals 11 along the outer periphery of the lower surface. Is attached. In the present embodiment, the mounting legs 12 are individually attached and erected at the four corners on the lower surface of the support base, and two write control terminals 11 are further adjacent to each other between the adjacent mounting legs 12. The IC elements 7 are mounted in the central area of the lower surface of the support base, which are arranged side by side and surrounded by the four mounting legs 12 and the two write control terminals 11.

  The support base 6 supports the container body 1 described above on its upper surface and supports the IC element 7, the write control terminal 11, the mounting leg 12 and the like on its lower surface. It is formed so as to have a flat plate shape by using a resin material such as epoxy resin, polycarbonate, epoxy resin or polyimide resin, or ceramic material such as glass-ceramic or alumina ceramic.

  Further, the plurality of mounting legs 12 attached / standing on the lower surface of the support base 6 are each formed by a metal post formed of a metal material such as copper in the shape of a quadrangular column, and serves as an external terminal. When the temperature compensated crystal oscillator is mounted on an external wiring board such as a mother board (not shown), it is electrically connected to the circuit wiring of the external electric circuit by soldering or the like.

  The four mounting legs 12 described above function as a power supply voltage terminal, a ground terminal, an oscillation output terminal, and an oscillation control terminal, and the lower surface of these mounting legs 12 is bonded to an external wiring board. For example, nickel plating, gold plating, or the like is applied to a predetermined thickness in order to improve the bonding state of solder or the like used for the soldering.

  Here, of the four mounting legs 12, if the ground mounting leg 12 and the oscillation output mounting leg 12 are arranged close to each other, the oscillation signal output from the oscillation output terminal can be reduced. It is possible to effectively prevent noise from interfering. Therefore, it is preferable that the mounting leg 12 for ground and the mounting leg 12 for oscillation output are arranged close to each other.

  On the other hand, as the IC element 7 attached to the lower surface of the support base 6, for example, a rectangular flip chip IC having a plurality of connection pads on the lower surface is used, and its circuit forming surface (lower surface). Includes a temperature sensing element (thermistor) for detecting an ambient temperature state, a memory for storing temperature compensation data for compensating the temperature characteristic of the crystal vibration element 5, and a vibration characteristic of the crystal vibration element 5 based on the temperature compensation data. Is provided with a temperature compensation circuit that compensates for changes in temperature, an oscillation circuit that is connected to the temperature compensation circuit and generates a predetermined oscillation output, and the oscillation output generated by the oscillation circuit is output to the outside Later, for example, it will be used as a reference signal such as a clock signal.

  The exposed side surface of the IC element 7 is slightly inward of the outer periphery of the container body 1 and the support base 6, for example, 1 μm to 500 μm inward of the outer periphery of the support base 6, along the outer periphery of the support base 6. It is arranged. In this case, since the width dimension of the support base 6 in the direction orthogonal to the exposed side surface of the IC element 7 is designed to be substantially equal to the length of one side of the IC element 7, the entire structure of the temperature compensated crystal oscillator is obtained. It can be configured in a small size.

  On the lower surface of the support base 6 on which the IC element 7 is disposed, electrode pads corresponding to the connection pads of the IC element 7 are provided on a one-to-one basis, and solder, gold bumps, or the like are provided on these electrode pads. The IC element 7 is attached to and mounted on the lower surface of the support base 6 by bonding the connection pads of the IC element 7 via the conductive bonding material, and thereby the electronic circuit in the IC element 7 is connected to the wiring of the container body 1. It is electrically connected to the crystal resonator element 5, the mounting leg 12, etc. via the pattern, the wiring pattern of the support base 6, and the like.

  When the support base 6 is made of a glass cloth base epoxy resin, the glass cloth base formed by weaving glass yarn is impregnated with a liquid precursor of the epoxy resin and the precursor is polymerized at a high temperature. A base is formed by the above, and a metal foil such as a copper foil adhered to the surface thereof is formed into a predetermined pattern by using a conventionally well-known photo-etching or the like to form mounting legs 12 and wiring conductors made of metal posts. Is done.

  A plurality of write control terminals 11 are arranged in parallel on the lower surface of the support base 6 described above.

  The write control terminal 11 is used to write temperature compensation data to the IC element 7, and similarly to the mounting leg 12 described above, by processing a metal material such as copper by a conventionally known photoetching or the like, It is formed as a triangular post-like metal post, and its length dimension is slightly shorter so that the lower end of the write control terminal 11 is located above the lower end of the mounting leg 12, and a part of the side surface is adjacently mounted. It is attached to the lower surface of the support base 6 so as to be exposed from between the legs. Here, the gap between the side surfaces of the write control terminal 11 and the mounting leg 12 is set so as to gradually narrow from the IC element 7 side toward the edge side of the support base 6.

  These write control terminals 11 are juxtaposed along the edge of the support base 6 and are electrically connected to the IC element 7 via the wiring pattern of the support base 6. Therefore, after assembling the temperature compensated crystal oscillator, the probe needle of the temperature compensation data writing device is applied to these write control terminals 11 from the side, and the temperature compensation data corresponding to the temperature characteristics of the crystal resonator element 5 is written. As a result, the temperature compensation data is stored in the memory of the IC element 7.

  Further, the above-described IC element 7 is sealed with a resin material 13 made of, for example, an epoxy resin, and the outer peripheral portion of the resin material 13 extends to the outer peripheral portion of the support base 6, and adjacent mounting legs. The gap between the parts is filled, and a part of the gap is also attached to the exposed surface of the IC element 7 described above. In this way, by filling the resin material 13 in the gaps between the adjacent mounting legs 12-12 and between the mounting legs 12 and the write control terminal 11, the IC element 7 and the write control terminal 11 are filled. The mounting strength of the mounting legs 12 and the like to the support base 6 can be reinforced, and the circuit forming surface of the IC element 7 can be well protected by the resin material 13. It is possible to maintain high strength and reliability.

  In addition, as described above, the gap between the side surfaces of the write control terminal 11 and the mounting leg 12 is set to gradually narrow from the IC element 7 side toward the edge side of the support base 6. The fluid-like resin material 13 can be satisfactorily permeated and introduced along the gap between the mounting leg 12 and the writing control terminal 11, and the resin material 13 can be inserted into the gap between the mounting leg 12 and the writing control terminal 11. It is possible to more effectively reinforce the attachment strength of the write control terminal 11, the mounting leg portion 12 and the like to the support base 6.

  In this case, if the resin material 13 is formed of a transparent material, even if the side surface of the IC element 7 exposed between the adjacent mounting legs is covered with the resin material 13, the joint portion to the support base 6 is used. Therefore, when the product is inspected, the joining state of the IC element 7 can be easily confirmed visually or the like, and the inspection workability can be improved.

  Thus, the above-described temperature compensated crystal oscillator is mounted on an external wiring board such as a mother board by soldering or the like, and crystal oscillation is performed while correcting the oscillation frequency according to the temperature state using the temperature compensation circuit of the IC element 7. By outputting a predetermined oscillation signal corresponding to the oscillation frequency of the element 5, it functions as a temperature compensated crystal oscillator.

  In this case, if the extending portion of the resin material 13 is also attached to the lower surface of the write control terminal 11, the temperature compensated crystal oscillator is melted when mounted on the motherboard by soldering or the like. The disadvantage that a part of the solder contacts the write control terminal 11 to cause a short circuit is effectively prevented, and there is an advantage that the temperature compensated crystal oscillator can be handled easily.

  According to the temperature-compensated crystal oscillator of this embodiment, the write control terminal 12 has another configuration simply by attaching the write control terminal 12 made of a metal post to a predetermined position on the lower surface of the support base. Because it is integrated with the elements, there is no need for complicated processing processes such as forming film-like write control terminals in conventional temperature compensated crystal oscillators. Simplification can greatly improve productivity.

  In this case, when a floating capacitance is generated between the wiring of the motherboard on which the temperature compensated crystal oscillator is mounted and the write control terminal 11, or when the temperature compensated crystal oscillator is mounted on the motherboard by soldering or the like. Since a part of the melted solder does not come into contact with the write control terminal 11 to cause a short circuit, there is an advantage that the temperature compensated crystal oscillator can be handled easily.

  In addition, this invention is not limited to the above-mentioned embodiment, A various change, improvement, etc. are possible in the range which does not deviate from the summary of this invention.

  For example, in the above-described embodiment, the opposing side surfaces of the adjacent write control terminals 11 are arranged in parallel, but instead of this, as shown in FIG. You may arrange | position so that the distance between the side surfaces which the terminal 11 opposes may become large gradually toward the inside from the outer side. In this case, the resin material 13 can easily and quickly flow between the side surfaces of the adjacent write control terminals 11, and the resin material 13 can be filled with higher productivity and the support base for the write control terminals 11. The attachment strength to 6 can be reinforced more effectively.

  In the above-described embodiment, the write control terminal 11 is formed by a triangular prismatic metal post. However, the shape of the write control terminal 11 is not limited to the triangular prism shape. For example, FIG. As shown in b), it may be formed by a metal post having a semi-cylindrical shape, or the write control terminal 11 may be formed by a metal post having a trapezoidal square columnar bottom.

  In the above-described embodiment, the mounting legs 12 are all formed of metal posts. Instead, the mounting legs 12 are formed of the same material as that of the support base 6 and the support base 6. You may make it form integrally. In this case, an external terminal for connecting the temperature-compensated crystal oscillator to an external wiring board such as a mother board is formed in a film shape on the lower surface of the mounting leg 12.

  Furthermore, in the above-described embodiment, a general conductive bonding material such as solder is used to attach the IC element 7, the write control terminal 11, the mounting leg 12, and the like to the lower surface of the support base 6. However, the present invention is not limited to this. For example, an anisotropic conductive adhesive or the like may be used as the conductive bonding material. In that case, the IC element 7 or the mounting leg 12 or the like for the support base 6 may be used. There is also an advantage that the attaching operation becomes extremely simple and the assembly process of the temperature compensated crystal oscillator is further simplified.

  Furthermore, in the embodiment described above, the lid 4 of the container body 1 is bonded to the substrate 2 via the seal ring 3. Instead, a metallized pattern for bonding is formed on the upper surface of the substrate 2. In addition, the lid 4 may be directly welded to the metallized pattern.

  Furthermore, in the above-described embodiment, the seal ring 3 is directly attached to the upper surface of the substrate of the container body 1, but instead, the upper surface of the substrate 2 is made of the same ceramic material as the substrate 2. The frame body may be attached integrally, and the seal ring 3 may be attached to the upper surface of the frame body.

  Furthermore, in the above-described embodiment, electronic component elements other than IC elements, for example, chip capacitors for noise removal, etc. are arranged on the lower surface of the support base 6 located between the adjacent mounting legs 12-12. In this case, the empty area on the lower surface of the support base 6 is used more effectively, so that the temperature compensated crystal oscillator can be further downsized.

BRIEF DESCRIPTION OF THE DRAWINGS It is a figure which shows the temperature compensation type | mold crystal oscillator based on one Embodiment of this invention, (a) is a disassembled perspective view, (b) is a front view, (c) consists of the support base | substrate of (a) upside down. It is a perspective view. It is sectional drawing of the temperature compensation type | mold crystal oscillator of FIG. It is a front view which shows the temperature compensation type | mold crystal oscillator which concerns on other embodiment of this invention. It is a figure which shows the conventional temperature compensation type | mold crystal oscillator, (a) is a disassembled perspective view, (b) is a perspective view which turns the mounting base | substrate of (a) upside down.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Container body 2 ... Board | substrate 3 ... Seal ring 4 ... Lid body 5 ... Crystal oscillation element 6 ... Support base | substrate 7 ... IC element 7a ... Connection pad 10. ..External terminal 11 ... Write control terminal 12 ... Mounting leg 13 ... Resin material

Claims (2)

A rectangular container body containing a quartz resonator element is fixed on a support substrate, and an oscillation signal corresponding to the oscillation frequency of the quartz resonator element is formed on the lower surface of the support substrate based on temperature compensation data. A temperature-compensated crystal oscillator in which an IC element that outputs while correcting, and a plurality of mounting legs arranged along the outer periphery of the support base,
A write control terminal made of a metal post for writing temperature compensation data to the IC element is attached to the IC element between the adjacent mounting legs in the outer peripheral area of the lower surface of the support base, spaced apart from the mounting legs, and attached. The distance between the side surfaces of the write control terminal and the mounting leg is set so as to gradually increase from the outside to the inside, and the IC element is placed in the gap between the mounting leg and the write control terminal. A temperature-compensated crystal oscillator in which a part of a resin material to be coated is allowed to flow. A rectangular container body containing a quartz resonator element is fixed on a support substrate, and an oscillation signal corresponding to the oscillation frequency of the quartz resonator element is formed on the lower surface of the support substrate based on temperature compensation data. A temperature-compensated crystal oscillator in which an IC element that outputs while correcting, and a plurality of mounting legs arranged along the outer periphery of the support base,
A plurality of write control terminals made of metal posts for writing temperature compensation data to the IC element are attached to the IC element between the adjacent mounting legs in the outer peripheral area of the lower surface of the support base, spaced apart from the mounting legs. And a resin material for setting the interval between the side surfaces of the adjacent write control terminals so as to gradually increase from the outside toward the inside, and covering the IC element in the gap between the adjacent write control terminals A temperature-compensated crystal oscillator characterized in that a part of the temperature is introduced.

Images