JP5228898B2 - Crystal oscillator - Google Patents

Description

  The present invention relates to a crystal resonator, and improves the structure of a metal support that holds a crystal diaphragm.

  Since quartz resonators have excellent resonance characteristics, they are widely used as a reference source for frequency and time. A metal thin film electrode is formed on the surface of the quartz diaphragm, and this metal thin film electrode is protected from the outside air. Is hermetically sealed.

  Among these, the crystal resonator used in the thermostatic chamber type crystal oscillator called OCXO currently uses a metallic package. Specifically, a pair of metal lead terminals are planted on the metal base via an insulating material such as glass, and a pair of metal flat plate support members are opposed to the inner lead portion of the metal lead terminal. Attached. The quartz diaphragm is, for example, an AT-cut quartz diaphragm that vibrates through a thickness, and an excitation electrode and an extraction electrode from each excitation electrode are formed on the front and back surfaces. A quartz diaphragm is mounted on the metal support and is electrically and mechanically connected by a conductive bonding material. The metal base is covered with a metal lid and hermetically sealed. .

  In addition, OCXO is one in which the frequency is stabilized by controlling the temperature of the crystal unit in a thermostat without affecting the external temperature change, and the frequency stability is 1 × 10 −7 to 1 Since the highest level of frequency stability that can be obtained with a crystal resonator of about × 10 −10 can be obtained, it is used as a reference frequency for radio base stations and transmission lines.

  Patent Document 1 proposes an improved configuration for a crystal structure holding structure for high stability using a metal brazing material such as AuGe (gold-germanium) that can obtain good aging characteristics used in such OCXO. Yes.

JP 2006-186839 A

  In the crystal structure holding structure for high stability, it is important to consider the effects of the thermal expansion and thermal conductivity of the support member accompanying changes in the external environment temperature. When a metal with high thermal expansion is used, if external heat is applied, unnecessary thermal mechanical stress is applied from the support member to the quartz diaphragm, and the aging characteristics of the quartz resonator tend to deteriorate. It is in. In addition, when a metal having poor heat conductivity is used, the thermal followability of the crystal unit with respect to changes in the external environment temperature also deteriorates. When using a crystal unit as an OCXO, the crystal unit is set in a constant temperature chamber. In some cases, the time until the frequency is stabilized after heating to the temperature becomes long, and the start-up characteristics are also deteriorated. On the other hand, when a metal having too good thermal conductivity is used, the temperature transmitted to the crystal diaphragm is sudden and gives a thermal shock, which may cause hunting (overshoot) of the frequency of the crystal unit.

  The present invention has been made in order to solve the above-described problems, and a highly reliable high-stable crystal resonator that does not adversely affect the thermal expansion and thermal conductivity of the support member accompanying changes in the external environment temperature. It is intended to provide.

Therefore, a crystal resonator according to the present invention includes a base in which at least two metal lead terminals are embedded through an insulating material, a metal support provided on the inner side of the metal lead terminal, and the metal support. A crystal unit for OCXO which is mounted on a plate and is bonded to each other through a conductive bonding material, wherein the base is covered with a lid and hermetically sealed in a vacuum atmosphere. The metal support is made of a metal material having a lower thermal expansion than quartz made of a nickel iron-based low thermal expansion alloy, and a metal film having a higher thermal conductivity than the metal support is formed on the outer surface of the metal support. Ri, characterized that you formed in 3-10% of the thickness of the thickness of the metal base material of the metal film is the metal support.

  With the above-described configuration, the metal support is made of a metal material having a lower thermal expansion than quartz, and a metal film having higher thermal conductivity than the metal support is formed on the outer surface of the metal support. As a result, thermal expansion of the metal support hardly occurs compared to the quartz diaphragm, and stress due to changes in environmental temperature is not applied from the metal support to the quartz diaphragm. it can. In such a low thermal expansion metal material, since the thermal conductivity tends to be smaller than that of a metal support used in the past, a metal film having a higher thermal conductivity is formed on the outer surface of the metal support. As a result, the metal film transmits the temperature to the crystal diaphragm without delay with respect to the temperature outside the package body (lid and base) of the crystal unit due to the change in the external environment temperature, and the temperature difference hardly occurs. By combining such configurations, the aging characteristics and thermal followability of the crystal resonator can be improved simultaneously and more effectively, and more stable frequency-temperature characteristics can be obtained. The starting characteristics when a crystal resonator is used as the OCXO can also be improved. That is, it is possible to start up the crystal resonator in a shorter time after the crystal resonator is heated to a predetermined temperature in the thermostat and the frequency is stabilized.

  Moreover, when forming the said metal film, forming on the front and back main surface of a metal support is more desirable. By forming the metal film on the front and back main surfaces of the metal support, there is no bias in the thermal deformation of the entire metal support, and no extra stress is applied to the crystal diaphragm. The effect of forming the metal film described above is particularly effective for a highly stable crystal resonator that is hermetically sealed in a vacuum atmosphere. When hermetically sealed in a vacuum atmosphere, the temperature difference with respect to the external environment is not affected by radiant heat from the outside of the package body, but the effect of only heat transfer via the metal lead terminals and metal support is enhanced, thus increasing thermal conductivity The benefits of metal films are particularly likely.

  Further, in the above-described metal support configuration, the low thermal expansion metal material is made of a nickel iron-based low thermal expansion alloy. For example, invar and super invar whose thermal expansion coefficient is close to zero from about half the thermal expansion coefficient of quartz. May be used. By using these metal supports, it is possible to select an optimum material desirable for a highly stable crystal resonator capable of obtaining the above-described effects. Specifically, Mitsubishi Materials Co., Ltd .: MA-INV36 <Fe-36Ni> (invar / amber) as an invar, MA-S-INVER <Fe-32Ni-5Co> (superinver) as a super invar, etc. can give. Invar and Super Invar are materials with low thermal expansion, but the thermal conductivity is poor and the thermal followability when external heat is applied is poor, so the heat transmitted to the quartz diaphragm is delayed, and the startup characteristics deteriorate. Tend to. In the present invention, by applying a metal film having higher thermal conductivity than Invar and Super Invar, the thermal conductivity can be increased at the same time while having low thermal expansion, and a desirable holding structure for a highly stable crystal unit is obtained. It is done.

In the above-described configuration, Cu plating may be formed as a metal film having higher thermal conductivity than the metal support. By using Cu plating, it is possible to select an optimum material desirable for a highly stable crystal resonator capable of obtaining the above-described effects. That is, Cu has good wettability when the metal brazing material (conductive bonding material) is melted, and can improve the bonding force by the metal brazing material. Compared to other precious metals with high thermal conductivity such as gold and silver, it is a metal material with extremely high thermal conductivity that can be stably supplied at a low cost. Cu plating is also relatively inexpensive and easy to plate using a general-purpose plating bath. It can be formed. Further, since Cu can be processed with the same etching solution as Invar and the like, a support material with high processability can be obtained by combining Cu and Invar or Super Invar. In addition, when forming a metal film by Cu plating, it is more desirable to form the film thickness in about 3-10 micrometers. By setting the Cu film thickness in this way, it is possible to maintain stable heat transfer while suppressing costs, and to maintain the low thermal expansion performance of the entire support and to eliminate the adverse effects of unnecessary thermal stress. When the copper plating is formed thinner than 3 μm, the heat conductivity is lowered. If the copper plating is formed thicker than 10 μm, the risk of plating cracking increases due to bending of the metal support, etc., and the thermal expansion performance of the support as a whole is adversely affected, and unnecessary thermal stress is applied to the crystal diaphragm. The risk of becoming more likely to join increases.

Further, in the above-described configuration, in the main surface region of the metal support where the crystal diaphragm is held via the conductive bonding material, a central portion where the metal film is not formed, and the metal film around the central portion A first annular portion in which is formed, and a second annular portion in which the metal film is not formed around the first annular portion. By comprising in this way, the said center part can be utilized as a mark for positioning joining of a metal brazing material (electroconductive joining material) , and the metal brazing material positioned and joined in the vicinity of the center part is the first. By performing fillet formation over the boundary portion between the annular portion and the second annular portion, stronger bonding can be performed. This is because the metal film is formed in the first annular part, so that the molten metal brazing material is easily diffused before joining, and the metal film is not formed in the second annular part. This is because the molten metal brazing material is difficult to diffuse.

Moreover, you may remove the said metal film by forming a recessed part about the above-mentioned center part and 2nd cyclic | annular part. By having the concave portion in the central portion, not only the positioning performance of the metal brazing material (conductive bonding material) is further enhanced, but also functions as a reservoir for the metal brazing material. By having the concave portion in the second annular portion, unnecessary flow out of the metal brazing material can be eliminated, and the bonding strength to the crystal diaphragm can be stabilized. In particular, the recesses of the metal support are more preferably formed with the same shape and volume. As a result, the stress of the holding part joined by the metal support and the conductive bonding material is also uniform, and the stress applied to the quartz diaphragm from the outside such as the metal support is distributed more uniformly and stably, and as a result Stress suppression against aging can be realized even more.

Further, in the above-described configuration, the conductive bonding material is made of a gold alloy brazing material such as AuGe, AuSn, or Au, and the excitation electrode formed on the front and back main surfaces of the crystal diaphragm has gold as a main component. An electrode material may be used. With this configuration, in addition to the above-described effects, the aging characteristics can be further enhanced because the excitation electrode material and the metal brazing material are stable materials that are less susceptible to deterioration of electrical characteristics such as oxidation.

  According to the present invention, it is possible to provide a highly stable and highly stable crystal resonator that does not adversely affect the thermal expansion and thermal conductivity of the support member due to changes in the external environment temperature.

  Next, embodiments of the present invention will be described with reference to the drawings, taking a crystal resonator as an example. FIG. 1 is an exploded perspective view showing an embodiment of the present invention, and FIG. 2 is an enlarged front view of a main surface area of a crystal diaphragm holding portion of a metal support in FIG. 1 (dotted oval portion in FIG. 1). 3 is a front view showing a first embodiment in a state where FIG. 1 is assembled, and FIG. 4 is a schematic view showing a manufacturing process in the first embodiment. FIG. 5 is a front view showing a second embodiment in a state where FIG. 1 is assembled, and FIG. 6 is a schematic view showing a manufacturing process in the second embodiment. FIG. 7 is a front view showing a crystal diaphragm according to an embodiment of the present invention, and FIGS. 8 and 9 are front views showing a crystal diaphragm according to another embodiment of the present invention. In addition, in each form, the same number is attached | subjected about the same part, and if there is no need in particular, the description is omitted.

  The base 1 as a whole has a low-profile long cylindrical shape, and has a structure in which metal lead terminals 11 and 12 are planted through a base body 10 mainly including a metal shell, and an insulating glass G is used as a base body. The metal lead terminals 11 and 12 are integrally formed integrally with each other by being partially filled.

  The metal lead terminals 11 and 12 have an elongated cylindrical shape. For example, the tip portions 11a and 12a on the inner side of the upper part of the base are formed in a nail head shape having a wide width and a flat upper part. Metal supports 13 and 14, which will be described later, are attached to the tip of the inner lead so as to face each other by a welding method (laser welding, spot welding, etc.). For this reason, when mounting the metal support on the metal lead terminal, it can be mounted horizontally and stably without tilting, and the welding area is expanded, so that the joint strength is improved and the reliability when welding the metal support to the metal lead terminal is increased. Will improve dramatically.

  The metal supports 13 and 14 are, for example, nickel iron-based low thermal expansion alloys, which use a metal material whose thermal expansion coefficient is close to zero from about half the thermal expansion coefficient of quartz, specifically manufactured by Mitsubishi Materials Corporation. MA-INV36 <Fe-36Ni> (invar / amber), MA-S-INVER <Fe-32Ni-5Co> (super invar) and the like.

  Such metal supports 13 and 14 have higher thermal conductivity than the metal support made of copper plating of 3 to 10 μm with respect to the front and back main surfaces of a metal base material such as Invar having a thickness of 0.1 mm, for example. A metal film M is formed, and lead connection portions 131 and 141 to be joined to the metal lead terminals, and a crystal diaphragm holding portion 132 that holds a quartz crystal plate to be described later with a substantially U-shaped cross section. 142. Further, in this embodiment, as shown in FIG. 2, central portions 1321 and 1421 in which the metal film M is not formed in the main surface regions of the crystal support plate holding portions 132 and 142 of the metal support, and the periphery of the central portion. First annular portions 1322 and 1422 in which the metal film M is formed, and second annular portions 1323 and 1423 in which the metal film is not formed are formed around the first annular portion. As shown in FIG. 1, when the welding with the lead terminals 11 and 12 is affected, the metal film M may not be formed on the lead connection portions 131 and 141 of the metal support.

  A solid metal brazing material 3 described later is attached in advance to the quartz support plate 132, 142 of the metal support by welding or the like, and a metal brazing material reservoir portion 133 of the metal support in which the molten metal brazing material is accumulated. 143 is formed. In this embodiment, as shown in FIG. 2, the shape of the metal brazing material reservoir portions 133 and 143 of the metal support is, for example, a concave portion (center portions 1321 and 1421) at the center and a convex portion (first annular portions 1322 and 1422) around the center. ), And a concave-convex shape having concave portions (second annular portions 1323, 1423) around it. It should be noted that the metal brazing metal reservoir portions 133 and 143 of the metal support are not limited to such an uneven shape, and may be mutually connected according to the shape of each solid metal brazing material 3 such as a metal brazing material pellet or a metal brazing material ball. It is sufficient that the metal brazing filler metal 3 after being melted can be retained, and only the concave portion, the convex portion, the hole portion, or a combination thereof may be used.

  In addition, window portions 134 and 144 (marks for the crystal diaphragm holding portion) are formed in part of the quartz support plate holding portions 132 and 142 of the metal support. The window portions 134 and 144 can be formed by notches, holes, or the like, and are formed so that part of connection electrodes 23 and 24 of a crystal diaphragm described later is exposed to the outside surface.

  The quartz diaphragm 2 is made of, for example, an AT cut quartz diaphragm, and is configured in a disk shape subjected to a single-side plano polishing process. Two points where the rotation axis obtained by rotating the plate surface by + 30 ° from the center point with respect to the Z ′ axis passing through the center point O of the main surface of the quartz crystal plate intersects the end of the quartz crystal plate and faces each other. At the intersections A and B, recesses 21 and 22 (a mark for the metal support joint and a metal brazing material reservoir portion of the crystal diaphragm) are formed at side ends by a method such as half etching. The recesses 21 and 22 are configured as a metal brazing material reservoir portion in which the molten metal brazing material 3 to be described later accumulates, and it is more preferable that the recesses 21 and 22 have the same shape and the same volume. On the upper surfaces of the recesses 21 and 22, connection electrodes 23 and 24 (marks for metal support joints) to which a metal brazing material 3 described later is connected are also formed. The connection electrodes 23 and 24 are made of an electrode material mainly composed of gold. For example, a gold electrode layer is formed on the upper surface of a base electrode layer of chromium or nickel. The metal brazing material reservoir portion in which the metal brazing material 3 accumulates is not limited to the recesses 21 and 22, but may be any shape as long as the molten metal brazing material can be accumulated, such as a hole portion, a groove portion, It may be a convex portion or a combination of these.

  The metal brazing material 3 (conductive bonding material) is made of, for example, a gold-based alloy brazing material pellet such as AuGe, AuSn, or Au, and is previously attached to the metal brazing material reservoir portions 133 and 143 of the metal support by welding or the like. Yes.

-First form-
Hereinafter, the configuration of the crystal resonator of the first embodiment and the manufacturing method thereof will be described with reference to FIGS. As shown in FIG. 4 (a), the crystal diaphragm 2 in which only the recesses 21 and 22 and the connection electrodes 23 and 24 are formed is mounted on the metal supports 13 and 14 to which the metal brazing material 3 is attached. . At this time, the concave portions 21 and 22 of the crystal diaphragm are arranged and mounted in the state where the concave portions 21 and 22 of the crystal diaphragm are close to the metal brazing material reservoir portions 133 and 143 of the metal support.

  Next, as shown in FIG. 4B, the metal brazing material 3 and the crystal diaphragm 2 are placed against the crystal diaphragm holding parts 132 and 142 of the metal support in a state where the metal brazing material reservoir and the recess are close to each other. The attached base 1 (pre-sealing crystal resonator) before hermetic sealing is carried into a heating furnace. For example, a high-vacuum annealing furnace is used as the heating furnace, and the whole pre-sealing crystal resonator (base) is heated in a vacuum atmosphere. Then, for example, by heating to a temperature equal to or higher than the melting point of the metal brazing material 3, the molten metal brazing material 3 remains in the recesses 21 and 22 of the crystal vibration plate, and the crystal vibration plate holding portions 132 and 142 of the metal support. And the metal brazing material connecting electrodes 23 and 24 of the crystal diaphragm are joined by the molten metal brazing material 3.

  Next, as shown in FIG. 4 (c), the base before airtight sealing in which the crystal diaphragm holding parts 132, 142 of the metal support and the metal brazing material connection electrodes 23, 24 of the crystal diaphragm are joined. 1 (pre-sealing crystal resonator), and a mask member (not shown) is arranged on the front and back main surfaces of the crystal diaphragm 2, and excitation electrodes 25 and 26 (the back surface 26 is not shown) and an extraction electrode 27 , 28 are provided by means such as vacuum deposition or sputtering. The excitation electrodes 25 and 26 and the extraction electrodes 27 and 28 are integrally formed at the same time and are made of an electrode material mainly composed of gold. For example, a gold electrode layer is formed on the upper surface of a base electrode layer of chromium or nickel. ing.

  As shown in FIG. 3, the extraction electrodes 27 and 28 are formed so as to connect the external surfaces of the quartz plate holding portions 132 and 142 of the metal support and the excitation electrodes 25 and 26 of the quartz plate. Therefore, the electrical connectivity between the metal supports 13 and 14 and the excitation electrodes 25 and 26 is ensured. In particular, in the embodiment of the present invention, windows 134 and 144 are formed in a part of the quartz support plate holding parts 132 and 142 of the metal support, and a part of the connection plate 23 and 24 of the crystal diaphragm is on the external surface. Since it is formed so as to be exposed, even if the extraction electrodes 27 and 28 are disconnected at a gap portion between the metal support and the crystal diaphragm, the extraction electrodes 27 and 28 are surely provided in the upper surface region where the metal brazing material 3 exists. It can be formed and the electrical connectivity is more reliable.

  In the pre-sealing crystal resonator configured as described above, the base of the first embodiment is completed by covering the base with a lid (not shown) and hermetically sealing in a vacuum atmosphere.

-Second form-
Hereinafter, the configuration of the crystal resonator of the second embodiment and the manufacturing method thereof will be described with reference to FIGS. As shown in FIG. 6A, the recesses 21 and 22, the connection electrodes 23 and 24, and the excitation electrodes 25 and 26 (explained on the back surface 26 are shown in FIG. (Not shown) on which a quartz diaphragm 2 is mounted. At this time, the concave portions 21 and 22 of the crystal vibrating plate are mounted so as to be close to the metal brazing material reservoir portions 133 and 143 of the metal support. At this time, the excitation electrodes 25 and 26 and the connection electrodes 23 and 24 of the crystal diaphragm are disconnected from each other.

  Next, as shown in FIG. 6B, the metal brazing material 3 and the crystal diaphragm 2 are placed against the crystal diaphragm holding parts 132 and 142 of the metal support in a state where the metal brazing material reservoir and the recess are close to each other. The attached base 1 (pre-sealing crystal resonator) before hermetic sealing is carried into a heating furnace. For example, a high-vacuum annealing furnace is used as the heating furnace, and the whole pre-sealing crystal resonator (base) is heated in a vacuum atmosphere. Then, for example, by heating to a temperature equal to or higher than the melting point of the metal brazing material 3, the molten metal brazing material 3 remains in the recesses 21 and 22 of the crystal vibration plate, and the crystal vibration plate holding portions 132 and 142 of the metal support. And the metal brazing material connecting electrodes 23 and 24 of the crystal diaphragm are joined by the molten metal brazing material 3.

  Next, as shown in FIG. 6 (c), the base before airtight sealing in which the crystal diaphragm holding portions 132, 142 of the metal support and the metal brazing material connection electrodes 23, 24 of the crystal diaphragm are joined. 1 (pre-sealing crystal resonator), and lead electrodes 27 and 28 are provided on the front and back main surfaces of the crystal vibrating plate 2 by means of vacuum deposition or sputtering while disposing a mask member (not shown). Yes. The excitation electrodes 25 and 26 and the extraction electrodes 27 and 28 are formed separately, but are made of an electrode material mainly composed of gold. For example, a gold electrode layer is formed on the upper surface of a base electrode layer of chromium or nickel. Has been.

  As shown in FIG. 5, the extraction electrodes 27 and 28 connect the external surfaces of the quartz support plate holding portions 132 and 142 of the metal support and the partial upper surfaces of the excitation electrodes 25 and 26 of the quartz plate. Therefore, the electrical connectivity between the metal supports 13 and 14 and the excitation electrodes 25 and 26 is ensured. In particular, in the embodiment of the present invention, windows 134 and 144 are formed in a part of the quartz support plate holding parts 132 and 142 of the metal support, and a part of the connection plate 23 and 24 of the crystal diaphragm is on the external surface. Since it is formed so as to be exposed, even if the extraction electrodes 27 and 28 are disconnected at a gap portion between the metal support and the crystal diaphragm, the extraction electrodes 27 and 28 are surely provided in the upper surface region where the metal brazing material 3 exists. It can be formed and the electrical connectivity is more reliable.

  In the pre-sealing crystal resonator configured as described above, the base of the second embodiment is completed by covering the base with a lid (not shown) and hermetically sealing in a vacuum atmosphere.

  According to the above embodiment, the metal supports 13 and 14 are made of a nickel iron-based low thermal expansion alloy, and “Invar”, “Super Invar”, etc. whose thermal expansion coefficient is close to zero from about half the thermal expansion coefficient of quartz are used. Therefore, the thermal expansion of the metal supports 13 and 14 hardly occurs due to the change of the external environment temperature, and stress due to the change of the external environment temperature is given from the metal supports 13 and 14 to the crystal diaphragm 2. The stress with respect to secular change can be further suppressed. The metal material as described above tends to have a lower thermal conductivity than the metal supports 13 and 14 conventionally used. Therefore, a metal film M having a higher thermal conductivity is formed on the outer surface of the metal supports 13 and 14. By being formed, the metal film transmits the temperature to the crystal diaphragm 2 without delay with respect to the temperature outside the package body (lid and base 1) of the crystal unit due to the change of the external environment temperature, and the temperature difference is It rarely happens. By combining such configurations, the aging characteristics and thermal followability of the crystal resonator can be improved simultaneously and more effectively, and more stable frequency-temperature characteristics can be obtained. The starting characteristics when a crystal resonator is used as the OCXO can also be improved. That is, it is possible to start up the crystal resonator in a shorter time after the crystal resonator is heated to a predetermined temperature in the thermostat and the frequency is stabilized.

  Further, since the metal film M is formed on the front and back main surfaces of the metal supports 13 and 14, there is no bias in thermal deformation as the whole metal support, and no excessive stress is applied to the crystal diaphragm 2. Preferred above. By using Cu plating as the metal film M, wettability is good when the metal brazing material is melted, and the joining force by the metal brazing material can be improved. Plating can be performed relatively inexpensively and easily using a commonly used plating bath, and a metal film having excellent heat conductivity can be formed. In particular, by forming the metal film M having a thickness of about 3 to 10% with respect to the thickness of the low thermal expansion metal base material, more specifically, nickel iron based low thermal expansion alloys such as invar and super invar. By forming a metal base material of 0.1 mm in thickness with a thickness of 3 to 10 μm as a Cu plating, it maintains stable heat transfer while suppressing costs, and maintains low thermal expansion performance as a whole support. The adverse effects of unnecessary thermal stress can be eliminated. When the Cu plating is formed thinner than 3 μm, the heat conductivity is lowered. If the Cu plating is thicker than 10 μm, the risk of cracking of the plating increases due to bending of the metal support, etc., and the thermal expansion performance of the entire support is adversely affected, and unnecessary thermal stress is applied to the crystal diaphragm. The risk of becoming more likely to join increases. Invar and Super Invar are materials with low thermal expansion, but the thermal conductivity is poor and the thermal followability when external heat is applied is poor, so the heat transmitted to the quartz diaphragm is delayed, and the startup characteristics deteriorate. Tend to. In the present invention, by applying Cu plating having a higher thermal conductivity than Invar and Super Invar, the thermal conductivity can be increased at the same time with low thermal expansion, and a desirable holding structure for a highly stable crystal unit is obtained. It is done. In particular, the thermal conductivity can be adjusted appropriately depending on the thickness of the Cu plating, and the hunting (overshoot) of the frequency of the crystal resonator is caused by forming the Cu plating with a thickness of 3 to 10 μm as described above. In addition, the holding member can be created under the condition that the heat transmitted to the quartz diaphragm is not delayed.

  In addition, the metal support crystal diaphragm holding portions 132 and 142 include metal brazing material reservoir portions 133 and 143, a recess where the metal film M is not formed at the center (center portions 1321 and 1421), and a metal film around the recess. It is constituted by a concavo-convex shape having convex portions (first annular portions 1322, 1422) in which M is formed and concave portions (second annular portions 1323, 1423) in which the metal film M is not formed around the convex portions. By being configured in this manner, the pellets of the metal brazing material 3 can be fitted into the central portions 1321 and 1421 and used as a mark for positioning and joining, and also function as a reservoir for the molten metal brazing material 3. . The metal brazing material positioned and joined in the vicinity of the center portion is filleted over the boundary portion between the first annular portions 1322 and 1422 and the second annular portions 1323 and 1423, whereby stronger joining can be performed.

  The metal brazing material 3 is made of a gold-based alloy brazing material such as AuGe, AuSn, Au, and the excitation electrodes 25 and 26 and the extraction electrodes 27 and 28 formed on the front and back main surfaces of the crystal diaphragm 2 are gold. A gold electrode layer is formed on the upper surface of a base electrode layer of chromium or nickel containing as a main component. For this reason, since the excitation electrodes 25 and 26 and the metal brazing material 3 are stable materials in which deterioration of electrical characteristics such as oxidation does not easily occur, the aging characteristics can be further enhanced.

  Further, the concave portion of the crystal diaphragm relative to the metal brazing metal reservoirs 133 and 143 (marks of the crystal diaphragm holding part) of the metal support or the windows 134 and 144 (marks of the crystal diaphragm holding part) of the metal support. Heating is performed in a high vacuum annealing furnace in a state where 21 and 22 are close to each other, and the crystal vibrating plate holding portions 132 and 142 of the metal support and the metal brazing material connecting electrodes 23 and 24 of the crystal vibrating plate are melted. By joining with the material 3, the concave portions 21 and 22 of the crystal diaphragm 2 and the metal brazing material connection electrode formations 23 and 24 are formed on the portions of the metal supports 13 and 14 where the solid metal brazing material 3 is attached. Can be positioned and fixed accurately with respect to each other, and at least two points of the end of the quartz diaphragm where there is no stress sensitivity are accurately positioned. It can be joined stomach. Further, during melting of the metal brazing material 3, the metal brazing material 3 is not joined to each other by shifting from a point having no stress sensitivity. In particular, the concave portions 21 and 22 of the crystal diaphragm (the marks of the metal support joints, which are attached to the metal brazing material reservoir portions 133 and 143 of the metal support in advance) The metal brazing material reservoir portion) is locked to ensure accurate alignment, and the metal brazing material 3 is not displaced until it is completely melted.

  That is, the stress applied to the quartz diaphragm 2 from the outside such as the metal supports 13 and 14 can be made stable, and the stress against the secular change can be suppressed. In particular, it is more preferable that the recesses 21 and 22 formed at the end portion of the quartz crystal plate have the same shape and the same volume, and the stress of the holding portion joined by the metal supports 13 and 14 and the metal brazing material 3. Also, the stress applied to the quartz diaphragm 2 from the outside such as the metal supports 13 and 14 is distributed more uniformly and stably, and as a result, the stress suppression against the secular change can be further realized.

  As a result, a highly reliable crystal resonator for high stability with higher positioning and bonding properties when bonding the metal supports 13 and 14 and the crystal diaphragm 2 using the metal brazing material 3 and good aging characteristics is provided. can do.

  Further, by heating the whole crystal resonator by atmospheric heating using a vacuum annealing furnace, the metal brazing material 3 is melted, and the metal supports 13 and 14 and the crystal diaphragm 2 are joined electrically and mechanically. Therefore, not only the heating for melting the metal brazing material 3 but also the base 1 having the two metal lead terminals 11 and 12 to which the metal supports 13 and 14 are attached and the crystal diaphragm 2 are heated simultaneously. Therefore, since it is possible to simultaneously remove the distortion of each member and to perform degassing, the metal brazing material 3 is used to join the metal supports 13 and 14 and the quartz crystal plate 2 together. The aging characteristics can be further enhanced. In particular, when the atmosphere heating is performed in a high vacuum annealing furnace, it is possible to perform the entire heating without oxidization or deterioration of each member.

  In the first and second embodiments of the present invention, the extraction electrodes 27 and 28 that connect the external surfaces of the quartz crystal plate holding portions 132 and 142 of the metal support and the excitation electrodes 25 and 26 of the quartz plate 2 are used. Is formed in a later step. In other words, in the first embodiment, only the metal brazing material connection electrodes 23 and 24 are formed on the crystal diaphragm 2, and the metal supports 13 and 14 and the crystal diaphragm 2 are melt-bonded with a metal brazing material 3 by a heating furnace. Thereafter, the excitation electrodes 25 and 26 and the extraction electrodes 27 and 28 of the quartz diaphragm including the outer surfaces of the quartz diaphragm holding parts 132 and 142 of the metal support are integrally formed. In the second embodiment, the excitation electrodes 25 and 26 and the metal brazing material connection electrodes 23 and 24 of the crystal diaphragm 2 are formed in advance in a disconnected state, and the metal supports 13 and 14 and the crystal diaphragm 2 are made of metal. After melting and joining with the brazing material 3 in a heating furnace, lead electrodes 27 and 28 are formed to connect the external surfaces of the quartz plate holding portions 132 and 142 of the metal support and the excitation electrodes 25 and 26 of the quartz plate. ing.

  Thus, by forming the extraction electrodes 27, 28 and the like in a later process, the metal brazing material 3 diffuses toward the excitation electrodes 25, 26, and the quartz support plate 132, 142 of the metal support and the crystal plate The metal brazing filler metal 3 interposed between the metal brazing filler metal connection electrodes 23 and 24 is in an insufficient state, and the electromechanical joint failure between the metal supports 13 and 14 and the crystal diaphragm 2 does not occur. Furthermore, the electrical connectivity between the metal supports 13 and 14 and the excitation electrodes 25 and 26 is ensured. In particular, a metal brazing material 3 having a very high aging characteristic such as AuGe but having a high melting point and a long melting time is used to heat the quartz diaphragm 2 having excitation electrodes 25 and 26 mainly composed of gold. When joining by atmospheric heating using a furnace, there is a problem that gold is likely to diffuse. However, since the metal brazing material 3 diffuses only within the range of the connection electrodes 23 and 24, excitation is performed while improving the joining property. The metal brazing material 3 never diffuses into the electrode. As described above, in the manufacturing method according to the embodiment of the present invention, the metal brazing material 3 can be easily joined by atmospheric heating, and the characteristics can be improved by annealing at the same time.

-Other embodiments-
In the first and second embodiments, as shown in FIG. 7, the plate surface is rotated + 30 ° from the center point with respect to the Z ′ axis passing through the center point O of the main surface of the crystal diaphragm. The rotation shaft and the end of the crystal diaphragm intersect, and the concave portions 21 and 22 are marks of the metal support joints at the two intersections A and B facing each other, and are metal brazing material reservoirs of the crystal diaphragm. And the configuration of the connection electrodes 23 and 24 to which the metal brazing material 3 is connected is described. However, it is not specified only for these two intersections.

  As shown in FIG. 8, with respect to the Z ′ axis passing through the center point O of the main surface of the crystal diaphragm, the rotation axis obtained by rotating the plate surface by −30 ° from the center point and the end of the crystal diaphragm Is a mark of the metal support joint with respect to the two intersections C and D facing each other, and the metal brazing material reservoir hole portions 211 and 221 which are the metal brazing material reservoir portions of the crystal diaphragm and the metal brazing material The connection electrodes 231 and 241 to which 3 is connected may be configured.

  Further, as shown in FIG. 9, the rotation axis obtained by rotating the plate surface by + 30 ° and −30 ° from the center point with respect to the Z ′ axis passing through the center point O of the main surface of the crystal plate and the crystal vibration. Recesses 213, 223, which are marks of the metal support joints with respect to four crossing points A, B, C, D, which are opposite to each other, and which are metal brazing material reservoirs of the crystal diaphragm, Further, the connection electrodes 23, 24, 231, and 241 to which the groove portions 212 and 222 and the metal brazing material 3 are connected may be configured.

  In addition to the configuration of the above-described embodiment, as a mark for the metal support joint portion of the crystal diaphragm, a material other than the metal brazing material reservoir and the connection electrode of the crystal diaphragm may be formed. A mark other than the metal brazing material reservoir portion of the metal support may be formed as a mark of the crystal support plate holding portion of the metal support. The tip of the inner lead of the lead terminal has only a nail head shape as an example, but it can also be applied to a normal inner lead shape. It is not limited to the AT-cut crystal diaphragm, but may be another crystal diaphragm such as an SC cut. The metal film M may be formed on one main surface of the front and back surfaces of the metal support or may be partially formed. Further, not only copper plating but also a metal film such as gold, silver, or aluminum may be used. Not only the gold alloy brazing material but also solder.

  The present invention can be implemented in various other forms without departing from the spirit or main features thereof, and should not be interpreted in a limited manner. The scope of the present invention is indicated by the claims, and is not limited by the text of the specification. Further, all modifications and changes belonging to the equivalent scope of the claims are within the scope of the present invention.

The disassembled perspective view which shows embodiment of this invention. The enlarged front view of the main surface area | region of the crystal diaphragm holding | maintenance part of the metal support of FIG. The front view which shows the 1st form of the state which assembled FIG. The schematic diagram which shows the manufacturing process in a 1st form. The front view which shows the 2nd form of the state which assembled FIG. The schematic diagram which shows the manufacturing process in a 2nd form. The front view which shows the crystal diaphragm of embodiment of this invention. The front view which shows the crystal diaphragm of other embodiment of this invention. The front view which shows the crystal diaphragm of other embodiment of this invention.

DESCRIPTION OF SYMBOLS 1 Base 10 Base main body 11,12 Lead terminal 13,14 Metal support 2 Crystal diaphragm 3 Metal brazing material M Metal film

Claims (4)

A base formed by penetrating at least two metal lead terminals through an insulating material; a metal support provided on the inner side of the metal lead terminal; and a metal support mounted on the metal support via a conductive bonding material A crystal unit for OCXO comprising a plate-shaped crystal diaphragm to be joined together,
The base is covered with a lid and hermetically sealed in a vacuum atmosphere,
Wherein the metal support is made of a low thermal expansion of the thermal expansion of the metal material from quartz made of an alloy of nickel-iron-based, Ri Na and metal film having a high thermal conductivity than the metal support is formed on the outer surface of the metal support ,
Crystal oscillator characterized that you formed in 3-10% of the thickness with respect to the metal film thickness of the base metal of the metal support. 2. The crystal resonator according to claim 1, wherein Cu plating is formed as a metal film having a higher thermal conductivity than the metal support. In the main surface region of the metal support where the crystal diaphragm is held via a conductive bonding material, a central portion where the metal film is not formed, and a first portion where the metal film is formed around the central portion. 3. The crystal resonator according to claim 1, wherein an annular portion and a second annular portion in which the metal film is not formed are formed around the first annular portion. . 2. The conductive bonding material according to claim 1, wherein the conductive bonding material is made of a gold-based alloy brazing material, and the excitation electrode formed on the front and back main surfaces of the crystal diaphragm is made of an electrode material mainly composed of gold. 3. The crystal resonator according to 3.

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