JP2012114536A - Piezoelectric vibrator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a piezoelectric vibrator that can implement a more reliable electrode structure keeping electrical characteristics intact while stabilizing bonding strength of a tin-based low melting point brazing metal.SOLUTION: In the piezoelectric vibrator which has a base 2 for airtight termination embedded with lead terminals 21, 22 and a piezoelectric vibrating reed 1 provided with excitation electrodes 13, 14 and electrode pads 17, 18 and in which the electrode pads of the piezoelectric vibrating reed are electromechanically bonded to tip portions of the lead terminals with a tin-based low melting point brazing metal to mount the piezoelectric vibrating reed on the base, the excitation electrodes and the electrode pads comprise the same conductive metal layer formed on an upper surface of the same base metal layer, the excitation electrodes are formed with a tin layer interposed between the base metal layer and the conductive metal layer, and the electrode pads are formed with an alloy layer comprising the base metal and conductive metal interposed between the base metal layer and the conductive metal layer.

Description

  The present invention relates to a piezoelectric vibrator.

  The piezoelectric vibrator is used as a reference oscillation source of communication equipment or a clock source of a microcomputer. For example, in a cylinder-type piezoelectric vibrator as shown in Patent Document 1, a base made by filling a metal shell with insulating glass and having lead terminals penetrated and fixed to the insulating glass is used. The piezoelectric vibrating piece and the like are hermetically sealed by wearing and press-fitting the cap into the base. In joining such a piezoelectric vibrating piece and a lead terminal (base joint), a solder material or a low melting point metal brazing material of 350 ° C. or lower is used so as not to adversely affect the piezoelectric vibrating piece. It is used.

JP-A-1-68007

  In the joining configuration with a solder material mainly composed of tin (Sn) or a low melting point metal brazing material, there are many that are relatively low melting point and do not damage the piezoelectric vibrating piece, and have high sag and joining strength, cracks, etc. Although there is an advantage that it does not easily occur, there is a problem that the bonding strength varies depending on the electrode material and the electrical characteristics are easily affected. For example, an electrode having a highly conductive surface electrode film such as silver (Ag) or gold (Au) on the upper surface of a base electrode film having high adhesion to quartz or the like such as chromium (Cr) or nickel (Ni). On the other hand, when a solder material or a low melting point metal brazing material containing tin (Sn) as a main component is used, the surface electrode film and the solder material or the metal brazing are compared with the intermetallic bonding force between the base electrode film and the surface electrode film. In some cases, the metal-to-metal bonding force with the material becomes very strong, and film peeling occurs between the base electrode film and the surface electrode film after bonding. For this reason, the impact resistance performance at the joint portion of the piezoelectric vibrator is remarkably lowered, which may lead to poor conduction. In addition, the tin phenomenon of the surface electrode film is accelerated by the tin, and the electrical characteristics may be deteriorated due to the diffusion of the tin in the surface electrode film with aging.

  In addition, with the recent lead-free request for electronic components, lead-free products are also required for the above-described piezoelectric vibrators. In response to such demands, lead-free products have been adopted for solder materials and low melting point metal brazing materials that support piezoelectric vibrating reeds. In such a lead-free product containing tin as a main component, the above-described problems are more conspicuous.

  The present invention has been made to solve the above-mentioned problems, and a more reliable electrode structure that does not deteriorate the electrical characteristics while stabilizing the bonding strength of the tin-based low melting point metal brazing material is obtained. An object of the present invention is to provide a piezoelectric vibrator.

  The present invention has been made in order to achieve the above object, and has a base and a piezoelectric vibrating piece in which an excitation electrode and an electrode pad are formed, and the piezoelectric vibrating piece of the base is provided. A piezoelectric vibrator having a piezoelectric vibration piece mounted on a base by electromechanically joining a joint portion and an electrode pad of the piezoelectric vibration piece with a tin-based low melting point metal brazing material, wherein the excitation electrode and the electrode pad And a conductive metal layer is formed on the upper surface of the base metal layer, the excitation electrode is formed with a tin layer interposed between the base metal layer and the conductive metal layer, and the electrode pad is connected to the base metal layer. An alloy layer made of the base metal and the conductive metal is interposed between the conductive metal layer and the conductive metal layer.

According to the above configuration, the excitation electrode is formed in a state where the tin layer is interposed between the base metal layer and the conductive metal layer, so that the soft tin layer is vibrated by the conductive metal layer. As a result, the series resonance resistance value (CI value) can be improved.
The electrode pad is formed in a state where an alloy layer composed of the base metal and the conductive metal is interposed between the base metal layer and the conductive metal layer, so that the alloy layer is formed of the base metal layer and the conductive metal layer. It can function as an intervening layer that improves the intermetallic bond with the metal layer. As a result, film peeling between the base electrode film and the surface electrode film does not occur after bonding with the tin-based low melting point metal brazing material, and the impact resistance performance is improved. In addition, since there is no tin layer under the conductive metal layer in the electrode pad region, the phenomenon of the cracking of the surface electrode film is suppressed by tin, and the tin diffuses in the surface electrode film with aging. It is also possible to suppress deterioration of electrical characteristics.

  According to a second aspect of the present invention, there is provided a base and a piezoelectric vibrating piece on which an excitation electrode and an electrode pad are formed, and the piezoelectric vibrating piece joint of the base and the electrode pad of the piezoelectric vibrating piece are made of a tin-based low A piezoelectric vibrator formed by electromechanically joining a melting point metal brazing material and mounting a piezoelectric vibrating piece on a base, the piezoelectric vibrating piece having a base portion having two main surfaces and two side surfaces, and the base portion A plurality of legs protruding from one end and having two main surfaces and two side surfaces, the excitation electrode and the electrode pad are formed with a conductive metal layer on an upper surface of a base metal layer, and the base The excitation electrode formed on the side surface of the leg is formed with a tin layer interposed between the base metal layer and the conductive metal layer, and the excitation electrode and electrode pad formed on the main surface of the base and the leg Is between the base metal layer and the conductive metal layer and the base metal Wherein the alloy layer made of a conductive metal is formed in a state interposed.

According to the above configuration, the excitation electrode formed on the two side surfaces of the base portion and the leg portion is formed in a state in which a tin layer is interposed between the base metal layer and the conductive metal layer. The tin layer can alleviate the adverse effect of the conductive metal layer on the vibration of the piezoelectric vibrating piece, and as a result, the series resonance resistance value (CI value) can be improved.
In particular, in a tuning fork piezoelectric vibrating piece in which a plurality of legs flexurally vibrate in the lateral direction, the influence of the side excitation electrode tends to be stronger than the main surface excitation electrode, and the series resonance resistance value (CI value) Related to improvement.
The excitation electrode and electrode pad formed on the two main surfaces of the base and the leg are formed with an alloy layer made of the base metal and the conductive metal interposed between the base metal layer and the conductive metal layer. Therefore, the alloy layer can function as an intervening layer that improves the intermetallic bond between the base metal layer and the conductive metal layer. As a result, film peeling between the base electrode film and the surface electrode film does not occur after bonding with the tin-based low melting point metal brazing material, and the impact resistance performance is improved. In addition, since there is no tin layer under the conductive metal layer in the electrode pad region, the phenomenon of the cracking of the surface electrode film is suppressed by tin, and the tin diffuses in the surface electrode film with aging. It is also possible to suppress deterioration of electrical characteristics.
In particular, in a tuning fork piezoelectric vibrating piece in which a plurality of legs are bent and vibrated in the lateral direction, the lead terminal and the tin-based electrode pad are formed on the main surface of the base while improving the reliability of the bonding as described above. Since the low melting point metal brazing material can be electromechanically joined, it is possible to provide a holding form in which the vibration of the tuning fork type piezoelectric vibrating piece is hardly hindered.

  According to a third aspect of the present invention, in the above configuration, the excitation electrode and the electrode pad are formed in a state of being separated from each other, and the connection electrode partially overlaps the upper surfaces of the separated excitation electrode and the electrode pad. The electrodes may be connected to each other in a state, and may be formed of an electrode film having a lower wettability of the low melting point metal brazing material than the excitation electrode and the electrode pad.

  According to the said structure, in addition to the above-mentioned effect, it is suppressed that the said tin causes the deterioration of the electrical property by diffusing to an excitation electrode with a secular change. The tin-based low melting point metal brazing material spreads only in the electrode pad, and the bonding strength with the piezoelectric vibrating piece bonding portion of the base is also stabilized.

  According to the present invention, it is possible to improve the series resonance resistance value of the piezoelectric vibrating piece without deteriorating the electrical characteristics while stabilizing the bonding strength of the tin-based low melting point metal brazing material, and more reliable. It is possible to provide a piezoelectric vibrator capable of obtaining a high electrode structure.

The exploded side view of the tuning fork type piezoelectric vibrator showing the embodiment by the present invention. Sectional drawing along the XX line of FIG. Sectional drawing along the YY line | wire of FIG. The perspective view of the state which mounted the piezoelectric vibrating piece of FIG. 1 in the base. The perspective view of the state which mounted in the base the piezoelectric vibrating piece which shows the modification of FIG. The perspective view of the piezoelectric vibrating piece which shows the modification of FIG. The perspective view of the piezoelectric vibrating piece which shows other embodiment. Sectional drawing along the ZZ line | wire of FIG.

  Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings, taking a tuning fork type piezoelectric vibrator as an example. The tuning fork type piezoelectric vibrator of the present invention includes a tuning fork type vibration piece (piezoelectric vibration piece) 1 and a base 2 having lead terminals 21 and 22 (22 not shown) on which the tuning fork type vibration piece is mounted and joined. And a lead-free solder material H as a tin-based low melting point metal brazing material for joining the tuning fork type vibrating piece 1 and the lead terminals 21 and 22 and a cap (not shown).

  The tuning fork type vibrating piece 1 is made of crystal and has a cutting angle with bending vibration such as XY cut or NT cut, and two legs extending in parallel in the same direction from the base 10 and one end side 101 of the base. 11 and 12 are configured. The base portion 10 has two main surfaces 103 and 104 connected to the leg portions 11 and 12 and two side surfaces 105 and 106. A first excitation electrode 13 and a second excitation electrode 14, which are excitation electrodes of different polarities, are formed on the legs 11 and 12. The leg portion 11 is formed with first excitation electrodes 13a and 13b on the front and back main surfaces and second excitation electrodes 14c and 14d on both side surfaces. The leg portion 12 has the second excitation electrodes 14a and 14b and both side surfaces on the front and back main surfaces. First excitation electrodes 13c and 13d are formed. Of these, the first excitation electrodes 13a and 13b on the front and back main surfaces of the leg portion 11 and the first excitation electrodes 13c and 13d on both side surfaces of the leg portion 12 are connected in common with the same polarity by the routing electrodes described later. The second excitation electrodes 14a and 14b on the front and back main surfaces and the second excitation electrodes 14c and 14d on both side surfaces of the leg 11 are connected in common with the same polarity by routing electrodes to be described later.

  The base 10 is conductively bonded to the front and back main surfaces by using lead terminals 21 and 22 (piezoelectric vibrating piece bonding portions) of the base 2 to be described later and a lead-free solder material H to be described later, and the first excitation electrode and the second excitation. The electrode pads 17 and 18 for individually deriving the electrodes are formed in a state of being in contact with the end of the other end side 102 of the main surfaces 103 and 104 of the base or in the vicinity of the end (per other end of the base). Yes. In FIG. 1, it forms near the base end. Further, as shown in FIG. 1, among these electrode pads 17 and 18, the end position A on the one end side 101 of the base (the leg side of the base of the tuning-fork type vibration piece) is the side excitation electrodes 13d and 14c. The other end side of the base (the bottom side of the tuning-fork type vibration piece) 102 with respect to the end position B of the other end side (the bottom side of the tuning fork type vibration piece) 102 of the base part (not shown for 14c) It is arranged at the position.

  Each excitation electrode and each electrode pad described above are connected in common by a plurality of routing electrodes and connection electrodes described below in a state of being separated from each other. Further, each electrode on the back side arranged in a state where the base portion 10 of the tuning fork type vibrating piece 1 shown in FIG. 1 is placed on the bottom side is reversed, and the same arrangement as each electrode on the front side shown in FIG. Since the electrodes have the same shape, the electrodes arranged at the same position when reversed are supplementarily described in parentheses in the figure.

  The first excitation electrode 13 is composed of first excitation electrodes 13 a and 13 b on the front and back main surfaces of the leg 11 and first excitation electrodes 13 c and 13 d on both sides of the leg 12, and is separated from the legs 11 and 12. It is led out to the electrode pad 17 formed on the base 10. Among these, the first excitation electrode 13a and the first excitation electrode 13b on the front and back main surfaces are connected by routing electrodes 15a and 15b formed near the tip of the leg portion 11, and the first excitation electrode 13a and the first excitation electrode are connected. 13c is connected by a lead-out electrode 15c formed near the root of the leg 12, and the first excitation electrode 13a and the first excitation electrode 13d are connected by connection electrodes 15d and 15e formed on the base 10 and an electrode pad 17. Has been.

  The connection electrode 15d is connected to the first excitation electrode 13a and the electrode pad 17 which are separated from each other in a state of being partially overlapped with each other, and the connection electrode 15e is connected to the first excitation electrode 13d on the side surface 106 which is separated from each other. The main surfaces 103 are connected to each other in a state where a part of the upper surface of the main surface 103 and the electrode pad 17 overlaps.

  The connection electrode 15e is formed in a state where the surface direction is changed from the main surface 103 of the base portion to the side surface 106, and the side surface 106 on the other end portion side 102 of the base portion is in contact with the other end portion or the other end portion. Only the connection electrode 15e is formed in the vicinity of the portion (around the other end of the base). In FIG. 1, the connection electrode 15e is formed in the vicinity of the other end of the base. That is, the connection electrode 15e constitutes a terminal region in which only the overlapping portion of the electrode pad 17 and the connection electrode 15e is formed in the vicinity of the end of the main surface 103 on the other end portion side 102 of the base of the tuning fork type vibrating piece, A terminal region in which only the connection electrode 15e is formed in the vicinity of the end of the side surface 106 is formed.

  The second excitation electrode 14 includes second excitation electrodes 14 a and 14 b on the front and back main surfaces of the leg portion 12 and second excitation electrodes 14 c and 14 d on both side surfaces of the leg portion 11, and is separated from the leg portions 11 and 12. It is led out to the electrode pad 18 formed on the base 10. Among these, the second excitation electrode 14a and the second excitation electrode 14b on the front and back main surfaces are connected by routing electrodes 16a and 16b formed near the tip of the leg portion 12, and the second excitation electrode 14b and the second excitation electrode are connected. 14d is connected by a routing electrode 16c (not shown) formed near the root of the leg 11, and the second excitation electrode 14b and the second excitation electrode 14c are connected to the connection electrodes 16d, 16e formed on the base 10, and They are connected by electrode pads 18 (not shown).

  The connection electrode 16d (not shown) connects the second excitation electrode 14b and the electrode pad 18 that are separated from each other in a state of being partially overlapped with each other, and the connection electrode 16e is connected to the second side electrode 105 that is spaced from each other. The two excitation electrodes 14c and the electrode pads 18 on the main surface 104 are connected to each other in a state of being partially overlapped.

  The connection electrode 16e is formed in a state where the surface direction is changed from the main surface 104 of the base portion to the side surface 105, and the side surface 105 on the other end portion side 102 of the base portion is in contact with the other end portion or the other end portion. Only the connection electrode 16e is formed in the vicinity of the portion (around the other end). That is, on the other end portion side 102 of the base of the tuning-fork type resonator element, a terminal region in which only the overlapping portion of the electrode pad 18 and the connection electrode 16e is formed in the vicinity of the end portion of the main surface 104 is formed. A terminal region is formed in which only the connection electrode 16e is formed in the vicinity of the portion.

  As shown in FIG. 2, each of the excitation electrodes and the routing electrodes described above is formed by a patterning method using a mask jig or a metal etching method using a photolithography technique. For example, a base metal layer M1 having high adhesion to quartz or the like such as chromium (Cr) or nickel (Ni) is formed, a tin (Sn) layer M2 is formed on the upper surface, and silver (Ag) or It is a metal thin film of at least three layers on which a conductive metal layer M3 having high conductivity such as gold (Au) is formed, and is formed by a vacuum deposition method, a sputtering method, or the like. As the conductive metal layer, silver (Ag) is desirable in terms of conductive performance and cost, and a combination of a chromium (Cr) base metal layer and a tin (Sn) intermediate layer is a series resonance resistance. Since the cost can be suppressed without deteriorating the value (CI value), it is the most preferable combination of optimum materials. In this embodiment, a four-layer structure in which an alloy layer M4 of these base metal and tin (Sn) is formed between the base metal layer and the tin (Sn) layer. With this configuration, the metal-to-metal bonding between the base metal layer and the tin (Sn) layer can be further enhanced, and this is a more desirable form that eliminates the adverse effects of film peeling. Note that the present invention is not limited to this embodiment, and a five-layer structure in which an alloy layer of the tin (Sn) layer and the conductive metal is further formed between the tin (Sn) layer and the conductive metal layer. In this configuration, the intermetallic bonding between the tin (Sn) layer and the conductive metal layer can be further enhanced.

  On the other hand, as shown in FIG. 3, each electrode pad 17, 18 is a base metal layer M <b> 1 having high adhesion to a crystal such as chromium (Cr) or nickel (Ni) by the same method. And a conductive metal layer M3 having high conductivity such as silver (Ag) or gold (Au) is formed on the uppermost surface, and between the base metal layer and the conductive metal layer, the base metal and It is a metal thin film having a three-layer structure formed with a conductive metal alloy layer M5 interposed therebetween. As the conductive metal layer, silver (Ag) is desirable in terms of conductive performance and cost, and a combination of this including a base metal layer of chromium (Cr) and an intermediate layer of these alloy layers is a series resonance. Since the cost can be suppressed without deteriorating the resistance value (CI value), the most preferable combination of optimum materials is obtained.

  Further, as shown in FIG. 3 in part, the connection electrodes 15d, 15e, 16d, and 16e (not shown for 15d and 16d) are a technique using a mask jig, for example, a chromium (Cr) electrode layer M6. It is a single-layered metal thin film composed of only this, and is formed by a vacuum deposition method or a sputtering method. This is formed as an electrode film having low wettability of a tin-based lead-free solder material H described later.

  The base 2 includes a metal shell, an insulating glass filled in the shell, and lead terminals 21 and 22 that are fixed through the insulating glass. The shell has, for example, a 42 alloy base and has a cylindrical shape penetrating vertically. In addition to the 42 alloy, Kovar or iron nickel alloy may be used as the material of the shell.

  The lead terminals 21 and 22 are processed into a linear shape using, for example, Kovar as a base. These lead terminals are disposed through the shell with a predetermined interval. The insulating glass filled in the shell is made of, for example, borosilicate glass, and is fixed in a state where the shell and the lead terminals 21 and 22 are electrically independent from each other.

  The following metal films are formed on the surface of the base shell and the lead terminals 21 and 22. Although not shown, a base metal layer made of a Cu layer is formed on the surface of the shell substrate and the lead terminal substrate, and an Sn—Cu layer is formed on the upper surface thereof. The Cu layer is formed with a thickness of 2 to 5 μm, for example, and the Sn—Cu layer is formed with a thickness of 9 to 15 μm. These layer thicknesses are examples, and may be adjusted and changed as appropriate according to the embodiment. A Ni layer may be used as the base metal layer. Such a Sn—Cu layer can cope with lead-free (lead-free) and can secure heat resistance.

  As shown in FIG. 4, the tuning fork type crystal resonator element 1 is electrically and mechanically joined to the inner sides 21 a and 22 a of the lead terminals of the base 2. That is, the electrode pads 17 and 18 formed on the base portion 10 and the inner sides 21a and 22a of the lead terminals are conductively joined by brazing using a tin-based lead-free solder material H such as Sn-3Ag-0.5Cu. . In addition to the tin-based lead-free metal brazing material, other materials may be used as the lead-free solder material, and a tin-based lead-free low melting point metal brazing material other than the solder material may be used. In the present invention, a lead-free solder material composed mainly of tin (Sn) that easily causes a diffusion phenomenon to a highly conductive electrode film made of an upper electrode of silver (Ag) or gold (Au) or lead It is suitable when a free low melting point metal brazing material is used.

  In addition, the inner side 21a, 22a (base piezoelectric vibrating piece bonding portion) of the base lead terminal and the tuning fork type crystal resonator piece 1 are not limited to the above-described embodiment, and the bonding configuration is limited to the above-described embodiment. As shown in FIG. 5, the other end side 102 of the base 10 of the tuning-fork type crystal vibrating piece and the flat portion 20 of the base 2 are formed by an insulating resin adhesive J such as a silicone resin, an epoxy resin, or an imide resin. It is good also as a structure which implement | achieved the further reinforcement of mechanical joining strength by joining each other so that a part of clearance gap may be filled.

  The cap (not shown) is made of white (Cu—Ni—Zn alloy) and has a bottomed cylindrical shape. A nickel layer having a thickness of 3 to 9 μm is formed on the outer and inner peripheral surfaces of the cap by means such as plating.

  The inner diameter of the cap is designed to be slightly smaller than the shell portion of the base, and is set to an inner diameter that is, for example, 2 to 5% smaller. Such a cap is covered with the tuning-fork type resonator element 1 in a vacuum atmosphere, and the cap opening is press-fitted into the base 2 so that the base 2 and the cap are in close contact with each other and the inside of the cap is kept in a vacuum state. Can be stopped.

  In the present invention, the connection electrode is made of chromium (external electrode) with respect to the excitation electrodes 13 and 14 and the electrode pads 17 and 18 made of a highly conductive electrode film made of an upper electrode made of silver (Ag) or gold (Au). It is constituted by an electrode film having low wettability of a tin-based lead-free low melting point metal brazing material composed only of an electrode layer of (Cr). Here, the configuration of the connection electrode that connects the excitation electrodes 13 and 14 and a part of the electrode pads 17 and 18 with each other is not limited to the above-described embodiment, but as shown in FIG. A simple connection configuration may be used.

  In FIG. 6, the overlapping regions 151 d and 151 e of the connection electrodes 15 d and 15 e and the electrode pad 17 are in a direction not close to the region where the excitation electrodes 13 and 14, which are the vibration regions of the tuning fork type resonator element, are formed from the electrode pad 17. It is comprised so that it may overlap only in the width direction of the base 10. In addition, the overlapping regions 161d and 161e (not shown) of the connection electrodes 16d and 16e and the electrode pad 18 are not close to the region where the excitation electrodes 13 and 14 that are the vibration regions of the tuning fork type resonator element are formed from the electrode pad 18. It is comprised so that it may overlap only in the width direction of the base 10 of a direction. In other words, the overlapping regions 151d, 151e, 161d, 161e (161d and 161e are not shown) are formed so as not to protrude from the upper end of the one end side 101 of the base of the electrode pads 17, 18. In addition, the connection electrodes 15d and 16d are also formed smaller than the electrode pads 17 and 18 so as not to protrude from the upper end portion on the one end side 101 of the base portion. In FIG. 6, the connection electrodes 15 i (16 i) that are not directly connected to the electrode pads 17 and 18 but are directly connected from the excitation electrodes (13 a in the drawing) on the front and back main surfaces to the excitation electrodes (13 d in the drawing) on both sides. It is formed separately.

According to the above-described embodiment, the excitation electrodes 13 and 14 and the electrode pads 17 and 18 are formed of the same metal material on the base metal layer M1 of chromium or nickel as the conductive metal layer M3 of silver or gold which is the same metal material. Therefore, an increase in the electrode material and an increase in the process accompanying the electrode formation can be eliminated, and a cheaper electrode configuration can be obtained. The excitation electrodes 13 and 14 are formed with the tin layer M2 interposed between the base metal layer M1 and the conductive metal layer M3.
The soft tin layer M2 can alleviate the adverse effect of the vibration of the tuning fork type resonator element 1 due to the conductive metal layer M3, and as a result, the series resonance resistance value (CI value) can be improved. The electrode pads 17 and 18 are formed with an alloy layer M5 made of chromium or nickel as the base metal material and silver or gold as the conductive metal material interposed between the base metal layer M1 and the conductive metal layer M3. Thus, the alloy layer M5 can function as an intervening layer that improves the intermetallic bond between the base metal layer M1 and the conductive metal layer M3. As a result, after joining with a tin-based low melting point metal brazing material (tin-based lead-free solder material H such as Sn-3Ag-0.5Cu), film peeling between the base metal layer M1 and the conductive metal layer M3 on the surface No longer occurs, improving impact resistance. In addition, since the tin layer M2 does not exist under the conductive metal layer M3 in the region of the electrode pads 17 and 18, the phenomenon that the conductive metal layer M3 on the surface is crushed by tin is suppressed. It is also possible to suppress deterioration of electrical characteristics due to diffusion in the conductive metal layer M3.

  The excitation electrodes 13 and 14 and the electrode pads 17 and 18 are formed so as to be separated from each other, and the connection electrodes 15d, 15e, 16d, and 16e are formed on the upper surfaces of the separated excitation electrodes 13 and 14 and the electrode pads 17 and 18, respectively. Connected to each other in a partially overlapped state, and a tin-based low-melting-point metal brazing material (tin-based lead-free solder material such as Sn-3Ag-0.5Cu) from the excitation electrodes 13, 14 and the electrode pads 17, 18 H) Since the electrode layer M6 is composed only of the chrome electrode layer M6 having low wettability, the deterioration of electrical characteristics due to diffusion of the tin to the excitation electrodes 13 and 14 with aging is also suppressed. The Tin-based low melting point metal brazing material (tin-based lead-free solder material H such as Sn-3Ag-0.5Cu) wets and spreads only within the electrode pads 17 and 18, and the bonding strength to the lead terminals 21 and 22 is also stable. To do. In particular, in the embodiment shown in FIG. 6, the overlapping regions 151 d, 151 e, 161 d, 161 e between the connection electrodes and the electrode pads are formed from the electrode pads 17, 18 to the excitation electrodes 13, 14 that are the vibration regions of the piezoelectric vibrating piece. Since it is configured to overlap only in the width direction of the base portion 10 in a direction not close to the region, a tin-based low melting point metal brazing material (Sn-3Ag-0. Even if tin-based lead-free solder material H) such as 5Cu diffuses, the vibration of the piezoelectric vibrator is not hindered, and the electrical characteristics of the piezoelectric vibrator can be further prevented from deteriorating.

  Further, the base 10 of the tuning fork type resonator element has main surfaces 103 and 104 and side surfaces 105 and 106, and the electrode pads 17 and 18 are formed only on the main surfaces 103 and 104 of the base, and the other end side of the base. Since only the connection electrodes 15e and 16e are formed on the side surfaces 105 and 106 of the 102, the connection electrodes 15e and 16e not only connect the electrode pads 17 and 18 and the excitation electrodes 13d and 14c on the side surfaces, but also the main surface. Since the surface direction is changed from 103 to the side surface 106 or from the main surface 104 to the side surface 105, wetting of the tin-based low melting point metal brazing material (tin-based lead-free solder material H such as Sn-3Ag-0.5Cu) Expansion can be further suppressed.

  Further, since the connection electrodes 15e and 16e on the side surfaces can be used as second electrode pads (terminal regions) formed on the side surface on the other end side 102 of the base portion where the electrode pads 17 and 18 are not present, The electrode pads 17 and 18 formed on the surfaces 103 and 104 and the connection electrodes 15e and 16e as the second electrode pads formed on the side surfaces 105 and 106 of the base can be properly used as terminals depending on the application. For example, in the case of a tuning-fork type vibrating piece 1 by machining, an automatic balancer process is performed in which the frequency of the tuning-fork type vibrating piece is roughly adjusted by grinding the tip of the leg of the tuning-fork type vibrating piece and adjusting the weight balance of each leg before mounting on the base. is there. When carrying out this process, the electrode terminals of the jig can be brought into contact only with the connection electrodes 15e and 16e as second electrode pads that are resistant to scratches made of chromium, and are joined to the lead terminals 21 and 22 and silver. The highly conductive electrode pads 17 and 18 mainly composed of metal are not damaged. When the tuning fork type resonator element 1 is fixed to the lead terminals 21 and 22 of the base, the electrode pads 17 and 18 that are intact and have excellent conduction performance can be joined.

  In addition, when the end position on the one end side 101 of the base portion of the electrode pads 17 and 18 is A, and the end position on the other end side 102 of the base portion of the side excitation electrodes 13d and 14c is B, B Since the position A is located at the position of the other end 102 side of the base, a tin-based low melting point metal brazing material (tin-based lead-free solder such as Sn-3Ag-0.5Cu) Since the wetting and spreading of the material H) can be reliably stopped by the connection electrodes 15e and 16e without reaching the formation region of the excitation electrodes 13d and 14c on the side surfaces, the vibration of the tuning fork type piezoelectric vibrator can be inhibited. This is further suppressed, and is more preferable for eliminating the deterioration of the electrical characteristics of the tuning fork type piezoelectric vibrator.

  Further, since the connection electrodes 15d, 15e, 16d, and 16e are made of chromium, it is possible to make the material hard and difficult to wet and spread the lead-free low melting point metal brazing material H. It is a strong and preferable electrode material.

  Next, another embodiment will be described with reference to FIGS. Since the basic configuration is the same as that of the above-described embodiment, a part of the description is omitted by assigning the same number, and only the difference will be described.

  In the present embodiment, the excitation electrodes 13c, 13d, 14c, 14d formed on the two side surfaces of the base 10 and the legs 11, 12 and the routing electrodes 15a, 15b, 16a, 16b are made of, for example, chromium (Cr) or nickel A base metal layer M1 having high adhesion to quartz or the like such as (Ni) is formed, an alloy layer M4 of the base metal and tin (Sn) is formed on the top surface, and a tin (Sn) layer M2 is formed on the top surface. A conductive metal layer M3 having high conductivity such as silver (Ag) or gold (Au) is formed on the upper surface thereof to form a four-layer metal thin film.

  The excitation electrodes 13a, 13b, 14a, 14b formed on the two main surfaces of the base 10 and the legs 11, 12 and the routing electrodes 15a, 15b, 16a, 16b and the electrode pads 17, 18 are made of, for example, chromium ( A base metal layer M1 having high adhesion to crystal such as Cr) or nickel (Ni) is formed, and a conductive metal layer M3 having high conductivity such as silver (Ag) or gold (Au) is formed on the top surface. In addition, it is configured as a three-layer metal thin film formed with an alloy layer M5 of the base metal and conductive metal interposed between the base metal layer and the conductive metal layer.

  Further, the connection electrodes 15d, 15e, 16d, and 16e (15d and 16d are not shown) are configured as, for example, a single-layer metal thin film having only a chromium (Cr) electrode layer M6. These electrodes are formed by a vacuum deposition method or a sputtering method by a patterning method using a mask jig.

  According to the other embodiment, the excitation electrodes 13 and 14 and the electrode pads 17 and 18 are silver (Ag) which is the same metal material on the upper surface of the base metal layer M1 of chromium (Cr) or nickel (Ni) which is the same metal material. By forming the conductive metal layer M3 of metal gold (Au), it is possible to obtain an inexpensive electrode configuration without an increase in the electrode material and an increase in the steps accompanying the electrode formation. Excitation electrodes 13c, 13d, 14c and 14d formed on the two side surfaces of the base 10 and the legs 11 and 12 and the lead-out electrodes 15a, 15b, 16a and 16b are formed between the base metal layer M1 and the conductive metal layer M3. Since the (Sn) layer M2 is formed, the soft tin layer M2 reduces the adverse effect of the vibration of the tuning-fork type resonator element 1 due to the conductive metal layer M3, resulting in a series resonance resistance value (CI value). Can be improved. In particular, in the tuning-fork piezoelectric vibrating piece 1 in which the legs 11 and 12 are bent and vibrated in the lateral direction, the influence of the excitation electrodes 13c, 13d, 14c, and 14d on the side surface is greater than the excitation electrodes 13a, 13b, 14a, and 14b on the main surface. The series resonance resistance value (CI value) can be improved by changing the necessary minimum material. Excitation electrodes 13a, 13b, 14a, 14b formed on the two main surfaces of the base 10 and the legs 11, 12 and the lead-out electrodes 15a, 15b, 16a, 16b, the electrode pads 17, 18 are electrically conductive with the underlying metal layer M1. An alloy layer M5 made of chromium (Cr) or nickel (Ni) as the base metal material and silver (Ag) or gold (Au) as the conductive metal material is interposed between the metal layer M3 and the metal layer M3. Thus, the alloy layer M5 can function as an intervening layer that improves the intermetallic bond between the base metal layer M1 and the conductive metal layer M3. As a result, after joining with a tin-based low melting point metal brazing material (tin-based lead-free solder material H such as Sn-3Ag-0.5Cu), film peeling between the base metal layer M1 and the conductive metal layer M3 on the surface No longer occurs, improving impact resistance. In addition, since the tin layer M2 does not exist under the conductive metal layer M3 in the region of the electrode pads 17 and 18, the phenomenon that the conductive metal layer M3 on the surface is bitten by tin (Sn) is suppressed, and the tin (Sn ) Is also prevented from being deteriorated in the electrical characteristics due to diffusion in the conductive metal layer M3 on the surface with aging. In particular, in the tuning fork piezoelectric resonator element 1 in which the leg portions 11 and 12 are bent and vibrated in the lateral direction, the electrodes formed on the two main surfaces 103 and 104 of the base portion 10 while improving the reliability of the bonding as described above. The pads 17 and 18 can be electromechanically joined to the lead terminals 21 and 22 by a tin-based low melting point metal brazing material (tin-based lead-free solder material H such as Sn-3Ag-0.5Cu). Further, the holding form in which the vibration of the tuning fork type piezoelectric vibrating piece 1 is not easily inhibited can be obtained. In addition, about the component similar to the said embodiment, while having the effect similar to the said embodiment, it can apply also about the content disclosed by the modification.

  It should be noted that the present invention can be implemented in various other forms without departing from the spirit, gist, or main features. For this reason, the above-described embodiment is merely an example in all respects and should not be interpreted in a limited manner. The scope of the present invention is indicated by the claims, and is not restricted 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 present invention can be applied not only to a tuning-fork-type vibrating piece formed by bending vibration but also to a piezoelectric vibrating piece having other shapes and vibration modes. Further, the present invention can be applied not only to lead type piezoelectric vibrators but also to surface mount type piezoelectric vibrators.

  It can be applied to mass production of piezoelectric vibration devices such as crystal resonators.

1 Tuning fork type resonator element 2 Base

Claims (3)

A base, a piezoelectric vibrating piece on which an excitation electrode and an electrode pad are formed, and the piezoelectric vibrating piece joint of the base and the electrode pad of the piezoelectric vibrating piece are electromechanically connected by a tin-based low melting point metal brazing material A piezoelectric vibrator formed by bonding and mounting a piezoelectric vibrating piece on a base,
The excitation electrode and the electrode pad have a conductive metal layer formed on the upper surface of the base metal layer,
The excitation electrode is formed with a tin layer interposed between the base metal layer and the conductive metal layer,
The piezoelectric vibrator is characterized in that the electrode pad is formed with an alloy layer made of the base metal and the conductive metal interposed between the base metal layer and the conductive metal layer. A base, a piezoelectric vibrating piece on which an excitation electrode and an electrode pad are formed, and the piezoelectric vibrating piece joint of the base and the electrode pad of the piezoelectric vibrating piece are electromechanically connected by a tin-based low melting point metal brazing material A piezoelectric vibrator formed by bonding and mounting a piezoelectric vibrating piece on a base,
The piezoelectric vibrating piece is composed of a base portion having two main surfaces and two side surfaces, and a plurality of legs protruding from one end of the base portion and having two main surfaces and two side surfaces,
The excitation electrode and the electrode pad have a conductive metal layer formed on the upper surface of the base metal layer,
Excitation electrodes formed on the side surfaces of the base and the leg are formed with a tin layer interposed between the base metal layer and the conductive metal layer,
The excitation electrodes and electrode pads formed on the main surfaces of the base and the leg are formed with an alloy layer made of the base metal and the conductive metal interposed between the base metal layer and the conductive metal layer. A piezoelectric vibrator characterized by that. The excitation electrode and the electrode pad are formed in a state of being separated from each other, and the connection electrode is connected to each other in a state where a part of the connection electrode is overlapped with the upper surface of the separated excitation electrode and the electrode pad. 3. The piezoelectric vibrator according to claim 1, wherein the low-melting-point metal brazing material is formed of an electrode film having lower wettability than a pad.

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