JP4314306B1 - Ultrasonic transducer - Google Patents

Ultrasonic transducer Download PDF

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JP4314306B1
JP4314306B1 JP2008028138A JP2008028138A JP4314306B1 JP 4314306 B1 JP4314306 B1 JP 4314306B1 JP 2008028138 A JP2008028138 A JP 2008028138A JP 2008028138 A JP2008028138 A JP 2008028138A JP 4314306 B1 JP4314306 B1 JP 4314306B1
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mandrel
thermal expansion
piezoelectric element
vibrator
ultrasonic transducer
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JP2009188841A (en
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耕平 瀬山
一昭 長野
豊 近藤
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Shinkawa Ltd
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Shinkawa Ltd
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Priority to TW97136282A priority patent/TW200934589A/en
Priority to PCT/JP2008/067605 priority patent/WO2009098799A1/en
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B06—GENERATING OR TRANSMITTING MECHANICAL VIBRATIONS IN GENERAL
    • B06B—METHODS OR APPARATUS FOR GENERATING OR TRANSMITTING MECHANICAL VIBRATIONS OF INFRASONIC, SONIC, OR ULTRASONIC FREQUENCY, e.g. FOR PERFORMING MECHANICAL WORK IN GENERAL
    • B06B1/00—Methods or apparatus for generating mechanical vibrations of infrasonic, sonic, or ultrasonic frequency
    • B06B1/02—Methods or apparatus for generating mechanical vibrations of infrasonic, sonic, or ultrasonic frequency making use of electrical energy
    • B06B1/06—Methods or apparatus for generating mechanical vibrations of infrasonic, sonic, or ultrasonic frequency making use of electrical energy operating with piezoelectric effect or with electrostriction
    • B06B1/0607—Methods or apparatus for generating mechanical vibrations of infrasonic, sonic, or ultrasonic frequency making use of electrical energy operating with piezoelectric effect or with electrostriction using multiple elements
    • B06B1/0611—Methods or apparatus for generating mechanical vibrations of infrasonic, sonic, or ultrasonic frequency making use of electrical energy operating with piezoelectric effect or with electrostriction using multiple elements in a pile
    • B06B1/0618—Methods or apparatus for generating mechanical vibrations of infrasonic, sonic, or ultrasonic frequency making use of electrical energy operating with piezoelectric effect or with electrostriction using multiple elements in a pile of piezo- and non-piezoelectric elements, e.g. 'Tonpilz'

Abstract

【課題】超音波振動子において、安定した構造で効果的に温度変化による圧電素子の与圧力の変化を低減することを目的とする。
【解決手段】圧電素子１４が同軸に積層される心棒１２と振動子本体１１とが一体に構成された心棒一体型ランジュバン型振動子の超音波振動子１０と、心棒端部のねじ部１３と、心棒１２と実質同一の熱膨張係数を備え、ねじ部１３にねじ込まれ圧電素子１４を振動子本体１１との間で圧縮する与圧用ナット１７を含む圧縮機構と、圧電素子１４と同軸に心棒に積層圧縮され、心棒１２と圧電素子１４との軸方向の熱膨張の差を吸収することのできる熱膨張係数と厚さを有する背面体１６とを備える。
【選択図】図１An object of the present invention is to reduce a change in pressure applied to a piezoelectric element due to a temperature change effectively with a stable structure in an ultrasonic vibrator.
An ultrasonic vibrator 10 of a mandrel-integrated Langevin vibrator, in which a mandrel 12 and a vibrator body 11 on which piezoelectric elements 14 are coaxially stacked, and a screw part 13 at the end of the mandrel are formed. A compression mechanism including a pressurizing nut 17 having a thermal expansion coefficient substantially the same as that of the mandrel 12 and screwed into the threaded portion 13 to compress the piezoelectric element 14 between the vibrator body 11 and the mandrel coaxially with the piezoelectric element 14. And a back body 16 having a coefficient of thermal expansion and a thickness that can absorb the difference in axial thermal expansion between the mandrel 12 and the piezoelectric element 14.
[Selection] Figure 1

Description

本発明は、超音波振動子の構造に関する。   The present invention relates to the structure of an ultrasonic transducer.

半導体装置の製造では、半導体チップのパッドとリードフレームのリードを金属細線のワイヤで接続するワイヤボンディング装置が用いられている。このようなワイヤボンディング装置では、ボンディングツールによってワイヤをパッド或いはリードに圧着させる際にボンディングツールを超音波振動によって加振する方法が多く用いられている。そして、ワイヤボンディング装置にはボンディングツールを振動させるための超音波振動子が設けられている。また、超音波振動子はボンディング装置に限らず、超音波を利用した各種の機器にも用いられている。   In the manufacture of a semiconductor device, a wire bonding apparatus for connecting a pad of a semiconductor chip and a lead of a lead frame with a thin metal wire is used. In such a wire bonding apparatus, a method in which a bonding tool is vibrated by ultrasonic vibration when a wire is pressed against a pad or a lead by a bonding tool is often used. The wire bonding apparatus is provided with an ultrasonic vibrator for vibrating the bonding tool. In addition, the ultrasonic transducer is used not only in the bonding apparatus but also in various devices using ultrasonic waves.

このような超音波振動子としては、両ねじボルトの心棒に同軸に圧電素子を積層し、両側からナットで締め上げて圧電素子を圧縮するランジュバン型超音波振動子が用いられることが多い。しかし、圧電素子の熱膨張係数は、心棒に用いられる金属製の両ねじボルトの熱膨張係数よりも小さい場合が多く、初期の組立において圧電素子に所定の与圧力がかかるようにボルト、ナットを組み立てていても、温度が上昇すると熱膨張差によってその与圧力が低下し、温度が低下するとその与圧力が上昇するというように、周囲温度によって圧電素子への与圧力が変動し、インピーダンスの上昇によって振動が低減してしまうという問題があった。   As such an ultrasonic transducer, a Langevin type ultrasonic transducer is often used in which piezoelectric elements are stacked coaxially on a mandrel of both screw bolts and tightened with nuts from both sides to compress the piezoelectric elements. However, the thermal expansion coefficient of the piezoelectric element is often smaller than the thermal expansion coefficient of the metal screw bolt used for the mandrel, and bolts and nuts are used so that a predetermined pressure is applied to the piezoelectric element in the initial assembly. Even when assembled, the applied pressure decreases due to the difference in thermal expansion when the temperature rises, and the applied pressure increases when the temperature decreases. As a result, there is a problem that vibration is reduced.

そこで、特許文献１では、両ねじボルトにねじ込むナットの圧電素子との当たり面と、ねじ部との間の内面にねじ部よりも径の大きな段部を設け、ナットの材料を両ねじボルトと異なる熱膨張係数を持つ材料によって構成し、ナットの段部の長さを両ねじボルトの熱膨張係数と圧電素子の熱膨張係数とナットの熱膨張係数を考慮して適当に選択することによって、ボルトと積層された圧電素子との温度変化に対する熱膨張差を吸収させ、温度変化による圧電素子の与圧力の変化を低減する方法が提案されている。   Therefore, in Patent Document 1, a step portion having a diameter larger than that of the screw portion is provided on the inner surface between the contact portion of the nut screwed into the screw screw bolt and the screw portion, and the material of the nut is the screw screw. It is composed of materials having different thermal expansion coefficients, and by appropriately selecting the length of the nut step in consideration of the thermal expansion coefficient of both screw bolts, the thermal expansion coefficient of the piezoelectric element, and the thermal expansion coefficient of the nut, A method has been proposed in which a difference in thermal expansion with respect to a temperature change between a bolt and a laminated piezoelectric element is absorbed, and a change in pressure applied to the piezoelectric element due to a temperature change is reduced.

特開昭６４―３２８００号公報JP-A 64-32800

しかし、特許文献１に記載された方法は、ナットとボルトとは異なる熱膨張係数を備えていることが必要となるので、圧電素子の与圧力の変化を低減することはできるものの、ボルトとナットのねじ部にはボルトとナットとの熱膨張係数の差による熱応力が発生してしまう。そして、ねじ部に発生する熱応力を低減しつつ圧電素子の与圧力の変化を低減しようとすると、ナットの段部長さを長くすることが必要となり、超音波振動子が大型化してしまうという問題があり、全体をコンパクトにまとめようとすると、ナットの熱膨張係数と両ねじボルトの熱膨張係数との差が大きくなるような材料を選択する必要があり、ねじ部の熱応力が大きなものとなってしまうという問題があった。特に、ねじ部に発生する熱応力が大きくなってくると、長時間使用した場合に、金属疲労によってねじ部が破損してしまうおそれがあった。また、熱応力によって発生する歪によってナットの圧電素子への当たり面に微小な変形が生じ、超音波振動のインピーダンスが上昇し、振動の低減を招く場合があった。   However, since the method described in Patent Document 1 needs to have a different coefficient of thermal expansion from that of the nut and the bolt, the change in the pressure applied to the piezoelectric element can be reduced. Thermal stress due to the difference in thermal expansion coefficient between the bolt and the nut is generated in the threaded portion. And, if it is attempted to reduce the change in the applied pressure of the piezoelectric element while reducing the thermal stress generated in the threaded portion, it is necessary to increase the length of the stepped portion of the nut, resulting in an increase in the size of the ultrasonic vibrator. In order to make the whole compact, it is necessary to select a material that increases the difference between the thermal expansion coefficient of the nut and the thermal expansion coefficient of both screw bolts. There was a problem of becoming. In particular, when the thermal stress generated in the threaded portion increases, the threaded portion may be damaged due to metal fatigue when used for a long time. In addition, the deformation generated by the thermal stress may cause a minute deformation on the contact surface of the nut with the piezoelectric element, resulting in an increase in the impedance of the ultrasonic vibration, which may reduce the vibration.

本発明は、超音波振動子において、安定した構造で効果的に温度変化による圧電素子の与圧力の変化を低減することを目的とする。   An object of the present invention is to reduce a change in pressure applied to a piezoelectric element due to a temperature change effectively in a stable structure in an ultrasonic vibrator.

本発明の超音波振動子は、一端にねじ部を有する心棒と、心棒の他端と一体に構成され、心棒より外形の大きい振動子本体と、心棒と同軸にその厚み方向に積層される複数の圧電素子と、心棒と実質同一の熱膨張係数を備え、心棒のねじ部にねじ込まれて圧電素子を振動子本体との間で圧縮する与圧用ナットと、を備える心棒一体ランジュバン型の超音波振動子であって、積層された圧電素子と与圧用ナットとの間に設けられて圧電素子と共に積層圧縮され、心棒と圧電素子との軸方向の熱膨張の差を吸収することのできる熱膨張係数と厚さとを有し、心棒と異なる材料で、その内部を伝搬する音速が振動子本体の内部を伝搬する音速と略同一である熱膨張差吸収体を有すること、を特徴とする。また、本発明の超音波振動子は、熱膨張吸収体は、心棒よりも比重の小さい材料であること、としても好適である。
The ultrasonic transducer according to the present invention includes a mandrel having a threaded portion at one end, a transducer main body having a larger outer shape than the mandrel, and a plurality of components laminated in the thickness direction coaxially with the mandrel. A mandrel-integrated Langevin type ultrasonic wave comprising: a piezoelectric element having a thermal expansion coefficient substantially the same as that of the mandrel, and a pressurizing nut that is screwed into a threaded portion of the mandrel and compresses the piezoelectric element with the vibrator body. A thermal expansion that is provided between a laminated piezoelectric element and a pressurizing nut, is laminated and compressed together with the piezoelectric element, and can absorb the difference in axial thermal expansion between the mandrel and the piezoelectric element. The thermal expansion difference absorber is characterized in that it has a coefficient and a thickness and is made of a material different from that of the mandrel, and the sound velocity propagating through the inside thereof is substantially the same as the sound velocity propagating through the inside of the vibrator body. In the ultrasonic transducer of the present invention, the thermal expansion absorber is preferably a material having a specific gravity smaller than that of the mandrel.

本発明は、超音波振動子において、安定した構造で効果的に温度変化による圧電素子の与圧力の変化を低減することができるという効果を奏する。   INDUSTRIAL APPLICABILITY The present invention has an effect that a change in pressure applied to a piezoelectric element due to a temperature change can be effectively reduced with a stable structure in an ultrasonic vibrator.

以下、本発明の好適な実施形態について、図面を参照しながら説明する。図１に示すように、ワイヤボンディング用の超音波ホーン３０に取付けられる超音波振動子１０は、円柱型の振動子本体１１と、振動子本体１１よりも直径が小さい円柱で振動子本体１１と同軸で一体に設けられた心棒１２と、振動子本体１１と略同一の外径寸法で心棒１２よりも大きな孔を備えるドーナツ状平板の圧電素子１４と、圧電素子１４と略同一の外径、内径寸法を有し、その厚さが圧電素子１４よりも薄い電極板１５と、圧電素子１４と略同一の外径、内径寸法を有している熱膨張吸収体である背面体１６と、心棒１２の端部に設けられたねじ部１３と、ねじ部１３にねじ込まれる与圧用ナット１７と、を含んでいる心棒一体型ランジュバン型振動子である。   Preferred embodiments of the present invention will be described below with reference to the drawings. As shown in FIG. 1, an ultrasonic vibrator 10 attached to an ultrasonic horn 30 for wire bonding includes a columnar vibrator body 11 and a cylinder having a diameter smaller than that of the vibrator body 11. A coaxially-integrated mandrel 12, a donut-shaped flat plate piezoelectric element 14 having an outer diameter substantially the same as that of the vibrator body 11 and larger than the mandrel 12, and an outer diameter substantially the same as the piezoelectric element 14. An electrode plate 15 having an inner diameter and a thickness smaller than that of the piezoelectric element 14, a back body 16 which is a thermal expansion absorber having substantially the same outer diameter and inner diameter as the piezoelectric element 14, and a mandrel 12 is a mandrel-integrated Langevin type vibrator including a threaded portion 13 provided at an end of 12 and a pressurizing nut 17 screwed into the threaded portion 13.

複数の圧電素子１４と電極板１５とはその中心の孔が心棒１２に入って心棒１２と同軸となるように交互に積層されている。背面体１６は積層された圧電素子１４と電極板１５との振動子本体１１と反対側に心棒１２と同軸となるように積層されている。与圧用ナット１７は心棒の端部に設けられたねじ部１３にねじ込まれ、心棒１２と同軸に積層された各圧電素子１４と、各電極板１５と、背面体１６を振動子本体１１との間で圧縮し、超音波振動子として必要な与圧力を与えている。   The plurality of piezoelectric elements 14 and the electrode plates 15 are alternately stacked so that the central hole enters the mandrel 12 and is coaxial with the mandrel 12. The back body 16 is laminated so as to be coaxial with the mandrel 12 on the opposite side of the vibrator body 11 between the laminated piezoelectric element 14 and electrode plate 15. The pressurizing nut 17 is screwed into a screw portion 13 provided at the end of the mandrel, and the piezoelectric elements 14, the electrode plates 15, and the back body 16 which are laminated coaxially with the mandrel 12 are connected to the vibrator body 11. It compresses between them and gives the necessary pressure as an ultrasonic vibrator.

振動子本体１１は先端にボンディングツールであるキャピラリ３１が取付けられ、中間に固定用フランジ３２が設けられている超音波ホーン３０に接続されている。超音波ホーン３０と振動子本体１１とは、一体成形によって製作されていてもよいし、ボルト等の接続部材で接続するよう構成されていてもよい。そして、ボンディングの際には超音波振動子１０によって発生した超音波振動は超音波ホーン３０を介してキャピラリ３１を振動させる。   The vibrator body 11 is connected to an ultrasonic horn 30 having a capillary 31 as a bonding tool attached to the tip and a fixing flange 32 provided in the middle. The ultrasonic horn 30 and the vibrator main body 11 may be manufactured by integral molding, or may be configured to be connected by a connecting member such as a bolt. The ultrasonic vibration generated by the ultrasonic transducer 10 during bonding causes the capillary 31 to vibrate via the ultrasonic horn 30.

振動子本体１１と心棒１２とは、例えば、チタンなどによって製作され、与圧用ナット１７は心棒１２と同様のチタン或いは、熱膨張係数が心棒１２と実質同一となるチタン合金などで製作され、圧電素子１４はチタン酸ジルコン酸鉛（ＰＺＴ）にて構成され、電極板１５は銅板によって製作されている。また、背面体１６としては、例えば、ジュラルミン或いは、オーステナイト系ステンレス鋼、高張力鋼等が用いられる。   The vibrator body 11 and the mandrel 12 are made of, for example, titanium, and the pressurizing nut 17 is made of titanium similar to that of the mandrel 12 or a titanium alloy having a thermal expansion coefficient substantially the same as that of the mandrel 12. The element 14 is made of lead zirconate titanate (PZT), and the electrode plate 15 is made of a copper plate. Moreover, as the back body 16, for example, duralumin, austenitic stainless steel, high-tensile steel or the like is used.

図２に示すように、圧電素子１４と電極板１５と背面体１６とは心棒１２に積層されており、圧電素子１４の厚さはｄ、電極板１５の厚さはｂ、圧電素子１４と電極板１５との積層厚さはＬ１となっている。また、背面体１６の厚さはＬ２で、圧電素子１４と電極板１５と背面体１６とが積層されている部分の心棒１２の長さをＬ３とすると、温度変化による各部分の熱膨張量は、それぞれΔＬ１、ΔＬ２、ΔＬ３、となる。超音波振動子１０の温度が変化すると、各熱膨張量ΔＬ１、ΔＬ２、ΔＬ３も変化してくる。本実施形態の様に心棒１２にチタンを用い、圧電素子１４にチタン酸ジルコン酸鉛（ＰＺＴ）を用い、電極板１５には薄い銅板を用いているような場合には、心棒１２の熱膨張量ΔＬ３は、圧電素子１４と電極板１５の積層部分の熱膨張量ΔＬ１よりも大きくなっている。そこでこの差のΔＬ３―ΔＬ１を背面体１６の熱膨張量でキャンセルする。つまり、背面体１６の熱膨張量ΔＬ２がΔＬ３―ΔＬ１に等しくなる様に次の式１のように設定する。
ΔＬ２＝ΔＬ３―ΔＬ１ （式１） As shown in FIG. 2, the piezoelectric element 14, the electrode plate 15, and the back body 16 are laminated on the mandrel 12, the thickness of the piezoelectric element 14 is d, the thickness of the electrode plate 15 is b, The laminated thickness with the electrode plate 15 is L1. Further, if the thickness of the back body 16 is L2, and the length of the mandrel 12 where the piezoelectric element 14, the electrode plate 15 and the back body 16 are laminated is L3, the amount of thermal expansion of each part due to temperature change Are ΔL1, ΔL2, and ΔL3, respectively. When the temperature of the ultrasonic transducer 10 changes, the thermal expansion amounts ΔL1, ΔL2, and ΔL3 also change. In the case where titanium is used for the mandrel 12, lead zirconate titanate (PZT) is used for the piezoelectric element 14, and a thin copper plate is used for the electrode plate 15 as in this embodiment, the thermal expansion of the mandrel 12 is achieved. The amount ΔL3 is larger than the thermal expansion amount ΔL1 of the laminated portion of the piezoelectric element 14 and the electrode plate 15. Therefore, the difference ΔL3−ΔL1 is canceled by the thermal expansion amount of the back body 16. That is, the following equation 1 is set so that the thermal expansion amount ΔL2 of the back body 16 is equal to ΔL3−ΔL1.
ΔL2 = ΔL3−ΔL1 (Formula 1)

ここで、背面体１６の熱膨張係数をαｘ、一枚の圧電素子１４の厚さをｄ、その熱膨張係数をαｄ、一枚の電極板１５の厚さをｂ、その熱膨張係数をαｂ、心棒１２の熱膨張係数をαａ、圧電素子１４と電極板１５の各枚数をＮとすると、背面体１６の熱膨張量キャンセル必要厚さＬｘは次の式２のように表すことができる。
Ｌｘ＝Ｎ×（ｂ×αｂ＋ｄ×αｄ−ｄ×αａ−ｂ×αａ）／（αａ−αｘ） （式２） Here, the thermal expansion coefficient of the back body 16 is αx, the thickness of one piezoelectric element 14 is d, the thermal expansion coefficient is αd, the thickness of one electrode plate 15 is b, and the thermal expansion coefficient is αb. Assuming that the thermal expansion coefficient of the mandrel 12 is αa and the number of each of the piezoelectric elements 14 and the electrode plates 15 is N, the thermal expansion amount canceling required thickness Lx of the back body 16 can be expressed as the following Expression 2.
Lx = N × (b × αb + d × αd−d × αa−b × αa) / (αa−αx) (Formula 2)

例えば、振動子本体１１及び心棒１２が熱膨張係数αａ＝８×１０−６のチタンで、圧電素子は厚さｄ＝４ｍｍ、熱膨張係数αｄ＝３×１０−６のチタン酸ジルコン酸鉛（ＰＺＴ）で、電極板１５が厚さｂ＝０．４ｍｍ、熱膨張係数αｂ＝１８×１０−６の銅板で、圧電素子１４、電極板１５の積層数がＮ＝４の場合、背面体１６材質を熱膨張係数αｘ＝２３×１０−６のジュラルミンとすると、背面体１６の熱膨張量キャンセル必要厚さＬｘは約１．０７ｍｍとなる。また、背面体１６の材質を熱膨張係数αｘ＝１７×１０−６のオーステナイト系ステンレス鋼とすると、背面体１６の熱膨張量キャンセル必要厚さＬｘは約１．７８ｍｍとなり、背面体１６材質を熱膨張係数αｘ＝１３×１０−６の高張力鋼とすると、背面体１６の熱膨張量キャンセル必要厚さＬｘは約３．２ｍｍとなる。 For example, the vibrator body 11 and the mandrel 12 are made of titanium having a thermal expansion coefficient αa = 8 × 10 −6 , and the piezoelectric element is lead zirconate titanate having a thickness d = 4 mm and a thermal expansion coefficient αd = 3 × 10 −6 ( PZT), when the electrode plate 15 is a copper plate having a thickness b = 0.4 mm and a thermal expansion coefficient αb = 18 × 10 −6 , and the number of stacked piezoelectric elements 14 and electrode plates 15 is N = 4, the back body 16 When the material is duralumin having a thermal expansion coefficient αx = 23 × 10 −6 , the thermal expansion amount necessary thickness Lx of the back body 16 is about 1.07 mm. If the material of the back body 16 is austenitic stainless steel having a thermal expansion coefficient αx = 17 × 10 −6 , the required thickness Lx of the back body 16 for canceling the thermal expansion amount is about 1.78 mm. When the high-tensile steel having a thermal expansion coefficient αx = 13 × 10 −6 , the thermal expansion amount canceling required thickness Lx of the back body 16 is about 3.2 mm.

以上説明した、本実施形態では、ボンディング装置のモータ、ヒータなどの発熱源からの熱によって超音波振動子１０の温度が変化した場合でも、背面体１６によって心棒１２と、圧電素子１４と電極板１５の積層体との間の熱膨張差をキャンセルすることができるという効果を奏する。また、周囲温度による圧電素子への与圧力の変動、インピーダンスの上昇による超音波振動の低減を抑制することができるので、キャピラリ３１を安定して加振することができ、良好なボンディング品質を保持することができるという効果を奏する。また、本実施形態では、心棒１２と与圧用ナット１７は熱膨張係数が略同一となる材料で構成されていることから、心棒１２の端部に設けられたねじ部１３のねじ山と与圧用ナット１７のねじ溝との間には熱膨張差による熱応力がほとんど発生せず、ねじ部１３の損傷を防止することができるという効果を奏する。特にボンディングの際の衝撃力による振動が長時間にわたって与圧用ナット１７とねじ部１３とに伝わった場合でも、ねじ部１３の損傷を抑制することができるという効果を奏する。   In the present embodiment described above, even if the temperature of the ultrasonic vibrator 10 is changed by heat from a heat source such as a motor or a heater of the bonding apparatus, the mandrel 12, the piezoelectric element 14, and the electrode plate are used by the back body 16. There exists an effect that the thermal expansion difference between 15 laminated bodies can be canceled. In addition, fluctuations in the pressure applied to the piezoelectric element due to the ambient temperature and reduction of ultrasonic vibration due to an increase in impedance can be suppressed, so that the capillary 31 can be vibrated stably and good bonding quality is maintained. There is an effect that can be done. Further, in the present embodiment, the mandrel 12 and the pressurizing nut 17 are made of a material having substantially the same thermal expansion coefficient. Therefore, the thread of the screw portion 13 provided at the end of the mandrel 12 and the pressurizing nut 17 are provided. There is almost no thermal stress due to the difference in thermal expansion between the nut 17 and the thread groove, and the screw portion 13 can be prevented from being damaged. In particular, even when vibration due to an impact force during bonding is transmitted to the pressurizing nut 17 and the screw portion 13 for a long time, there is an effect that damage to the screw portion 13 can be suppressed.

また、ねじ部１３における熱応力が低減できることから、超音波振動子１０の温度が変化した場合であっても、与圧用ナット１７の背面体１６に接する面１８の変形を抑制することができ、超音波振動のインピーダンス上昇や振動の低減を抑制することができ、良好なボンディングを継続することができるという効果を奏する。   Further, since the thermal stress in the threaded portion 13 can be reduced, even when the temperature of the ultrasonic vibrator 10 changes, the deformation of the surface 18 in contact with the back body 16 of the pressurizing nut 17 can be suppressed. It is possible to suppress an increase in impedance of ultrasonic vibrations and a reduction in vibrations, and it is possible to continue good bonding.

本実施形態では、振動子本体１１はその内部を伝搬する音速が約５０００ｍ／ｓのチタンで構成されている。一方、背面体１６にジュラルミン、オーステナイト系ステンレス鋼、高張力鋼を使用した場合、各材料の内部を伝搬する音速は略４０００〜５２００ｍ／ｓで振動子本体１１の内部を伝搬する音速に近くなっている。このため、背面体１６が超音波振動を減衰させたりすること無く、一様な超音波振動を得ることができるという効果を奏する。更に、背面体１６をジュラルミンで構成した場合には、大きさも小さくその比重も小さいものとなることから、超音波振動子１０を軽量化することができ、高速ボンディングに対応するという効果を奏する。   In the present embodiment, the vibrator body 11 is made of titanium having a sound velocity of about 5000 m / s propagating through the vibrator body 11. On the other hand, when duralumin, austenitic stainless steel, or high-tensile steel is used for the back body 16, the speed of sound propagating through each material is approximately 4000 to 5200 m / s, which is close to the speed of sound propagating through the vibrator body 11. ing. For this reason, there exists an effect that the back body 16 can obtain uniform ultrasonic vibration, without attenuating ultrasonic vibration. Furthermore, when the back body 16 is made of duralumin, the size is small and the specific gravity thereof is small. Therefore, the ultrasonic transducer 10 can be reduced in weight, and the effect of being compatible with high-speed bonding is achieved.

図３及び図４を参照しながら本発明の参考例について説明する。図３に示すように、ワイヤボンディング用の圧電素子内蔵型超音波振動子１００は、軸方向に延びる振動子本体５０と、振動子本体５０の中央部に設けられた軸方向に長い長方形の開口４２と、開口４２の中に軸方向に積層して嵌めこまれた圧電素子４４と、圧電素子４４と共に積層された金属薄板の電極板４５と、圧電素子４４の間に差し込まれる第１、第２のテーパ部材４７，４８と、第２のテーパ部材４８と圧電素子４４との間に設けられる熱膨張吸収体である背面体４６とを備えている。また、振動子本体５０はその先端にボンディングツールであるキャピラリ５１が取付けられており、その側面には振動子本体５０を固定するためのフランジ５２が両側に設けられている。 A reference example of the present invention will be described with reference to FIGS. As shown in FIG. 3, an ultrasonic transducer 100 with a built-in piezoelectric element for wire bonding includes a transducer main body 50 extending in the axial direction, and a rectangular opening provided in the center of the transducer main body 50 in the axial direction. 42, a piezoelectric element 44 that is stacked and fitted in the opening 42 in the axial direction, a thin metal electrode plate 45 that is stacked together with the piezoelectric element 44, and the first and second electrodes that are inserted between the piezoelectric elements 44. 2 taper members 47, 48, and a back body 46, which is a thermal expansion absorber provided between the second taper member 48 and the piezoelectric element 44. The vibrator body 50 has a capillary 51 as a bonding tool attached to the tip thereof, and flanges 52 for fixing the vibrator body 50 are provided on both sides thereof.

図４に示すように、開口４２は振動子本体５０を上下方向に貫通しており、その中央に第１、第２のテーパ部材４７，４８が配置され、第１のテーパ部材４７と開口４２の壁面との間に圧電素子４４と電極板４５とが積層配置されている。第１のテーパ部材４７は、上方向に向かって先端が薄くなるくさび型で、第２のテーパ部材４８は下方に向かって先端が細くなるくさび型で、各テーパ部材４７，４８のテーパ角度は、二枚の第１のテーパ部材４７と一枚の第２のテーパ部材４８とを組み合わせた際に第１のテーパ部材４７の各外側の面が平行となるような角度となっている。そして、第２のテーパ部材４８を二枚の第１のテーパ部材４７の間に差し込むことによって、各圧電素子４４と電極板４５とを第１のテーパ部材４７と開口４２の壁との間に圧縮して圧電素子４４に所定の与圧力がかかるように構成されている。   As shown in FIG. 4, the opening 42 penetrates the vibrator body 50 in the vertical direction, and the first and second taper members 47 and 48 are arranged at the center thereof, and the first taper member 47 and the opening 42 are arranged. A piezoelectric element 44 and an electrode plate 45 are stacked between the two wall surfaces. The first taper member 47 has a wedge shape with a tip that becomes thinner upward, and the second taper member 48 has a wedge shape with a tip that becomes narrower downward. The taper angle of each of the taper members 47 and 48 is as follows. When the two first taper members 47 and the second taper member 48 are combined, the respective outer surfaces of the first taper member 47 are at an angle. Then, by inserting the second taper member 48 between the two first taper members 47, each piezoelectric element 44 and the electrode plate 45 are placed between the first taper member 47 and the wall of the opening 42. The piezoelectric element 44 is configured to be compressed so that a predetermined pressure is applied.

振動子本体５０は、例えば、チタンなどによって製作され、各テーパ部材４７，４８は振動子本体５０と同一のチタンで製作され、圧電素子４４はチタン酸ジルコン酸鉛（ＰＺＴ）にて構成され、電極板１５は銅板によって製作されている。また、背面体４６としては、例えば、ジュラルミン或いは、オーステナイト系ステンレス鋼、高張力鋼等が用いられる。   The vibrator body 50 is made of, for example, titanium, the taper members 47 and 48 are made of the same titanium as the vibrator body 50, the piezoelectric element 44 is made of lead zirconate titanate (PZT), The electrode plate 15 is made of a copper plate. Further, as the back body 46, for example, duralumin, austenitic stainless steel, high-tensile steel or the like is used.

このように構成された圧電素子内蔵型超音波振動子１００において、先に説明した実施形態と同様、背面体４６の熱膨張係数をαｘ、一枚の圧電素子４４の厚さをｄ、その熱膨張係数をαｄ、一枚の電極板４５の厚さをｂ、その熱膨張係数をαｂ、振動子本体５０の熱膨張係数をαａ、圧電素子４４と電極板４５の各枚数をＮとすると、背面体４６の熱膨張量キャンセル必要厚さＬｘは先に示した（式２）によって表すことができる。また、背面体４６にジュラルミン等の各種材料を使用した場合の熱膨張量キャンセル必要厚さＬｘは先に説明した実施形態と同様の（式２）によって表される。   In the piezoelectric element built-in type ultrasonic transducer 100 configured as described above, the thermal expansion coefficient of the back body 46 is αx, the thickness of one piezoelectric element 44 is d, and the heat is the same as in the above-described embodiment. If the expansion coefficient is αd, the thickness of one electrode plate 45 is b, the thermal expansion coefficient is αb, the thermal expansion coefficient of the vibrator body 50 is αa, and the number of piezoelectric elements 44 and electrode plates 45 is N, The thickness Lx required for canceling the thermal expansion amount of the back body 46 can be expressed by (Expression 2) shown above. Further, the thermal expansion amount canceling required thickness Lx when various materials such as duralumin are used for the back body 46 is expressed by (Equation 2) similar to the above-described embodiment.

以上説明した、本参考例では、ボンディング装置の発熱源からの熱で圧電素子内蔵型超音波振動子１００の温度が変化した場合でも、背面体４６によって、振動子本体５０と圧電素子１４と電極板１５の積層体との間の熱膨張差をキャンセルすることができ、良好なボンディング品質を維持することができるという効果を奏する。また、先に説明した実施形態と同様、振動子本体５０と背面体４６及び第１、第２のテーパ部材４７，４８の内部を伝搬する音速は略４０００〜５２００ｍ／ｓで振動子本体５０の内部を伝搬する音速に近くなっている。このため、背面体４６が超音波振動を減衰させたりすること無く、一様な超音波振動を得ることができ、良好なボンディングを継続することができるという効果を奏する。 In the present reference example described above, even when the temperature of the piezoelectric element built-in type ultrasonic transducer 100 is changed by the heat from the heat source of the bonding apparatus, the vibrator main body 50, the piezoelectric element 14, and the electrode are formed by the back body 46. The difference in thermal expansion between the laminated body of the plates 15 can be canceled, and there is an effect that good bonding quality can be maintained. Similarly to the embodiment described above, the speed of sound propagating through the vibrator body 50, the back body 46, and the first and second taper members 47 and 48 is approximately 4000 to 5200 m / s, and It is close to the speed of sound propagating inside. For this reason, the back body 46 can obtain uniform ultrasonic vibration without attenuating the ultrasonic vibration, and there is an effect that good bonding can be continued.

図５を参照しながら本発明の他の参考例について説明する。図５は、図３、図４を参照して説明した圧電素子内蔵型超音波振動子１００の圧電素子の加圧を、押圧ブロック６８をねじ込むことによって行うように構成したものである。図５に示すように、本参考例の圧電素子内蔵型超音波振動子１００は、軸方向に延びる振動子本体６０と、振動子本体６０の内部に軸方向に設けられた内部空間である空洞６２と、空洞６２の中に軸方向に積層された圧電素子６４と、圧電素子６４と共に積層された金属薄板の電極板６５と、圧電素子６４と共に軸方向に積層された背面体６６と、振動子本体６０の一端に設けられたねじ孔６７にねじ込まれる与圧用ボルトである押圧ブロック６８と、を備えている。ねじ孔６７にねじ込まれた押圧ブロック６８は、積層された圧電素子６４、電極板６５、背面体６６を加圧し超音波振動子として必要な与圧力を与える様構成されている。 Another reference example of the present invention will be described with reference to FIG. FIG. 5 is configured to press the piezoelectric element of the ultrasonic transducer 100 with a built-in piezoelectric element described with reference to FIGS. 3 and 4 by screwing a pressing block 68. As shown in FIG. 5, the piezoelectric element built-in type ultrasonic transducer 100 of this reference example includes a transducer body 60 extending in the axial direction and a cavity that is an internal space provided in the axial direction inside the transducer body 60. 62, a piezoelectric element 64 laminated in the cavity 62 in the axial direction, a metal plate electrode plate 65 laminated together with the piezoelectric element 64, a back body 66 laminated together with the piezoelectric element 64 in the axial direction, and vibration And a pressing block 68 that is a pressurizing bolt screwed into a screw hole 67 provided at one end of the child main body 60. The pressing block 68 screwed into the screw hole 67 is configured to pressurize the laminated piezoelectric element 64, the electrode plate 65, and the back body 66 so as to give a necessary pressure as an ultrasonic vibrator.

一端にねじ孔６７が設けられた振動子本体６０は、例えば、チタンなどによって製作され、ねじ孔６７にねじ込まれる押圧ブロック６８は振動子本体６０と同様のチタン或いは、熱膨張係数が振動子本体６０と実質同一となるチタン合金などで製作されている。圧電素子６４、電極板６５、背面体６６には先に説明した実施形態と同様の材料が用いられている。   The vibrator body 60 provided with the screw hole 67 at one end is made of, for example, titanium, and the pressing block 68 screwed into the screw hole 67 is made of titanium similar to the vibrator body 60 or has a thermal expansion coefficient of the vibrator body. It is made of a titanium alloy that is substantially the same as 60. The piezoelectric element 64, the electrode plate 65, and the back body 66 are made of the same material as that of the above-described embodiment.

このように構成された圧電素子内蔵型超音波振動子１００において、先に説明した実施形態と同様、背面体６６の熱膨張係数をαｘ、一枚の圧電素子６４の厚さをｄ、その熱膨張係数をαｄ、一枚の電極板６５の厚さをｂ、その熱膨張係数をαｂ、振動子本体６０の熱膨張係数をαａ、圧電素子６４と電極板６５の各枚数をＮとすると、背面体６６にジュラルミン等の各種材料を使用した場合の熱膨張量キャンセル必要厚さＬｘは先に説明した実施形態と同様の（式２）によって表される。また、本参考例は、先に説明した実施形態と同様の効果を奏する。 In the piezoelectric element built-in type ultrasonic transducer 100 configured as described above, the thermal expansion coefficient of the back body 66 is αx, the thickness of one piezoelectric element 64 is d, and the heat is the same as in the embodiment described above. If the expansion coefficient is αd, the thickness of one electrode plate 65 is b, the thermal expansion coefficient is αb, the thermal expansion coefficient of the vibrator body 60 is αa, and the number of piezoelectric elements 64 and electrode plates 65 is N, The required thermal expansion amount canceling thickness Lx when various materials such as duralumin are used for the back body 66 is expressed by (Equation 2) similar to the above-described embodiment. Moreover, this reference example has the same effect as the embodiment described above.

以上、本発明の実施形態は、本発明をワイヤボンディング用の超音波振動子に適用した例について説明したが、本発明はワイヤボンディング用の超音波振動子に限らず、超音波振動を利用した計器、機器などに広く適用することができる。 Above, implementation forms of the present invention, the present invention has been described an example of application to the ultrasonic transducer for wire bonding, the present invention is not limited to the ultrasonic transducer for wire bonding, using ultrasonic vibrations The present invention can be widely applied to instruments, devices, etc.

本発明の実施形態における超音波振動子の斜視図である。It is a perspective view of the ultrasonic transducer | vibrator in embodiment of this invention. 本発明の実施形態における超音波振動子の断面図である。It is sectional drawing of the ultrasonic transducer | vibrator in embodiment of this invention. 本発明の参考例における超音波振動子の斜視図である。It is a perspective view of the ultrasonic transducer | vibrator in the reference example of this invention. 本発明の参考例における超音波振動子の断面図である。It is sectional drawing of the ultrasonic transducer | vibrator in the reference example of this invention. 本発明の他の参考例における超音波振動子の断面図である。It is sectional drawing of the ultrasonic transducer | vibrator in the other reference example of this invention.

符号の説明Explanation of symbols

１０ 超音波振動子、１１，５０，６０ 振動子本体、１２ 心棒、１３ ねじ部、１４，４４，６４ 圧電素子、１５，４５，６５ 電極板、１６，４６，６６ 背面体、１７ 与圧用ナット、１８ 面、３０ 超音波ホーン、３１，５１ キャピラリ、３２，５２ 固定用フランジ、４２ 開口、４７ 第１のテーパ部材、４８ 第２のテーパ部材、６２ 空洞、６７ ねじ孔、６８ 押圧ブロック、１００ 圧電素子内蔵型超音波振動子、ｂ 電極板の厚さ、ｄ 圧電素子の厚さ、Ｌｘ 背面体の熱膨張量キャンセル必要厚さ、Ｎ 圧電素子と電極板の積層枚数、αａ 心棒及び振動子本体の熱膨張係数、αｂ 電極板の熱膨張係数、αｄ 圧電素子の熱膨張係数、αｘ 背面体の熱膨張係数。   DESCRIPTION OF SYMBOLS 10 Ultrasonic vibrator, 11, 50, 60 Vibrator body, 12 Mandrel, 13 Screw part, 14, 44, 64 Piezoelectric element, 15, 45, 65 Electrode plate, 16, 46, 66 Back body, 17 Pressurizing nut , 18 surface, 30 ultrasonic horn, 31, 51 capillary, 32, 52 fixing flange, 42 opening, 47 first taper member, 48 second taper member, 62 cavity, 67 screw hole, 68 pressing block, 100 Piezoelectric element built-in type ultrasonic vibrator, b thickness of electrode plate, d thickness of piezoelectric element, Lx thickness required to cancel thermal expansion amount of back body, N number of laminated piezoelectric elements and electrode plate, αa mandrel and vibrator The thermal expansion coefficient of the main body, the thermal expansion coefficient of the αb electrode plate, the thermal expansion coefficient of the αd piezoelectric element, and the thermal expansion coefficient of the αx back body.

Claims (2)

一端にねじ部を有する心棒と、
心棒の他端と一体に構成され、心棒より外形の大きい振動子本体と、
心棒と同軸にその厚み方向に積層される複数の圧電素子と、
心棒と実質同一の熱膨張係数を備え、心棒のねじ部にねじ込まれて圧電素子を振動子本体との間で圧縮する与圧用ナットと、を備える心棒一体ランジュバン型の超音波振動子であって、
積層された圧電素子と与圧用ナットとの間に設けられて圧電素子と共に積層圧縮され、心棒と圧電素子との軸方向の熱膨張の差を吸収することのできる熱膨張係数と厚さとを有し、心棒と異なる材料で、その内部を伝搬する音速が振動子本体の内部を伝搬する音速と略同一である熱膨張差吸収体を有すること、
を特徴とする超音波振動子。 A mandrel having a thread at one end;
A vibrator main body configured integrally with the other end of the mandrel and having a larger outer shape than the mandrel;
A plurality of piezoelectric elements laminated in the thickness direction coaxially with the mandrel;
A mandrel integrated Langevin type ultrasonic transducer having a thermal expansion coefficient substantially the same as that of a mandrel, and a pressurizing nut that is screwed into a threaded portion of the mandrel to compress a piezoelectric element between the mandrel and the mandrel ,
The thermal expansion coefficient and thickness are provided between the laminated piezoelectric element and the pressurizing nut, and are laminated and compressed together with the piezoelectric element to absorb the difference in axial thermal expansion between the mandrel and the piezoelectric element. And having a thermal expansion difference absorber that is made of a material different from that of the mandrel, and whose sound velocity propagating through the inside thereof is substantially the same as the sound velocity propagating through the vibrator body
Ultrasonic transducer characterized by. 請求項１に記載の超音波振動子であって、The ultrasonic transducer according to claim 1,
熱膨張吸収体は、心棒よりも比重の小さい材料であること、The thermal expansion absorber is a material having a specific gravity smaller than that of the mandrel,
を特徴とする超音波振動子。Ultrasonic transducer characterized by.
JP2008028138A 2008-02-07 2008-02-07 Ultrasonic transducer Expired - Fee Related JP4314306B1 (en)

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PCT/JP2008/067605 WO2009098799A1 (en) 2008-02-07 2008-09-29 Ultrasonic vibrator

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CN108065964B (en) * 2018-01-16 2021-04-20 中国科学院苏州生物医学工程技术研究所 Ultrasonic imaging method, device and equipment and ultrasonic imaging probe
JPWO2021024764A1 (en) * 2019-08-05 2021-02-11
CN111716573B (en) * 2020-06-18 2021-06-04 浙江大学 Ultrasonic knife handle capable of adjusting piezoelectric ceramic pretightening force in grading manner

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