JPH01106611A - Piezoelectric element - Google Patents
Piezoelectric elementInfo
- Publication number
- JPH01106611A JPH01106611A JP26410387A JP26410387A JPH01106611A JP H01106611 A JPH01106611 A JP H01106611A JP 26410387 A JP26410387 A JP 26410387A JP 26410387 A JP26410387 A JP 26410387A JP H01106611 A JPH01106611 A JP H01106611A
- Authority
- JP
- Japan
- Prior art keywords
- substrate
- piezoelectric
- resistive film
- attached
- edge
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Pending
Links
- 239000000758 substrate Substances 0.000 claims abstract description 47
- 238000010897 surface acoustic wave method Methods 0.000 claims abstract description 23
- 239000004020 conductor Substances 0.000 claims abstract description 20
- 230000002093 peripheral effect Effects 0.000 claims description 3
- 239000010409 thin film Substances 0.000 abstract description 22
- 239000010408 film Substances 0.000 abstract description 20
- 239000013078 crystal Substances 0.000 abstract description 7
- 239000011347 resin Substances 0.000 abstract description 2
- 229920005989 resin Polymers 0.000 abstract description 2
- 239000011248 coating agent Substances 0.000 abstract 1
- 238000000576 coating method Methods 0.000 abstract 1
- 239000000853 adhesive Substances 0.000 description 9
- 230000001070 adhesive effect Effects 0.000 description 9
- 230000000694 effects Effects 0.000 description 7
- 238000001514 detection method Methods 0.000 description 6
- 230000005616 pyroelectricity Effects 0.000 description 4
- 230000010287 polarization Effects 0.000 description 3
- VYZAMTAEIAYCRO-UHFFFAOYSA-N Chromium Chemical compound [Cr] VYZAMTAEIAYCRO-UHFFFAOYSA-N 0.000 description 2
- 229910019974 CrSi Inorganic materials 0.000 description 2
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 description 2
- 239000000470 constituent Substances 0.000 description 2
- 238000000151 deposition Methods 0.000 description 2
- 229910052710 silicon Inorganic materials 0.000 description 2
- 239000010703 silicon Substances 0.000 description 2
- WSMQKESQZFQMFW-UHFFFAOYSA-N 5-methyl-pyrazole-3-carboxylic acid Chemical compound CC1=CC(C(O)=O)=NN1 WSMQKESQZFQMFW-UHFFFAOYSA-N 0.000 description 1
- PEDCQBHIVMGVHV-UHFFFAOYSA-N Glycerine Chemical compound OCC(O)CO PEDCQBHIVMGVHV-UHFFFAOYSA-N 0.000 description 1
- 229910012463 LiTaO3 Inorganic materials 0.000 description 1
- 239000003989 dielectric material Substances 0.000 description 1
- 230000005684 electric field Effects 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- GQYHUHYESMUTHG-UHFFFAOYSA-N lithium niobate Chemical compound [Li+].[O-][Nb](=O)=O GQYHUHYESMUTHG-UHFFFAOYSA-N 0.000 description 1
- 230000002269 spontaneous effect Effects 0.000 description 1
- 239000002023 wood Substances 0.000 description 1
Landscapes
- Surface Acoustic Wave Elements And Circuit Networks Thereof (AREA)
Abstract
Description
【発明の詳細な説明】
〔概要〕
圧電素子、特に焦電対策を講じた圧電素子の構成に関し
、
抵抗膜を利用した焦電雑音の排除を、従来より確実にす
ることを目的とし、
少なくとも一対の対向電極を表面または表面と裏面に分
けて形成した圧電基板の少なくとも周側面に抵抗膜を被
着し、該基板のエツジ部には該エツジ構成面にそれぞれ
被着された該抵抗膜の双方に重なる導体層を被着し構成
する。[Detailed Description of the Invention] [Summary] With regard to the structure of a piezoelectric element, particularly a piezoelectric element that takes measures against pyroelectricity, the present invention aims to more reliably eliminate pyroelectric noise using a resistive film than before. A resistive film is attached to at least the circumferential side of a piezoelectric substrate having a counter electrode formed on the front surface or on the front and back surfaces, and both of the resistive films respectively attached to the edge forming surfaces are attached to the edge portions of the substrate. A conductor layer is deposited to overlap the conductor layer.
本発明は圧電性と共に焦電性を有する圧電体を使用した
弾性表面波素子や圧力検出素子等の圧電素子、特に圧電
体に焦電対策を施した圧電素子の構成に関する。The present invention relates to a piezoelectric element such as a surface acoustic wave element or a pressure detection element that uses a piezoelectric body having both piezoelectricity and pyroelectricity, and particularly to a structure of a piezoelectric element in which pyroelectricity measures are applied to the piezoelectric body.
圧電性および焦電性を有する基板を使用した圧電素子と
して、ニオブ酸リチウム(LiNbO,a)の単結晶板
やタンタル酸リチウム(LiTaOz)の単結晶板から
基板を切り出し、該基板の表面を伝播する弾性表面波の
発生および検出用にすだれ状の対向電極を該表面に形成
した弾性表面波素子および、該基板に付加された外力に
よって発生する電界を基板の表面および裏面に分けて形
成した対向電極によって検出する圧力検出素子等がある
。As a piezoelectric element using a substrate with piezoelectricity and pyroelectricity, the substrate is cut out from a single crystal plate of lithium niobate (LiNbO,a) or a single crystal plate of lithium tantalate (LiTaOz), and propagation is carried out on the surface of the substrate. A surface acoustic wave element has a transducer-like counter electrode formed on its surface for generating and detecting surface acoustic waves, and a counter electrode is formed by dividing the electric field generated by an external force applied to the substrate into the front and back surfaces of the substrate. There are pressure detection elements that detect pressure using electrodes.
圧電効果の大きい前記圧電基板は、誘電体に温度変化を
与えたとき分極が現れる現象もしくは、既に自発分極を
もっている結晶で温度変化に基づいて分極の変化が起こ
る現象である焦電効果も大きく、焦電効果による放電に
よって生じたパルスが雑音となり、圧電素子の特性が損
なわれることになる。The piezoelectric substrate, which has a large piezoelectric effect, also has a large pyroelectric effect, which is a phenomenon in which polarization occurs when a temperature change is applied to a dielectric material, or a phenomenon in which a change in polarization occurs in a crystal that already has spontaneous polarization based on a temperature change. Pulses generated by discharge due to the pyroelectric effect become noise, which impairs the characteristics of the piezoelectric element.
そこで、従来の圧電素子には、焦電対策用の抵抗膜を圧
電基板に被着さ廿たもの、例えば弾性表面波素子におい
て圧電基板の表面及び側面にクロームシリコン等の抵抗
薄膜を被着したものが、使用されるようになった。Therefore, conventional piezoelectric elements include those in which a resistive film for pyroelectric countermeasures is attached to a piezoelectric substrate; for example, in surface acoustic wave elements, a resistive thin film of chrome silicon or the like is attached to the surface and side surfaces of the piezoelectric substrate. things have come into use.
第4図は従来の弾性表面波素子の平面図(イ)と該素子
を配線板に搭載した側面図(ロ)である。FIG. 4 is a plan view (a) of a conventional surface acoustic wave device and a side view (b) of the device mounted on a wiring board.
第4図(イ)において、弾性表面波素子1はLiTaO
3単結晶板から切り出した圧電基板2の表面に、一対の
すだれ状電極3と4を噛み合う如き対向に形成し、電極
3と4の外部接続部を除く圧電基板2の表面および周側
面にクロームシリコン(CrSi)等にてなる抵抗薄膜
5を被着してなる。In FIG. 4(a), the surface acoustic wave element 1 is made of LiTaO
3 A pair of interdigital electrodes 3 and 4 are formed on the surface of the piezoelectric substrate 2 cut out from a single crystal plate so as to interlock with each other, and chrome is applied to the surface and circumferential surface of the piezoelectric substrate 2 excluding the external connection portions of the electrodes 3 and 4. A resistive thin film 5 made of silicon (CrSi) or the like is deposited.
一部分を破断して示す第4図(0)において、導体層6
と7を形成した配線板8に搭載した弾性表面波素子1は
、絶縁性接着剤9で配線板8に固着したのち、電極3と
導体層6および電極4と導体層7は、それぞれが導電性
接着剤10で接続されるようになる。In FIG. 4 (0), which is partially cut away, the conductor layer 6
The surface acoustic wave element 1 mounted on the wiring board 8 on which the electrodes 3 and 7 are formed is fixed to the wiring board 8 with an insulating adhesive 9, and then the electrode 3 and the conductor layer 6 and the electrode 4 and the conductor layer They are connected using adhesive 10.
以上説明したように、抵抗膜を利用した従来の圧電素子
は、抵抗膜を被着しない圧電素子に対し焦電効果による
雑音が著しく減少し、高性能の弾性表面波装置を実現し
得たが、該雑音除去に対する確実性に難点があり、製品
の一部に僅かながら雑音除去が充分でないものが発生す
るため、その解決が強く要望されるようになった。As explained above, conventional piezoelectric elements using a resistive film have significantly reduced noise due to the pyroelectric effect compared to piezoelectric elements without a resistive film, and have been able to realize high-performance surface acoustic wave devices. However, there is a problem in the reliability of noise removal, and some products do not have enough noise removal, so there is a strong demand for a solution to this problem.
上記問題点の除去を目的とした本発明は、一実施例を示
す第1図によれば、一対の対向電極を表面に形成した圧
電基板2の表面と周側面および裏面に前記抵抗膜12を
被着し、該表面に被着した抵抗膜12aと該側面に被着
した抵抗膜12b、12d、該側面に被着した抵抗膜1
2b、12dと該裏面に被着した抵抗膜12cとを、基
板2のエツジ部に被着した前記導体層13〜16で電気
的に接続してなることを特徴とする圧電素子である。According to FIG. 1 which shows an embodiment, the present invention aims to eliminate the above-mentioned problems, and as shown in FIG. The resistive film 12a is deposited on the surface, the resistive films 12b and 12d are deposited on the side surfaces, and the resistive film 1 is deposited on the side surfaces.
2b, 12d and a resistive film 12c attached to the back surface thereof are electrically connected by the conductor layers 13 to 16 attached to the edge portions of the substrate 2.
本発明によれば、圧電素子の構成主体たる圧電基板に、
温度変化によって該基板に発生する焦電電荷対策用の抵
抗膜を被着し、さらに該基板のエツジ部には異なる基板
構成面に被着した該抵抗膜を電気的に接続する導体層を
被着したことにより、焦電電荷によって発生する雑音の
除去は、抵抗膜の被着のみで果たせない確実性が得られ
るようになった。According to the present invention, the piezoelectric substrate, which is the main component of the piezoelectric element, includes
A resistive film is deposited to prevent pyroelectric charges generated on the substrate due to temperature changes, and a conductive layer is further coated on the edge portion of the substrate to electrically connect the resistive films deposited on different substrate constituent surfaces. By attaching a resistive film to the resistive film, noise generated by pyroelectric charges can be removed with certainty, which cannot be achieved by simply attaching a resistive film.
以下に、図面を用いて本発明による圧電素子を説明する
。Below, a piezoelectric element according to the present invention will be explained using the drawings.
第1図は本発明の一実施例による弾性表面波素子の平面
図(イ)とその側面図(0)である。FIG. 1 is a plan view (A) and a side view (0) of a surface acoustic wave element according to an embodiment of the present invention.
第1図において、弾性表面波素子11はLiTa0z等
の単結晶板から切り出した圧電基板20表面に、一対の
すだれ状電極3と4を噛み合う如き対向に形成し、電極
3と4の外部接続部を除き圧電基板2の表面と裏面およ
び、周側面にCrSi等にてなる抵抗薄膜12を被着し
たのち、圧電基板2の表面の前端部とその前側面とで構
成するエツジ、該前側面と圧電基板2の裏面とで構成す
るエツジ、該表面の後端部とその後側面とで構成するエ
ツジ、該後側面と該裏面とで構成するエツジのそれぞれ
に、導電性樹脂にてなる導体層13〜16を被着してな
る。In FIG. 1, a surface acoustic wave element 11 is formed by forming a pair of interdigitated electrodes 3 and 4 on the surface of a piezoelectric substrate 20 cut out from a single crystal board such as LiTa0z, so that the electrodes 3 and 4 face each other in an interlocking manner. After depositing a resistive thin film 12 made of CrSi or the like on the front and back surfaces of the piezoelectric substrate 2 and the circumferential side, an edge consisting of the front end of the front surface of the piezoelectric substrate 2 and its front side, and the front side and A conductive layer 13 made of a conductive resin is provided on each of the edge formed by the back surface of the piezoelectric substrate 2, the edge formed by the rear end of the surface and the rear side surface, and the edge formed by the rear surface and the back surface. ~16 is coated.
このような弾性表面波素子11は、該表面に被着した抵
抗薄膜12aと該前側面に被着した抵抗薄膜12b、抵
抗薄膜12bと該裏面に被着した抵抗薄膜12C1抵抗
薄膜12aと該後側面に被着した抵抗薄膜12d、抵抗
薄膜12dと抵抗薄膜12cとは、導体層13〜16に
よって電気的に接続されるため、圧電基板2に焦電電荷
が生じ該電荷の放電による雑音は、確実に皆無となった
。Such a surface acoustic wave element 11 includes a resistive thin film 12a deposited on the front surface, a resistive thin film 12b deposited on the front surface, a resistive thin film 12b, a resistive thin film 12C1 deposited on the back surface, a resistive thin film 12a and the rear surface. Since the resistive thin film 12d attached to the side surface and the resistive thin film 12d and the resistive thin film 12c are electrically connected by the conductor layers 13 to 16, pyroelectric charges are generated on the piezoelectric substrate 2, and noise due to discharge of the charges is generated. All of them are definitely gone.
第2図は本発明の他の実施例による弾性表面波素子を配
線板に搭載した側面図である。FIG. 2 is a side view of a surface acoustic wave device according to another embodiment of the present invention mounted on a wiring board.
第2図において、弾性表面波素子21は弾性表面波素子
11の導体層13〜16を被着しない構成であり、導体
層6と7および抵抗薄膜12を形成し配線板8に搭載し
た弾性表面波素子21は、圧電基板2の裏面の周辺部を
残すように被着した絶縁性接着剤22で配線板8に固着
したのち、電極3と導体層6を電気的に接続すると共に
圧電基板2の裏面の周辺部の一部分に接続する導電性接
着剤23および、電極4と導体層7を電気的に接続する
と共に圧電基板2の裏面の周辺部の他の一部分に接続す
る導電性接着剤24を被着してなる。In FIG. 2, the surface acoustic wave element 21 has a structure in which the conductor layers 13 to 16 of the surface acoustic wave element 11 are not attached, and the conductor layers 6 and 7 and the resistive thin film 12 are formed on the elastic surface mounted on the wiring board 8. After the wave element 21 is fixed to the wiring board 8 with an insulating adhesive 22 applied so as to leave the peripheral part of the back surface of the piezoelectric substrate 2, the electrode 3 and the conductor layer 6 are electrically connected and the wave element 21 is attached to the piezoelectric substrate 2. a conductive adhesive 23 that connects to a portion of the periphery of the back surface of the piezoelectric substrate 2; and a conductive adhesive 24 that electrically connects the electrode 4 and the conductor layer 7 and connects to another portion of the periphery of the back surface of the piezoelectric substrate 2. It becomes covered with.
即ち弾性表面波素子21は、弾性表面波素子1工の導体
層13〜16に変えて導電性接着剤23と24を使用す
るものであり、絶縁性接着剤22の制御にやや煩わしさ
を伴う反面、導体層13〜16を被着することな(、弾
性表面波素子11と同等の焦電雑音を除去できるという
利点がある。That is, the surface acoustic wave element 21 uses conductive adhesives 23 and 24 instead of the conductor layers 13 to 16 of the first surface acoustic wave element, and the control of the insulating adhesive 22 is somewhat troublesome. On the other hand, there is an advantage that pyroelectric noise equivalent to that of the surface acoustic wave element 11 can be removed without depositing the conductor layers 13 to 16.
第3図は本発明のさらに他の実施例による圧力検出素子
の斜視図(イ)とその平面図(0)である。FIG. 3 is a perspective view (A) and a plan view (0) of a pressure detection element according to still another embodiment of the present invention.
第3図において、圧力検出素子31は、LiTaO3等
の単結晶板から切り出した圧電体(実電基板)32の表
面と裏面に分かれて対向する電極33と34を形成し、
圧電体32の全周側面には電極33と34と接触しない
抵抗薄膜35を形成したのち、圧電体32の前側面と左
側面とで構成するエツジ、該左側面と圧電体32の後側
面とで構成するエツジ、該後側面と圧電体32の右側面
とで構成するエツジ−1該右側面と前側面とで構成する
エツジのそれぞれに、電極33と34と接触しない導体
層36〜39を被着してなる。In FIG. 3, the pressure detection element 31 is formed by forming opposing electrodes 33 and 34 on the front and back surfaces of a piezoelectric body (actual electric substrate) 32 cut out from a single crystal plate such as LiTaO3,
After forming a resistive thin film 35 that does not contact the electrodes 33 and 34 on the entire circumferential side surface of the piezoelectric body 32, an edge formed by the front side and left side of the piezoelectric body 32, and an edge formed by the left side and the rear side of the piezoelectric body 32 are formed. An edge consisting of the rear side and the right side of the piezoelectric body 32 - 1 Edges consisting of the right side and the front side are provided with conductor layers 36 to 39 that do not contact the electrodes 33 and 34, respectively. It becomes attached.
その結果、該前側面に被着した抵抗薄膜35aと該左側
面に被着した抵抗薄膜35b、抵抗薄膜35bと該後側
面に被着した抵抗薄膜35c、抵抗薄膜35c該右側面
に被着した抵抗1111!35d、抵抗薄膜35dと抵
抗薄膜35aとは、導体層36〜39によって確実に電
気的に接続されるようになる。As a result, the resistive thin film 35a deposited on the front side, the resistive thin film 35b deposited on the left side, the resistive thin film 35c deposited on the resistive thin film 35b and the rear side, and the resistive thin film 35c deposited on the right side. The resistor 1111!35d, the resistive thin film 35d, and the resistive thin film 35a are reliably electrically connected by the conductor layers 36 to 39.
以上説明したように本発明は、圧電基板にその焦電対策
用の抵抗膜を被着し、さらに、該基板の異なる構成面に
被着した該抵抗膜を導体層で電気的に接続したことによ
って、焦電電荷により発生する雑音を確実に皆無となし
得た効果がある。As explained above, the present invention has a piezoelectric substrate coated with a resistive film for pyroelectric countermeasures, and furthermore, the resistive films coated on different constituent surfaces of the substrate are electrically connected by a conductive layer. This has the effect of completely eliminating noise generated by pyroelectric charges.
第1図は本発明の一実施例による弾性表面波素子、
第2図は本発明の他の実施例による弾性表面波素子、
第3図は本発明のさらに他の実施例による圧力検出素子
、
第4図は従来の弾性表面波素子、
である。
図中において、
2.32は圧電基板、
3.4.33.34は電極、
9.22は絶縁性接着剤、
10.23は導電性接着剤、
11.21は弾性表面波素子、
12、12a、 12b、 12c、 12d、 35
.35a、 35b、 35c。
35dは抵抗膜、
13〜16.36〜39は導体層、
31は圧力検出素子、
を示す。
(イ) (コラ木屑〉8
月のイちびν釘方色ヂダ」にまろ弾・r1d口仮素子第
2図FIG. 1 shows a surface acoustic wave device according to one embodiment of the present invention, FIG. 2 shows a surface acoustic wave device according to another embodiment of the present invention, and FIG. 3 shows a pressure detection device according to yet another embodiment of the present invention. FIG. 4 shows a conventional surface acoustic wave element. In the figure, 2.32 is a piezoelectric substrate, 3.4.33.34 is an electrode, 9.22 is an insulating adhesive, 10.23 is a conductive adhesive, 11.21 is a surface acoustic wave element, 12, 12a, 12b, 12c, 12d, 35
.. 35a, 35b, 35c. 35d is a resistive film, 13 to 16, 36 to 39 are conductor layers, and 31 is a pressure detection element. (A) (Kora wood shavings>8
Moon's Ichibi ν Nagigata Irojida "Nimaro bullet/r1d mouth temporary element figure 2
Claims (3)
面に分けて形成した圧電基板(2または32)の少なく
とも周側面に抵抗膜(12または35)を被着し、該基
板(2または32)のエッジ部にはそのエッジ構成面に
それぞれ被着された該抵抗膜(12a〜12dまたは3
5a〜35d)の双方に重なる導体層(13〜16また
は36〜39)を被着してなることを特徴とする圧電素
子。(1) A resistive film (12 or 35) is coated on at least the circumferential side of a piezoelectric substrate (2 or 32) on which at least one pair of opposing electrodes is formed on the front surface or on the front and back surfaces, and the substrate (2 or 32) The resistive film (12a to 12d or 3
A piezoelectric element characterized in that a conductor layer (13 to 16 or 36 to 39) that overlaps both of (5a to 35d) is adhered.
成した弾性表面波素子基板であり、該基板(2)の表面
と周側面および裏面に前記抵抗膜(12)を被着し、該
表面に被着した抵抗膜(12a)と該側面に被着した抵
抗膜(12b,12d)該側面に被着した抵抗膜(12
b,12d)と該裏面に被着した抵抗膜(12c)とを
、該基板(2)のエッジ部に被着した前記導体層(13
〜16)で電気的に接続してなることを特徴とする前記
特許請求の範囲第1項記載の圧電素子。(2) The piezoelectric substrate (2) is a surface acoustic wave element substrate on which electrodes (3, 4) are formed, and the resistive film (12) is coated on the front, circumferential, and back surfaces of the substrate (2). The resistive film (12a) is attached to the surface, the resistive film (12b, 12d) is attached to the side surface, and the resistive film (12a) is attached to the side surface.
b, 12d) and the resistive film (12c) attached to the back surface of the conductive layer (13) attached to the edge of the substrate (2).
16). The piezoelectric element according to claim 1, characterized in that the piezoelectric element is electrically connected to the piezoelectric elements 1 to 16).
34)を形成した圧力検出素子基板であり、該基板(3
2)の周側面に該電極(33,34)と接触しない前記
抵抗膜(35)を被着し、該側面のそれぞれに被着した
該抵抗膜(35a〜35d)を該基板(32)のエッジ
部に被着した前記導体層(36〜39)で電気的に接続
してなることを特徴とする前記特許請求の範囲第1項記
載の圧電素子。(3) The pressure substrate (32) has electrodes (33,
34) is a pressure sensing element substrate formed with the substrate (34).
2), the resistive film (35) not in contact with the electrodes (33, 34) is deposited on the peripheral side of the substrate (32), and the resistive film (35a to 35d) deposited on each side is attached to the peripheral side of the substrate (32). The piezoelectric element according to claim 1, characterized in that the piezoelectric element is electrically connected by the conductor layers (36 to 39) attached to the edge portions.
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP26410387A JPH01106611A (en) | 1987-10-20 | 1987-10-20 | Piezoelectric element |
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP26410387A JPH01106611A (en) | 1987-10-20 | 1987-10-20 | Piezoelectric element |
Publications (1)
Publication Number | Publication Date |
---|---|
JPH01106611A true JPH01106611A (en) | 1989-04-24 |
Family
ID=17398554
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
JP26410387A Pending JPH01106611A (en) | 1987-10-20 | 1987-10-20 | Piezoelectric element |
Country Status (1)
Country | Link |
---|---|
JP (1) | JPH01106611A (en) |
Cited By (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
EP0785620A3 (en) * | 1996-01-19 | 1998-05-06 | Nec Corporation | Surface acoustic wave device |
US6984540B2 (en) | 1999-09-30 | 2006-01-10 | Matsushita Electric Industrial Co., Ltd. | Surface acoustic wave device and method for producing the same |
-
1987
- 1987-10-20 JP JP26410387A patent/JPH01106611A/en active Pending
Cited By (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
EP0785620A3 (en) * | 1996-01-19 | 1998-05-06 | Nec Corporation | Surface acoustic wave device |
US5889446A (en) * | 1996-01-19 | 1999-03-30 | Nec Corporation | Surface acoustic wave device with a resistor thin film to remove pyroelectric effect charges |
US6984540B2 (en) | 1999-09-30 | 2006-01-10 | Matsushita Electric Industrial Co., Ltd. | Surface acoustic wave device and method for producing the same |
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