JP2010004036A - Apparatus for suspension and contacting of piezoelectric component - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an apparatus in which vibrations of the piezoelectric element remain extensively unaffected. <P>SOLUTION: The apparatus is disclosed for the suspension and contacting of the piezoelectric component 1 which has multiple electrode layers. The apparatus has a substrate 2 on which electrical conductor tracks 3 are arranged. The piezoelectric component 1 is suspended above the substrate 2 and electrically contacted at a minimum of two of its edge areas, in which the component has vibration nodes 4a and 4b. The piezoelectric component 1 is spaced apart from the substrate 2 and the vibrations of the piezoelectric component 1 remain extensively unaffected by the suspension. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  A piezoelectric transformer is known from US Pat.

German Patent Application Publication No. 10 2006 050 110

  The problem addressed by the present invention is to disclose a device comprising a piezoelectric element that can be suspended and contacted in an extremely non-damped manner.

  This problem is solved with the device according to claim 1. Advantageous configurations of the device are the subject of the dependent claims.

  Disclosed is a piezoelectric element suspension and contact device comprising a piezoelectric element having a number of electrode layers that can be alternately stacked with piezoelectric layers. The apparatus further comprises a substrate composed of conductor tracks. The piezoelectric element is suspended on and electrically contacted with the substrate in at least two end regions thereof. The piezoelectric element has a region where a vibration node occurs. The suspension and contact of the piezoelectric element is preferably carried out in at least two end regions of the element, the end region being located in the region of the vibration node. In order to minimize the vibration of the piezoelectric element, the piezoelectric element is arranged away from the substrate. The vibration of the piezoelectric element is not significantly affected by contact with the suspension.

  The electrode layer of the piezoelectric element is preferably disposed inside the piezoelectric element.

  In a preferred embodiment, the piezoelectric element has a metal contact region outside the piezoelectric element in the region of the vibration node. The metal contact region of the piezoelectric element is preferably in electrical contact with the electrode layer of the piezoelectric element.

  The contact region is preferably disposed on the side surface of the piezoelectric element. In other embodiments, the contact area may extend to the top and bottom of the piezoelectric element. In one embodiment, the contact area is applied by jet printing of a conductor track made of, for example, silver.

  In one embodiment, the piezoelectric element is suspended on the substrate using a wire. The wire is preferably bonded onto the substrate. The wire, in one embodiment, has a circular or rectangular cross section.

  The fixing of the wire at or at the contact surface of the piezoelectric element is performed using, for example, adhesive, laser welding or laser soldering at one or more points.

  In another embodiment, the suspension of the electrical element having the substrate is implemented using a clip. The clip at least partially surrounds the piezoelectric element, and the placed clip is separated from the element on all sides and only makes electrical contact with the piezoelectric element in the region of the vibration node. The contact of the clip in the piezoelectric element is preferably performed in the contact area. Contact of the piezoelectric element with the clip may be performed at one or more points at the top, bottom, or sides of the piezoelectric element in the contact area.

  In one embodiment, the clip can be coated in such a way that the clip is soldered to the piezoelectric element at the location of the vibration node or contact area during the heat treatment for assembly.

  In other embodiments, suspension of the piezoelectric element on the substrate is performed using a solder tail. The solder tail is located away from the piezoelectric element by using a conductor portion provided in the piezoelectric element. The conductor portion is in electrical contact with the piezoelectric element in the contact area.

  In one preferred embodiment, a piezoelectric element having a copper foil-like solder tail can be bonded to a polymer conductor track, for example, filled with uncured silver.

  In other embodiments, the contact of the piezoelectric element is performed on the substrate using bumps. In one embodiment, the bumps can be placed at the bottom of the piezoelectric element in the contact area. In other embodiments, the piezoelectric element has a conductor track or conductor track on the top or bottom, which is electrically connected to the contact area. On these conductor tracks, one or more bumps used for suspension and contact of the piezoelectric elements on the substrate are arranged. The conductor track portion of the piezoelectric element is preferably arranged along the vibration node of the piezoelectric element. The connection of the piezoelectric element to the substrate using the bump is performed by, for example, soldering or thermosonic bonding.

  In other embodiments, the suspension of the piezoelectric element on the substrate is implemented by elastic spring contact. The spring contact preferably surrounds the piezoelectric element at least partially, while the spring contact is located remotely and preferably contacts the piezoelectric element in the region of the vibration node. The spring contact has an area suitable for contact on the substrate. Contact is preferably made at one or more points on the surface, bottom or side of the piezoelectric element in the contact area.

  In other embodiments, the spring contact can be coated in such a way as to form a partial solder connection with the piezoelectric element after an appropriate temperature step.

  In other embodiments, the casting composition is disposed between the piezoelectric element and the substrate.

  In one embodiment, elastic spring contact is used to suspend and contact the piezoelectric element on the substrate, and the contact area can be embedded in, for example, a casting composition on the substrate.

  In other embodiments of the device, other electrical elements can be embedded in the casting composition. The electrical element is preferably placed directly on the substrate and is in electrical contact with the conductor tracks of the substrate. In other embodiments, the piezoelectric element may be fixed and placed over the embedded electrical element, for example using a spring contact or a solder tail.

  The piezoelectric element may be configured in the form of a transformer in a preferred embodiment. The piezoelectric element realizes an additional function, but it is guaranteed that the vibration of the piezoelectric element is not damped by its own contact and suspension.

In very small piezoelectric elements, in particular in the region of the vibration nodes, they exhibit residual vibrations, so in these cases the suspension and contact of the element that is not damped to the limit must be provided or guaranteed. In a preferred embodiment, the piezoelectric element is a maximum, has a footprint of approximately 15 mm ^2.

  The distance between the individual suspensions and the contacts is preferably chosen such that the contacts are arranged in SMD grid size on the sides of the substrate. This means that simple assembly of a prefabricated piezoelectric element with a suspension device is possible in other processes.

  In a preferred embodiment, the piezoelectric element is a piezoelectric transformer having an output in the range of 0.2-0.5W.

  What has been described above is explained in more detail on the basis of the following figures and exemplary embodiments.

  The figures shown below are not to be construed as actual scale. Rather, individual dimensions may be shown enlarged, reduced, or modified for better explanation. Elements that match each other or perform the same function are assigned the same reference numerals.

It is a three-dimensional figure of the separated state of a 1st embodiment. It is a figure which shows the connection of embodiment described in FIG. FIG. 6 shows another embodiment in which the suspension and contact are implemented using clips. FIG. 6 shows another embodiment in which the suspension is implemented using a solder tail. It is a figure which shows other embodiment by which a bump is arrange | positioned on a piezoelectric element. It is a figure which shows other embodiment provided with the suspension and the clip for contact. It is a figure which shows other embodiment by which another electric element is arrange | positioned between a piezoelectric element and a board | substrate. It is a figure which shows other embodiment of a piezoelectric element. It is a figure which shows other embodiment of the contact of a piezoelectric element. It is a figure which shows other embodiment of the contact of a piezoelectric element. It is a figure which shows other embodiment of the contact of a piezoelectric element. It is a figure which shows other embodiment of the contact of a piezoelectric element. It is a figure which shows other embodiment of the piezoelectric element by which a movement is restrict | limited by a stopper. FIG. 11 is a side view of the embodiment of FIG. 10. It is a figure which shows arrangement | positioning of the electrode layer in a piezoelectric element. It is a figure which shows the contact of the electrode of FIG. 12 in detail.

  FIG. 1 shows a first embodiment of a piezoelectric element 1 and is shown away from a substrate 2 for better explanation. The connection and contact of the piezoelectric element 1 with the substrate 2 can be seen from FIG.

  The piezoelectric element 1 of FIG. 1 has internal electrodes and, in the illustrated embodiment, forms at least one input region and one output region of the piezoelectric element. The internal electrodes are not shown in FIG. However, the internal electrode corresponds to the embodiment used in the piezoelectric element. The piezoelectric element 1 has two regions 4a and 4b in which vibration nodes are generated during operation.

  For contact and suspension of the piezoelectric element 1, the contact area 5 is arranged in the area of the vibration nodes 4 a, 4 b at the end of the piezoelectric element 1. The contact area 5 is preferably formed using a deposited metallized layer. The contact region 5 is in electrical contact with the internal electrode of the piezoelectric element 1.

  The substrate 2 in FIG. 1 only shows an excerpt from a larger circuit device. The substrate 2 shows a plurality of conductor tracks 3 on its surface and is formed, for example, by galvanic or differently deposited metallization. In order to make contact with the piezoelectric element 1, the substrate 2 has wires 6 and is bonded onto the substrate, for example in the region of the conductor tracks 3. In the bonding area, the conductor tracks can be enlarged or connected to such areas to form contact areas. The wire 3 has, for example, a circular or angular cross section.

  FIG. 2 shows an arrangement of the piezoelectric elements 1 on the substrate 2 shown in FIG. The piezoelectric element 1 is connected to the substrate 2 via a wire 6 in the region of the vibration nodes 4a and 4b. The wire 6 is preferably in electrical contact with the contact area 5 of the piezoelectric element 1. The wire 6 is preferably connected to the contact region 5 of the piezoelectric element 1 by a dot-like connection. The smallest possible connection area between the suspension and the piezoelectric element 1 is used to dampen the vibration to a minimum.

  The gap 14 is preferably between the piezoelectric element 1 and the substrate 2. Therefore, the bottom of the piezoelectric element 1 does not come into direct contact with the substrate 2. This means that the vibration of the piezoelectric element 1 is not attenuated as much as possible.

  FIG. 3 shows another embodiment of the device for suspension and contact of the piezoelectric element 1 on the substrate 2. The piezoelectric element 1 has a contact region 5 at least in the region of the vibration nodes 4a and 5b in the end region. The contact area 5 also at least partially covers the top and bottom of the piezoelectric element 1.

  The clip 7 is used for suspension and contact of the piezoelectric element 1 on the substrate 2 of the embodiment. The clip 7 at least partially surrounds the piezoelectric element 1 and the clip 7 is located away from the piezoelectric element 1 on every side. For the purpose of contact, the clip 7 is preferably in a point-like contact with the region between the clip 7 and the contact region 5 of the piezoelectric element 1. The clip 7 preferably has one electrical contact with the piezoelectric element 1 at the top and bottom of the piezoelectric element 1. In other embodiments, the electrical contact between the clip 7 and the contact area 5 can be formed in a striped or even planar area, and the contact can cause minimal or no attenuation. Should be guaranteed. In FIG. 3, two different embodiments of the clip 7 are illustrated, which can be soldered to the right side, for example directly to the conductor tracks of the substrate 2. The left clip 7 has a solder foot 15, which is connected and fixed in a hole embedded in the substrate 2. The piezoelectric element 1 is preferably suspended on the substrate 2 using a clip in such a way that a gap 14 remains between the piezoelectric element 1 and the substrate 2. This gives minimal attenuation in the suspension of the piezoelectric element 1.

  FIG. 4 shows another embodiment of the suspension and contact device of the piezoelectric element 1. For this purpose, the piezoelectric element 1 has a conductor part 9 at the bottom of the piezoelectric element 1, and the conductor part 9 is in electrical contact with the contact area 5 of the piezoelectric element 1. The solder tail 8 is disposed on the conductor track portion 9, and the solder tail 8 is located away from the piezoelectric element 1. The piezoelectric element 1 is provided on the substrate 2 using a solder tail 8. The solder tail 8 is preferably in electrical contact with the conductor tracks of the substrate 2. Due to the conductor 9 between the piezoelectric element 1 and the solder tail 8, the device has a gap 14 between the piezoelectric element 1 and the substrate 2.

  FIG. 5 shows another embodiment of the piezoelectric element 1 in which the bumps 10 are arranged at the bottom of the piezoelectric element 1. In one possible embodiment, the bump 10 can be placed directly on the contact area 5 of the piezoelectric element 1. Each contact area 5 on the left side of the piezoelectric element 1 has a bump 10 disposed directly on the contact area 5 of the piezoelectric element 1. The contact area 5 on the right side of the piezoelectric element 1 shows another possible embodiment, and the bump 10 is located in the area of the vibration nodes 4a, 4b via the conductor track part 9 arranged as far as possible. To the contact area 5. Due to the bumps 10, the piezoelectric element 1 has a suspension that ensures that the vibration of the piezoelectric element 1 is only slightly affected.

  In FIG. 6, another embodiment of the device is illustrated. The piezoelectric element 1 is suspended using a spring contact 11. The spring contact 11 is preferably placed directly on the substrate 2 and is in electrical contact with a conductor track on the substrate 2. The contact between the piezoelectric element 1 and the spring contact 11 is preferably carried out in the contact area 5, but is not explicitly shown in FIG. As shown in FIG. 6, the spring contact 11 can be wrapped with a casting compound 12 in the region of the substrate 2, and a gap 14 remains between the casting compound 12 and the piezoelectric element 1. Is slightly attenuated. In other embodiments, the spring contact 11 may be free of the cast composite 12.

  FIG. 7 shows another embodiment of the device in which another electrical element 13 is arranged at the bottom of the piezoelectric element 1. The electrical element 13 can be embedded in the casting composition 12, as shown in FIG. However, the electrical element 13 can also be arranged on the substrate 2 in order not to use the casting composition 12. For example, as depicted in FIG. 6, the piezoelectric element 1 is disposed on the electric element 13, and the piezoelectric element is contacted and suspended using the spring contact 11. In other embodiments, as depicted in FIG. 4, the piezoelectric element 1 can be suspended using a solder tail 8. The solder tail 8 is disposed in the contact region 5 of the piezoelectric element 1 and is contacted using the conductor portion 9.

  In other embodiments, the apparatus of FIG. 7 can be combined with the variations of FIGS. In one embodiment, the piezoelectric element 1 can be in electrical contact with the electrical element 13 via the solder tail 8 or the spring contact 11. In other embodiments, the piezoelectric element 1 can be in direct contact with the conductor track of the substrate 2, and no direct electrical contact to the electrical element 13 need be present.

  FIG. 8 shows another embodiment of the piezoelectric element 1 arranged on the substrate 2. The piezoelectric element 1 includes a contact area 5, and the contact area is disposed on a side surface of the piezoelectric element 1. Each side surface of the piezoelectric element 1 is provided with two contact areas 5, which are preferably specified within the range of the vibration nodes 4a, 4b. Electrical contact is made by the conductive medium 16 between the contact area 5 and the conductor track 3 on the substrate 2.

  FIGS. 9 a and 9 b show in more detail an embodiment of the electrical contact between the piezoelectric element 1 and the conductor track 3 on the substrate 2. The conductive medium 16 is disposed within the range of the vibration node of the piezoelectric element 1. The support element 17 is located between the bottom of the piezoelectric element 1 and the substrate while the conductive medium 16 is attached. After removing the support element 17, the element 1 has only mechanical contact via the conductive medium 16.

  In other embodiments, as shown in FIGS. 9 c and 9 d, electrical contact between the piezoelectric element 1 and the conductive path 3 (conductor track) is provided at the bottom of the element 1. In this case, the contact area 5 extends a little on the top and / or bottom surface of the element 1 or at least in the area of contact points or bumps 10. The embodiment shown in FIG. 9d is well suited for soldering the element 1 to the substrate 2 using well-known flip chip technology.

  The support element 17 between the bottom of the element 1 and the substrate 2 is made such that it can be removed and is preferably used only in a technical process during the application and fixing of the conductive medium 16. After removing the support element 17, the piezoelectric element 1 has mechanical contact only with the substrate 2 via the conductive medium 16 in the region of electrical contact. The gap between the piezoelectric element 1 and the substrate is preferably 10 to 500 μm.

  10 and 11 show another embodiment of the piezoelectric element 1 disposed on the substrate 2. The movement of the piezoelectric element 1 is limited with respect to the maximum amount of movement by an additional stopper 18 arranged around the element 1. If the conductive medium 16 is flexible and has a play that allows the piezoelectric element 1 to deviate from its initial position, the maximum value of this movement can be limited in any direction by the stopper 18. The stopper 18 penetrates the substrate 2 at the position of each side surface of the piezoelectric element 1. In a normal state of piezoelectric operation, the element 1 does not contact the surface of the stopper 18, but in a state of being greatly accelerated, the element 1 moves, contacts the stopper 19, and cannot move beyond the stopper. Accordingly, it is possible to prevent the conductive medium 16 from being destroyed by moving too much. The same effect is also provided when the stopper 18 is implemented with one common lid that covers the element 1 and restricts movement relative to the substrate 2.

  During the fixing technical process, the element 1 is placed on a support element 17 which is removed by means of a conductive medium 16 after the element has been soldered.

  In other embodiments not shown, the piezoelectric element 1 is initially placed in a housing that is later sealed by a lid. Between the contact area 5 on the surface of the element 1 and the internal contact of the housing, an electrical connection inside the housing is carried out in the same way as described in FIG. Thereafter, the inner contact of the housing and the outer contact of the housing electrically connected are soldered to the conductor track 3 on the surface of the substrate 2.

  FIG. 12 shows the arrangement of the electrode layers of the piezoelectric element 1. The piezoelectric element 1 includes a left input unit or output unit including electrodes 19 ′ and 20 ′ stacked alternately by being electrically connected to the contact region 5 on the side surface of the piezoelectric element 1. The corresponding output section or input section on the right side is composed of electrodes 19 and 20 that are alternately connected to and stacked on another set of two contact areas 5 on the side surface of the piezoelectric element 1. The structure of the electrodes 19, 20 is such that the distance between the end of the electrode 19 that does not contact a given contact area 5 and the contact area 5 connected to an adjacent electrode 20 of the same electrode stack is maximized. Made in the way. This can be done by forming a recess at the non-contact end of the electrode 19 concentrically around the contact area 5, which increases the distance from the electrode 19 to the contact area 5. The recess makes it possible to optimize the distance to the electrode area and at the same time to the opposite contact area.

  A more detailed view of the electrode structure of the piezoelectric element 1 of FIG. 12 is shown in FIG. The structure of the left electrode 19 ′ or 20 ′ of the piezoelectric element 1 or the structure of the right electrodes 19, 20 can be used similarly on the input side and the output side. The structure of the electrodes 19, 19 ′, 20, 20 ′ is preferably symmetrical with respect to the axial direction of the vibration node of the piezoelectric element 1. The structure of the left electrodes 19 ′, 20 ′ in FIG. 12 is used for the electrodes arranged inside the piezoelectric element, while the right electrode is used to maximize the distance to the opposite contact area 5. The structure is preferably used for electrodes arranged in the top and bottom regions of the piezoelectric element 1. By maximizing the distance from the electrode to the opposite contact area 5 and the side surface of the piezoelectric element 1, it is possible to avoid sparks between the electrode and the contact area 5.

  Although a limited number of possible extensions of the invention may be described in the exemplary embodiments, the invention is not limited thereto. It is possible in principle to select any shape of the suspension, as long as it is guaranteed that the suspension will cause only minimal damping of the piezoelectric element.

  The invention is not limited to the number of elements shown.

  The descriptions of items presented herein are not limited to each particular embodiment, but rather the features of each embodiment may be combined as desired in a technically meaningful manner. .

DESCRIPTION OF SYMBOLS 1 Piezoelectric element 2 Board | substrate 3 Conductor track 4a, 4b Vibration node 5 Contact area 6 Wire 7 Clip 8 Solder tail 9 Conductor part 10 Bump 11 Spring contact 12 Cast compound 13 Electrical element 14 Crevice 15 Solder foot 16 Conductive medium 17 Support element 18 Stopper 19, 19 'electrode 20, 20' electrode

Claims (14)

A piezoelectric element (1) having a plurality of electrode layers;
A substrate (2) having conductor tracks (3);
With
The piezoelectric element (1) is suspended on the substrate (2), and the piezoelectric element (1) is in electrical contact with at least two end regions having vibration nodes (4a, 4b);
The piezoelectric element (1) is located away from the substrate (2);
The apparatus for suspension and contact of a piezoelectric element, wherein the vibration of the piezoelectric element (1) is not greatly affected by being suspended (suspension). In the region of the vibration nodes (4a, 4b), the piezoelectric element (1) has a metal contact region (5) in electrical contact with the electrode layer of the piezoelectric element (1) on the outside. The apparatus of claim 1. The device according to claim 1 or 2, characterized in that the suspension is implemented using a wire (6) bonded to the substrate (2). The suspension is implemented using a clip (7) that at least partially surrounds the piezoelectric element (1), the clip being located away from the piezoelectric element (1) and of the vibration nodes (4a, 4b). The device according to claim 1, wherein the device contacts the piezoelectric element only in the region. The suspension is implemented using a solder tail (8) that contacts the substrate (2), and the solder tail is located away from the piezoelectric element (1) using a conductor portion (9). The apparatus according to claim 1 or 2. The suspension is implemented using bumps (10) arranged in the region of the vibration nodes (4a, 4b) of the piezoelectric element (1),
The device according to claim 1 or 2, wherein the piezoelectric element (1) is located away from the substrate (2) using the bump (10). The suspension is implemented using an elastic spring contact (11), and the first elastic spring contact presses the piezoelectric element (1) in the region of the vibration nodes (4a, 4b) and contacts the substrate (2). The device according to claim 1, wherein the device has a region suitable for the following. The apparatus according to any one of the preceding claims, characterized in that a casting compound (12) is arranged between the piezoelectric element (1) and the substrate (2). The device according to claim 8, wherein the casting composition (12) surrounds an electrical element (13) arranged on the substrate (2). 10. A device according to any one of the preceding claims, characterized in that the piezoelectric element (1) is configured as a transformer. The piezoelectric element (1) Apparatus according to any one of claims 1 to 10, characterized in that it has a footprint up to 15 mm ^2. The apparatus according to any one of claims 1 to 11, characterized in that the distance of the suspension from the side of the substrate (2) corresponds to the SMD grid size. Device according to any one of the preceding claims, characterized in that the maximum movement of the piezoelectric element (1) is limited by a stopper (18). 14. A device according to any one of claims 1 to 13, characterized in that the distance from the electrode (19, 20) to the contact area (5) on the opposite side is maximized.

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