DE102006050064A1 - Piezoelectric transformer, has two passages formed in ceramic body, penetrating functional parts and insulation area and extending in longitudinal direction of body, and filling material or passivation layer arranged in each passage - Google Patents

Abstract

The transformer has a ceramic body (3), which comprises two functional parts (5, 7) and an insulation area (10), which mechanically connects the functional parts. Passages (1, 2) are formed in the body and penetrate through both the functional parts and the insulation area. The passages extend in a longitudinal direction of the body, where each functional part has alternatively arranged inner electrodes (4a, 4b, 8a, 8b), which are aligned perpendicularly to the longitudinal direction. A filling material or a passivation layer (12) is arranged in each of the passages. An independent claim is also included for a method for manufacturing a piezoelectric transformer.

Description

Each piezotransformer is in the document US 6,353,278 B1 and JP 11-354855 A described.

A to be solved The object is to specify a piezoelectric transformer, the one on a carrier Space saving can be mounted.

It a piezoelectric transformer is indicated with a body, comprising two functional parts and an insulating region, which mechanically connecting the functional parts. In the body is a first breakthrough and a second breakthrough formed. The respective breakthrough Penetrates both functional parts and the insulation area.

Of the piezoelectric transformer is hereafter piezotransformer called.

When Functional parts are called areas of the transformer, in where an electromechanical conversion takes place. A first functional part is an input part and a second functional part is an output part of the transformer.

The breakthroughs are each suitable for receiving a support member, preferably as an electrical connection element for contacting the functional parts is provided. The connection element is for example a pin or a pipe. One end of the carrier element sticks out of the body out and is in a carrier fixable. By the arrangement of a part of the support elements in body inside a space-saving installation of the transformer on the carrier is possible.

Of the Breakthrough is a through opening that extends from one first front of the body up extends to the second end face. A through opening is particularly robust and durable compared to a blind hole characterized by a lower probability of cracking. This is of particular importance since the body in the operation of the transformer vibrates, causing cracking can.

Out above reasons the specified piezotransformer is highly reliable.

Of the respective functional part comprises alternately arranged first and second internal electrodes aligned perpendicular to the longitudinal direction of the body are. The internal electrodes are each between two piezoelectric Layers arranged. The piezoelectric layers are in Following called piezo layers. The terminal internal electrodes of the respective functional part are in a variant between a Piezo layer and the insulating region arranged.

The openings preferably extend in the longitudinal direction of the body, ie perpendicular to the internal electrodes. In the body, mechanical vibrations are excited, which preferably also propagate in the longitudinal direction. The vibrations are characterized by an electromechanical coupling coefficient k ₃₃ .

The breakthroughs preferably have at least one contact layer, the one Group of internal electrodes interconnects. In the respective breakthrough is an elongated connecting element, preferably a metal pin, a metal tube or a composite of metal fibers, e.g. B. a wire rope, arranged. Instead of the metal, other conductive materials come into consideration, for. As electrically conductive ceramics, carbon fiber materials, composites.

The Connecting element protrudes out of the body. The connection element can be connected to an external carrier, preferably a printed circuit board, firmly connected. The connecting element is preferably sufficient stable and suitable as a supporting element for the body.

Between the connection element and the body is preferably a resilient device arranged for the damping of Vibrations of the body suitable is. The connection element can alternatively self-vibration damping Have properties or a spring device.

The respective contact layer is in a variant with an externally accessible terminal area conductively connected, which is arranged on a front side of the body. At this Terminal surface can a connecting wire to be attached.

At least an area of the inner surface the first breakthrough is covered by a first contact layer, the conducting the first internal electrodes of the first functional part combines. At least a portion of the inner surface of the second aperture is covered by a second contact layer comprising the second internal electrodes the first functional part conductively connects.

In a variant is at least a portion of the inner surface of the first breakthrough covered by a third contact layer, the the first internal electrodes of the second functional part conductively connects. In this case, at least one region of the inner surface of the second opening covered by a fourth contact layer comprising the second internal electrodes the second functional part conductively connects.

In Another variant is in the body a third breakthrough and a fourth breakthrough formed. At least an area of the inner surface the third breakthrough is covered by a third contact layer, the conducting the first internal electrodes of the second functional part combines. At least a portion of the inner surface of the fourth aperture is covered by a fourth contact layer comprising the second internal electrodes the second functional part conductively connects.

The first internal electrodes of the respective functional part have a Recess on, in which the second opening is arranged. The second internal electrodes of the respective functional part have a Recess on, in which the first opening is arranged.

in the each breakthrough is preferably arranged a filling material. The filling material is preferably electrically insulating. The filling material is preferably arranged at least in a region of the breakthrough, to the Isolation area adjacent. The filling material preferably has hydrophobic properties. As filler For example, silicone is suitable. But there are others, too electrically insulating materials with a high dielectric strength be used.

The Piezo layers preferably contain a ceramic material such. B. lead zirconate titanate. Alternatively, others may also be preferred ceramic, in particular lead-free piezoelectric materials be used.

Of the Insulating area comprises in one variant an electrically insulating Material, preferably ceramic, which differs from the material of the piezoelectric layers. The material of the insulating area can also be equal to the material be the piezo layers.

Of the Piezotransformator example, prepared as follows. It becomes a body with two partial bodies and an insulating region disposed therebetween, where the part body each provided by stacking ceramic layers and metal layers become. Become in the body at least two breakthroughs generated perpendicular to the layer orientation. In one variant, the body with the breakthroughs sintered. Alternatively you can the breakthroughs be generated even after sintering. The breakthroughs can, for example by drilling - z. As mechanical drilling, laser drilling, jet drilling - or punching be generated.

The breakthroughs are each preferably metallized after sintering. For example while on the inner surface the breakthroughs applied a metal paste and then baked. alternative it is possible, the breakthroughs otherwise provided with a contact layer. For example is the vapor deposition of a conductive layer possible.

Of the specified piezoelectric transformer is now based on schematic and not to scale Figures explained. Show it:

1A in longitudinal section a piezotransformer having two through openings;

1B a plan view of a metallization of the piezoelectric transformer according to the 1A ;

2A partial, a piezotransformer with four breakthroughs;

2 B a fragmentary first longitudinal section of the piezotransformer according to the 2A ;

2C partially a second longitudinal section of the piezotransformer according to the 2A ,

In 1A is a piezotransformer with a ceramic body 3 shown an entrance part 5 , an output part 7 and an insulating region disposed therebetween 10 includes.

The entrance part 5 and the output part 7 are by means of the insulating area 10 mechanically coupled with each other. They are electrically insulated from each other by the insulating area. An electrical input signal is converted in the input part of the piezoelectric transformer into mechanical vibrations of the main body of the transformer. Due to the mechanical coupling of the input part and the output part both parts are affected by the mechanical vibration. The conversion of electrical energy into mechanical energy occurs due to the inverse piezoelectric effect. In the output part, the mechanical vibrations are transformed back into an electrical output signal due to the direct piezoelectric effect. Depending on the transformation ratio of the transformer, the output voltage may be lower or higher than the input voltage. The input and output voltage can also be the same size, the transformer is used for example for a galvanic decoupling of two circuits.

In the body 3 is a first breakthrough 1 and a second breakthrough 2 educated. The breakthroughs connect two opposite forehead surfaces of the body.

The entrance part 5 includes first internal electrodes 4a and second internal electrodes 4b which are arranged alternately. The first internal electrodes 4a are over a first contact layer 6a conductively connected with each other in the first breakthrough 1 is arranged. The second internal electrodes 4b are over a second contact layer 6b conductively connected to each other in the second breakthrough 2 is arranged.

The starting part 7 includes first internal electrodes 8a and second internal electrodes 8b which are arranged alternately. The first internal electrodes 8a are over a first contact layer 9a conductively connected with each other in the first breakthrough 1 is arranged. The second internal electrodes 8b are over a second contact layer 9b conductively connected to each other in the second breakthrough 2 is arranged.

The contact layers 6a . 6b . 9a . 9b are conductor surfaces, each one arranged in the input part or output part of the inner wall of the opening 1 . 2 cover. The internal electrodes of the piezotransformer are above the contact layers 6a . 6b . 9a . 9b electrically contactable.

In order to prevent an electrical flashover between the input part and the output part along the surface of the respective breakthrough, at least one region of the opening, which is in the insulating region 10 is arranged, formed free of metallization. In order to further increase the dielectric strength of the piezotransformer, an electrically insulating filling material is in this region of the opening 11 or a passivation layer 12 intended. The passivation layer 12 covers a region of the respective contact layer 6a . 6b . 9a . 9b , Thus, an electrical creepage distance is extended.

The Dielectric strength of the filler or exceeds the passivation layer preferably that of the piezoelectric layers. The filling material or the passivation layer may be organic and / or inorganic Shares have.

The internal electrodes 4a . 4b . 8a . 8b are in the body 3 embedded. The configuration of an inner electrode is in the 1B for the inner electrode 4a explained (section AA). It applies correspondingly to the internal electrodes 4b . 8a . 8b ,

The first inner electrode 4a contacts the first contact layer 6a but is from the second contact layer 6b spaced. The first inner electrode 8a contacts the first contact layer 9a and is from the second contact layer 9b spaced. The second inner electrode 4b contacts the second contact layer 6b and is from the first contact layer 6a spaced. The second inner electrode 8b contacts the second contact layer 9b and is from the first contact layer 9a spaced.

The second breakthrough 2 is in a recess 41 the first inner electrode 4a and a recess 43 the first inner electrode 8a arranged. Thus, the second contact layer 6b in the recess 41 the first inner electrode 4a and in a corresponding manner the second contact layer 9b in the recess 43 the first inner electrode 8a arranged. The first breakthrough 1 is in a recess 42 the second inner electrode 4b and a recess 44 the second inner electrode 8b arranged. Thus, the first contact layer 6a in the recess 42 the second inner electrode 4b and correspondingly, the first contact layer 9a in the recess 44 the second inner electrode 8b arranged.

The breakthroughs 1 . 2 lie in the variant according to the 1A . 1B along a line passing through the middle of the body 3 goes and is parallel to first side surfaces of the body. The breakthroughs 1 . 2 lie in a further variant along a diagonal. In principle, any, including asymmetric, arrangement of breakthroughs is possible.

In the 1A the transformer parts are shown with the same distance between the first and second internal electrodes. This distance can also be chosen differently in order to achieve a desired transmission ratio.

In the 2A . 2 B . 2C is shown a further piezotransformer. The 2 B corresponds to the section AA and the 2C the cut BB.

In this case, there are four breakthroughs 1 . 2 . 21 . 22 provided, ie for each contact layer a separate breakthrough. The contact layers 9a . 9b are in the breakthroughs 21 and 22 arranged.

In this case, only one is in the entrance section 5 arranged area of breakthroughs 1 . 2 to form the contact layers 6a . 6b as well as in the starting part 7 arranged area of breakthroughs 21 . 22 to form the contact layers 9a . 9b metallized.

Each inner electrode is conductively connected to the respective contact layer of one of the openings. The other breakthroughs are each in a recess 42 . 43 . 44 arranged this inner electrode. Because the breakthroughs 21 . 22 in the entrance section 5 are not metallized, can on the aussparun gene 43 . 44 be waived.

The Embodiment of the piezotransformer, in particular the shape and the number of transformer elements is the same as in the figures presented variants not limited.

Of the body is preferably formed in the shape of a cuboid. The end faces of the Body can be rectangular or be square. The body can but also be cylindrical.

1

first breakthrough

2

second breakthrough

3

body

4a

first Inner electrode of the input part

4b

second Inner electrode of the input part

5

introductory

6a

first Contact layer of the input part

6b

second Contact layer of the input part

7

output portion

8a

first Inner electrode of the output part

8b

second Inner electrode of the output part

9a

first Contact layer of the output part

9b

second Contact layer of the output part

10

isolation

11

filling material

12

passivation

21

third breakthrough

22

fourth breakthrough

41 42, 43, 44

 recess in an inner electrode

Claims (11)

Piezoelectric transformer - with one body ( 3 ), the two functional parts ( 5 . 7 ) and an insulating area ( 10 ) comprising the functional parts ( 5 . 7 ) mechanically connects, - being in the body ( 3 ) a first breakthrough ( 1 ) and a second breakthrough ( 2 ), the respective breakthrough ( 1 . 2 ) both functional parts ( 5 . 7 ) and the insulating area ( 10 ) penetrates. Transformer according to claim 1, - wherein the breakthroughs ( 1 . 2 ) in the longitudinal direction of the body ( 3 ). Transformer according to claim 1 or 2, - wherein the respective functional part ( 5 . 7 ) alternately arranged first and second internal electrodes ( 4a . 4b . 8a . 8b ) perpendicular to the longitudinal direction of the body ( 3 ) are aligned. Transformer according to one of claims 1 to 3, - wherein at least a portion of the inner surface of the first opening ( 1 ) by a first contact layer ( 6a ) covering the first internal electrodes ( 4a ) of the first functional part ( 5 ) conductively interconnects, and - wherein at least a portion of the inner surface of the second aperture ( 2 ) by a second contact layer ( 6b ) covering the second internal electrodes ( 4b ) of the first functional part ( 5 ) conductively connects with each other. Transformer according to one of claims 1 to 4, - wherein at least a portion of the inner surface of the first opening ( 1 ) by a third contact layer ( 9a ) covering the first internal electrodes ( 8a ) of the second functional part ( 7 ) conductively connects, and - wherein at least a portion of the inner surface of the second aperture ( 2 ) through a fourth contact layer ( 9b ) covering the second internal electrodes ( 8b ) of the second functional part ( 7 ) conductively connects. Transformer according to one of claims 1 to 4, - wherein in the body a third breakthrough ( 21 ) and a fourth breakthrough ( 22 ) is formed, - wherein at least a portion of the inner surface of the third opening ( 21 ) by a third contact layer ( 9a ) covering the first internal electrodes of the second functional part ( 5 ) conductively connects, and - wherein at least a portion of the inner surface of the fourth aperture ( 22 ) through a fourth contact layer ( 9b ) covering the second internal electrodes of the second functional part ( 7 ) conductively connects. Transformer according to one of claims 1 to 6, - wherein the first internal electrodes ( 4a . 8a ) of the respective functional part a recess ( 41 . 43 ) in which the second breakthrough ( 2 ), and - wherein the second internal electrodes ( 4b . 8b ) of the respective functional part a recess ( 42 . 44 ) in which the first breakthrough ( 1 ) is arranged. Transformer according to one of claims 1 to 7, - wherein in the respective breakthrough ( 1 . 2 ) a filling material ( 11 ) or a passivation layer ( 12 ) is orders. Transformer according to one of claims 1 to 8, - wherein in the respective breakthrough ( 1 . 2 . 21 . 22 ) An electrical connection element for contacting the functional parts is arranged. Method for producing a piezotransformer, comprising the following steps: A body with two partial bodies and an insulating region arranged between them is provided, where the part body each provided by stacking ceramic layers and metal layers, - be in the body at least two openings vertically generated for layer alignment, - the body with breakthroughs will sintered. Method according to claim 10, - in which the breakthroughs be generated after sintering.