JP2007096247A - Chip-type electronic part - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a chip-type electronic part allowing easy and accurate identification of the direction of a device. <P>SOLUTION: The chip-type electronic part 1 is provided with a ZnO system varistor device 2. The ZnO system varistor device 2 is provided with an element assembly 3 configured such that a varistor, an inductor, and a protective layer are laminated sequentially from below, and terminal electrodes 4 to 6 and an external conductor 7 provided on the surface of the element assembly 3. A direction identifying mark 19 that identifies the upward/downward directions of the ZnO system varistor device 2 is provided on the surface on a protective layer side of the element assembly 3. Here, the surface to which the direction identifying mark 19 is affixed in the element assembly 3 is to be an upper surface to a circuit substrate that should be mounted. The direction identifying mark 19 is composed of ZrO<SB>2</SB>. The direction identifying mark 19 composed of ZrO<SB>2</SB>is formed by simultaneous sintering with the ZnO system varistor device 2. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a chip-type electronic component such as a chip varistor.

As a conventional chip-type electronic component, for example, as described in Patent Document 1, a plurality of varistor layers made of a material mainly composed of ZnO, an internal electrode formed between the varistor layers, an internal electrode, A varistor including an external terminal electrode that is electrically connected is known.
JP 2002-246207 A

  In recent years, chip varistors for high-speed transmission have been developed. A chip varistor for high-speed transmission has a varistor part and an inductor part. When such a chip varistor is mounted on a circuit board, if the inductor section is mistakenly mounted on the circuit board side, the L value of the inductor section decreases. Therefore, when a directional element such as the chip varistor is mounted on a circuit board, it is necessary to identify the direction of the element.

  An object of the present invention is to provide a chip-type electronic component that can easily and accurately identify the direction of an element.

The chip-type electronic component according to the present invention has a ZnO-based semiconductor element having an element body containing a material containing ZnO as a main component and a surface of the element body for identifying the direction of the ZnO-based semiconductor element. And the mark is made of ZrO ₂ .

By forming the mark on the surface of the element body in the ZnO-based semiconductor element in this manner, the direction of the ZnO-based semiconductor element can be easily recognized by image recognition or the like, so that the direction of the ZnO-based semiconductor element is surely identified. be able to. Here, an element body containing a material containing ZnO as a main component tends to be colored by making it into a semiconductor. Therefore, for a ZnO-based semiconductor element, a white mark such as ZrO ₂ is used. Is preferred. Further, when the mark material is ZrO ₂ , the mark is less likely to be peeled off, discolored, and the characteristics of the element are changed as compared with the case where the mark material is Mg (OH) ₂ or TiO ₂ , for example. There is little to let you. This has been clarified by experiments of the present inventors. Therefore, by using such a ZrO ₂ mark, high durability of the mark can be realized without substantially affecting the characteristics of the ZnO-based semiconductor element.

Preferably, the mark made of ZrO ₂ is formed by simultaneous firing with a ZnO-based semiconductor element. In the state before firing, the direction of the ZnO-based semiconductor element can be easily selected as compared with after firing. Therefore, by forming the mark made of ZrO ₂ by simultaneous firing with the ZnO-based semiconductor element, the mark can be reliably formed at an appropriate position on the surface of the element body in the directional ZnO-based semiconductor element. Moreover, since a part of the process of forming the mark on the surface of the element body is performed together with the firing process, the manufacturing process of the chip-type electronic component can be simplified.

Also, preferably, ZnO based semiconductor device includes a varistor portion constituting a part of the body, is laminated to the varistor portion, and a inductor portion constituting the other part of the body, ZrO ₂ The mark made of is formed on the surface of the element body on the inductor portion side. In this case, when mounting a ZnO-based semiconductor element having a varistor part and an inductor part on a circuit board, the ZnO-based semiconductor element is mounted so that the surface on which the mark made of ZrO ₂ is formed is the upper surface. Thus, it is possible to easily prevent the inductor portion from being erroneously mounted on the circuit board side.

According to the present invention, since the mark made of ZrO ₂ is formed on the surface of the element body in the ZnO-based semiconductor element, the direction of the ZnO-based semiconductor element can be easily and accurately identified. Thereby, for example, when mounting a ZnO-based semiconductor element on a circuit board, it is possible to avoid making a mistake in the direction of the ZnO-based semiconductor element. In addition, since the disappearance and discoloration of the mark are prevented, the image of the mark can be reliably recognized. Furthermore, it is possible to prevent the mark from affecting the characteristics of the ZnO-based semiconductor element.

  DESCRIPTION OF EMBODIMENTS Hereinafter, a preferred embodiment of a chip-type electronic component according to the present invention will be described in detail with reference to the drawings.

  FIG. 1 is a perspective view showing an embodiment of a chip-type electronic component according to the present invention. In the figure, a chip-type electronic component 1 of this embodiment includes a ZnO varistor element 2 for high-speed transmission.

  The ZnO-based varistor element 2 includes a rectangular parallelepiped element body 3, terminal electrodes 4 and 5 provided on portions including end faces 3 a and 3 b on both sides of the element body 3, and a portion including a side surface 3 c of the element body 3. And an external conductor 7 provided so as to face the terminal electrode 6 in a portion including the side surface 3d on the opposite side of the element body 3. The dimension of the element body 3 is, for example, about 1 mm in length × about 0.5 mm in width × about 0.3 mm in height. The terminal electrode 4 functions as an input terminal electrode of the ZnO varistor element 2, and the terminal electrode 5 functions as an output terminal electrode of the ZnO varistor element 2. The terminal electrode 6 functions as a ground terminal electrode of the ZnO-based varistor element 2.

  FIG. 2 is an exploded perspective view showing the configuration of the element body 3. In the figure, the element body 3 has an inductor part (coil part) 8, a varistor part 9, and a protective layer 10. The element body 3 has a structure in which a varistor part 9, an inductor part 8, and a protective layer 10 are sequentially laminated from below.

  The inductor unit 8 includes internal conductors 11 and 12 that are coupled to each other by polarity inversion. The inductor unit 8 is configured by laminating an inductor layer 13 in which the internal conductor 11 is formed and an inductor layer 14 in which the internal conductor 12 is formed. Here, “polarity reversal coupling” means that the start of winding of the inductance component corresponding to the internal conductor 11 is the terminal electrode 4 side, and the start of winding of the inductance component corresponding to the internal conductor 12 is the side connected to the internal conductor 11. In this case, it means that the coupling between the inner conductors 11 and 12 is “positive”. That is, “polarity reversal coupling” means that current flows from the terminal electrode 4 to the internal conductor 11, current flows from the side connected to the internal conductor 11 to the internal conductor 12, and the magnetic flux generated in the internal conductor 11 and the internal conductor 12. This means that the generated magnetic flux 12 is strengthened.

  One end of the internal conductor 11 is drawn out so as to be exposed at the end face 3 a of the element body 3 and connected to the terminal electrode 4. One end of the internal conductor 12 is drawn out so as to be exposed at the end face 3 b of the element body 3 and connected to the terminal electrode 5. The other ends of the inner conductors 11 and 12 are drawn out so as to be exposed on the side surface 3 d of the element body 3 and connected to the outer conductor 7. That is, the other ends of the inner conductors 11 and 12 are electrically connected through the outer conductor 7.

  The inner conductors 11 and 12 include regions 11a and 12a that overlap each other when viewed from the stacking direction of the inductor layers 13 and 14, respectively. The inner conductors 11 and 12 are capacitively coupled in the regions 11a and 12a. Note that the internal conductors 11 and 12 may be connected not by the external conductor 7 as described above but by a through-hole conductor or the like formed inside the element body 3. The conductive material forming the inner conductors 11 and 12 is, for example, any one of Pd, Ag, Ag—Pd alloy, and the like.

  The inductor layers 13 and 14 are made of a ceramic material mainly composed of ZnO. The ceramic material forming the inductor layers 13 and 14 contains, in addition to ZnO, one or more of rare earths (for example, Pr) or Bi and metal elements such as Cr, Ca, Si, and K as additives. . Further, rare earth or Bi may be added to the inductor layers 13 and 14 for the purpose of reducing the difference in volume change rate from the varistor portion 9. The metal elements contained in the inductor layers 13 and 14 can be present in various forms such as simple metals or their oxides.

  The varistor section 9 has internal electrodes 15 and 16. The varistor section 9 is configured by laminating a varistor layer 17 in which an internal electrode 15 is formed and a varistor layer 18 in which an internal electrode 16 is formed.

  One end of the internal electrode 15 is drawn out so as to be exposed on the side surface 3 d of the element body 3 and connected to the external conductor 7. Thereby, the other ends of the internal conductors 11 and 12 and one end of the internal electrode 15 are electrically connected through the external conductor 7. The other end of the internal electrode 15 is not exposed to the side surface 3c of the element body 3 and is in a position drawn from the side surface 3c. One end of the internal electrode 16 is drawn out so as to be exposed on the side surface 3 c of the element body 3 and connected to the terminal electrode 6. The other end of the internal electrode 16 is not exposed to the side surface 3d of the element body 3 and is in a position drawn from the side surface 3d.

  The internal electrodes 15 and 16 include regions 15a and 16a that overlap each other when viewed from the stacking direction of the varistor layers 17 and 18, respectively. Thereby, the site | part corresponding to the area | regions 15a and 16a in the varistor layer 17 functions as an area | region which expresses a voltage nonlinear characteristic (varistor characteristic). The conductive material forming the internal electrodes 15 and 16 is, for example, any one of Pd, Ag, Ag—Pd alloy, and the like.

  The varistor layers 17 and 18 are made of a ceramic material mainly composed of ZnO. This ceramic material further contains Co as an additive, at least one element selected from the group consisting of rare earths (eg, Pr) and Bi. Here, since the varistor layers 17 and 18 contain Co in addition to the rare earth, the varistor layers 17 and 18 have excellent varistor characteristics and also have a high dielectric constant (ε). The ceramic material forming the varistor layers 17 and 18 may further contain Al as an additive. In this case, the varistor layers 17 and 18 have low resistance. The metal elements contained in the varistor layers 17 and 18 can be present in the form of simple metals or their oxides. The varistor layers 17 and 18 may further contain a metal element other than the above (for example, Cr, Ca, Si, K, etc.) as an additive in order to further improve the characteristics.

  The protective layer 10 is a layer made of a ceramic material mainly composed of ZnO, and protects the inductor portion 8. The protective layer 10 contains, for example, rare earth, Cr, Ca, Si, K or the like as an additive in addition to ZnO. The protective layer 10 may be a single layer or a plurality of layers.

  The terminal electrodes 4 to 6 and the outer conductor 7 provided on the element body 3 composed of the inductor section 8, the varistor section 9 and the protective layer 10 are Pd or the inner conductors 11 and 12 and the inner electrodes 15 and 16. It is made of a metal material such as Ag, which can be electrically connected to a metal such as Ag—Pd well and has good adhesion to the element body 3. Further, in order to improve solderability, a plating layer such as Ni or Sn may be further formed.

In the ZnO-based varistor element 2 as described above, for example, a circular direction identification mark 19 for identifying the vertical direction of the ZnO-based varistor element 2 is provided on the surface of the element body 3 on the protective layer 10 side. Here, the surface to which the direction identification mark 19 is attached in the element body 3 is the upper surface with respect to a circuit board (not shown) to be mounted. The direction identification mark 19 is made of ZrO ₂ . The direction identification mark 19 made of ZrO ₂ is formed by simultaneous firing (described later) with the ZnO-based varistor element 2.

A ceramic material containing ZnO as a main component is colored when fired in a semiconductor state by injection of an additive. For example, when Pr is added to a ceramic material containing ZnO as a main component, ZnO, which is originally white, exists in the form of Pr oxide in the grain boundary portion of the sintered body, and the Pr oxide as a whole Color (brown) comes to be exhibited. That is, the sintered body 3 is colored brown. For this reason, in order to clearly distinguish the direction identification mark 19 from the element body 3, it is appropriate to attach a white mark such as a ZrO ₂ mark.

  Next, a method for manufacturing the chip-type electronic component 1 will be described with reference to FIG. First, a paste containing a ceramic material as a raw material for the inductor layers 13 and 14, the varistor layers 17 and 18 and the protective layer 10 is prepared (step 101). Specifically, these pastes are prepared by adding the above-described additives to ZnO which is a main component, and further adding and mixing a binder or the like.

  Subsequently, the paste is applied on a plastic film by a doctor blade method or the like, and then the paste is dried to form a ceramic green sheet (step 102). Accordingly, the required number of green sheets for forming the inductor layer (hereinafter referred to as inductor sheet), green sheets for forming the varistor layer (hereinafter referred to as varistor sheet), and green sheets for forming the protective layer (hereinafter referred to as protective sheet) are respectively required. can get.

  Subsequently, a conductive paste for forming the internal conductors 11 and 12 and the internal electrodes 15 and 16 is prepared, and this conductive paste is screen-printed on the inductor sheet and the varistor sheet so as to form a desired pattern ( Step 103). As a result, the internal conductors 11 and 12 are formed on the inductor sheet, and the internal electrodes 15 and 16 are formed on the varistor sheet.

Further, a ZrO ₂ paste for forming the direction identification mark 19 is prepared, and this ZrO ₂ paste is screen-printed at a predetermined position on the protective sheet (step 104). At this time, since the protective sheet is a green sheet made of a material containing ZnO as a main component, it is whitish. For this reason, if the white ZrO ₂ paste is printed on the protective sheet as it is, it is difficult to perform image recognition of ZrO ₂ . Therefore, by mixing carbon black or organic pigment in ZrO ₂ paste (eg amaranth) to trace, it is desirable to color the ZrO ₂ paste. Since carbon black and organic pigments are scattered by firing described later, they do not remain after firing. Thus, after firing, ZrO ₂ becomes white state.

Subsequently, the varistor sheets on which the internal electrodes 15 and 16 are printed are sequentially laminated, and the inductor sheets on which the internal conductors 11 and 12 are printed are sequentially laminated thereon. And in the state which accumulated the protective sheet on these laminated structures, these sheets are crimped | bonded and a laminated body is obtained (process 105). At this time, when the protective sheet is a plurality, for example, by an image analyzer recognizes ZrO _2, the protective sheet ZrO ₂ paste is printed are laminated protective sheet such that the top layer.

  Subsequently, the laminated body thus obtained is cut into chips so as to have a desired size, and then the chip is baked at a predetermined temperature (for example, 1000 to 1400 ° C.), whereby the element body 3 is obtained. Obtain (step 106). As a result, a whitish direction identification mark 19 is formed on the surface of the colored element body 3 on the protective layer 10 side.

  Finally, a paste containing Ag as a main component is transferred and baked in a predetermined region on the surface of the element body 3 and then plated to form the terminal electrodes 4 to 6 and the external conductor 7. (Step 107). Thereby, the chip-type electronic component 1 described above is completed.

Here, FIG. 4 shows a comparison result between the case where the material of the direction identification mark 19 is ZrO ₂ as in this embodiment and the case where the material is Mg (OH) ₂ and TiO ₂ . All of these materials have almost no influence on the firing temperature.

As can be seen from FIG. 4, when the material of the direction identification mark 19 is Mg (OH) ₂ and TiO ₂ , peeling of the mark was observed in the manufacturing process. Further, when the material of the direction identification mark 19 is Mg (OH) ₂ , the mark changes color from white in the manufacturing process, and when the material of the direction identification mark 19 is TiO ₂ , the direction identification mark 19 is changed. As a result, the electrical characteristics of the varistor element 2 were changed.

On the other hand, when the material of the direction identification mark 19 is ZrO ₂ , there is no particular peeling or discoloration of the mark in the manufacturing process, and furthermore, the electrical characteristics of the varistor element 2 hardly change. .

In addition, when a molecular orbital calculation was performed to determine what level ZrO ₂ forms with respect to ZnO, no level was formed between the band gaps of ZnO, and it was predicted that there was a low possibility of making ZnO a semiconductor. .

From the above, it has been proved that the ZrO ₂ mark is the most appropriate as the direction identification mark 19 attached to the green sheet mainly composed of ZnO.

  In the chip-type electronic component 1 of the present embodiment as described above, since the direction identification mark 19 is provided on the surface of the element body 3 on the protective layer 10 side, the vertical direction of the ZnO-based varistor element 2 can be easily and reliably established. Can be identified. That is, it can be immediately known that the surface side with the direction identification mark 19 in the ZnO varistor element 2 is the inductor section 8 side.

  Here, when the chip-type electronic component 1 is mounted on a circuit board (not shown), if the inductor section 8 of the ZnO-based varistor element 2 is mistakenly mounted on the circuit board side, the inductor section 8 becomes the circuit board. For example, stray capacitance is generated between the ground electrode of the circuit board and the inner conductors 11 and 12 of the inductor unit 8, and the L value itself of the inductor unit 8 is changed, so that the ZnO varistor element 2 is changed. Adversely affects the characteristics of Therefore, by mounting the chip-type electronic component 1 on the circuit board so that the surface on which the direction identification mark 19 is attached is the upper surface of the ZnO-based varistor element 2 with respect to the circuit board, the varistor section 9 is always It will be located on the circuit board side. In this case, adverse effects on the characteristics of the ZnO-based varistor element 2 can be avoided.

Further, since the direction identification mark 19 is made of ZrO ₂ , the direction identification mark 19 is not easily lost, and the direction identification mark 19 is not easily discolored. For this reason, the direction identification mark 19 can be reliably identified over a long period of time by an image analyzer or the like. Furthermore, by making the direction identification mark 19 a ZrO ₂ mark, it is possible to prevent the electrical characteristics of the ZnO-based varistor element 2 from being adversely affected.

Further, the direction identification mark 19 is formed together with the firing of the laminated body after the ZrO ₂ paste is screen-printed to form the laminated body. That is, since the ZrO ₂ paste, which is the basis for marking, is printed in advance on the inductor side surface of the laminate before firing the laminate, it is easy to form the direction identification mark 19 at the correct vertical position. And it can be done reliably. Moreover, the manufacturing process of the chip-type electronic component 1 can be simplified as compared with the case where the firing process of the laminated body and the forming process of the direction identification mark 19 are performed completely separately.

Further, when the direction identification mark 19 is formed of a metal material, plating is attached to the surface of the mark underlayer, so that the direction identification mark 19 is deformed or the terminal electrode 4 is generated due to the elongation of the plating. Although there is a possibility that a short circuit will occur with ˜6 etc., such a problem can be prevented by making the direction identification mark 19 a ZrO ₂ mark.

  The present invention is not limited to the above embodiment. For example, in the above embodiment, the inductor layers 13 and 14 having the inner conductors are provided one by one, and the varistor layers 17 and 18 having the inner electrodes are provided one by one. However, the inner conductors are formed. In addition, the inductor layers 13 and 14 may be repeatedly stacked to increase the number of turns of the coil in the inductor portion, or the varistor layers 17 and 18 having the internal electrodes may be stacked repeatedly.

  Moreover, in the said embodiment, although the terminal electrodes 4-6 and the external conductor 7 are each provided in the element | base_body 3 one each, as shown in FIG. 5, the terminal electrodes 4-6 and the external conductor 7 are an element | element body. A plurality (two in FIG. 5) may be provided for each of the three elements, and an array element having a plurality of sets of inductors and varistors may be used.

  Further, the position and shape of the direction identification mark 19 are not limited to the above embodiment. As shown in FIGS. 6 and 7, a rectangular direction identification mark 19 may be provided substantially at the center of the surface of the element body 3. The direction identification mark 19 has an elongated shape extending in the longitudinal direction of the element body 3. As a result, interference between the direction identification mark 19 and the terminal electrodes 4 to 6 and the external conductor 7 is suppressed, and the recognition accuracy of the direction identification mark 19 is improved and the ZnO-based varistor element 2 (element body 3) is improved. ) Can be miniaturized.

  Moreover, in the said embodiment, although a part of formation process of the direction identification mark 19 was performed simultaneously with baking of a laminated body, you may form the direction identification mark 19 after baking of a laminated body.

Furthermore, the chip-type electronic component 1 of the above embodiment includes a ZnO-based varistor element 2 that is directional in the vertical direction. However, the present invention is not particularly limited to this, and for example, ZnO is the main component. Any element may be used as long as it has an element body containing the material to be processed and includes a directional ZnO-based semiconductor element. At this time, the ZnO-based semiconductor element may be not only those having directionality in the vertical direction but also those having directionality in the horizontal direction. For a ZnO-based semiconductor element having directionality in the lateral direction, a direction identification mark made of ZrO ₂ may be provided on one side surface of the element body.

It is a perspective view showing one embodiment of a chip type electronic component concerning the present invention. It is a disassembled perspective view which shows the structure of the element | base_body shown in FIG. It is a flowchart which shows the process of manufacturing the chip type electronic component shown in FIG. It is a table | surface which shows the comparison result in the case of changing various materials of the direction identification mark shown in FIG. It is a perspective view which shows the modification of the chip type electronic component shown in FIG. It is a perspective view which shows the further modification of the chip-type electronic component shown in FIG. It is a perspective view which shows the further modification of the chip-type electronic component shown in FIG.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Chip-type electronic component, 2 ... ZnO type varistor element (ZnO type semiconductor element), 3 ... Element body, 8 ... Inductor part, 9 ... Varistor part, 10 ... Protective layer, 13, 14 ... Inductor layer, 17, 18 ... varistor layer, 19 ... direction identification mark.

Claims (3)

A ZnO-based semiconductor element having an element body containing a material mainly composed of ZnO;
A mark formed on the surface of the element body for identifying the direction of the ZnO-based semiconductor element;
The chip-type electronic component, wherein the mark is made of ZrO ₂ . _2. The chip-type electronic component according to claim 1, wherein the mark made of ZrO ₂ is formed by simultaneous firing with the ZnO-based semiconductor element. The ZnO-based semiconductor element has a varistor part that constitutes a part of the element body, and an inductor part that is stacked on the varistor part and constitutes another part of the element body,
3. The chip-type electronic component according to claim 1, wherein the mark made of ZrO ₂ is formed on a surface of the element body on the inductor portion side.

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