JP2015029008A - Chip-type electronic components - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a chip-type electronic component in which ion migration is prevented.SOLUTION: A ceramic capacitor 10 includes: a ceramic element body 20 having a first end surface 21A and a second end surface 21B facing to each other, and a side surface 22 connecting the first end surface 21A and the second end surface 21B; a first terminal electrode 30A covering the first end surface 21A and a part of the side surface 22 on a side of the first end surface 21A, and containing Ag; and a second terminal electrode 30B covering the second end surface 21B and a part of the side surface 22 on a side of the second end surface 21B, and containing Ag. The ceramic capacitor 10 has a substantially rectangular parallelepiped shape. When the thickness of the first terminal electrode 30A on the side surface 22 side is H1, the thickness of the second terminal electrode 30B on the side surface 22 side is H2, and the maximum projection height of the side surface 22 is Y, the following formulas are satisfied: H1>Y and H2>Y.

Description

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

  Conventionally, multilayer ceramic capacitors, inductors, resistors, semiconductor elements, and the like are known as chip-type electronic components. Patent Document 1 below discloses a multilayer ceramic capacitor having a substantially rectangular parallelepiped outer shape as a small chip-type electronic component. Patent Document 1 shows that the multilayer ceramic capacitor expands in the thickness direction (that is, the stacking direction of the ceramic green sheets), and the side surface of the ceramic body is curved in a convex shape. Patent Document 2 below discloses a multilayer ceramic capacitor in which terminal electrodes are made of Ag or an Ag alloy as a chip-type electronic component.

JP 2006-270010 A JP 2011-139021 A

  In the electronic component of Patent Document 1 described above, the space between the electronic component and the mounting substrate is remarkably narrowed because the protruding side surface of the ceramic body contacts or is close to the mounting substrate during mounting. Therefore, when the terminal electrode is made of Ag or an Ag alloy as in the electronic component of Patent Document 2, ion migration is likely to occur. That is, when the electronic component is driven, a part of Ag of both terminal electrodes is ionized and, for example, on the side surface where the ceramic body protrudes between the electronic component and the mounting substrate via a conductive adhesive used at the time of mounting. It is easy to move so as to approach each other along. As a result of such ion migration, a short circuit may occur between the terminal electrodes.

  The present invention has been made to solve the above-described problems, and an object thereof is to provide a chip-type electronic component in which ion migration is suppressed.

  A chip-type electronic component according to an aspect of the present invention includes a ceramic body having a first end surface and a second end surface facing each other, and a side surface connecting the first end surface and the second end surface, A first terminal electrode that covers a part of the first end face and the side surface on the side of the first end surface and whose surface layer includes Ag; and a part of the second end face and the side face on the second end face side A chip-type electronic component having a substantially rectangular parallelepiped outer shape, the thickness of the side surface of the first terminal electrode being H1, H1> Y and H2> Y, where H2 is the thickness of the side surface of the terminal electrode 2 and Y is the maximum protruding height of the side surface.

  In this chip-type electronic component, the maximum protrusion height Y of the side surface of the ceramic body is H1> Y and H2> Y, and the side surface of the ceramic body does not contact the mounting substrate during mounting. The thickness H1 on the side surface side of the first terminal electrode, the thickness H2 on the side surface side of the second terminal electrode, and the maximum so that a sufficient space is secured between the side surface of the element body and the mounting substrate. The protruding height Y is designed. Thereby, the ion migration of Ag contained in the surface layer of the terminal electrode is suppressed.

  Of the thickness H1 on the side surface of the first terminal electrode and the thickness H2 on the side surface of the second terminal electrode, the thicker thickness is H, and Z = H−Y, and 10 μm. The aspect which satisfy | fills <= Z <= 30micrometer may be sufficient. In this case, ion migration can be more effectively suppressed by satisfying 10 μm ≦ Z, and high mounting strength can be obtained by satisfying Z ≦ 30 μm.

  Furthermore, when the length of the element body in the opposing direction of the first end face and the second end face is L and P = L / Z, 25 <P <100 may be satisfied. In this case, ion migration can be more effectively suppressed by satisfying P <100, and high mounting strength can be obtained by satisfying 25 <P.

  According to the present invention, a chip-type electronic component in which ion migration is suppressed is provided.

FIG. 1 is a side view showing a ceramic capacitor according to an embodiment of the present invention. FIG. 2 is a cross-sectional view showing a state of mounting a ceramic capacitor according to the prior art.

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the description, the same reference numerals are used for the same elements or elements having the same function, and redundant description is omitted.

  As a chip-type electronic component according to an embodiment of the present invention, a ceramic capacitor 10 will be described as an example with reference to FIG.

  As shown in FIG. 1, the ceramic capacitor 10 includes a ceramic body 20 and a pair of terminal electrodes 30A and 30B provided at both ends of the ceramic body 20, and has a substantially rectangular parallelepiped outer shape. ing.

  The ceramic body 20 has a configuration in which internal electrode layers and ceramic layers (not shown) are alternately stacked, and has a substantially rectangular parallelepiped shape. More specifically, the ceramic body 20 has a first end surface 21A and a second end surface 21B that face each other, and a side surface 22 that connects the first end surface 21A and the second end surface 21B. The opposing direction of the first end surface 21A and the second end surface 21B is the longitudinal direction of the ceramic body 20.

  In the following, for convenience of explanation, the thickness direction of the ceramic body 20 that is the stacking direction of the internal electrode layer and the ceramic layer is the Z direction, and the first end face 21A and the second end face 21B of the ceramic body 20 are opposed to each other. The direction is the X direction, the Z direction, and the direction orthogonal to the X direction is the Y direction. In addition, the X direction length (L), the Y direction length, and the Z direction length of the ceramic body 20 are, for example, 1000 μm, 500 μm, and 500 μm.

  The pair of terminal electrodes 30A and 30B includes a first terminal electrode 30A on the first end face 21A side and a second terminal electrode 30B on the second end face 21B side. Each of the terminal electrodes 30A and 30B covers the corresponding end faces 21A and 21B as a whole, and covers a part of the side face 22. That is, the first terminal electrode 30 </ b> A covers the first end surface 21 </ b> A and a part of the side surface 22 on the first end surface 21 </ b> A side, and is formed to wrap around the side surface 22 from the end surface 21 </ b> A. The second terminal electrode 30B is also formed so as to cover the second end surface 21B and a part of the side surface 22 on the second end surface 21B side and to wrap around the side surface 22 from the end surface 21B.

  Each of the terminal electrodes 30A and 30B is configured by plating with a conductive material (Ag or Ag alloy) containing Ag, and is electrically connected to the internal electrode layer exposed on the end faces 21A and 21B. Each terminal electrode 30A, 30B has an underlying layer that directly covers the end faces 21A, 21B and the side surface 22 even if the surface layer contains Ag, even if the terminal electrode 30A, 30B has a single layer structure (single layer structure). The structure (multilayer structure) which consists of (for example, Cu sintered layer) and the surface layer containing Ag may be sufficient.

  Here, in the ceramic body 20 described above, as shown in FIG. 1, the side surface 22 is expanded and curved in a convex shape. Such expansion occurs, for example, due to a difference in thermal expansion coefficient between the green sheet serving as the ceramic layer and the electrode paste serving as the internal electrode layer, and occurs when the ceramic body 20 is fired. Then, when the degree of expansion of the ceramic body 20 is determined from the protruding height based on the position of the corner defined by the end faces 21A, 21B and the side surface 22, the maximum value (maximum protruding height) is obtained. Y.

  Then, the thickness obtained on the side surface 22 side of each of the terminal electrodes 30A, 30B, that is, the thickness obtained as the Z-direction length based on the position of the corner defined by the end surfaces 21A, 21B and the side surface 22, When H1 and H2 are set, the maximum protrusion height Y is higher than both the thicknesses H1 and H2. That is, the maximum protrusion height Y satisfies the conditions of H1> Y and H2> Y. As shown in FIG. 1, this does not exceed the line connecting the lowest points in the Z direction of the terminal electrodes 30 </ b> A and 30 </ b> B (the chain line of FIG. 1). It means that you are away to the side. Therefore, when the ceramic capacitor 10 is mounted on a flat substrate, the side surface 22 does not come into contact with the mounting substrate. FIG. 1 shows an example in which the thickness H1 of the first terminal electrode 30A and the thickness H2 of the second terminal electrode 30B are the same. However, even when these thicknesses are the same, they are different. However, if the conditions of H1> Y and H2> Y are satisfied, the side surface 22 does not contact the mounting board.

  The inventors set the thickness H1 of the first terminal electrode 30A, the thickness H2 of the second terminal electrode 30B, and the maximum protruding height Y of the side surface 22 of the ceramic body 20 to H1> Y, and It has been found that ion migration is suppressed by designing so as to satisfy the condition of H2> Y.

  Hereinafter, ion migration will be described with reference to FIG.

  As shown in FIG. 2, in the ceramic capacitor according to the prior art, the amount of expansion of the side surface 122 of the ceramic body 120 is large, so that the side surface 122 is close to the surface of the mounting substrate 40 on which the ceramic capacitor is mounted. Proximity. When the electrode patterns 41A and 41B on the mounting substrate 40 corresponding to the terminal electrodes 30A and 30B are thinner, the side surface 122 may come into contact with the mounting substrate 40. Thus, when the expanded side surface 122 approaches or contacts the mounting substrate 40, the space S between the ceramic capacitor and the mounting substrate is remarkably reduced.

On the other hand, when voltage is applied between the terminal electrodes 30A and 30B and the ceramic capacitor is driven, a part of Ag contained in each of the terminal electrodes 30A and 30B is ionized. Ag ions (Ag ⁺ ) generated in this manner have fluidity, move (migrate) away from the terminal electrodes 30A and 30B, and some of them approach each other along the expanded side surface 122. Thus, the space S between the ceramic capacitor and the mounting board is reached. At this time, migration of the Ag ions is promoted by the conductive adhesives 50A and 50B that are interposed between the terminal electrodes 30A and 30B and the electrode patterns 41A and 41B and contain Ag filler.

  Such ion migration is particularly noticeable when the terminal electrodes 30A and 30B contain Ag having a high ionization tendency.

  Ag ions reaching the space S are precipitated as Ag around the space S, and the electrical separation distance between the first terminal electrode 30A and the second terminal electrode 30B is narrowed. As a result, a short circuit is likely to occur between the first terminal electrode 30A and the second terminal electrode 30B.

  Therefore, in the ceramic capacitor 10 described above, the thickness H1 of the first terminal electrode 30A, the thickness H2 of the second terminal electrode 30B, and the maximum protrusion height Y of the side surface 22 of the ceramic body 20 are set as H1. It is designed to satisfy the conditions of> Y and H2> Y to suppress the ion migration. In order to satisfy the above condition, the maximum protrusion height Y can be designed to be low by, for example, forming a dummy electrode (electrode formed in the same layer as the internal electrode and not contributing to capacity formation) or blank printing. (Technique for forming a dielectric layer having the same height as the inner electrode around the inner electrode) is used, and these methods are particularly effective in the case of a multilayer ceramic capacitor. In order to satisfy the above condition, a method of increasing the thickness H1 of the first terminal electrode 30A and the thickness H2 of the second terminal electrode 30B is to form a thick terminal electrode, for example. .

  As described above, the ceramic capacitor 10 has the thickness H1 of the first terminal electrode 30A, the thickness H2 of the second terminal electrode 30B, and the maximum protruding height Y of the side surface 22 of the ceramic body 20 as follows. By designing so that the conditions of H1> Y and H2> Y are satisfied, the side surface 22 of the ceramic body 20 does not contact the mounting substrate 40 during mounting, and the side surface 22 of the ceramic body 20 and the mounting substrate 40 are not contacted. A sufficient space S is ensured between them. Thereby, ion migration of Ag contained in the terminal electrodes 30A and 30B as shown in FIG. 2 is suppressed.

  Further, the ceramic capacitor 10 has the thickness H of the first terminal electrode 30A and the thickness H2 of the second terminal electrode 30B as H, and Z = H−Y. Since the value of Z is 15 μm, ion migration is more effectively suppressed and high mounting strength is obtained in the ceramic capacitor 10. FIG. 1 shows an example in which the thickness H1 of the first terminal electrode 30A and the thickness H2 of the second terminal electrode 30B are the same, and therefore H = H1 = H2. Further, even if a design tolerance of about several μm is taken into consideration, the thickness H1 of the first terminal electrode 30A and the thickness H2 of the second terminal electrode 30B are substantially the same (H1≈H2). Can think. Unlike FIG. 1, for example, when the thickness H1 of the first terminal electrode 30A is larger than the thickness H2 of the second terminal electrode 30B (H1> H2), it is defined as Z = H1-Y. When the thickness H1 of the first terminal electrode 30A is smaller than the thickness H2 of the second terminal electrode 30B (H1 <H2), it is defined as Z = H2-Y.

  The inventors have found that ion migration can be more effectively suppressed by satisfying 10 μm ≦ Z, and that high mounting strength can be obtained by satisfying Z ≦ 30 μm. That is, if Z is 10 μm or more, a sufficient space S for suppressing ion migration is secured between the side surface 22 of the ceramic body 20 and the mounting substrate 40, and if Z is 30 μm or less, the terminal A sufficiently large grounding area for the electrode pattern of the mounting substrate of the electrodes 30A and 30B can be secured. In addition, when Z becomes larger than 30 μm, the ground contact area becomes small, and it becomes difficult to secure a practically sufficient mounting strength.

  Further, the ceramic capacitor 10 has a value P of 67 when the length of the ceramic body 20 in the X direction is L and P = L / Z as shown in FIG. The ion migration is more effectively suppressed and a high mounting strength can be obtained.

  The inventors have found that ion migration can be more effectively suppressed by satisfying P <100, and that high mounting strength can be obtained by satisfying 25 <P. That is, if P is less than 100, a space S sufficient for suppressing ion migration is secured between the side surface 22 of the ceramic body 20 and the mounting substrate 40, and if P is greater than 25, the terminal electrode A sufficiently large contact area between 30A and 30B and the electrode pattern of the mounting substrate can be secured. When P is 25 or less, the ground contact area becomes small, and it becomes difficult to ensure practically sufficient mounting strength.

  The present invention is not limited to the above-described embodiment, and various modifications can be made.

  For example, the chip-type electronic component is not limited to a ceramic capacitor, and may be an inductor, a resistor, a semiconductor element, or the like. In the above-described embodiment, the example in which the thickness H1 of the first terminal electrode 30A and the thickness H2 of the second terminal electrode 30B are the same is shown. The design may be different.

  DESCRIPTION OF SYMBOLS 10 ... Chip-type electronic component (ceramic capacitor), 20 ... Ceramic body, 21A, 21B ... End face, 22 ... Side surface, 30A, 30B ... Terminal electrode, 40 ... Mounting board.

Claims (3)

A ceramic body having a first end surface and a second end surface facing each other, and a side surface connecting the first end surface and the second end surface;
On the first end face side, a first terminal electrode that covers the first end face and a part of the side face, and whose surface layer includes Ag,
Chip-type electrons having a substantially rectangular parallelepiped outer shape on the second end face side, the second end electrode covering the second end face and a part of the side face, and a surface layer including a second terminal electrode containing Ag. Parts,
When the thickness of the side surface side of the first terminal electrode is H1, the thickness of the side surface side of the second terminal electrode is H2, and the maximum protruding height of the side surface is Y, H1> Y, A chip-type electronic component that satisfies H2> Y.   Of the thickness H1 on the side surface of the first terminal electrode and the thickness H2 on the side surface of the second terminal electrode, the thicker one is H, and Z = H−Y. The chip-type electronic component according to claim 1, wherein 10 μm ≦ Z ≦ 30 μm is satisfied.   3. The chip according to claim 2, wherein when the length of the element body in the facing direction of the first end surface and the second end surface is L and P = L / Z, 25 <P <100 is satisfied. Type electronic components.

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