Patent Application
20250014829
This application claims the benefit of priority to Japanese Patent Application No. 2023-109261 filed on Jul. 3, 2023. The entire contents of this application are hereby incorporated herein by reference.
The present disclosure relates to multilayer ceramic capacitors.
As a conventional multilayer ceramic capacitor, Japanese Patent Laid-Open No. 2006-179873 discloses a configuration including a multilayer body in which a plurality of dielectric layers and a plurality of internal electrode layers are laminated, chip protection members provided on both side surfaces of the multilayer body, and a pair of external electrodes provided on both end surfaces of the multilayer body.
The internal electrode layer includes an opposing portion opposing the electrode layer adjacent to the opposing portion in a lamination direction and a lead-out portion led out from the opposing portion to the end surface of the multilayer body. The lead-out portion has a width that is narrower than a width of the opposing portion.
In recent years, multilayer ceramic capacitors have been increasingly miniaturized and increased in capacitance. This reduces the size of a multilayer ceramic capacitor itself, but requires internal electrode layers embedded therein to be increased in size. Therefore, the volume of the region other than the internal electrode layers is further reduced, and if no measures are taken, dielectric layers and the internal electrode layers are more likely to be peeled off from each other, and the anti-fracture strength is reduced.
Example embodiments of the present invention provide multilayer ceramic capacitors each able to reduce or prevent interlayer peeling, the multilayer ceramic capacitors having a configuration in which a width of a lead-out portion of an internal electrode layer extending to an end surface of an element body portion is narrower than that of an opposing portion of the internal electrode layer.
A multilayer ceramic capacitor according to an example embodiment of the present invention includes an element body portion including a first principal surface and a second principal surface opposite to each other in a thickness direction, a first side surface and a second side surface opposite to each other in a width direction, and a first end surface and a second end surface opposite to each other in a length direction, a plurality of dielectric layers and a plurality of internal electrode layers laminated in the thickness direction, and a pair of external electrodes respectively on the first end surface and the second end surface, and electrically connected to the plurality of internal electrode layers. Each of the plurality of internal electrode layers includes an opposing portion opposed to an adjacent internal electrode layer of the plurality of internal electrode layers in the thickness direction, and a lead-out portion connected to the opposing portion and extending to the first end surface or the second end surface. A width of the opposing portion is larger than a width of the lead-out portion in the width direction. A relationship of C1>C2 is satisfied when a continuity of an end portion of the opposing portion in the width direction is defined as C1 and a continuity of an end portion of the lead-out portion in the width direction is defined as C2.
In a multilayer ceramic capacitor according to an example embodiment of the present invention, a relationship of T1>T2 may be satisfied when a thickness of the end portion of the opposing portion in the width direction is defined as T1 and a thickness of the end portion of the lead-out portion in the width direction is defined as T2.
In a multilayer ceramic capacitor according to an example embodiment of the present invention, a relationship of D1>D2 may be satisfied when a deviation amount in the width direction between the lead-out portion located closest to the first side surface and the lead-out portion located closest to the second side surface among the plurality of lead-out portions is defined as D1 and a deviation amount in the width direction between the opposing portion located closest to the first side surface and the opposing portion located closest to the second side surface among the plurality of opposing portions is defined as D2.
In a multilayer capacitor according to an example embodiment of the present invention, the element body portion may include a first outer layer portion and a second outer layer portion on both sides in the thickness direction. A first cross section of the element body portion parallel or substantially parallel to the thickness direction and the width direction may include four first corner portions which are rounded at a central portion of the element body portion in the length direction. When a curvature radius of each of the four first corner portions is defined as r1, r1 may be smaller than each of thicknesses of the first outer layer portion and the second outer layer portion in the thickness direction in the first cross section.
In a multilayer ceramic capacitor according to an example embodiment of the present invention, a second cross section of the element body portion parallel or substantially parallel to the thickness direction and the width direction in a portion where the lead-out portions overlap in the thickness direction may include four second corner portions which are rounded. When a curvature radius of each of the four second corner portions is defined as r2, r2 may be larger than r1. In the second cross section, r2 may be larger than each of the thicknesses of the first outer layer portion and the second outer layer portion in the thickness direction.
The above and other elements, features, steps, characteristics and advantages of the present invention will become more apparent from the following detailed description of the example embodiments with reference to the attached drawings.
Hereinafter, example the present embodiments of disclosure will be described in detail with reference to the drawings. In the example embodiments described below, the same or common portions are denoted by the same reference signs in the drawings, and description thereof will not be repeated. In the drawings, L, W, and T denote the length direction, width direction, and thickness direction of an element body portion to be described later, respectively.
As shown in
Element body portion 110 has a rectangular or substantially rectangular parallelepiped shape. Element body portion 110 includes a first principal surface 111 and a second principal surface 112 opposed to each other in a thickness direction T, a first side surface 113 and a second side surface 114 opposed to each other in a width direction W intersecting thickness direction T, and a first end surface 115 and a second end surface 116 opposed to each other in a length direction L intersecting thickness direction T and width direction W.
It is preferable that element body portion 110 includes rounded corner portions and ridge portions. Here, each corner portion is a portion where three surfaces of element body portion 110 intersect, and each ridge portion is a portion where two surfaces of element body portion 110 intersect.
First external electrode 120 is provided on first end surface 115. Specifically, first external electrode 120 is provided on the entire or substantially the entire first end surface 115, and extends from first end surface 115 to first principal surface 111, second principal surface 112, first side surface 113, and second side surface 114.
Second external electrode 130 is provided on second end surface 116. Specifically, second external electrode 130 is provided on the entire or substantially the entire second end surface 116, and extends from second end surface 116 to first principal surface 111, second principal surface 112, first side surface 113, and second side surface 114.
The detailed configurations of first external electrode 120 and second external electrode 130 will be described later with reference to
Element body portion 110 includes a multilayer body 101, a first side margin portion S1, and a second side margin portion S2.
Multilayer body 101 includes a pair of principal surfaces 101a and 101b opposed to each other in thickness direction T, a pair of side surfaces 101c and 101d opposed to each other in the width direction, and a pair of end surfaces 101e and 101f opposed to each other in the length direction. The pair of principal surfaces 101a and 101b define a portion of first principal surface 111 and second principal surface 112 of element body portion 110 described above. Side surface 101c is covered with first side margin portion S1, and side surface 101d is covered with second side margin portion S2. The pair of end surfaces 101e and 101f define a portion of first end surface 115 and second end surface 116 of element body portion 110 described above.
Multilayer body 101 includes a plurality of dielectric layers 140 and a plurality of internal electrode layers 150 alternately laminated in thickness direction T.
The plurality of internal electrode layers 150 includes a plurality of first internal electrode layers 151 and a plurality of second internal electrode layers 152. The plurality of first internal electrode layers 151 and the plurality of second internal electrode layers 152 are alternately laminated in thickness direction T.
The plurality of first internal electrode layers 151 extend to first end surface 115. The plurality of first internal electrode layers 151 are connected to first external electrode 120. The plurality of second internal electrode layers 152 extend to second end surface 116. The plurality of second internal electrode layers 152 are connected to second external electrode 130. Both end portions of the plurality of first internal electrode layers 151 and the plurality of second internal electrode layers 152 in width direction W are exposed at side surfaces 101c and 101d.
Although
Each of the plurality of dielectric layers 140 is made of, for example, a dielectric ceramic material including, as a primary component, a perovskite compound containing Ba and Ti. Dielectric layer 140 may include, for example, Si, Mg, Mn, V, Cr, and rare earth elements as additives.
Each of first internal electrode layer 151 and second internal electrode layer 152 includes Ni, for example. Each of first internal electrode layer 151 and second internal electrode layer 152 may further include dielectric particles of the same composition system as the ceramic included in dielectric layer 140. Each of first internal electrode layer 151 and second internal electrode layer 152 may include, for example, Sn at the interface with dielectric layer 140.
Multilayer body 101 is divided into an inner layer portion C, a first outer layer portion X1 and a second outer layer portion X2, and a first end margin portion E1 and a second end margin portion E2. Inner layer portion C has an electrostatic capacitance due to a first opposing portion 151C, which will be described later, of first internal electrode layer 151 and a second opposing portion 152C, which will be described later, of second internal electrode layer 152 being laminated in thickness direction T.
First outer layer portion X1 and second outer layer portion X2 are located on both sides of multilayer body 101 in the thickness direction. First outer layer portion X1 and second outer layer portion X2 sandwich inner layer portion C in thickness direction T. First outer layer portion X1 is located outside inner layer portion C in thickness direction T and is located on first principal surface 111 side. Second outer layer portion X2 is located outside inner layer portion C in thickness direction T and is located on second principal surface 112 side.
First outer layer portion X1 and second outer layer portion X2 are made of a dielectric ceramic material including, for example, as a primary component, a perovskite compound containing Ba and Ti. First outer layer portion X1 and second outer layer portion X2 may be made of the same dielectric ceramic material as the plurality of dielectric layers 140, or may be made of a dielectric ceramic material different from the plurality of dielectric layers 140.
First end margin portion E1 and second end margin portion E2 sandwich inner layer portion C in length direction L. First end margin portion E1 is located outside inner layer portion C in length direction L and is located on first end surface 115 side. Second end margin portion E2 is located outside inner layer portion C in length direction L and is located on second end surface 116 side.
First side margin portion S1 is provided on side surface 101c of the multilayer body. First side margin portion S1 is provided to cover the entire or substantially the entire side surface 101c. In element body portion 110, first side margin portion S1 extends from one end of internal electrode layer 150 located on one side in width direction W to first side surface 113.
Second side margin portion S2 is provided on side surface 101d of the multilayer body. Second side margin portion S2 is provided to cover the entire or substantially the entire side surface 101d. In element body portion 110, second side margin portion S2 extends from the other end of internal electrode layer 150 located on the other side in width direction W to second side surface 114.
First side margin portion S1 and second side margin portion S2 are each made of a dielectric ceramic material including, for example, as a primary component, a perovskite compound containing Ba and Ti. First side margin portion S1 and second side margin portion S2 may be made of the same dielectric ceramic material as the plurality of dielectric layers 140, or may be made of a dielectric ceramic material different from the plurality of dielectric layers 140.
First side margin portion S1 and second side margin portion S2 may be, for example, a dielectric manufactured by a solid-phase method. In this case, no pores are present in the grains (granular materials) included in first side margin portion S1 and second side margin portion S2.
First side margin portion S1 and second side margin portion S2 may include, for example, Si and/or Mg. First side margin portion S1 and second side margin portion S2 may include, for example, Mn.
Si is segregated in first side margin portion S1 and second side margin portion S2. The segregation of Si can be confirmed by, for example, observing a cross section by SEM/EDX. Mn can be confirmed by observing Ti, Ba, or the like, which is the primary component, with an EPMA or the like, for example.
First side margin portion S1 and second side margin portion S2 may include a plurality of layers. The plurality of layers does not particularly require the interfaces among the layers to be observed. For example, the grain size of the grains may be different on the side surface side and internal electrode layer 150 side, that is, the plurality of layers may include grains having different grain sizes in the width direction. The grain size of the grains can be measured using, for example, an electron microscope such as a TEM. For example, the area of each grain in the visual field is measured in a range of about 10 μm×about 10 μm, respectively. A circle equivalent diameter of each grain is calculated by area conversion, and an average value of circle equivalent diameter is defined as the grain size.
As described above, the size of multilayer ceramic capacitor 100 including element body portion 110, first external electrode 120, and second external electrode 130 is not particularly limited, for example, the following range can be used.
Multilayer ceramic capacitor 100 has a dimension (length dimension L0) which is greater than or equal to about 0.2 mm and less than or equal to about 4.5 mm in length direction L, for example. Multilayer ceramic capacitor 100 has a dimension (width dimension W0) which is greater than or equal to about 0.125 mm and less than or equal to about 3.2 mm in width direction W, for example. Multilayer ceramic capacitor 100 has a dimension (thickness dimension TO) which is greater than or equal to about 0.125 mm and less than or equal to about 2.5 mm in thickness direction T.
Multilayer ceramic capacitor 100 has, for example, a size with length dimension L0 of about 0.2 mm, width dimension W0 of about 0.125 mm, and thickness dimension T0 of about 0.125 mm, a size with length dimension L0 of about 0.4 mm, width dimension W0 of about 0.2 mm, and thickness dimension T0 of about 0.2 mm, a size with length dimension L0 of about 0.6 mm, width dimension W0 of about 0.3 mm, and thickness dimension TO of about 0.3 mm, a size with length dimension L0 of about 1.0 mm, width dimension W0 of about 0.5 mm, and thickness dimension TO of about 0.5 mm, a size with length dimension L0 of about 3.2 mm, width dimension W0 of about 1.6 mm, and thickness dimension TO of about 1.6 mm, or a size with length dimension L0 of about 4.5 mm, width dimension W0 of about 3.2 mm, and thickness dimension TO of about 2.5 mm. A tolerance is added to each of the sizes described above.
As shown in
As shown in
First lead-out portion 151X and second lead-out portion 152X may be simply referred to as lead-out portions when they are not particularly distinguished from each other, and first opposing portion 151C and second opposing portion 152C may be simply referred to as opposing portions when they are not particularly distinguished from each other. Similarly, when first internal electrode layer 151 and second internal electrode layer 152 are not particularly distinguished from each other, they may be simply referred to as internal electrode layers. Thus, when first internal electrode layer 151, second internal electrode layer 152, and the like are not distinguished, each of the plurality of internal electrode layers can be said to include an opposing portion opposing an adjacent internal electrode layer and a lead-out portion connected to the opposing portion and led out to first end surface 115 or second end surface 116 in the thickness direction. In addition, when first external electrode 120 and second external electrode 130 are not particularly distinguished, first external electrode 120 and second external electrode 130 may be simply referred to as external electrodes.
In element body portion 110, both within the portion sandwiched in thickness direction T by first external electrode 120 provided on first principal surface 111 and second principal surface 112, and within the portion sandwiched in thickness direction T by second external electrode 130 provided on first principal surface 111 and second principal surface 112, a portion of the plurality of internal electrode layers 150 has a shape bulging toward one of the principal surfaces, either first principal surface 111 or second principal surface 112.
Specifically, for example, on first end surface 115 side, the lead-out portion side of internal electrode layer 150 arranged closest to first principal surface 111 bulges toward first principal surface 111.
On second end surface 116 side, the lead-out portion side of internal electrode layer 150, which is arranged on second principal surface 112 side by one layer from internal electrode layer 150 arranged closest to first principal surface 111, bulges toward first principal surface 111. On the other hand, internal electrode layer 150 located closest to second principal surface 112 has a flat shape.
Internal electrode layers 150 that bulge toward first principal surface 111 are not limited to internal electrode layer 150 arranged closest to first principal surface 111 and internal electrode layer 150 adjacent thereto. For example, internal electrode layers 150 from internal electrode layer 150 located closest to first principal surface 111 to the third internal electrode layer on second principal surface 112 side may be curved. For example, about 20% or less of internal electrode layers 150 from internal electrode layer 150 arranged closest to first principal surface 111 among all of the plurality of internal electrode layers 150 may bulge toward first principal surface 111.
In element body portion 110 within the portion sandwiched in thickness direction T by first external electrode 120 provided on first principal surface 111 and second principal surface 112, the portion of internal electrode layer 150 bulging toward first principal surface 111 is not limited to the lead-out portion, and may include the opposing portion of the portion located on the lead-out portion side.
Further, a portion of internal electrode layer 150 where the lead-out portion is not provided on first end surface 115 side may bulge toward first principal surface 111. In this case, the end portion side of internal electrode layer 150, which is located on the side opposite to the side where the lead-out portion is located, bulges.
The same applies to the portion of element body portion 110 sandwiched in thickness direction T by second external electrode 130 provided on first principal surface 111 and second principal surface 112.
A portion of the plurality of internal electrode layers 150 is curved toward first principal surface 111, and thus the contact area between inner layer portion C and first outer layer portion X1 can be increased. This can reduce or prevent delamination between the inner layer portion C and the first outer layer portion X1.
First end surface 115 and second end surface 116 each have a shape that is recessed inward in length direction L toward the central portion in thickness direction T. This can increase the contact area between first end surface 115 and first external electrode 120, as well as the contact area between second end surface 116 and second external electrode 130. As a result, the connection efficiency between internal electrode layer 150 and first external electrode 120 or second external electrode 130 can be increased.
When Lgap denotes the region to first end surface 115 of element body portion 110 in which internal electrode layers 150 adjacent to each other do not overlap in thickness direction T on first end surface 115 side (region outside the region where internal electrode layers 150 adjacent to each other overlap in thickness direction T), the length of Lgap in length direction L increases from first principal surface 111 toward second principal surface 112. At least the Lgap from internal electrode layer 150 arranged closest to second principal surface 112 to first end surface 115 is longer than the Lgap from internal electrode layer 150 arranged closest to first principal surface 111 to first end surface 115.
Specifically, for example, the length of Lgap from internal electrode layer 150, which is located in the fourth layer from first principal surface 111 side, to first end surface 115 is longer than the length of Lgap from internal electrode layer 150, which is located in the second layer from first principal surface 111 side, to first end surface 115.
By increasing the length of Lgap in this way, even if the Lgap of element body portion 110 is cracked, multilayer ceramic capacitor 100 can be prevented from being short circuited.
The relationship between the shape and the length described with reference to
As shown in
The widths of the plurality of first lead-out portions 151X in width direction W may decrease toward one side in thickness direction T. Specifically, the widths of the plurality of first lead-out portions 151X may decrease from second principal surface 112 side toward first principal surface 111 side. The same applies to the plurality of second lead-out portions 152X.
When Sgm denotes the shortest distance from the end portions of the plurality of first lead-out portions 151X to first side surface 113 or second side surface 114 in the width direction, Sgm is, for example, greater than or equal to about 90 μm and less than or equal to about 110 μm. The numerical value of Sgm is not limited to the above.
The relationship between the shape and the length described with reference to
As shown in
At least one of internal electrode layers 150, which are, for example, about 20% or less of the plurality of internal electrode layers 150 from a side closest to second principal surface 112 toward the central portion side in the thickness direction, protrudes outward in width direction W from internal electrode layer 150 located at the central portion in the thickness direction.
Thus, internal electrode layers 150 protruding in the width direction are provided on first principal surface 111 side and second principal surface 112 side, and thus, side surfaces 101c and 101d of multilayer body 101 each have an irregular shape. This can increase the contact area between side surface 101c and first side margin portion S1, and the contact area between side surface 101d and second side margin portion S2. This can reduce or prevent first side margin portion S1 and second side margin portion S2 from peeling off from multilayer body 101.
In a cross section of element body portion 110 parallel or substantially parallel to thickness direction T and width direction W at the central portion of element body portion 110 in length direction L, the deviation amount in width direction W between internal electrode layers 150 adjacent to each other in thickness direction T is, for example, smaller than about 3 μm.
When Sgc denotes the shortest distance from the end portions of the plurality of internal electrode layers 150 (more specifically, the opposing portion) to first side surface 113 or second side surface 114 in the width direction, Sgc is, for example, greater than or equal to about 10 μm and less than or equal to about 20 μm. The numerical value of Sgc is not limited to the above.
It is preferable that, for example, the Sgm is greater than or equal to about 5 times the Sgc. Thus, the moisture reliability of multilayer ceramic capacitor 100 can be improved.
In a cross section of element body portion 110 parallel or substantially parallel to thickness direction T and width direction W at the central portion of element body portion 110 in length direction L, each of first side surface 113 and second side surface 114 has a shape that is recessed inward in width direction W toward the central portion in thickness direction T.
The relationship between the shape and the length described with reference to
As shown in
As will be described later, the thick portion is provided in a region where a ceramic paste to eliminate bumps is arranged on a conductive paste to be internal electrode layer 150 in a manufacturing process.
Element body portion 110 is provided in a manner that the thickness gradually increases from a position about length W6 inward in length direction L from the end portion of inner layer portion C in length direction L and the thickness gradually decreases from a position where the thickness is the highest to the end surface. Length W6 is, for example, about 5 μm or less.
By providing the thick portion as described above, as indicated by an arrow AR1, the range covered by first external electrode 120 or second external electrode 130 from first principal surface 111 side to the end portion of the lead-out portion arranged at the position closest to first principal surface 111 is longer than in a configuration without the thick portion. This makes it difficult for moisture that enters from the tip end side of first external electrode 120 or second external electrode 130 located on first principal surface 111 to reach the end portion of the lead-out portion. As a result, the moisture resistance reliability of multilayer ceramic capacitor 100 can be improved.
As shown in
A deviation amount D1 in width direction W between first lead-out portion 151X located closest to first side surface 113 and first lead-out portion 151X located closest to second side surface 114 among the plurality of first lead-out portions 151X is, for example, greater than or equal to 3 μm. The deviation amount between first lead-out portions 151X adjacent to each other in the width direction is about 3 μm or more. The deviation amounts of the plurality of second lead-out portions 152X are the same or substantially the same as those of first lead-out portions 151X.
As described above, the deviation amount between the lead-out portions adjacent to each other in the thickness direction is, for example, about 3 μm or more, and thus, when moisture, which has entered the interface between first external electrode 120 or second external electrode 130 and first principal surface 111 from the tip end sides of first external electrode 120 and second external electrode 130, is about to reach a lead-out portion different from the lead-out portion located closest to the first principal surface, the path length from the tip end to the different lead-out portion is increased. This also makes it difficult for moisture to reach the lead-out portions, and thus, the moisture resistance reliability of multilayer ceramic capacitor 100 can be improved.
For example, Si or Mg is segregated in both end portions 151t1 and 151t2 of each of the plurality of first lead-out portions 151X in width direction W.
The end portions of the plurality of first lead-out portions 151X in the width direction are not aligned in thickness direction T, and are deviated in width direction W. In this case, a portion of internal electrode layers 150 adjacent to each other in the thickness direction may come close to one of end portions 151t1 and 151t2 of the plurality of first lead-out portions 151X in the width direction. Si or Mg is segregated in both end portions 151t1 and 151t2, and thus, the insulation properties of both end portions 151t1 and 151t2 are improved, and short-circuiting between internal electrode layers 150 adjacent to each other in the thickness direction can be reduced or prevented. As a result, the reliability of multilayer ceramic capacitor 100 can be improved.
Si or Mg is segregated also at the end portion in the width direction of each of the plurality of second lead-out portions 152x, and the same advantageous effect as described above is obtained.
In each of the plurality of first lead-out portions 151X and the plurality of second lead-out portions 152X, for example, Si or Mg is segregated on the principal surface on one side in thickness direction. The principal surface on one side in the thickness direction is a principal surface on the side where the ceramic paste to eliminate bumps is arranged in the manufacturing process of multilayer ceramic capacitor 100 to be described later. Thus, Si or Mg is segregated on the principal surface on the one side in the thickness direction of the lead-out portion, such that insulation properties with respect to adjacent internal electrode layers 150 can be ensured. Thus, the reliability of multilayer ceramic capacitor 100 can be improved.
A segregation amount of Si or Mg at an end portion of each of the plurality of lead-out portions in the width direction is larger than a segregation amount of Si or Mg on a principal surface on one side of the lead-out portion in the thickness direction. Thus, the reliability of multilayer ceramic capacitor 100 can be further improved.
Each of the plurality of internal electrode layers 150 has a non-connection end portion 150U (see
As shown in
A deviation amount D2 in width direction W between the opposing portion located closest to first side surface 113 and the opposing portion located closest to second side surface 114 among the plurality of opposing portions (more specifically, a plurality of first opposing portions 151C and a plurality of second opposing portions 152C) is, for example, smaller than about 3 μm. The deviation amount D2 is smaller than the deviation amount D1 described above, and satisfies the relation of D1>D2. By making the deviation amount on the lead-out portion side larger than the deviation amount on the opposing portion side, dielectric layers 140 are laminated in a complex manner on the lead-out portion side, and therefore, in the manufacturing process to be described later, interlayer peeling can be reduced or prevented at the cut surface when cutting the structure into multilayer chips. The deviation amount between the opposing portions adjacent to each other in the width direction is also, for example, smaller than about 3 μm.
When T1 denotes the thickness of the end portion of the opposing portion in width direction W and T2 denotes the thickness of the end portion of the lead-out portion in the width direction (see
As shown in
The continuity of the end portions of first lead-out portions 151X and the continuity of the end portions of first opposing portions 151C can be measured as follows. First, first external electrode 120 is polished in a manner that first lead-out portions 151X are exposed in the cross section of multilayer ceramic capacitor 100 which is parallel or substantially parallel to the width direction and the thickness direction. Some of first lead-out portions 151X located on the central portion side in thickness direction T are selected from the plurality of first lead-out portions 151X as first lead-out portions 151X to be measured.
At the end portion of selected first lead-out portion 151X, a range from the outermost position to a region inward by W10 in width direction W is confirmed by SEM/EDX, and widths W11 and W12 of a region where Ni is not detected are measured. For each of the selected plurality of first lead-out portions 151X, a value obtained by (W10−(W11+W12))/W10 (that is, a value obtained by subtracting the sum of the widths of the regions where Ni is not detected from the width of the measurement range and dividing the value after subtraction by the width of the measurement range) is calculated, and the average value of about 10 above values excluding abnormal values is used to indicate continuity.
W10 may be, for example, about 20 μm, and may be appropriately set in accordance with the size of multilayer ceramic capacitor 100.
The continuity of first opposing portions 151C, the continuity of second lead-out portions 152X, and the continuity of second opposing portions 152C can also be calculated in the same or substantially the same manner as described above.
As shown in
Specifically, first region R1 is a portion from the end portion of first lead-out portion 151X in the width direction located on second side surface 114 side to second side margin portion S2. Second region R2 and third region R3 define second side margin portion S2.
A width of first region R1 in width direction W is larger than a width of second region R2 in width direction W. The width of second region R2 in width direction W is larger than a width of third region R3 in width direction W.
Specifically, for example, first region R1 has a width that is greater than or equal to about 50 μm. Second region R2 has a width that is less than or equal to about 10 μm. Third region R3 has a width that is less than or equal to about 3 μm. These widths are measured at the central portion in the thickness direction of the cross section of element body portion 110, which is parallel to width direction W and thickness direction T, from which first lead-out portion 151X is exposed.
Here, the amount of Mn is larger in second side margin portion S2 than in dielectric layer 140 of multilayer body 101 (more specifically, dielectric layer 140 of inner layer portion C). Accordingly, the grain size of second side margin portion S2 is smaller than the grain size of dielectric layer 140.
Specifically, when gr1 denotes the grain size of first region R1, gr2 denotes the grain size of second region R2, and gr3 denotes the grain size of third region R3, a relation of gr1>gr2>gr3 is satisfied. The grain size is the above-described circle equivalent diameter.
As described above, when dielectric layer 140 and the side margin portions are produced using the solid-phase method, no pores are present in the grains, and voids are formed between the grains. The holes formed in the grains are defined as pores, and the gaps formed between the grains are defined as voids. The voids between the grains refer to, for example, a state such as a triple point.
The quantity of the voids included in second region R2 and third region R3 is smaller than the quantity of the voids included in first region R1.
On the other hand, when the plurality of dielectric layers 140 is produced, for example, using a hydro-thermal synthesis method, the grain size of dielectric layers 140 (more specifically, dielectric layers 140 of inner layer portion C) of multilayer body 101 is smaller than the grain size of second side margin portion S2. In this case, pores may be provided in the grains of dielectric layers 140.
In the above description, the pores or voids can be observed using an electron microscope such as SEM or TEM.
As shown in
Cu layer 121 includes a first layer portion 125 connected to the plurality of first lead-out portions 151X or the plurality of second lead-out portions 152X, and a second layer portion 126 covering first layer portion 125.
First layer portion 125 is a Cu-rich layer, and has a higher Cu content than second layer portion 126. First layer portion 125 extends in thickness direction T on first end surface 115 or second end surface 116. Second layer portion 126 is a glass-rich layer, and has a higher glass content than first layer portion 125.
First layer portion 125 has high continuity in thickness direction T. In a cross section of multilayer ceramic capacitor 100 that passes through the central portion in the width direction and is parallel or substantially parallel to the thickness direction and the length direction, first layer portion 125 extends in thickness direction T bridging between the lead-out portions adjacent to each other in thickness direction T. In the above description, high continuity means a state in which Cu is in contact with the exposed portion of the end surface of the internal electrode layer and these are continuously connected in the thickness direction in a layer configuration. First layer portion 125 ensures the connectivity with internal electrode layer 150. Cu contained in first layer portion 125 can be made continuous by making Cu powder in Cu paste used for the Cu layer minute and appropriately adjusting sintering conditions.
First layer portion 125 of first external electrode 120 is connected to the plurality of first lead-out portions 151X. First layer portion 125 of first external electrode 120 is a layer in which Cu is continuous so as to connect first lead-out portions 151X which are adjacent to each other.
In the cross section of multilayer ceramic capacitor 100 that passes through the central portion in the width direction and is parallel or substantially parallel to the thickness direction and the length direction, first layer portion 125 of first external electrode 120 extends in thickness direction T so as to connect, for example, about 80% or more of the plurality of first lead-out portions 151X.
First layer portion 125 of second external electrode 130 is connected to the plurality of second lead-out portions 152x. First layer portion 125 of second external electrode 130 is a layer in which Cu is continuous so as to connect second lead-out portions 152X which are adjacent to each other.
In the cross section of multilayer ceramic capacitor 100 that passes through the central portion in the width direction and is parallel or substantially parallel to the thickness direction and the length direction, first layer portion 125 of second external electrode 130 extends in thickness direction T so as to connect, for example, 80% or more of the plurality of second lead-out portions 152X.
Ni is diffused in first layer portion 125. The plurality of internal electrode layers 150 include Ni as described above, and Ni is diffused from first lead-out portion 151X and second lead-out portion 152X into first layer portion 125. In first layer portion 125, the concentration of Ni increases toward element body portion 110. By diffusing Ni in this way, even when the widths of first lead-out portion 151X and second lead-out portion 152X are small, the connectivity between first lead-out portion 151X or second lead-out portion 152X and first layer portion 125 can be improved.
In the cross section of multilayer ceramic capacitor 100 that passes through the central portion in width direction W and is parallel or substantially parallel to thickness direction T and length direction L, the thickness of first layer portion 125 in length direction L at the central portion in thickness direction T is, for example, about 25% or less of the total thickness of Cu layer 121 in length direction L at the central portion in thickness direction T. It is preferable that the thickness of first layer portion 125 is, for example, about 5% or less of the total thickness of Cu layer 121.
First layer portion 125 can be observed using SEM/EDX. The degree of diffusion of Ni in first layer portion 125 can be detected by composition analysis such as WDX or EDX in the cross section.
Second layer portion 126 includes Cu and glass. Glass occupies, for example, about 10% or more of the cross-sectional area of second layer portion 126 in the cross section of multilayer ceramic capacitor 100 that passes through the central portion in the width direction and is parallel or substantially parallel to the thickness direction and the length direction. More specifically, for example, in the cross section, glass may occupy about 25% or more of the cross-sectional area of second layer portion 126. By including Cu in second layer portion 126, hydrogen is easily adsorbed, and reliability is improved.
In the cross section of multilayer ceramic capacitor 100 that passes through the central portion in width direction W and is parallel or substantially parallel to thickness direction T and length direction L, the thickness of second layer portion 126 in length direction L is, for example, about 75% or more of the thickness of Cu layer 121 in the length direction at a portion where the thickness of first external electrode 120 in length direction L is the greatest. Thus, hydrogen can be sufficiently adsorbed by second layer portion 126. The thickness and the like of second layer portion 126 can be measured using an SEM or the like.
In manufacturing multilayer ceramic capacitor 100, a ceramic slurry including a ceramic powder, a binder, and a solvent is first prepared. The ceramic powder can be synthesized by a known method such as, for example, solid-phase method or hydro-thermal synthesis method.
The ceramic slurry is formed into a sheet shape on a carrier film using, for example, a die coater, a gravure coater, a micro-gravure coater, or the like, and thus, an inner layer ceramic green sheet 23 and an outer layer ceramic green sheet 26, which will be described later, are produced.
Next, as shown in
Conductive patterns 24 are printed on inner layer ceramic green sheet 23 by, for example, screen printing, ink jet printing, gravure printing, or the like.
Next, as shown in
In order to facilitate the alignment, ceramic paste 25 is applied in a manner of partially overlapping conductive patterns 24. It is preferable that in the arrangement direction in which the plurality of conductive patterns 24 is arranged, ceramic paste 25 applied to the outside of each conductive pattern 24 overlaps conductive patterns 24 in a range within 5 μm from the end portions of conductive patterns 24 in the arrangement direction.
Ceramic paste 25 is printed by, for example, screen printing, inkjet printing, gravure printing, or the like.
Ceramic paste 25 may be formed of the same material as the material of inner layer ceramic green sheet 23, or may include a different component. As described above, when Si or Mg is segregated on both end portions of the lead-out portion in the width direction and on the principal surface of the lead-out portion on one side in the thickness direction, Si and/or Mg is added to ceramic paste 25.
In the above description, the case where ceramic paste 25 is applied after conductive patterns 24 are applied is exemplified. However, conductive patterns 24 may be applied after ceramic paste 25 is applied.
As shown in
The plurality of inner layer ceramic green sheets 23 are laminated such that strip-shaped conductive patterns 24 are deviated in the arrangement direction by about half the printing pitch of conductive patterns 24 between adjacent inner layer ceramic green sheets 23. Specifically, the plurality of inner layer ceramic green sheets 23 are laminated in a manner that openings 24h of conductive patterns 24 provided on inner layer ceramic green sheets 23 adjacent to each other in a lamination direction are alternately arranged in the arrangement direction when viewed in the lamination direction. The lamination direction is parallel or substantially parallel to thickness direction T, and the arrangement direction is parallel or substantially parallel to length direction L.
The plurality of outer layer ceramic green sheets 26 are laminated on both sides of the laminated plurality of inner layer ceramic green sheets 23 in the lamination direction.
Next, the laminated plurality of inner layer ceramic green sheets 23 and the laminated plurality of outer layer ceramic green sheets 26 are thermo-compression bonded to form a structure 200 (see
Then, as shown in
Ceramic paste 25 for eliminating bumps overlaps conductive pattern 24 in a region R6 and a region R7. Region R6 is a region where lead-out region 24X is formed and opposing region 24C of a portion located close to lead-out region 24X. Region R7 is a region on the end portion side of opposing region 24C, which is located on the side opposite to the side where lead-out region 24X is located.
Therefore, conductive pattern 24 defining and functioning as internal electrode layer 150 and ceramic paste 25, which defines a portion of dielectric layer 140, overlap in region R6 and region R7, and thus, a portion of multilayer body 101 bulges on both sides in length direction L as described above.
Furthermore, by adding Si and/or Mg to ceramic paste 25 for eliminating bumps, Si and/or Mg can be segregated in region R6 and region R7 of internal electrode layer 150.
Subsequently, a ceramic paste is applied to both end surfaces of multilayer chip 10 in the width direction.
Specifically, the ceramic paste is filled in a plurality of recesses (grooves) provided on an application surface of a plate, and the end surface of multilayer chip 10 in the width direction is brought into contact with the application surface. Thus, the ceramic paste can be applied only to the end surface by capillary action. The applied ceramic paste is sintered to form first side margin portion S1 and second side margin portion S2.
The ceramic paste may be formed of the same material as the material of inner layer ceramic green sheet 23, or may include a different component. First side margin portion S1 and second side margin portion S2 can be densified by making the ceramic paste include more Mn than inner layer ceramic green sheet 23. The ceramic powder included in the ceramic paste is synthesized by, for example, the solid-phase method.
Subsequently, multilayer chip 10 on which the ceramic paste is applied is sintered to form element body portion 110.
As shown in
In region R6, Si and/or Mg is segregated on the principal surface on one side of first lead-out portion 151X in the thickness direction and on the principal surface on one side of first opposing portion 151C of a portion located on first lead-out portion 151X side. In particular, the segregation amount of Si or Mg in the regions on both end sides in width direction W of the outer periphery of region R6 is larger than that in an inner region R8 of region R6.
In region R7, Si and/or Mg is segregated on the principal surface on one side of first opposing portion 151C on the end portion side located on the side opposite to the side located on first lead-out portion 151X side in length direction L. In particular, in a portion of the outer periphery of region R7 along first side margin portion S1, second side margin portion S2, and dielectric layer 140, the segregation amount of Si or Mg is larger than that in an inner region R9 of region R7. That is, in the internal electrode layer, the segregation amount of Si or Mg is increased in non-connection end portion 150U which is located on the side opposite to the side where the lead-out portion is located in length direction L and is not connected to the external electrodes.
On second internal electrode layer 152 side, Si and/or Mg is segregated as in first internal electrode layer 151.
Subsequently, first external electrode 120 and second external electrode 130 are formed on both end surfaces (first end surface 115 and second end surface 116) of element body portion 110, respectively. Specifically, a Cu paste including, for example, micronized Cu particles is applied to both end surfaces of element body portion 110. As the application method, for example, a method of forming a paste layer defining the first layer portion on a plate and immersing the end surfaces in the paste layer can be employed. The applied paste layer is baked, and plating is performed in the order of Cu plating, Ni plating, and Sn plating.
Through the above steps, multilayer ceramic capacitor 100 according to the above-described example embodiment can be manufactured.
While example embodiments of the present invention have been described above, it is to be understood that variations and modifications will be apparent to those skilled in the art without departing from the scope and spirit of the present invention. The scope of the present invention, therefore, is to be determined solely by the following claims.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2023-109261 | Jul 2023 | JP | national |
