JP2012023322A - Chip type laminated ceramic capacitor and method for manufacturing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a chip type laminated ceramic capacitor capable of improving a mounting efficiency when leg-shaped external terminals are attached thereto, and suppressing vibration sound of a circuit board when mounted on the board.SOLUTION: A method for manufacturing a chip type laminated ceramic capacitor is provided. In the method, when leg-shaped external terminals 14a and 14b are attached to external electrodes 12a and 12b at both ends of the chip type laminated ceramic capacitor 10, first metal plating layers 13a and 13b having a melting point of 400°C or more are formed on external electrodes, respectively, and the external terminals, each having a nealy U-shaped front shape in which the center of an upper end is cut away, and having a L-shaped side surface formed by bending its lower end at a nealy right angle, are fixed to the external electrodes with spot welding via the first metal plating layers, respectively, and second metal plating layers 16a and 16b are formed on the lower ends 15d of the external terminals, respectively. Accordingly, when the external terminals are soldered on lands of a circuit board, this improves solder wettability and prevents the external terminals from removing due to heating at the time of soldering.

Description

  The present invention relates to a chip-type multilayer ceramic capacitor in which leg-shaped external terminals are fixed to external electrodes, and a method for manufacturing the same.

  Conventionally, as shown in FIG. 17, a chip-type multilayer ceramic capacitor 3 in which a leg-like external terminal 1 is fixed to an external electrode 2 is known (Japanese Patent Laid-Open No. 2008-130954, FIG. 6). That is, the same applies to the chip-type multilayer ceramic body 5 in which a plurality of layers of internal electrodes (not shown) are alternately stacked near the both ends 4a and 4b with a predetermined interval inside the chip-type ceramic body 4. A chip-type multilayer ceramic capacitor 3 having a structure that can be mounted on a land of an electronic circuit board (not shown) via leg-like external terminals 1 extending downward from external electrodes 2 existing at both ends 4a and 4b is known. It is.

  According to this known technique, as the external terminal 1, the center of the upper end portion 1a is cut out, the front shape is substantially U-shaped, and the lower end portion 1b is bent at a substantially right angle so that the side surface is L-shaped. A metal plate is used. The external electrode 1 and the external electrode 2 are fixed by soldering.

    JP 2008-130954 A

  Since the external terminal 1 according to this known example is manufactured through a specific process, the chip-type multilayer ceramic capacitor 3 itself becomes an electronic circuit board such as a DC-DC converter due to the vibration absorption effect of the external terminal 1 with respect to the external electrode 2. When mounted, the dielectric ceramic vibrates due to the electrostrictive effect, thereby exhibiting the effect of suppressing so-called “substrate squealing” generated by propagating the vibration to the electronic circuit board.

  However, the efficiency of attaching to the external terminal 2 with respect to the external electrode 1 can be further improved, and the component can be prevented from falling off due to the remelting of the solder between the connection portion of the external terminal and the chip-type multilayer ceramic capacitor due to heating during soldering mounting on the circuit board There is a limit to the known technology. Accordingly, an object of the present invention is to improve the efficiency of attachment to an external terminal with respect to an external electrode in the process of manufacturing a chip-type multilayer ceramic capacitor in which leg-shaped external terminals are fixed to the external electrode, and to obtain the obtained chip-type multilayer ceramic When soldering and mounting a capacitor to a circuit board, it is intended to prevent the external terminal from being detached by heating and further suppress board noise.

  In order to solve the above-described problems, the present invention provides a chip-type laminated structure that can be mounted on an electronic circuit board via leg-shaped external terminals extending downward from external electrodes present at opposite ends. In the ceramic capacitor, as the external terminal, a band-shaped metal plate is used in which the center of the upper end is notched and the front shape is substantially U-shaped, the lower end is bent at a substantially right angle, and the side surface is L-shaped. The external terminal is fixed to the external electrode by forming a first metal plating layer having a melting point of 400 ° C. or higher on at least the end surface of the external electrode and spot welding the upper end of the external terminal to the metal layer. In addition, a second metal plating layer made of a single metal selected from one of Sn, Ag, Au, Bi, and Zn or a metal alloy selected from a plurality of types is formed on the lower end of the external terminal. To flop type multilayer ceramic capacitor.

  In the chip-type multilayer ceramic capacitor of the present invention, since the first metal plating layer is formed with a predetermined thickness on the end face of the external electrode, spot welding of the external terminal to the external electrode becomes possible. Mounting efficiency is improved on the external terminal with respect to the electrode. Further, since the second metal plating layer having a predetermined height is formed on the lower end portion of the external terminal, the chip type multilayer ceramic capacitor is soldered and mounted on the land of the electronic circuit board via the external terminal. In this case, the height of the solder rising from the lower end of the external terminal can be suppressed to a predetermined height of the second metal plating layer, and as a result, vibration due to the electrostrictive effect of the dielectric ceramic propagates from the external terminal to the electronic circuit board. Can be suppressed to a minimum, and separation of the external terminal connection portion due to heating during the solder welding can be prevented.

  In order to solve the above problems, the present invention provides a chip-type multilayer ceramic body in which a plurality of layers of internal electrodes are alternately stacked and oriented closer to both ends at a predetermined interval inside the chip-type ceramic body. A step of forming an external electrode, a step of coating the end surface of the external electrode with a first metal plating layer having a melting point of 400 ° C. or higher, a center of the upper end portion is notched, and the front shape is substantially U-shaped, and the lower end A chip-type multilayer ceramic capacitor comprising a step of spot-welding and fixing a leg-shaped external terminal made of a strip-shaped metal plate whose side is bent at a substantially right angle and having an L-shaped side surface to the first metal plating layer Adopt manufacturing method.

  In this manufacturing method, the external terminal is a single step or a plurality of types selected from the following steps, that is, (1) Sn, Ag, Au, Bi, Zn on one edge side along the longitudinal direction of the strip-shaped metal plate. A plating metal plate manufacturing step for forming a second metal plating layer made of a metal alloy selected from: (2) punching the plating metal plate, and an upper end portion of the external terminal on the other edge side of the plating metal plate; A precursor manufacturing step of branching a plurality of precursors of external terminals having a lower end portion; and (3) a first metal of the chip-type multilayer ceramic body that is the upper end portion of the external terminal in the precursor. A precursor fixing step for fixing by spot welding to the plating layer; and (4) a plurality of legs by cutting off the precursor fixed to the chip-type multilayer ceramic body from the plated metal plate. Through and separating the external terminals are fabricated external terminal, as a result, be significantly more efficient manufacturing and fixing of the external terminals for the external electrodes.

  By adopting the above-mentioned means, the present invention can improve the efficiency of attaching to the external terminal with respect to the external electrode in the process of manufacturing the chip type multilayer ceramic capacitor in which the leg-shaped external terminal is fixed to the external electrode. When the obtained chip-type multilayer ceramic capacitor is solder-welded to the substrate, the external terminal connection portion can be prevented from being detached due to heating, and the excellent effect of enabling further suppression of substrate squealing is exhibited.

FIG. 1 is a perspective view of a chip type multilayer ceramic capacitor according to the present invention. FIG. 2 is a front view of the same. FIG. 3 is a front view showing another embodiment of the chip-type multilayer ceramic capacitor according to the present invention. FIG. 4 is a partially broken front view showing the manufacturing process of the chip type multilayer ceramic capacitor according to the present invention. FIG. 5 is a perspective view showing an external terminal according to the present invention. FIG. 6 is a perspective view of a band-shaped metal plate for manufacturing an external terminal. FIG. 7 is a perspective view showing a first processing step of the metal plate. FIG. 8 is a perspective view showing a second processing step of the metal plate. FIG. 9 is a perspective view showing a third processing step of the metal plate. FIG. 10 is a front view showing a first step of processing the plated metal plate according to the present invention into a precursor of an external terminal. FIG. 11 is a side view of the same. FIG. 12 is a front view showing the second step. FIG. 13 is a side view of the same. FIG. 14 is a side view showing a state in which the precursor is spot-welded to a chip-type multilayer ceramic capacitor. FIG. 15 is a front view of the same. FIG. 16 is a side view showing a state in which external terminals are cut out from the precursor. FIG. 17 is a perspective view of a known technique.

  Next, a mode for carrying out the present invention will be described. As shown in FIGS. 1 and 2, a chip-type multilayer ceramic capacitor (hereinafter referred to as “ceramic capacitor”) 10 according to the present invention is a known ceramic. A rectangular parallelepiped chip-type ceramic body 11 made of a dielectric, a plurality of layers of internal electrodes (not shown) that are alternately stacked near the both end portions 11a and 11b at a predetermined interval, and the both end portions The external electrodes 12a and 12b are formed on the 11a and 11b.

  Furthermore, the ceramic capacitor 10 according to the present invention has Ni, Fe—Ni, Fe—Ni—Co, Fe—Ni—Cr, Cu, Cu—Sn, at least the end surfaces of the external electrodes 12a and 12b, preferably exposed surfaces. The first metal plating layers 13a and 13b made of a melting point selected from Cu-Sn-P, Cu-Ni, Cu-Zn, and Cu-Zn-Ni, a metal having a temperature of 400 ° C or higher, preferably Ni, have a thickness of 2 to 20 µm, Preferably, it is formed by plating to a thickness of 5 to 15 μm. In addition, if the thickness is less than 2 μm, the strength of spot welding is reduced with respect to the external terminals described in detail below. Conversely, if the thickness exceeds 20 μm, the plating time is increased more than necessary and the cost is increased. .

  Further, leg-shaped external terminals 14a and 14b are fixed to both end faces of the external electrodes 12a and 12b of the ceramic capacitor 10 according to the present invention via the first metal plating layers 13a and 13b. The external terminals 14a and 14b are manufactured through a predetermined step, which will be described later, using a short belt-like metal plate, and the upper end portion 15u and the lower end portion 15d have a specific shape and structure. That is, the center of the upper end portion 15u is notched and the front shape is substantially U-shaped, and the lower end portion 15d is bent outward or inward substantially at a right angle so that the side surface is L-shaped. I am doing.

  In addition, at the lower end 15d of the two external terminals 14a and 14b, as will be described later, when soldering the ceramic capacitor according to the present invention to the land of the electronic circuit board, Sn, Second metal plating layers 16a and 16b made of a single metal selected from Ag, Au, Bi and Zn or a metal alloy selected from a plurality of types have a height H of 0.1 to 1.5 mm from the lower end surface, preferably Is coated in a range ranging from 0.2 to 1.0 mm. When the height H is more than 1.5 mm, the fillet height due to solder wetting increases, and the proportion of the vibration due to the electrostrictive effect of the dielectric ceramic propagates to the electronic circuit board increases, and the squeal suppression effect of the board is increased. descend. On the other hand, when the height H is less than 0.1, the solder fillet of the land of the electronic circuit board is hardly formed in the soldering, and as a result, the solder joint strength is lowered.

  In the description of the ceramic capacitor 10 described above, the case where the single ceramic capacitor 10 is attached to the pair of external terminals 14a and 14b has been described. However, the present invention, as shown in FIG. The present invention is also applied to a so-called stack type capacitor in which a plurality of ceramic capacitors 10 are attached to a pair of external terminals 14a and 14b.

  Next, a method for manufacturing the ceramic capacitor having the above structure will be described. The method includes the following steps.

  (First Step) First, based on a known technique, as shown in FIG. 4, a chip type in which a plurality of layers of internal electrodes are alternately stacked and oriented closer to both end portions 11a and 11b with a predetermined interval inside. A ceramic capacitor 10 made of a multilayer ceramic body 11 and having external electrodes 12a and 12b attached to both end portions 11a and 11b is produced.

  (Second Step) Next, a metal having a melting point of 400 ° C. or higher, preferably nickel, is used on at least end surfaces of the external electrodes 12a and 12b of the ceramic capacitor 10, preferably on the exposed surfaces of the external electrodes 12a and 12b. The metal plating layers 13a and 13b are covered.

(Third Step) Subsequently, as shown in FIG. 5, a leg-shaped external terminal 14 made of a strip-shaped metal plate is fixed to the external electrode 12 via a first metal plating layer 13 by spot welding. The external terminal 14 is cut out at the center of the upper end portion 15u and has a substantially U-shaped front surface, and the lower end portion 15d is bent at a substantially right angle to form an L-shaped side surface. In addition, in FIG. 5, although the aspect in which the external electrode 12, the 1st plating layer 13, and the external terminal 14 were drawn one by one was demonstrated, also when there are two of them as shown in FIG. The same applies.

  The external terminals 14a and 14b are manufactured through a precursor manufacturing process including the following steps. That is, first, as shown in FIG. 6, one strip-shaped metal plate 20 is prepared (first step). Ni, Fe-Ni, Fe-Ni-Co, Fe-Ni-Cr, Cu, Cu-Sn, Cu having a thickness of 0.05 to 0.5 mm, preferably 0.05 to 0.2 mm, as the band-shaped metal plate 20 A single metal or an alloy selected from —Sn—P, Cu—Ni, Cu—Zn, and Cu—Zn—Ni is used. Depending on the type of the metal, in consideration of spot weldability, surface oxidative discoloration, etc., a metal having a melting point of 400 ° C. or more, preferably Ni, as the surface treatment is applied to the entire surface before press punching or after press punching. 0.3 μm or more shall be applied.

  Next, as shown in FIG. 7, masking 21 is applied to the one edge side 20 a along the longitudinal direction of the band-shaped metal plate 20 in preparation for the plating process performed in the next step (second step).

  After applying the base material to 20b which is the other edge side of the band-shaped metal plate 20 to which the masking 21 has been applied, as shown in FIG. 8, nickel or a metal such as tin, silver or gold is plated, The second metal plating layer 16 is formed on the band-shaped metal plate 20 (third step).

  Subsequently, the masking 21 is removed to form a plated metal plate 22 having the second metal plating layer 16 on the second edge side 20b of the strip-shaped metal plate 20 as shown in FIG. 9 (fourth step).

  As shown in FIG. 10, the metal plate 22 is punched to form a precursor 23 composed of the upper end portion 15u and the lower end portion 15d of the external terminals 14a, 14b (fifth step). Then, the plated metal plate 22 has a planar shape obtained by branching a plurality of precursors 23 to be the external terminals 14a and 14b on the second edge side 20c, and the plated metal plate 22 has the first edge side 20a facing upward. When the side surface made vertical is viewed, the lower end portion of the precursor 23 has a shape covered with the second metal plating layer 16 as shown in FIG. In this way, at least an even number of precursors 23 are manufactured (precursor manufacturing step).

  In addition, as a method of forming the second metal plating layer 16 of the plated metal plate 22, it is also possible to form the metal plate by immersing it in a plating solution at a predetermined depth without masking the metal plate. In addition, after punching the metal plate into a predetermined shape, the second metal plating layer 16 is formed by masking with the above-described plating resist or immersing in a plating solution at a predetermined depth without masking. You can also.

  Next, the third step consisting of the following sixth to ninth steps and the external terminal separation step are simultaneously performed. First, the second metal plating layer 16 portion is bent in the precursor 23 of the plated metal plate 22 shown in FIG. 12 to make the side surface substantially L-shaped as shown in FIG. 13 (sixth step).

  An even number of plated metal plates 22 obtained in this way are prepared, and the precursor 23 hanging on the metal plate 22 is applied to the external electrode 12 of the ceramic capacitor 10 manufactured in the first and second steps. As shown in FIG. 14, spot welding is performed via the first metal plating layer 13 (seventh step). When the ceramic capacitor 10 is fixed to all of the plurality of precursors 23 existing on one plated metal plate 22, the external electrode 12 on the other end side of the ceramic capacitor 10 is attached to the other one plated metal plate 22. Fix it. Then, as shown in FIG. 15, a semi-finished product 25 in which the ceramic capacitor 10 is sandwiched between the two plated metal plates 22 on the both end portions 11 a and 11 b side is completed (eighth step).

  When the precursor 23 is separated from the semi-finished product 25 by a laser cutting machine or the like as shown in FIG. 16, a legged ceramic capacitor 10 according to the present invention as shown in FIGS. 1 and 2 appears (ninth step). ).

  Therefore, in the ceramic capacitor 10 thus obtained, the upper end surfaces 15t of the external terminals 14a and 14b are slightly above the upper end surfaces 12t of the external electrodes 12a and 12b, preferably the upper end surfaces 13t of the external terminals 13a and 13b. The protrusion is inevitable, and as a result, the external load on the external electrodes 12a and 12b can be reduced.

  The external terminals 13a and 13b are covered with the second metal plating layers 16a and 16b from the lower end surface to a predetermined height H, so that the ceramic capacitor 10 according to the present invention is mounted on an electronic circuit board. When the external terminals 13a and 13b are soldered to the lands, the second metal plating layers 16a and 16b not only increase the solder wettability but also the height at which the solder rises from the lower end of the external terminals. The vibration due to the electrostrictive effect of the dielectric ceramic can be suppressed to the minimum from the external terminal to the electronic circuit board, and the ceramic capacitor is mounted on the electronic circuit board. The board noise of electronic products can be suppressed.

  Further, as described above, since the upper end portion 15u and the first metal plating layers 13a and 13b employ means for fixing by spot welding, not only can the fixing work of both be made efficient, but also the substrate Detachment of the external terminal connection portion due to heating during soldering can be prevented.

Industrial application fields

  The present invention can be widely used in the field of electronic equipment using an electronic circuit board on which a ceramic capacitor is mounted.

  1: external terminal, 1a: upper end portion, 1b: lower end portion, 2: external electrode, 3: chip type multilayer ceramic capacitor, 4: chip type ceramic body, 4a: one end portion, 4b: other end portion, 5: chip type Multilayer ceramic body, 10: chip-type multilayer ceramic capacitor, 11: chip-type ceramic body, 11a, 11b: end, 12a, 12b: external electrode, 13a, 13b: first metal plating layer, 14a, 14b: external terminal, 15u: upper end portion, 15d: lower end portion, 16a, 16b: second metal plating layer, 20: strip metal plate, 20a: first edge side, 20b: second edge side, 21: masking, 22: plating metal plate, 23: Precursor, 24: spot welding, 25: semi-finished product.

Claims (6)

Chip-type multilayer ceramic capacitors having a structure that can be mounted on an electronic circuit board via leg-like external terminals (14a, 14b) extending downward from external electrodes (12a, 12b) existing at opposite ends. 10), as the external terminal, a band-shaped metal plate is used in which the center of the upper end is notched and the front shape is substantially U-shaped, the lower end is bent at a substantially right angle, and the side surface is L-shaped. Forming a first metal plating layer (13a, 13b) having a melting point of 400 ° C. or higher on at least an end face of the external electrode, and spot-welding the upper end of the external terminal to the metal layer; In addition, the external terminal is fixed, and the lower end (15d) of the external terminal is a single metal selected from one of Sn, Ag, Au, Bi, and Zn, or a metal alloy selected from a plurality of these. Ranaru second metal plating layer (16a, 16b) chip-type monolithic ceramic capacitor, characterized in that the formation of the. The metal forming the external terminal is Ni, Fe-Ni, Fe-Ni-Co, Fe-Ni-Cr, Cu, Cu-Sn, Cu-Sn-P, Cu-Ni, Cu-Zn, Cu-Zn-Ni. The chip type multilayer ceramic capacitor according to claim 1, which is selected from the group consisting of: The chip-type multilayer ceramic capacitor according to claim 3, wherein a height (H) of the second metal plating layer (16a, 16b) is 0.2 to 1.0 mm. 2. The chip-type laminate according to claim 1, wherein a metal plating having a melting point of 400 ° C. or higher is formed on the surface of the external terminal where the second metal plating layer is not formed. Ceramic capacitor. A first step of forming an external electrode on a chip-type multilayer ceramic body (11) in which a plurality of layers of internal electrodes are alternately laminated and oriented near both ends at a predetermined interval inside the chip-type ceramic body; A second step of covering at least an end face of the electrode with a first metal plating layer (13a, 13b) having a melting point of 400 ° C. or higher, a center of the upper end portion is cut off, and the front shape is substantially U-shaped, and the lower end portion is A chip comprising a third step in which leg-shaped external terminals (14a, 14b) made of a strip-shaped metal plate bent at a substantially right angle and having an L-shaped side surface are fixed to the first metal plating layer by spot welding. Of manufacturing a multilayer ceramic capacitor. The method for manufacturing a chip-type multilayer ceramic capacitor according to claim 6, wherein the external terminals (14a, 14b) are manufactured through the following steps and then fixed to the chip-type multilayer ceramic body (11). A plated metal plate manufacturing step for manufacturing a metal plate (22) having a second metal plating layer (16) formed by coating a plating resist (21) on one edge side (20b) along the longitudinal direction of the plate; (2) The plated metal plate is punched to separate a plurality of external terminal precursors (23) having portions that become the upper end portion (15u) and the lower end portion (15d) of the external terminal on the other edge side of the plated metal plate. A precursor manufacturing step for branching; and (3) a portion that becomes the upper end portion of the external terminal in the precursor is spot-welded to the first metal plating layer (13a, 13b) of the chip-type multilayer ceramic body and fixed. A precursor fixing step of, (4) external terminals completed step of separating a plurality of leg-like external terminals by cutting off the precursor which is fixed to the chip-type monolithic ceramic body from said plated metal plate.

Images