JP5625405B2 - Surface mount electronic components - Google Patents

Description

  The present invention relates to a surface mount electronic component.

  As a technique related to this type of field, for example, there is a surface mount electronic component described in Patent Document 1. This conventional surface mount electronic component includes rectangular terminal electrodes at both ends in the length direction on the bottom surface of the element body. The exposed area of the terminal electrode is adjusted so that the surface tension of the molten solder acting on the end face of the element body does not exceed the surface tension of the molten solder acting on the terminal electrode, thereby preventing chip standing during mounting. It has been. Further, for example, in the surface-mounted electronic component described in Patent Document 2, rectangular terminal electrodes are arranged at the four corners of the bottom surface of the element body, and concave portions are provided between the terminal electrodes, so that short-circuiting between the terminal electrodes by solder is prevented. It comes to prevent.

JP 7-66074 A JP 2001-326445 A

  The surface mount electronic component as described above has a problem that it is difficult to control the tilt of the element body because the convex surface of the molten solder hits the rectangular terminal electrode during mounting. In particular, since there is only one connection point between the terminal electrode and the molten solder in the width direction of the element body, it is difficult to balance the element body and it is difficult to suppress the inclination. Further, since voids generated in the molten solder are difficult to escape, connection strength may be reduced or cracks may be caused by voids remaining in the solder.

  On the other hand, in the surface-mount type electronic component described in Patent Document 2, there are two connection portions between the terminal electrode and the molten solder in the width direction of the element body, and a recess is provided between the terminal electrodes. This is considered to be more advantageous than the surface-mount type electronic component described in Patent Document 1 in that the inclination of the element body in the width direction can be suppressed and the voids inside the solder can be prevented. However, with this structure, it is difficult to ensure the area of the terminal electrode, and the connection strength with the wiring board may be reduced.

  The present invention has been made to solve the above-mentioned problems, and can sufficiently secure the connection strength with the wiring board, suppress the inclination of the element body in the width direction during mounting, and prevent voids inside the solder. An object of the present invention is to provide a surface mount electronic component capable of suppressing the residual.

  In order to solve the above problems, a surface mount electronic component according to the present invention is a surface mount electronic component in which a terminal electrode soldered to a wiring board is provided on a bottom surface of an element body, and the terminal electrodes are connected to each other. The first electrode portion and the second electrode portion extending in the length direction of the bottom surface in a separated state, and the first electrode portion extending in the width direction of the bottom surface between the first electrode portion and the second electrode portion. A connecting electrode portion that connects the portion and the second electrode portion, and the width of the connecting electrode portion is smaller than the length of the first electrode portion and the length of the second electrode portion. It is characterized by.

  In this surface mount type electronic component, when mounting on a wiring board, the wet solder spreads in the width direction of the element body from the connection electrode portion of the terminal electrode toward the first electrode portion and the second electrode portion. Be guided. For this reason, the surface tension of the molten solder is dispersed in the width direction of the element body, and it becomes easy to balance the element body, so that the inclination in the width direction of the element body during mounting is suppressed. In addition, since the molten solder is dispersed in each of the first electrode portion, the second electrode portion, and the connection electrode portion, sufficient connection strength with the wiring board can be ensured. Further, in this surface mount electronic component, since the width of the connection electrode portion is smaller than the length of the first electrode portion and the length of the second electrode portion, the outer peripheral shape of the terminal electrode includes There is a recess formed by the first electrode portion, the second electrode portion, and the connecting electrode portion, and voids in the molten solder can easily escape from the recess. Therefore, it is possible to prevent voids from remaining inside the solder.

  Moreover, it is preferable that the length of the 1st electrode part and the length of the 2nd electrode part are substantially equal length. In this case, since the wetting spread of the molten solder in the width direction of the element body is equalized, the inclination in the width direction of the element body during mounting is further effectively suppressed.

  Moreover, it is preferable that the connection electrode part has connected the center part of the 1st electrode part, and the center part of the 2nd electrode part. In this case, it is possible to equalize the wet spread of the molten solder in the length direction of the element body.

  Moreover, it is preferable that the connection electrode part has connected the part near the center of the bottom face in the 1st electrode part, and the part near the center of the bottom face in the 2nd electrode part. In this case, since the size of the outer concave portion facing the outside of the element body can be secured, the void in the molten solder can be more easily escaped to the outside of the mounting region of the electronic component.

  Further, it is preferable that the bottom surface of the element body has a substantially rectangular shape, and the shape of the terminal electrode is symmetric with respect to the center line in the length direction of the bottom surface. This makes it easier to balance the element bodies, so that the inclination in the width direction of the element bodies during mounting is more reliably suppressed.

  According to the present invention, it is possible to sufficiently secure the connection strength with the wiring board, and it is possible to suppress the inclination in the width direction of the element body during mounting and to suppress the residual voids in the solder.

It is a perspective view which shows the mounting state of the surface mount type electronic component which concerns on 1st Embodiment of this invention. It is a side view of the length direction in FIG. It is a side view of the width direction in FIG. FIG. 2 is a bottom view of the surface mount electronic component shown in FIG. 1. It is the schematic diagram which showed the mode of the wet spread of the fusion | melting solder | solder in an Example, and the attitude | position of the surface mounted electronic component after mounting. It is the schematic diagram which showed the mode of the wet spread of the molten solder in a comparative example, and the attitude | position of the surface mounted electronic component after mounting. It is a bottom view of the surface mounting type electronic component which concerns on 2nd Embodiment of this invention. It is a bottom view of the surface mount electronic component which concerns on 3rd Embodiment of this invention.

  Hereinafter, preferred embodiments of a surface mount electronic component according to the present invention will be described in detail with reference to the drawings.

[First Embodiment]
FIG. 1 is a perspective view showing a mounted state of the surface mount electronic component according to the first embodiment of the present invention. 2 is a side view in the length direction in FIG. 1, and FIG. 3 is a side view in the width direction in FIG.

  As shown in FIGS. 1 to 3, the surface-mounted electronic component 1 </ b> A is a chip-type multilayer electronic component represented by, for example, a chip inductor, a chip capacitor, a chip varistor, and a chip bead, and has a substantially rectangular parallelepiped shape. An element body 2 and a pair of terminal electrodes 3A and 3A provided on the bottom surface 7 of the element body 2 are provided.

  The element body 2 is formed, for example, by laminating a plurality of ceramic green sheets (not shown) having a conductor pattern and firing them. The boundary of the ceramic green sheet is integrated so as not to be visible. The size of the element body 2 is, for example, about 400 μm in length, 200 μm in width, and 160 μm in height.

  The pair of terminal electrodes 3 </ b> A and 3 </ b> A are provided in a state of being separated from each other on the bottom surface 7 of the element body 2. The terminal electrode 3A is formed, for example, by transferring an electrode paste containing Ag, Cu or Ni as a main component to the bottom surface 7 of the element body 2 and baking it at a predetermined temperature, followed by electroplating. For electroplating, for example, Cu, Ni and Sn can be used.

  As shown in FIG. 4, the terminal electrode 3 </ b> A is formed by a first electrode portion 31, a second electrode portion 32, and a connecting electrode portion 33. The shape is symmetric with respect to the line H. Each of the first electrode portion 31 and the second electrode portion 32 has, for example, a belt shape having a length L1 of about 115 μm and a width W1 of about 60 μm, and extends in the length direction of the bottom surface 7 in a state of being separated from each other. Further, the connecting electrode portion 33 has a strip shape with a length L2 of about 60 μm and a width W2 of about 55 μm, for example, and extends in the width direction of the bottom surface 7 between the first electrode portion 31 and the second electrode portion 32. Yes.

  The width W2 of the connection electrode portion 33 is smaller than the length L1 of the first electrode portion 31 and the second electrode portion 32 as described above. Further, the center of the connection electrode portion 33 is a portion closer to the center of the element body 2 by about 5 μm than the center portion in the length direction of the first electrode portion 31, and the length direction of the second electrode portion 32. A portion closer to the center of the element body 2 is connected by about 5 μm than the center portion.

  Therefore, a recess is formed in the outer peripheral shape of the terminal electrode 3 </ b> A by the first electrode portion 31, the second electrode portion 32, and the connecting electrode portion 33, and specifically faces the outside of the element body 2. There will be an outer recess 34A and an inner recess 35A facing the inside of the element body 2 respectively. The length of the outer recessed portion 34A is, for example, 32.5 μm, and the length of the inner recessed portion 35A is, for example, 22.5 μm.

  The terminal electrode 3A as described above is electrically connected to the land electrode 4 on the wiring board 5 by the solder 6. When the terminal electrode 3A and the land electrode 4 are connected, ball-shaped cream solder is disposed on the land electrode 4 and reflow of the cream solder is performed.

  Then, the effect of the surface mount electronic component 1A mentioned above is demonstrated.

  FIG. 5 is a schematic diagram illustrating the state of wet solder spreading and the posture of the surface-mounted electronic component after mounting in the example. As shown in FIG. 5A, in the surface-mounted electronic component 1A, the molten solder P that spreads wet starting from the center Ma of the terminal electrode 3A is guided by the strip-shaped connecting electrode portion 33, and the first electrode portion 31 is formed. In addition, the element body 2 is dispersed substantially uniformly in the width direction of the element body 2 toward the second electrode portion 32.

  The molten solder P dispersed in the first electrode portion 31 and the second electrode portion 32 is then guided by the strip-like first electrode portion 31 and the second electrode portion 32, and the length direction of the element body 2. To disperse. As a result, in the surface mount electronic component 1A, the surface tension of the molten solder P is dispersed in the width direction of the element body 2, and even if some dispersion variation occurs, the element body 2 can be easily balanced. As shown in FIG. 5B, the widthwise inclination of the element body 2 during mounting is suppressed. In the surface mount electronic component 1 </ b> A, the molten solder P is dispersed in each of the first electrode portion 31, the second electrode portion 32, and the connection electrode portion 33, thereby connecting strength with the wiring board 5. Can be secured sufficiently.

  Further, in the surface mount electronic component 1A, an outer recess 34A facing the outside of the element body 2 and an inner recess 35A facing the inside of the element body 2 are present in the terminal electrode 3A. For this reason, even if voids are generated in the molten solder P during reflow, the voids can easily escape from the outer recesses 34A and the inner recesses 35A, and the voids are prevented from remaining inside the solder 6 after connection. it can. Thereby, the fall of the connection strength resulting from a void and generation | occurrence | production of a crack can be prevented.

  In the surface mount electronic component 1A, the center of the connection electrode portion 33 is closer to the center of the element body 2 than the center portion in the length direction of the first electrode portion 31, and the second electrode portion 32. The portion closer to the center of the element body 2 than the center portion in the length direction is connected. Therefore, the size of the outer concave portion 34A facing the outside of the element body 2 is sufficiently secured, and the voids in the molten solder P are more easily escaped to the outside of the mounting area of the electronic component, and the length of the element body 2 is increased. Since a large amount of solder 6 adheres to both ends in the direction, the bonding strength against bending stress caused by the deformation of the wiring board 5 is improved.

  On the other hand, FIG. 6 is a schematic diagram showing the state of wet solder spreading and the posture of the surface-mounted electronic component after mounting in the comparative example. As shown in FIG. 6A, the surface-mount type electronic component 41 according to the comparative example has substantially rectangular terminal electrodes 42 and 42 on the bottom surface 7 of the element body 2. In this surface-mounted electronic component 41, the molten solder P that spreads wet starting from the center Mb of the terminal electrode 42 spreads in all directions.

  Accordingly, the balance of the element body 2 is deteriorated due to dispersion of the surface tension of the molten solder P, and as shown in FIG. 6B, the width direction of the element body 2 is easily inclined during mounting. Further, in the surface mount electronic component 41, the terminal electrodes 42, 42 are simple rectangles. For this reason, voids generated in the molten solder P during reflow (particularly, voids generated in the central portion of the terminal electrode 42) are difficult to escape, and voids are likely to remain in the solder 6 after connection.

  In the surface-mounted electronic component 41 according to the comparative example, the inclination of the element body 2 with respect to the mounted wiring board 5 occurs in a range of about ± 10 °, whereas in the surface-mounted electronic component 1A according to the embodiment, the mounting is performed. The inclination of the element body 2 with respect to the subsequent wiring board 5 can be suppressed within a range of ± 3 °. Further, in the surface mount electronic component 41 according to the comparative example, the void residual ratio exceeds 15% of the terminal area per terminal, whereas in the surface mount electronic component 1A according to the embodiment, the void residual ratio is 1 It can be suppressed to 15% or less of the terminal area per terminal.

[Second Embodiment]
Next, a surface mount electronic component according to a second embodiment of the present invention will be described. FIG. 7 is a bottom view of the surface mount electronic component according to the second embodiment of the present invention.

  As shown in the figure, the surface mount type electronic component 1B is different from the first embodiment in the formation position of the connecting electrode portion 33 in the terminal electrode 3B, and the other points are the same as in the first embodiment. That is, in the terminal electrode 3 </ b> B of the surface mount electronic component 1 </ b> B, the center of the connection electrode portion 33 connects the center portion of the first electrode portion 31 and the center portion of the second electrode portion 32.

  In the surface mount electronic component 1B, as in the first embodiment, the surface tension of the molten solder P is dispersed in the width direction of the element body 2, and even if some dispersion occurs, the balance of the element body 2 is maintained. Therefore, the inclination of the element body 2 in the width direction during mounting is suppressed. Further, since the molten solder P is dispersed in each of the first electrode portion 31, the second electrode portion 32, and the connecting electrode portion 33, sufficient connection strength with the wiring board 5 can be ensured.

  Further, in the surface mount electronic component 1B, the outer concave portion 34B and the inner concave portion 35B are present in a length along the length direction of the substantially equal body 2, and the voids escape evenly from the outer concave portion 34A and the inner concave portion 35A. It is easy. As a result, voids can be prevented from remaining inside the solder 6 after connection, and a reduction in connection strength and occurrence of cracks due to the voids can be prevented.

  In addition, in the surface-mounted electronic component 1B, the terminal electrode 3B has a symmetrical shape with respect to both the length direction and the width direction of the element body 2. Therefore, the surface tension of the molten solder P is evenly distributed not only in the width direction of the element body 2 but also in the length direction, and the inclination of the element body 2 in the length direction during mounting is also suppressed.

[Third Embodiment]
Next, a surface mount electronic component according to a third embodiment of the present invention will be described. FIG. 8 is a bottom view of the surface mount electronic component according to the third embodiment of the present invention.

  As shown in the figure, the surface mount type electronic component 1C is further different from the first embodiment in the formation position of the connecting electrode portion 33 in the terminal electrode 3C, and the other points are the same as in the first embodiment. . That is, in the terminal electrode 3 </ b> C of the surface mount electronic component 1 </ b> C, the center of the connection electrode portion 33 connects the inner end portion of the first electrode portion 31 and the inner end portion of the second electrode portion 32.

  In the surface mount electronic component 1C, as in the first embodiment, the surface tension of the molten solder P is dispersed in the width direction of the element body 2, and even if some dispersion occurs, the balance of the element body 2 is maintained. Therefore, the inclination of the element body 2 in the width direction during mounting is suppressed. Further, since the molten solder P is dispersed in each of the first electrode portion 31, the second electrode portion 32, and the connecting electrode portion 33, sufficient connection strength with the wiring board 5 can be ensured.

  In addition, in the surface-mounted electronic component 1C, the outer concave portion 34C is formed long instead of the inner concave portion 35C, and the voids can easily escape from the outer concave portion 34C to the outside of the mounting region of the electronic component. As a result, voids can be prevented from remaining inside the solder 6 after connection, and a reduction in connection strength and occurrence of cracks due to the voids can be prevented.

  The present invention is not limited to the above embodiment. For example, in the embodiment described above, the terminal electrodes 3 </ b> A, 3 </ b> B, and 3 </ b> C are all symmetrical with respect to the center line H in the length direction on the bottom surface 7 of the element body 2, but are shifted with respect to the center line H. The first electrode portion 31 and the second electrode portion 32 may have different lengths from each other. Further, the number of the terminal electrodes 3A, 3B, 3C and the shape of the bottom surface 7 of the element body 2 may be appropriately changed according to the specifications.

  DESCRIPTION OF SYMBOLS 1A, 1B, 1C ... Surface mount type electronic component, 2 ... Element body, 3A, 3B, 3C ... Terminal electrode, 5 ... Wiring board, 7 ... Bottom face, 31 ... 1st electrode part, 32 ... 2nd electrode part 33: connecting electrode portion, H: center line, L1: length of first electrode portion and second electrode portion, W2: width of connecting electrode portion.

Claims (3)

A surface mount type electronic component in which a terminal electrode soldered to a wiring board is provided on the bottom surface of the element body,
The terminal electrode is
It is arranged only at the position where it overlaps the element body when viewed from the height direction of the element body
A first electrode portion and a second electrode portion extending in the length direction of the bottom surface in a state of being separated from each other;
A connecting electrode portion extending in the width direction of the bottom surface between the first electrode portion and the second electrode portion, and connecting the first electrode portion and the second electrode portion; ,
The width of the connecting electrode portion is smaller than the length of the first electrode portion and the length of the second electrode portion ,
The surface-mount type electronic component according to claim 1, wherein the connecting electrode portion connects a central portion of the first electrode portion and a central portion of the second electrode portion .   The surface-mount type electronic component according to claim 1, wherein the length of the first electrode portion and the length of the second electrode portion are substantially equal. The bottom surface of the element body has a substantially rectangular shape,
3. The surface-mount type electronic component according to claim 1, wherein a shape of the terminal electrode is symmetric with respect to a center line in a length direction of the bottom surface.

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