JP5063200B2 - Surface mount chip components - Google Patents

Description

  The present invention relates to a chip component, and more particularly to a surface mount type chip component that is surface-mounted on a circuit board.

  In recent years, many chip components have been used in electronic devices such as portable terminals and AV devices. There are various types of chip components such as capacitors, inductors, common mode filters, chip beads, and the like, but all of them are surface-mount types (see Patent Documents 1 to 4).

The surface-mounted chip component is mounted on the circuit board by the following procedure. First, cream-like solder is supplied to the electrode pattern on the circuit board, and a chip component is placed thereon. Then, by performing batch reflow, the solder is melted, and the solder is spread over the electrode pattern on the circuit board and the terminal electrode on the chip component. As a result, the chip component is electrically connected to the circuit board and mechanically fixed.
JP 2005-223280 A JP 2002-367852 A JP 2002-367851 A JP-A-11-103229

  In recent years, surface-mounted chip components have been miniaturized, and some products have a weight of 3 mg or less. When such a small chip component is mounted on a circuit board, a phenomenon may occur in which the chip component rotates 90 degrees due to the surface tension of the solder melted during reflow. Since the rotated chip component is not properly connected to the circuit board, connection failure occurs.

  As a result of extensive research on the rising phenomenon of chip parts, the present inventors have found that this phenomenon occurs frequently when predetermined conditions are met. That is, according to the study by the present inventors, it has been found that the rising phenomenon during reflow occurs in a product having a weight of 3 mg or less, and hardly occurs in a product heavier than that. On the other hand, even if the product has a weight of 3 mg or less, the relationship between the distance T that defines the height of the chip component and the distance W between both side surfaces on which the terminal electrodes are formed is T / W <0.6. Then, it became clear that the rising phenomenon at the time of reflow hardly occurred. That is, it has been found that the rising phenomenon frequently occurs in a product having a weight of 3 mg or less and T / W ≧ 0.6.

  The present invention has been made based on such technical knowledge, and an object of the present invention is to provide a small surface-mounted chip component in which a rising phenomenon during reflow is prevented.

  A surface-mount type chip component according to the present invention is a surface-mount type chip component that is surface-mounted on a circuit board, wherein the first and second mounting surfaces that are parallel to the circuit board at the time of mounting, A first and second side surfaces that are perpendicular to the second mounting surface and parallel to each other; and at least the first mounting surface and terminal electrodes formed on the first and second side surfaces; Is 3 mg or less, where T is the distance between the first mounting surface and the second mounting surface, and W is the distance between the first side surface and the second side surface, T / W ≧ 0.6, and the total area of the terminal electrodes formed on the first mounting surface is larger than the total area of the terminal electrodes formed on the first or second side surface. .

  According to the present invention, in a surface-mounted chip component having a condition that a rising phenomenon is likely to occur during reflow, the area of the terminal electrode formed on the first mounting surface is large and formed on the first or second side surface. The area of the terminal electrode formed is set small. As a result, the downward force due to the surface tension becomes stronger and the lateral force becomes weaker, so it is possible to prevent the rising phenomenon during reflow.

  In the present invention, it is preferable that the electrode width of the terminal electrode formed on the first mounting surface is wider than the electrode width of the terminal electrode formed on the first and second side surfaces. According to this, it becomes easy to increase the area of the terminal electrode formed on the first mounting surface and reduce the area of the terminal electrode formed on the first or second side surface.

  As described above, according to the present invention, it is possible to provide a small surface-mounted chip component in which the rising phenomenon during reflow is prevented.

  The rising phenomenon at the time of reflow becomes extremely remarkable in a product having a weight of 1 mg or less or a product having T / W ≧ 0.8, and therefore the present invention is particularly preferably applied to such a product.

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

  FIG. 1 is a schematic perspective view showing the structure of a surface mount chip component 10 according to a preferred embodiment of the present invention.

  As shown in FIG. 1, the surface-mounted chip component 10 according to the present embodiment is perpendicular to the first and second mounting surfaces 21 and 22 that are parallel to each other and the first and second mounting surfaces 21 and 22. The first to fourth side surfaces 31 to 34 are provided.

  One of the first and second mounting surfaces 21 and 22 is a bottom surface facing the circuit board during mounting, and the other is an upper surface. Terminal electrodes 41 a to 44 a are provided on the first mounting surface 21, and terminal electrodes 41 c to 44 c are provided on the second mounting surface 22. The terminal electrodes 41 a to 44 a provided on the first mounting surface 21 and the terminal electrodes 41 c to 44 c provided on the second mounting surface 22 have substantially the same pattern. For this reason, any mounting surface may be directed to the circuit board side during mounting. As shown in FIG. 1, the distance between the first mounting surface 21 and the second mounting surface 22, that is, the height is defined as T.

  The first and second side surfaces 31 and 32 are surfaces perpendicular to the first and second mounting surfaces 21 and 22 and parallel to each other. Terminal electrodes 41 b and 42 b are provided on the first side surface 31, and terminal electrodes 43 b and 44 b are provided on the second side surface 32. The terminal electrodes 41b and 42b provided on the first side surface 31 and the terminal electrodes 43b and 44b provided on the second side surface 32 have substantially the same pattern. For this reason, the 1st and 2nd side surfaces 31 and 32 are exchangeable at the time of mounting. As shown in FIG. 1, the distance between the first side surface 31 and the second side surface 32 is defined as W.

  The third and fourth side surfaces 33 and 34 are surfaces which are perpendicular to the first and second mounting surfaces 21 and 22 and the first and second side surfaces 31 and 32 and are parallel to each other. Terminal electrodes are not provided on the third and fourth side surfaces 33 and 34. As shown in FIG. 1, the distance between the third side surface 33 and the fourth side surface 34 is defined as L.

  As shown in FIG. 1, terminal electrodes 41a, 41b, 41c (sometimes collectively referred to as terminal electrode 41) are one continuous terminal electrode, and terminal electrodes 42a, 42b, 42c (collectively referred to as terminal electrode 42). Is one continuous terminal electrode, and terminal electrodes 43a, 43b, and 43c (sometimes collectively referred to as terminal electrode 43) are one continuous terminal electrode and terminal electrodes 44a, 44b, and 44c (terminals). (Sometimes collectively referred to as electrode 44) is one continuous terminal electrode. Therefore, the surface-mounted chip component 10 according to the present embodiment is a four-terminal chip component.

  In the present embodiment, the electrode width w1 of the terminal electrode formed on the first and second mounting surfaces 21 and 22 is greater than the electrode width w2 of the terminal electrode formed on the first and second side surfaces 31 and 32. Is also widely set. Here, “electrode width” refers to the width of the terminal electrode in the direction defining the distance L. The reason why the terminal electrode has such a shape is that the area of the terminal electrode on the first and second mounting surfaces 21 and 22 is made larger, while the terminal on the first or second side surfaces 31 and 32. This is to make the area of the electrode narrower. As a result, when the solder is melted during reflow, the downward force due to the surface tension becomes stronger, while the lateral force becomes weaker, thereby preventing the rising phenomenon.

  The type of the surface mount chip component 10 according to the present embodiment is not particularly limited, but a common mode filter can be given as an example. In this case, as shown in FIG. 2, a circuit in which a coil C1 formed between the terminal electrode 41 and the terminal electrode 43 and a coil C2 formed between the terminal electrode 42 and the terminal electrode 44 are magnetically coupled. It becomes composition.

  Here, the rising phenomenon of the chip component will be described.

  FIG. 3 is a diagram for explaining a moment of force generated when solder is melted during reflow. (A) shows a case where wettability is good, and (b) shows a case where wettability is not good. Yes.

  As shown in FIGS. 3A and 3B, since the chip component 10 has its own weight, only the downward moment Fg substantially acts in the state before the reflow. For this reason, the chip component 10 is in a state of being placed on the circuit board 50 by its own weight. In addition, when the solder 51 is melted by reflow, a moment due to the surface tension of the melted solder 51 is generated. The moment due to the surface tension of the solder 51 is due to the moment Fe1 due to contact with the terminal electrode 41a (and 42a), the moment Fe2 due to contact with the terminal electrode 43a (and 44a), and the contact with the terminal electrode 41b (and 42b). The moment Fs1 and the moment Fs2 due to the contact with the terminal electrode 43b (and 44b) are included. Moments Fe1 and Fe2 are moments of force acting in the downward direction, and moments Fs1 and Fs2 are moments of force acting in the lateral direction.

  At this time, when the wettability of the solder 51 is good, the moments Fs1 and Fs2 in the lateral direction are substantially equal as shown in FIG. Will not move. For this reason, the terminal electrode 41 (and 42) and the electrode pattern 52 on the circuit board are electrically connected, and the terminal electrode 43 (and 44) and the electrode pattern 53 on the circuit board are electrically connected. .

  However, when the wettability of the solder 51 is not good and the moment Fs2 is not acting, as shown in FIG. 3B, only the moment Fs1 acts in the lateral direction. Therefore, when the weight of the chip component 10 is light (when the moment Fg is small) or when the relationship T / W between the distance T and the distance W is large, the chip component 10 rises due to the moment Fs1 in the lateral direction. As shown in FIG. 4, it is rotated 90 degrees. As a result, the terminal electrode 43 (and 44) and the electrode pattern 53 are not connected. That is, connection failure occurs.

  This is a rising phenomenon of the chip component, which is more likely to occur as the weight of the chip component 10 is lighter. According to the study by the present inventors, the rise phenomenon hardly occurs in the product having a weight of more than 3 mg, whereas the probability of the rise phenomenon increases as the weight is reduced in the product having a weight of 3 mg or less. It has been found that when the amount is 1 mg or less, the occurrence of the rising phenomenon becomes extremely remarkable.

  However, it was found that even if the product has a weight of 3 mg or less, the rising phenomenon hardly occurs if T / W <0.6. This is because if W is sufficiently large with respect to T, the center of gravity is low and the posture is stabilized. On the other hand, when T / W ≧ 0.6, the cross-sectional shape is close to a square, so that the center of gravity is increased, and the rising phenomenon is considered to occur. In particular, in the product where T / W ≧ 0.8, since the center of gravity is higher, it has also been found that the occurrence of the rising phenomenon becomes extremely remarkable.

  In summary, it can be seen that the rising phenomenon occurs in a product having a weight of 3 mg or less and T / W ≧ 0.6.

  In this embodiment, the total area of the terminal electrodes formed on the first mounting surface 21 or the second mounting surface 22 is formed on the first side surface 31 in order to prevent the occurrence of such a rising phenomenon. The total area of the terminal electrodes is set to be larger than the total area of the terminal electrodes formed on the second side surface 32.

Specifically, as shown in FIG. 1, since the terminal electrodes 41a to 44a formed on the first mounting surface 21 all have the electrode width w1 and the electrode length w3, the first electrode The total area S1 of the terminal electrodes on the mounting surface 21 is
S1 = 4 × w1 × w3
It becomes. Here, “electrode length” refers to the length in the direction defining W or T. The total area of the terminal electrodes 41c to 44c formed on the second mounting surface 22 is also the same.

On the other hand, since the terminal electrodes 41b and 42b formed on the first side surface 31 both have the electrode width w2 and the electrode length T, the total area S2 of the terminal electrodes on the first side surface 31 is
S2 = 2 × w2 × T
It becomes. The total area of the terminal electrodes 43b and 44b formed on the second side surface 32 is also the same.

  In the present invention, S1> S2 is set, thereby increasing the moments Fe1 and Fe2 in the downward direction and decreasing the moments Fs1 and Fs2 in the lateral direction. As a result, as shown in FIG. 3B, even if only the moment Fs1 in the lateral direction (or only Fs2) acts because the solder wettability is not good, the rising phenomenon is less likely to occur.

  For this reason, the surface-mounted chip component 10 according to the present embodiment can have a weight of 3 mg or less, particularly 1 mg or less without causing connection failure due to the rising phenomenon, and the shape is T / W ≧ 0.6. In particular, it is possible to satisfy T / W ≧ 0.8.

  The preferred embodiments of the present invention have been described above, but the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the spirit of the present invention. Needless to say, it is included in the range.

  For example, the surface-mounted chip component 10 according to the above embodiment is a four-terminal chip component, but the subject of the present invention is not limited to this.

  Further, in the surface-mounted chip component 10 according to the above-described embodiment, the electrode width of the terminal electrode formed on the first and second mounting surfaces 21 and 22 is formed on the first and second side surfaces 31 and 32. Although it is set wider than the electrode width of the terminal electrode, this shape is a preferable shape in the present invention, and the present invention is not limited to this.

  Furthermore, in the surface-mounted chip component 10 according to the above embodiment, the terminal electrodes are not formed on the third and fourth side surfaces 33 and 34, but the terminal electrodes may be formed here.

  Furthermore, in the surface-mounted chip component 10 according to the above embodiment, the terminal electrodes are formed on both the first mounting surface 21 and the second mounting surface 22, but the terminal electrodes are formed on at least one of these. If it is enough. Similarly, in the surface-mounted chip component 10 according to the above embodiment, the terminal electrodes are formed on both the first side surface 31 and the second side surface 32, but the terminal electrodes are formed on at least one of these. It's enough.

  Hereinafter, although the Example of this invention is described, this invention is not limited to this Example at all.

  First, samples # 1 and # 2 having the same appearance as the surface-mounted chip component 10 shown in FIG. 1, samples # 3 to # 5 having the appearance shown in FIG. 5, and samples having the appearance shown in FIG. A large number of # 6 and # 7 were prepared.

  The appearance of samples # 3 to # 5 is different from samples # 1 and # 2 in that the electrode widths w1 and w2 of the terminal electrodes match as shown in FIG. Further, as shown in FIG. 6, the external appearance of samples # 6 and # 7 is an 8-terminal chip component having eight terminal electrodes 41 to 48, and the electrode widths w1 and w2 of the terminal electrodes are one. It differs from sample # 1 in that it does.

  The sizes, weights, and terminal electrode shapes of Samples # 1 to # 7 are as shown in FIG.

  As is apparent from FIG. 7, the chip parts having a weight of 3 mg or less and T / W ≧ 0.6 are only samples # 1 to # 4, and the other samples # 5 to # 7 are one of these. Or both conditions are not met. In other words, samples # 1 to # 4 are chip parts that are likely to rise, and samples # 5 to # 7 are chip parts that are less likely to cause the rise phenomenon.

  On the other hand, sample # 1 weighs only 0.5 mg and has a condition that the rising phenomenon is very likely to occur. The chip shapes of Samples # 2 to # 4 are the same as each other, and all have a weight of 1 mg and T / W = 0.8. For this reason, there is a condition that the rising phenomenon is very likely to occur. Samples # 2 to # 4 have different terminal electrode shapes.

  Next, samples # 1 to # 7 were placed on the circuit board supplied with cream-like solder, and batch reflow was performed. Then, the occurrence probability of the rising phenomenon was confirmed by visual observation, and the occurrence probability was calculated. The occurrence probability of the rising phenomenon in each sample # 1 to # 7 is shown in FIG.

  As shown in FIG. 7, the occurrence of the rising phenomenon was not observed in Samples # 5 to # 7, which are not applicable to the present invention, although S1 ≦ S2.

  On the other hand, the results were divided in samples # 1 to # 4, which are within the scope of application of the present invention. That is, for samples # 1 and # 2 that satisfy the condition of S1> S2, the occurrence of the rising phenomenon was not observed, but for samples # 3 and # 4 where S1 ≦ S2, the rising phenomenon occurred with a predetermined probability. Occurred. The probability of occurrence of the rising phenomenon becomes higher as S2 is larger than S1.

  As described above, although the samples # 1 and # 2 have the condition that the rising phenomenon is very likely to occur, the occurrence of the rising phenomenon is suppressed to zero by satisfying the condition of S1> S2. It was confirmed.

1 is a schematic perspective view showing the structure of a surface-mounted chip component 10 according to a preferred embodiment of the present invention. 1 is a circuit diagram of a surface mount chip component 10. FIG. It is a figure for demonstrating the moment of the force produced when a solder fuse | melts at the time of reflow, (a) shows the case where wettability is favorable, (b) has shown the case where wettability is not favorable. It is a figure which shows the state which the rise phenomenon generate | occur | produced. It is a figure which shows the external appearance of sample # 2- # 4. It is a figure which shows the external appearance of sample # 5 and # 6. It is a table | surface which shows the conditions of sample # 1- # 6, and the generation | occurrence | production probability of a rising phenomenon.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Surface mount type chip component 21 1st mounting surface 22 2nd mounting surface 31 1st side surface 32 2nd side surface 33 3rd side surface 34 4th side surface 41-48 Terminal electrode 41a-44a, 41b-44b , 41c to 44c Terminal electrode 50 Circuit board 51 Solder 52, 53 Electrode pattern C1, C2 Coil

Claims (4)

A surface-mounted chip component that is surface-mounted on a circuit board,
First and second mounting surfaces that are parallel to the circuit board during mounting; first and second side surfaces that are perpendicular to and parallel to the first and second mounting surfaces; and the first And the second mounting surface and the third and fourth side surfaces perpendicular to and parallel to the first and second side surfaces, and at least the first mounting surface and the first side surface. First and second terminal electrodes, and at least the first mounting surface and the third and fourth terminal electrodes formed on the second side surface,
The weight is 3 mg or less,
T / W ≧ 0.6, where T is the distance between the first mounting surface and the second mounting surface, and W is the distance between the first side surface and the second side surface,
When the distance between the third side surface and the fourth side surface is L, L> W,
A total area of the first to fourth terminal electrodes formed on the first mounting surface is larger than a total area of the first and second terminal electrodes formed on the first side surface; Larger than the total area of the third and fourth terminal electrodes formed on the second side surface,
The electrode widths of the first to fourth terminal electrodes formed on the first mounting surface are wider than the electrode widths of the first and second terminal electrodes formed on the first side surface, and A surface-mount type chip component having a width wider than the electrode width of the third and fourth terminal electrodes formed on the second side surface.   2. The surface mount chip component according to claim 1, wherein the weight is 1 mg or less.   The surface-mounted chip component according to claim 1, wherein T / W ≧ 0.8. A first coil formed between the first terminal electrode and the third terminal electrode; and a second coil formed between the second terminal electrode and the fourth terminal electrode. Including
The first and second coils constitute a common mode filter by being magnetically coupled to each other;
The first to fourth terminal electrodes are also formed on the second mounting surface,
The first and second terminal electrodes formed on the first side surface are formed on the first mounting surface and the first terminal electrode formed on the first mounting surface. One conductor connecting each of the first and second terminal electrodes;
The third and fourth terminal electrodes formed on the second side surface are formed on the second mounting surface and the third and fourth terminal electrodes formed on the first mounting surface. 4. The surface-mount type chip component according to claim 1, wherein the surface-mount type chip component is one conductor that connects the third and fourth terminal electrodes. 5.

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