JP2002208765A - Surface mount electronic component - Google Patents

Abstract

PROBLEM TO BE SOLVED: To easily perform loading and unloading of an electronic component by inserting a soldering iron into a narrow space between an electrode pad and the bottom face of a package, when the electronic component equipped with a box-shaped package structure such as a piezoelectric device is mounted on a printed-circuit board, even in a case where a castellation is installed on the side face of the package corresponding to an external electrode on the bottom face so that a solder fillet can be formed between itself and the electrode pad on the printed-circuit board. SOLUTION: A recessed part 23 for soldering-iron insertion is formed on the side face of the package 21. The castellation 24 is formed in the innermost part of the recessed part.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement of a surface mount type electronic component. For example, when an electronic component having a box-shaped package structure such as a piezoelectric device is mounted on a printed circuit board, it is mounted on a wiring pattern by soldering. The present invention relates to a surface-mounted electronic component capable of easily visually observing the quality of a connection state while sufficiently securing a fixing force of the electronic component.

[0002]

2. Description of the Related Art In recent years, mobile communication devices such as portable telephones have been reduced in size and weight, while demands for higher functionality have been increasing. In order to satisfy the demand for increased number of components and miniaturization due to the advancement of functions, it is important to reduce the area of the printed circuit board that constitutes the electrical components and to effectively utilize the board area by increasing the density of mounted components. It has become so. Quartz resonators (vibrators and filters), which are frequency control devices used in mobile communication devices and transmission communication devices, are no exception, and surface-mount type devices are mainly used for high-density mounting.

FIG. 3 is a view showing an example of mounting a piezoelectric device as an example of a conventional surface mount type electronic component.
Is an exploded perspective view, (b) is a view showing a state immediately before mounting,
(C) is an enlarged view of a solder connection part. Reference numeral 1 denotes a printed board on which a wiring pattern (electrode pad) 2 for mounting an electronic component 5 is formed. The electronic component 5 is, for example, a crystal resonator, and has external terminals 7 on the bottom surface of the package 6. Each external terminal 7 corresponds to each of the electrode pads 2 on the printed circuit board in one-to-one correspondence with the solder 3. Connection is fixed. The area of the electrode pad 2 is sufficiently larger than the external terminals 7, and a part of the electrode pad 2 projects outside the side wall of the package 6. The solder is considered to form a fillet shape (Fig. 3
(C)). The fillet-shaped portion proves that the connection strength is strong, and by visually observing this, the connection state after the connection step can be easily inspected. By the way, if it becomes difficult to secure the area of the electrode pad 2 as large as before with the downsizing of the printed circuit board and the high-density mounting of mounted components, a situation may occur in which the solder fillet cannot be formed sufficiently. That is, as shown in FIG. 4, when the area of the electrode pad 2 is reduced, the portion protruding outside the side wall of the package 6 is reduced, so that a solder fillet is formed between the electrode pad 2 and the side wall of the package 6. There is no room to spare. For this reason, not only does the connection strength due to the solder significantly decrease, but also it becomes difficult to visually judge the suitability of the connection strength due to the solder.
For this reason, it is necessary to increase the number of inspection steps using a special device and inspect the connection strength.

Therefore, conventionally, an arc-shaped recess 10 as shown in FIGS.
And a metallization 11 is formed in the recess 10 (castellation 1).
When the external terminal 7 is connected to the electrode pad 2 by the solder 3 as shown in FIG. 5C, a part of the solder is formed between the metallized portion 11 of the castellation 12 and the electrode pad 2 as shown in FIG. Thus, it is possible to enhance the connection strength and visually determine the quality of the connection strength by forming a fillet shape. However, when the castellation 12 is employed, there is a problem that it is difficult to appropriately set the radius of the arc-shaped recess 10. That is, FIG.
If the radius of the castellation 12 is too large as shown in FIG.
The uncured solder is sucked between the two due to the capillary phenomenon between them, and it becomes difficult for the solder 3 to climb into the recess 10 of the castellation 12 to form a fillet shape. Such a large-diameter castellation is problematic in a mass production process using a reflow process because it increases the reject rate. On the other hand, when the radius of the castellation 12 is reduced to an appropriate value, the solder can be sucked up by the capillary phenomenon on the side of the recess 10, so that the fillet shape as shown in FIG. 5 can be formed. . By the way, when the radius is made small enough to form a fillet shape in the recess 10, for example, when the radius of the recess 10 is made small to about 0.3 mm, a special problem occurs during mass production by the reflow process. This does not occur, but when it is necessary to frequently attach or detach the electronic component 5 from the printed circuit board 1 using a soldering iron, such as when conducting an experiment or a prototype, the tip of the soldering iron 15 (diameter 1. 0 mm) with a small-diameter recess 10
6B, it is not possible to make contact with the contact position P on the electrode pad 2 as shown in FIG. 6B, and as a result, it becomes difficult to perform the operation of melting the solder. Therefore,
When performing trial manufacture, experiments, and the like, the electronic components 5 having castellations could not be used, which was extremely inconvenient.

[0005]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances. For example, when an electronic component having a box-shaped package structure, such as a piezoelectric device, is mounted on a printed circuit board, an external part of the bottom surface is required. Even if it is configured such that a solder fillet can be formed between the electrode and the electrode pad on the printed board by providing castellation on the side of the package corresponding to the electrode, insert the soldering iron on the electrode pad and make it abut An object of the present invention is to provide a surface-mounted electronic component capable of easily attaching and detaching electronic components.

[0006]

According to a first aspect of the present invention, there is provided a surface-mounted electronic component having an external terminal connected to and fixed to an electrode pad of a printed circuit board by solder at a bottom portion. The surface mount type electronic component includes a package having the external terminal on a bottom portion, a recess is formed on a side wall of the package corresponding to the external terminal, and a part of an electrode pad on a printed board is formed below the recess. Is formed so as to be exposed, and a concave portion having a small diameter is formed in communication with an inner deep portion of the concave portion, and a metallized portion that is electrically connected to an external electrode corresponding to an inner wall of the concave portion having the small diameter is formed. And In the invention according to claim 2, the plane shape of the recess is V-shaped,
It is characterized in that it has an arc shape or a rectangular shape. The invention according to claim 3 is characterized in that the surface-mounted electronic component is a piezoelectric resonator.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail with reference to embodiments shown in the drawings. FIG. 1A is a perspective view showing an essential configuration of an example of a surface mount electronic component according to an embodiment of the present invention, FIG. 1B is a cross-sectional view showing a connection procedure, and FIG.
FIG. 3 is a sectional view showing a state after connection. This surface-mounted electronic component 20 has external electrodes 22 on the bottom surface of a package 21 made of an insulating material such as ceramic or resin, and has a V-shaped planar shape on the side wall of the package 21 corresponding to each external electrode 22. A concave portion (a concave portion for inserting a soldering iron) 23 is formed, and a castellation 24 is formed in the inner portion of the concave portion 23. The recess 23 and the castellation 24 are formed to penetrate the package 21 vertically. Inside the package 21, an IC chip (not shown), a piezoelectric resonator, and other elements are housed. The castellation 24 is formed in a substantially cylindrical hole-shaped recess 25 communicating with the inner deep portion corresponding to the apex of the V-shaped recess 23, and is formed on the inner wall of the recess 25 to conduct with the external electrode 22. Metallized section 26,
Consists of The recess 23 has such an opening size that the tip of the soldering iron 30 to be used can be inserted into the position shown in FIG. 1B, and the recess 25 has the molten solder 27 inside by the capillary phenomenon as shown in FIG. The dimensions and shape of the solder fillet 27a are determined so that the solder fillet 27a having an ideal shape can be formed. Further, a part of the electrode pad 2 located immediately below is exposed below the recess 23.

That is, each electrode pad 2 on the printed board 1
When positioning the external electrodes 22 on the bottom surface of the package 21 so as to correspond one-to-one, the external electrodes 22 are placed on the cream solder 27 that has been previously applied to the respective electrode pads 2 by a predetermined amount. When the printed circuit board 1 is placed in a reflow furnace and heated in this state, the cream solder is melted, and a part thereof is sucked up into the recess 25 by capillary action to form a fillet. Thereafter, by cooling, the fillet-shaped portion 27a is reliably formed,
The electrode pad 22 is firmly fixed between the external electrode 22 and the metallized portion 26. The fillet-shaped portion 27a
The presence or absence and the quality of the shape can be easily determined by visually observing the inside of the V-shaped recess 23 from above. Also,
In trial production, experiments, etc., solder 2
When the electronic component 20 is detached from the printed circuit board 1 by melting the electronic component 7, the tip of the soldering iron 30 is inserted into the recess 23, the electrode pad 2 is heated to melt the solder 27, and then the electronic component 20 is melted. 20 is removed, but this operation is very easy because the recess 23 has a width sufficient to insert the tip of the soldering iron. The planar shape of the recess 23 is not limited to the V-shape, but may be an arc shape, a rectangular shape, or the like as shown in FIGS. In any case, the dimension may be such that the tip of the soldering iron (about 1.0 mm in diameter) can be inserted. Further, the concave portion 25 constituting the castellation 24 has a small diameter such that the molten solder can be sucked by utilizing the capillary phenomenon, and the fillet-shaped portion 2 formed between the electrode pad 2 and the fillet-shaped portion 2 is formed.
7a has a diameter large enough to secure sufficient connection strength.

As described above, in the surface mount type component of the present invention, a recess for inserting a soldering iron is formed on the side surface of the package, and a metallized portion 26 that is electrically connected to an external electrode is formed inside the recess 23. Since the castellations 24 were formed continuously, a large-diameter recess 23 allowing the soldering iron to be inserted separately from the castellations was provided, so that when the electronic components were removed, the soldering irons were placed inside the castellations themselves. There is no need to insert the castellation, and the diameter of the castellation can be made sufficiently small. For this reason, it is possible to suck up the molten solder by utilizing the capillary phenomenon of the castellation and form a fillet-shaped portion of the solder between the electrode pad and the molten solder. The surface-mount type electronic component having the recesses 23 for inserting the soldering iron and the castellations 24 as described above is mainly manufactured as a prototype,
This is effective in facilitating the work with the soldering iron when mounting and removing the mounted parts frequently performed during the experiment. It also helps to make it easier. The structure of the recess 23 and the castellation 24 for inserting a soldering iron according to the present invention can be applied to any type of electronic component as long as it is a surface-mounted electronic component having an external electrode on the bottom of the insulating package. Can be.

[0010]

As described above, according to the present invention, when an electronic component having a box-shaped package structure, such as a piezoelectric device, is mounted on a printed circuit board, the package is formed on the package side corresponding to the external electrode on the bottom surface. Even if it is configured to form a solder fillet between the electrode pads on the printed circuit board by providing castellations, insert the soldering iron into the narrow space between the electrode pads and the bottom of the package, and Parts can be easily attached and detached. That is, in the present invention, a recess for inserting a soldering iron is formed on the side surface of the package, and further, a castellation is formed on the inner side of the recess, so that the soldering iron can be inserted separately from the castellation. By providing the large-diameter recess, it is not necessary to insert a soldering iron into the castellation itself when removing the electronic component, and the diameter of the castellation can be sufficiently reduced. For this reason, it is possible to suck up the molten solder by utilizing the capillary phenomenon of the castellation and form a fillet-shaped portion of the solder between the electrode pad and the molten solder. Checking whether or not a solder fillet having an ideal shape is formed can be easily and practically performed by visually confirming the connection portion from above the recess, so that no extra trouble and cost increase are caused. Good products can be found.

[Brief description of the drawings]

FIG. 1A is a perspective view showing an essential configuration of an example of a surface-mounted electronic component according to an embodiment of the present invention, FIG. 1B is a cross-sectional view showing a connection procedure, and FIG. Sectional drawing which shows a state.

FIGS. 2A and 2B are plan views illustrating a main configuration of a surface-mounted electronic component according to another embodiment.

3A and 3B are views showing an example of mounting a piezoelectric device as an example of a conventional surface mount electronic component, wherein FIG. 3A is an exploded perspective view, FIG. 3B is a view showing a state immediately before mounting, and FIG. The enlarged view of a solder connection part.

FIG. 4 is a diagram illustrating a configuration of a main part of a surface mount electronic component according to another conventional example.

5 (a), (b) and (c) are explanatory views of another conventional example.

6 (a) and (b) are explanatory diagrams showing the drawbacks of the conventional example.

[Explanation of symbols]

20 surface mount electronic components, 21 package, 22
External electrode, 23 recess (recess for soldering iron), 2
4 castellation, 25 recess, 26 metallization, 27 solder, 27a solder fillet, 30 solder iron

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) H05K 3/34 512 H01L 23/12 L

Claims (3)

[Claims] 1. A surface-mounted electronic component having an external terminal connected and fixed by solder on an electrode pad of a printed circuit board at a bottom portion, wherein the surface-mounted electronic component includes a package having the external terminal at a bottom portion. A recess is formed in a package side wall corresponding to the external terminal, and a portion of an electrode pad on a printed circuit board is exposed at a lower portion of the recess. A surface-mounted electronic component, wherein a small-diameter concave portion is formed in communication with a metallized portion formed to communicate with an external electrode corresponding to an inner wall of the small-diameter concave portion. 2. The planar shape of the recess is V-shaped, arc-shaped,
The surface-mounted electronic component according to claim 1, wherein the component is rectangular. 3. The surface-mounted electronic component according to claim 1, wherein the surface-mounted electronic component is a piezoelectric resonator.