JP2003068921A - Surface mount electronic component - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a surface mount electronic component wherein the width of a seal ring of a package outer frame upper surface is sufficiently ensured and airtightness after metal lid bonding is improved, while the diameter of a recessed part constituting a castellation is sufficiently ensured and formation of a fillet having a sufficient amount of solder is enabled, while the package outer frame is thin-walled, when the solder fillet is formed to an electrode pad on a printed board by arranging the castellation on a package side surface and corners which correspond to external electrode on a package bottom surface. SOLUTION: The surface mount electronic component is provided with a package body 21 constituted by laminating at least two insulating sheet members and forming them integrally, the external electrode 22 for surface mount which is formed on an outer bottom surface of the package body, the recessed part 24 which is formed on the side surface of the package body corresponding to the external electrode and stretched in the vertical direction, and a metallized part 25 which is formed in the recessed part and electrically continuous to the bottom surface electrode. The recessed part is formed at least in the insulating sheet member 30 of the lowermost first layer, and the metallized part is formed in 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, and when mounting an electronic component having a box-shaped package structure such as a piezoelectric device on a printed circuit board, a wiring pattern is formed by soldering. The present invention relates to a surface mount type electronic component which can secure a sufficient fixing force and can secure a sufficient space for welding a metal lid while reducing the area of a package.

[0002]

2. Description of the Related Art In recent years, mobile communication devices such as mobile phones have been made smaller and lighter, but there has been an increasing demand for higher functionality. In order to meet the increasing number of components and miniaturization requirements associated with the higher functionality of these communication devices, the printed circuit boards that make up the electrical components are made smaller in area and the board area is effectively utilized by increasing the density of mounted components. It has come to be emphasized. Quartz resonators (resonators, filters), which are frequency control devices used in mobile communication equipment and transmission communication equipment, are no exception, and surface mount type is the mainstream for high density mounting. 3A and 3B are diagrams showing a mounting example of a piezoelectric device as an example of a conventional surface mount electronic component, FIG. 3A is an exploded perspective view, FIG. 3B is a diagram showing a state immediately before mounting, and FIG. It is an enlarged view of a solder connection part. Reference numeral 1 is a printed circuit board, and a wiring pattern (electrode pad) for mounting an electronic component 5 on the printed circuit board 1.
2 is formed. The electronic component 5 is, for example, a crystal resonator, and has external terminals 7 on the bottom surface of its package 6. Each external terminal 7 is an electrode pad 2 on a printed circuit board.
They are connected and fixed by the solder 3 in a one-to-one correspondence with.
The area of the electrode pad 2 is made sufficiently larger than that of the external terminal 7 and a part of the electrode pad 2 is projected to the outside of the side wall of the package 6, thereby increasing the amount of solder used for connection and after curing. The solder is designed so as to form a fillet shape ((c)). The fillet-shaped portion is a proof that the connection strength is strong, and by visually observing this, the connection state after the connection step can be easily inspected.

Meanwhile, when it becomes difficult to secure the area of the electrode pad 2 as large as the conventional one with the miniaturization of the printed circuit board and the high density mounting of mounting components, a situation occurs in which the solder fillet cannot be formed sufficiently. That is, when the area of the electrode pad 2 becomes smaller as shown in FIG.
Since there is less portion projecting outward than the side wall of, the solder fillet is not formed between the electrode pad 2 and the side wall of the package 6. For this reason, not only the connection strength due to the solder is significantly lowered, but also it becomes difficult to visually judge the suitability of the connection strength due to the solder. Therefore, it is necessary to increase the number of inspection processes using a special device to inspect the connection strength. Therefore,
Conventionally, an arc-shaped recess 1 as shown in FIGS.
0 is formed on the side surface of the package corresponding to the external terminal 7 on the bottom surface of the package, and the inner wall of the recess 10 is metalized 11 (castellation 12).
When the external terminal 7 is connected to the electrode pad 2 by the solder 3 as shown in (c), a part of the solder forms a fillet shape between the metallized portion 11 of the castellation 12 and the electrode pad 2. It is possible to increase the connection strength and visually judge the connection strength.
Alternatively, although not shown, a structure is also known in which a recess having a quarter circumference is formed in a vertical direction at a corner of the package and a metallized portion is formed on an inner wall of the recess.

By the way, FIGS. 6 (a), 6 (b) and 6 (c)
FIG. 4A is a cross-sectional view, a perspective view and a bottom view of a main portion of a piezoelectric device having a structure in which a piezoelectric vibrating element is hermetically sealed inside a package, and shows a side wall (or a corner) of a package 6 having a structure in which a plurality of ceramic sheets are laminated. Part), a recess 1 over the entire height
0 is set. A seal ring 16 is formed on the upper surface of the outer frame of the package 6 with a tungsten metallized film 15 interposed therebetween.
Are fixed, and a metal lid 17 is integrated with the upper surface of the seal ring 16 by welding or the like to hermetically seal the concave portion 18 on the upper surface of the package. The metal lid 17 is disposed on the upper surface of the outer frame of the package inside the recess 10 avoiding the recess 10. An internal terminal 20 that is electrically connected to the external terminal 7 is disposed on the step inside the recess 18, and a crystal vibrating element 22 is connected to the internal terminal 20 by a conductive adhesive 21. As the piezoelectric device becomes smaller, the package 6
Although it is required to further reduce the thickness of the outer frame of the seal ring 16, in order to secure the metal lid 17 on the seal ring 16 with sufficient strength and ensure the airtight sealing property, the width of the seal ring 16 is sufficiently wide. It is necessary to ensure that the contact area with the metal lid is large. However, since the space for installing the seal ring on the upper surface of the outer frame is reduced by forming the recesses 10 on the package side wall and the corners, there is a limit to the thinning of the outer frame of the package, which reduces the size of the piezoelectric device. Was an obstacle to. In other words, it was difficult to simultaneously satisfy the two requirements, that is, the requirement to secure a sufficiently wide width of the seal ring 16 and the requirement to reduce the thickness of the outer frame of the package that supports the seal ring 16 at the same time. Heretofore, by making the diameter of the recess 10 small, priority has been given to ensuring airtightness with a metal lid. For this reason, when soldering the package 6 to the electrode pad 2 on the printed circuit board, it is difficult to form a solder fillet having a sufficient size, and defective bonding (non-conduction, insufficient strength) is likely to occur.

[0005]

SUMMARY OF THE INVENTION The present invention has been made in view of the above, and when the electronic component having a box-shaped package structure such as a piezoelectric device is surface-mounted on a printed circuit board, the package bottom surface is mounted. When the casters are provided on the side and corners of the package that correspond to the external electrodes of the package and solder fillets can be formed between the external pads and the electrode pads on the printed circuit board, the casters can be made thin while the package outer frame is thin. It is possible to secure a large diameter for the recesses that make up the base plate and to form a sufficient amount of fillet, while ensuring a sufficiently large width of the seal ring on the top surface of the package outer frame to ensure that the An object of the present invention is to provide a surface mount electronic component having enhanced airtightness.

[0006]

In order to solve the above-mentioned problems, the invention of claim 1 is a package body formed by laminating at least two insulating sheet members made of an insulating material, and the package body. A surface mounting external electrode provided on the outer bottom surface of the package, a vertically extending recess provided on a side surface of the package body corresponding to the external electrode, and a metallized portion formed in the recess and electrically connected to the bottom electrode. In the surface mount type electronic component having the above, the recess is provided in at least the lowermost first-layer insulating sheet member, and the metallized portion is formed in the recess. And According to a second aspect of the present invention, when a recess communicating with the recess is formed in the insulating sheet member located above the insulating sheet member having the recess provided with the metallized portion, the diameter of the upper recess is formed. Is smaller than the diameter of the lower recess. According to a third aspect of the present invention, a part of the insulating sheet member located directly above the insulating sheet member provided with the recess is overhanged directly above the recess in an eaves-like shape, and the metallized portion is electrically connected to the metallized portion on the lower surface of the eaves portion. It is characterized in that a part is formed. According to a fourth aspect of the present invention, the surface mount electronic component is a piezoelectric resonator.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described in detail below with reference to the embodiments shown in the drawings. FIG. 1A is an external perspective view of an example of a surface-mounted electronic component according to an embodiment of the present invention, FIG. 1B is a sectional view taken along line AA of FIG. 1, and FIG. It is sectional drawing which shows the state after connecting. This surface mount type electronic component 20 is a package (package body) 2 made of an insulating material such as ceramic or resin.
The external electrodes 22 are provided on the bottom surface of the package 1, and castellations 23 each having a planar arc shape are formed on the side wall of the package 21 corresponding to each external electrode 22. The castellation 23 includes a recess 24 having a circular arc shape in a plan view, a metallized portion 25 formed on an inner wall of the recess,
It consists of Package 2 according to this embodiment
1 is three ceramic sheets (insulating sheet member) 3
It has a structure in which 0, 31, and 32 are laminated and integrated, and a piezoelectric resonator 34 is housed in a concave portion 33 provided on the upper surface. An annular seal ring 41 is laminated on the upper surface of the uppermost ceramic sheet 32 (the upper surface of the outer frame of the package) via an annular tungsten metallization 40, and a metal lid 42 is welded to the upper surface of the seal ring 41. The external electrode 22 is electrically connected to the internal electrodes 45, 46, etc.,
A recess 24 is formed on the side surface of the package corresponding to each external electrode 22.
And a metallization section 25
Are formed.

The characteristic structure of the present invention is that at least the lowermost ceramic sheet 3 has a structure of an arc-shaped recess 24 that vertically penetrates the three ceramic sheets 30, 31, 32.
This is because the diameter of the recessed portion 24a provided on the side surface of 0 is maximized, and the diameters of the recessed portions 24b and 24c provided on the ceramic sheets 31 and 32 located immediately above are reduced. In other words, at least the uppermost ceramic sheet 32
By making the diameter of the recessed portion 24c provided on the side surface of the device as small as possible or not providing the recessed portion 24c,
By securing the area of the upper surface of the ceramic sheet 32 as wide as possible, the annular tungsten metallization 4
The configuration is characterized in that the width and total area of the annular seal ring 41 fixed via 0 are secured large. Further, the metallized portion 25 is provided on the inner wall and the ceiling surface of the lowermost recessed portion 24a. Therefore, strictly speaking, the castellation 23 is provided only at the lowermost recess portion 2.
4a only. For the purpose of ensuring a sufficiently large area of the upper surface of the outer frame of the package, the upper ceramic sheets 31 except the lowermost ceramic sheet 30,
With respect to 32, it seems that it is not necessary to form the recessed portions 24b and 24c which cause the area of the outer frame upper surface to be narrowed. However, in the actual manufacturing process, after stacking three ceramic sheet base materials with a large area and baking them,
When the ceramic sheet is finally divided into individual pieces, the processes such as mounting the piezoelectric resonator in the concave portion at the site corresponding to each piece and sealing the concave portion with a metal lid are sequentially performed. If a through hole is not formed at a position corresponding to each recessed portion, burrs are likely to occur when dividing. In this way, in order to prevent burrs from being generated at the time of division, the side wall of the package piece is formed with a recess 24 that is continuous over the entire length in the vertical direction.

Even when the castellations 23 are formed at the corners of the package as shown in FIG. 2, the diameter of the lowermost recessed portion 24a is maximized. The other structure of the metallization unit 25 is the same as that of the embodiment of FIG. In the claims, the side surface of the package body includes the corners. The metallized portion 25 may be provided only on the inner wall of the lowermost recessed portion 24a, but it is also necessary to continuously form the metallized portion 25 on the lower surface of the ceramic sheet 31 projecting just above the recessed portion 24a in an eaves-like shape. It is preferable for ensuring solder joint strength. That is, it is preferable that the metallized portion 25 includes a metallized portion 25a corresponding to the inner wall of the recessed portion 24a and a metallized portion 25b corresponding to the ceiling surface of the recessed portion 24a. Since the castellation 23 for holding the solder 62 with the electrode pad 61 on the printed circuit board 60 is composed of the large-diameter recessed portion 24a and the metallized portion 25, the electrode pad 6 on the printed circuit board 60 is formed.
While a fillet made of a sufficient amount of solder can be formed when it is connected by means of 1 and the solder 62, the area of the upper surface of the outer frame of the package, that is, the uppermost ceramic sheet 32 is sufficiently wide, so that the metal lid 42 and the seal are secured. Ring 4
It is possible to secure a sufficiently large connection area with 1 and improve airtightness. In the above example, a package including three ceramic sheets has been described as an example, but the present invention can be applied to a package including two or more insulating sheets (not limited to ceramics). In the above embodiment, the electronic component that hermetically seals the piezoelectric resonator in the package is illustrated, but the present invention can be applied to other surface mount electronic components.

[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 surface-mounted on a printed circuit board, it corresponds to an external electrode on the bottom surface of the package. When the castellation is provided on the side and corners of the package to form a solder fillet between it and the electrode pad on the printed circuit board, the recess that forms the castellation while thinning the outer frame of the package The surface of the package outer frame that has a sufficiently large seal ring width while ensuring a sufficiently large diameter to form a sufficient amount of fillet, while increasing the airtightness after joining the metal lid. A mountable electronic component can be provided.

[Brief description of drawings]

FIG. 1A is an external perspective view of an example of a surface mount electronic component according to an embodiment of the present invention, FIG. 1B is a sectional view taken along line AA of FIG. 1, and FIG. It is sectional drawing which shows the state after connecting to.

FIG. 2 is a main part configuration diagram of an electronic component according to another embodiment of the present invention.

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

FIG. 4 is a diagram illustrating a main part configuration 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), (b) and (c) are explanatory views of another conventional example.

[Explanation of symbols]

20 surface mount type electronic component, 21 package (package body), 22 external electrode, 23 castellation, 24 recess, 24a, 24b, 24c recess part (recess), 25 metallized part, 30, 31, 32 ceramic sheet (Insulating sheet member), 33 concave portion, 3
4 Piezoelectric resonator, 40 Tungsten metallization, 41
Seal ring, 42 metal lid, 45, 46 internal electrode, 60 printed circuit board, 61 electrode pad, 62 solder.

Claims (4)

[Claims] 1. A package body formed by laminating at least two insulating sheet members made of an insulating material, a surface mounting external electrode provided on an outer bottom surface of the package body, and the external electrode. In a surface-mounted electronic component including a vertically extending recess provided on a side surface of a corresponding package body, and a metallized portion formed in the recess and electrically connected to the bottom electrode, the recess is at least A surface mount type electronic component, which is provided on the insulating sheet member of the first layer at the bottom and has the metallized portion formed in the recess. 2. When a recess communicating with the recess is formed in the insulating sheet member located above the insulating sheet member having the recess provided with the metallized portion, the diameter of the upper recess is reduced. The surface mount type electronic component according to claim 1, wherein the diameter is smaller than the diameter of the side recess. 3. A portion of the insulating sheet member located directly above the insulating sheet member provided with the recess is overhanged directly above the recess in the shape of an eaves, and a metallized portion electrically connected to the metallized portion is provided on the lower surface of the eaves portion. The surface mount electronic component according to claim 1, wherein the surface mount electronic component is formed. 4. The surface mount electronic component according to claim 1, wherein the surface mount electronic component is a piezoelectric resonator.