JP3501192B2 - Surface mount type electronic unit package - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a surface mount type unit package, and in particular, a metal thin plate lead terminal is integrally molded to expose the lead terminal on the bottom surface and a circuit element or the like on the top surface. In an electronic unit package having a resin base portion provided and an inverted bowl-shaped metal container covering the base portion from above, a solder connection strength between the base portion and the metal container is increased and a solder bridge between lead terminals is provided. A surface mount electronic unit package capable of preventing the occurrence of

[0002]

2. Description of the Related Art In recent years, various electronic devices have been miniaturized, but in communication devices such as mobile phones and pagers, the tendency toward smaller size and lighter weight is particularly remarkable. Also, in accordance with the demand for miniaturization, the parts and functional packages used have become smaller,
As a mounting form of electronic parts, a surface mounting type suitable for double-sided mounting of a printed circuit board is generally used. by the way,
In the case of surface mount type electronic unit package, it may be difficult to solder the lead terminals drawn from the bottom of the package, etc. onto the conductor pattern of the printed circuit board, which may be difficult. Was a big problem. That is, in the past, since a thin metal plate bent in an L shape or a crank shape and easily deformed was taken out from the package as a lead terminal, if the lead terminal is deformed during handling, the conductor on the printed circuit board may be changed. The adhesion to the pattern surface was lost, and as a result, defective soldering was likely to occur.

As a means for solving such a problem, there is a functional package disclosed in Japanese Patent Laid-Open No. 5-37279. As shown in FIG. 5 (a), each lead terminal 1 is integrally formed on the bottom surface by mold resin molding, and metal holding pieces 3 are vertically provided on two opposing side walls. The base 2 and the metal container 5 placed on the base 2 so as to cover the entire side wall of the base 2 are provided, and the metal holding piece 3 and the corresponding metal container 5 have a notch 4 in the side wall thereof. The lead terminal 1 is shown in FIGS.
As shown in FIG. 3, the end portion 1a is bent in a crank shape and is in contact with the conductor pattern 7 on the printed circuit board 9 so as to be flush with the bottom surface of the base portion 2. When assembling the base 2 and the metal container 5, as shown in the perspective view of FIG. 5 (b) and the AA cross-sectional view of FIG. 5 (c), a cutout is formed when the base 2 is covered with the metal container 5. The metal holding piece 3 exposed from the portion 4 and the peripheral portion of the cutout portion 4 of the metal container 5 are joined by solder 6.

[0004]

However, in such a conventional joining structure, the holding piece 3 and the metal container 5 are provided.
In order to avoid problems such as the solder 6 protruding beyond the external dimension standard when soldering the notch 4 of
High accuracy is required for soldering, and work efficiency is poor. Further, when mounting the surface mount type electronic component on the printed circuit board in a reflow bath or the like, if the base 2 and the metal container 5 are simply fixed by soldering, the solder 6 is melted by the heat at the time of reflow and the base 2 is melted. Therefore, the metal container 5 is likely to be displaced. In particular, when the surface mount unit package is a crystal oscillator, the sensitivity of the crystal blank, which is an internal component of the container, is sensitive to changes in electrical capacitance, so that the internal component and the metal container 5 are relatively separated from each other. When the position shifts, the frequency precisely adjusted by the unit manufacturing manufacturer at the time of shipment shifts, and it is necessary to readjust the frequency. Further, in the case of a double-sided printed circuit board, after the components are mounted on the board surface on one side, the work is performed by reversing the board surface and reflow-mounting it on the opposite side surface.
When the base portion 2 and the metal container 5 are joined only by themselves, the metal container 5 often comes off when the substrate is reversed. In order to prevent this, measures such as using an adhesive together to strengthen the bonding force may be considered, but it is not suitable for cost reduction because the number of steps increases.

Further, in the lead-out structure of the lead terminal 1 as shown in FIG. 6 (a), when the lead terminal 1 is pressed against the conductor pattern 7 for reflow connection, the conductor pattern 7 is used.
There is a possibility that the upper cream solder 8 may get over the conductor pattern and spread on the printed board 9 to form a solder bridge between the adjacent conductor patterns, resulting in a short circuit between terminals. It is difficult to find the inter-terminal bridge hidden in the parts,
In some cases, not only the parts but the device itself was defective. 6B shows the shape of the solder fillet 16 formed between the conductor pattern 7 and the lead terminal 1 when the electronic unit package of FIG. 6A is mounted on the printed board. The solder fillet 16 is formed only between the lead terminal 1 protruding from the bottom edge of the base 2 and the conductor pattern 7, and the lead terminal 1 and the conductor pattern 7 located in the bottom edge of the base 2 are formed. No solder fillet is formed between and. For this reason, the solder joint strength at the time of mounting was insufficient, and the solder was likely to drop off.

The present invention has been made in order to solve the various problems associated with the conventional electronic surface mount type unit package as described above, and the shift of the metal container at the time of reflow is achieved by a simple structure. We provide a surface mount type unit package that prevents the oscillation frequency from being shifted and the metal container from falling off when the board is inverted for double-sided mounting, and eliminates unnecessary work such as applying adhesive. The purpose is to do. Further, it is possible to eliminate problems such as occurrence of solder bridging due to invasion of solder between the unit and the printed circuit board, and defective bonding due to a narrow area where the solder is bonded in a fillet shape.

[0007]

In order to solve the above-mentioned problems, in claim 1, the metal thin plate lead terminal and the lead frame are integrally molded to expose the lead terminal on the bottom surface and the upper surface. In an electronic unit package having a resin base provided with circuit elements and the like, and an inverted bowl-shaped metal container covering the base from above, a notch is provided in a part of the peripheral edge of the base, A part of the ground electrode of the lead frame is exposed in the cutout portion, and the grounded electrode portion exposed in the cutout portion and the inner wall of the metal container are fixed by soldering. Is characterized by. According to a second aspect of the present invention, an inclined surface is provided in the notch provided in the base portion, and a part of the ground electrode of the lead frame is exposed on the inclined surface and exposed on the inclined surface. The ground electrode part and the inner wall of the metal container are soldered. In Claim 3, a recess (hole) or a protrusion is provided in a part of the metal container, and the base is provided with a protrusion or a recess (hole) that can be engaged with the recess or protrusion of the metal container, respectively. Is provided. According to a fourth aspect of the present invention, the lead terminal is provided on the bottom surface of the base portion so as to be substantially flush with the bottom surface, and a groove is provided in the bottom surface portion of the base portion surrounding the lead terminal.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described in detail below with reference to the illustrated embodiments. FIG. 1A is an exploded perspective view of a crystal oscillator unit package adopting the present invention,
2B is a perspective view of the assembled state, and FIG.
FIG. 2B is a cross-sectional view taken along the line BB in FIG. 2B, and FIG. 2B is a perspective view showing the overall structure of the lead terminal. The lead terminal 1 and the lead-out terminal 31 arranged as shown in FIG.
The base portion 32 is integrally formed by the mold resin molding, and the convex portions 10 for locking are formed on the two opposing side surfaces of the base portion 32, and the side surfaces immediately below each convex portion 10 are formed. An inclined cutout 11 is provided. This slanted notch 1
As shown in FIG. 2 (d), the metal surface 12 located at the end of the ground plate (lead frame) 31A connected to the lead-out terminal 31 is exposed at 1. Further, a hole 13 is provided in a portion of each side wall of the inverted bowl-shaped metal container 35 which covers the base 32, corresponding to each protrusion 10, so that the protrusion 10 can be detachably engaged with the hole 23. To configure. As shown in FIG. 1B, when the base 32 is covered with the metal container 35, the convex portion 10 is fitted into the hole 13 so that the metal container 35 is fixed to the base 3.
Fixed to 2. Also, FIG. 2 (a) is shown in FIG. 1 (b).
FIG. 9 is a cross-sectional view taken along line BB of FIG.
The metal surface 12 and the lower portion of the inner wall of the metal container 35 are joined by the solder 36 in order to have a heating effect.

According to this embodiment, the base portion 32 and the metal container 35 are joined not only by the solder 36 but also by the mechanical joining between the convex portion 10 and the hole portion 13. Therefore, at the time of reflowing. Even if the solder 36 is melted and the joining force is reduced, the metal container 35 is prevented from being displaced due to the joining force between the convex portion 10 and the hole portion 13.
The relative position of the metal container 35 with respect to 2 can be secured. Moreover, since the connection between the convex portion 10 and the hole portion 13 is utilized, accurate assembly can be easily performed. Further, when soldering the base 32 and the metal container 35, the metal surface 12 and the inner wall of the metal container 35 at the recessed position secure a soldering space, so that the solder 36 protrudes from the external dimension standard. It is possible to avoid such problems.

Next, FIGS. 3 (a) and 3 (b) are an exploded perspective view and a sectional view taken along line CC of another embodiment of the present invention. The package of this embodiment is shown in FIG. 1 (a). Base 32 of
It is a modification of the fixing method of the metal container 35 and the. That is, the recesses 14 are provided on the two side surfaces of the base 42, and the metal container 45
In this case, a convex portion 15 is provided at a portion corresponding to the concave portion 14 to fit and fix the both. The base 42
You may provide a convex part on the side and provide a concave part on the metal container 45 side. Other configurations are similar to those of the base and the metal container of the first embodiment.

According to the structure of this embodiment, when the base 42 and the metal container 45 are soldered, the metal surface 12 and the inner wall of the metal container 45 secure the soldering space, so that the external dimension standard is satisfied. It is possible to avoid problems such as the solder 36 protruding from the concave portion 14 and the convex portion 15.
Since the base portion 42 and the metal container 45 are fixed by the above, accurate assembly can be easily performed. Further, even if the solder 36 is melted by mounting in a reflow tank or the like, the relative position of the metal container 45 with respect to the base 42 can be secured. Therefore, even if the oscillator is housed in this package, the relative position of the metal container and the oscillator element plate will not be displaced, so that stable frequency characteristics are always ensured and productivity and yield are kept high. can do.

Next, FIGS. 4 (a) and 4 (b) are a perspective view and a partial cross-sectional perspective view of a main part of another embodiment of the present invention. -It is characteristic that the groove 15 is provided around the terminal 1. That is, in the above-mentioned conventional example, since the outer peripheral edge portion of the lead terminal 1 and the base bottom surface are in close contact with each other, a solder bridge occurs between adjacent lead terminals, or the amount of solder solidified in a fillet shape is extremely limited. However, since the groove 15 is provided between the outer peripheral edge of the lead terminal and the bottom surface of the base in this embodiment,
Such problems can be solved all at once.

That is, FIG. 4B illustrates the effect of the embodiment shown in FIG. 4A, and shows the solder fillet shape 16 after the unit is mounted. That is, as in this embodiment, the groove 15 is provided at the boundary between the lead terminal 1 and the base portion 32, which is in contact with the lead terminal 1, so that the melted solder is melted from the bottom surface of the base portion 32 and the printed board. 9
Even if an attempt is made to spread between and, it will be absorbed by the groove 15 and will not spread any further. Therefore, it is possible to prevent a solder bridge from occurring between the adjacent lead terminals 1. With the miniaturization of lead terminals year by year,
The lead terminal 1 and the conductor pattern 7 are joined to each other by a fillet-like solder joint over a wide area around the peripheral edge of the lead terminal, so that not only electrical contact but also mechanical strength is improved. .

[0014]

Since the present invention is constructed as described above, the base portion and the metal container, which are once joined together, will not be separated or displaced during reflow mounting. Therefore, there is no need to readjust the frequency after product assembly. In addition,
Providing a groove on the peripheral edge of the terminal prevents the occurrence of a hard-to-find blit such as the bottom surface of the unit, and is effective in significantly reducing the defective rate of the product.

[Brief description of drawings]

1A is an exploded perspective view of a crystal oscillator unit package adopting the present invention, and FIG. 1B is a perspective view of an assembled state.

2A is a sectional view taken along line BB in FIG. 1B, FIG.
FIG. 3B is a perspective view showing the overall structure of the lead terminal.

3A and 3B are exploded perspective views and CC of a surface mount type electronic unit package according to another embodiment of the present invention.
Sectional view.

4 (a) and 4 (b) are configuration explanatory views of a lead terminal portion of the surface mount type electronic unit package of the present invention.

5 (a), (b) and (c) are exploded perspective views, assembly diagrams, and examples of a conventional surface mount type electronic unit package.
And AA sectional drawing.

6 (a) and 6 (b) are views for explaining a defect in a lead terminal portion of a conventional surface mount type electronic unit package.

[Explanation of symbols]

1: lead terminal, 31: ground lead terminal, 2: base,
32: base part, 42: base part, 3: holding piece, 4: notch,
5: Metal container ,: Solder, 36: Solder, 7: Print pattern, 8: Cream solder, 9: Printed board, 1
0: convex part, 11: notch part, 12: metal surface, 13: hole part, 14: concave part, 15: convex part, 15: groove, 16: fillet shape 35: metal container, 45: metal container,

─────────────────────────────────────────────────── ─── Continuation of the front page (58) Fields surveyed (Int.Cl. ⁷ , DB name) H01L 23/50 H01L 23/28 H03B 5/32

Claims (4)

(57) [Claims] 1. A resin-made base having a thin metal plate lead terminal and a lead frame integrated with each other so that the lead terminal is exposed at the bottom and a circuit element or the like is provided on the top. In an electronic unit package having an inverted bowl-shaped metal container to be covered from above, a notch is provided in a part of the peripheral edge of the bottom surface of the base, and the ground electrode of the lead frame is provided in the notch. A surface mount type electronic unit package, characterized in that a part of the metal is exposed and the earth electrode part exposed in the notch and the inner wall of the metal container are fixed by soldering. 2. A sloping surface is provided in the notch formed in the base portion, and a part of the ground electrode of the lead frame is exposed on the sloping surface and is exposed on the sloping surface. I did
The surface mount type electronic unit package according to claim 1, wherein the electrode portion and the inner wall of the metal container are soldered. 3. A concave portion (hole portion) or a convex portion is provided in a part of the metal container, and a convex portion or a concave portion (hole portion) which can be engaged with the concave portion or the convex portion of the metal container, respectively, is provided in the base portion. The surface mount type electronic unit package according to claim 1 or 2, further comprising: 4. The bottom surface of the base portion is provided with a lead terminal extending substantially flush with the bottom surface, and a groove is provided in a bottom surface portion of the base portion surrounding the lead terminal. The surface mount type electronic unit package according to item 2, 3 or 4.