JP3745835B2 - Package structure of electronic components - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an improvement of a package having a structure in which a printed circuit board on which an electronic component is mounted is sealed with a case, and in particular, a package structure of an electronic component that does not cause complicated structure, large case height, and complicated assembly work. About.
[0002]
[Prior art]
For an electronic circuit that requires temperature compensation, electromagnetic shielding, etc., such as an oscillation circuit using a piezoelectric device such as a crystal resonator, the printed circuit board with the electronic circuit is sealed in a shield case. Are unitized and incorporated into apparatus main bodies such as electronic devices and communication devices.
FIGS. 6A and 6B are an external perspective view and a bottom perspective view of an example of a conventional electronic component package. The package 1 has an upper surface of a printed circuit board 3 having a wiring pattern and an electronic component 2 on the upper surface. The package 1 is provided with a notch 3a at the center of two opposing edges of the printed circuit board 3, and a case edge corresponding to the notch 3a. The case 4 is assembled to the printed circuit board 3 in a state in which the protruding piece 4a that fits into the notch 3a is projected from the lower edge portion, and the protruding piece 4a is fitted into the notch 3a. The case 4 is fixed to the printed board 3 with solder 5 between the back side of the protruding piece 4a and the back side of the printed board in a state where the package is turned over as shown in FIG.
However, in this conventional example, since a part of the case protrudes on the back side of the printed circuit board, there is a problem that the total height of the package becomes large and violates the demand for miniaturization, and the package is turned over. Since it is necessary to perform solder connection, there is a drawback that workability is deteriorated.
[0003]
6 is a type in which the L-shaped lead terminal 6 protrudes below the printed circuit board 3, but in addition to this, pad-shaped lead terminals are arranged in a plane along the bottom surface of the printed circuit board. There are also things. However, in this type, the protrusion 4a cannot be protruded from the case, so it is necessary to fix the case side wall and the substrate edge with solder or an adhesive. However, it is difficult to secure a soldering cost and the like, resulting in problems such as an increase in the size of the package and a complicated assembly work.
JP-A-8-37421 discloses a constant potential having the same area as that of the multilayer structure substrate via the multilayer structure substrate below the multilayer structure substrate on which the crystal resonator and the plurality of circuit elements are placed. A temperature-compensated crystal oscillator having a configuration in which a shield layer 8 as a surface is interposed is disclosed, and by providing the configuration as described above, the labor for fine frequency adjustment at the time of mounting on a substrate is omitted, resulting from the adjustment. Thus, fluctuations in electrical characteristics such as oscillation frequency, frequency temperature characteristics, current consumption, and output voltage are prevented. However, this conventional example has a drawback that since the board structure is complicated, the board itself is expensive and it is difficult to automate the process of mounting the components in the recesses on the board.
[0004]
[Problems to be solved by the invention]
The present invention has been made in view of the above, and in a package having a structure in which a printed circuit board on which electronic components are mounted is sealed by a case, the structure is complicated, the case is enlarged, and the assembly work is complicated. It is an object of the present invention to provide a package structure for electronic components that does not have any problem.
[0005]
[Means for Solving the Problems]
In order to achieve the above object, the invention of claim 1 is directed to a printed circuit board having a surface mounting pad on the lower surface, an electronic component mounted on the upper surface of the printed circuit board , and surrounding and storing the electronic component. And a box-shaped metal case having four open side walls that seals the upper space of the printed circuit board, and a conductor formed at each of two opposing edge positions on the upper surface of the printed circuit board. with a film, the tilt angle of one position to the inward direction of the two opposing husband a lower side wall portions corresponding to portions of the respective conductive film s formed two right and left sandwiched sidewall portion cut in the metal casing a retraction piece formed by bending retracted, and respectively formed protrusions or recesses in place of the lower edge of the other two opposite side walls of the metal case, the print corresponding to the convex portion or concave portion With the other two edges respectively formed concave or convex portion of the plate, wherein the side wall portion constituting the respective retraction piece has a length which does not protrude from said two side walls lower down, The convex portions and the concave portions are fitted to each other, and the lower end edge of each retracting piece is electrically and mechanically connected and fixed with solder in a state of being in contact with each conductive film surface. The convex portions or concave portions provided on the side walls and the edge of the printed circuit board are respectively provided on the other two side walls of the metal case and the other two edge portions of the printed circuit board. Is characterized by an asymmetric positional relationship .
A second aspect of the present invention provides the first side wall of the metal case or the central portion of one end edge of the printed circuit board according to the first aspect, with one convex portion or a concave portion and the other side wall facing the other side or the other side. It is characterized in that two convex portions or concave portions are arranged at symmetrical positions across the other side wall or the central portion of the other end edge at the end edge.
A third aspect of the present invention provides the first side wall of the metal case or the central portion of one end edge of the printed circuit board according to the first aspect. One convex portion or a concave portion is provided at a non-central position of the end edge of this.
According to a fourth aspect of the present invention, in the first aspect, the one side wall of the metal case or the one edge of the printed circuit board is provided with one convex portion or a concave portion, and the other side wall facing each other, or One convex portion or a concave portion is provided at a position that is a non-center position of the other end edge and is opposed to the one convex portion or the concave portion.
According to a fifth aspect of the present invention, in the first, second, third, or fourth aspect, the conductor film is connected to a ground of an electronic circuit on the printed circuit board.
According to a sixth aspect of the present invention, in any one of the first to fifth aspects, the conductive film is obtained by metallizing a surface of a base material made of a nonconductive material with a conductive metal.
[0006]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be described in detail with reference to embodiments shown in the drawings. Figure 1 (a) and (b) an embodiment exploded perspective view of the electronic component package of the present invention, and is a rear view of the printed circuit board, FIG. 2 (a) (b) and (c) assembled state FIG. 3 is a perspective view, an enlarged view of a main part, and an AA cross-sectional view. The package 10 includes a printed circuit board 12 on which an electronic component 11 is mounted, and a metal case 13 (the lower part is opened) that encloses the electronic component 11 on the printed circuit board 12 and seals the upper space of the printed circuit board 12. And a box having four side walls ). The characteristic configuration of the package 10 is that a conductor film 15 is formed at an appropriate position on the edge of the upper surface of the printed circuit board 12, and a portion corresponding to the conductor film at the lower portion of the side wall of the metal case 13 is free inward and outward. Thus, the retracting piece 16 formed by forming a cut in the lower portion of the side wall is provided. Then, when the metal case 13 is placed on the printed circuit board with the retracting piece 16 inclined to the inside of the metal case 13 by a predetermined angle, the tip of the retracting piece 16 comes into contact with the conductor film 15. The electrical and mechanical connection is fixed. This contact state may be an elastic pressure contact or an inelastic simple contact.
[0007]
In FIG. 1, the conductive film 15 and the retracting piece 16 are provided in the center part of the short side where the printed circuit board 12 and the metal case 13 face each other, but this is an example, and these are on the short side or the long side. It may be provided at any position.
The illustrated retraction piece 16 is formed by bending inward a portion formed by forming two cuts in the case side wall, but this is only an example, and a part of the side wall is pressed. The retracting piece may be formed by indenting inward.
The conductor film 15 is formed, for example, by metallizing the base material of the printed circuit board 12, that is, the surface of a nonconductive material, with a conductive metal. As the metal material to be used, for example, a silver-palladium film, a nickel film, and a gold film which are sequentially stacked and plated are used. The silver-palladium film is used as the lowermost film because it is easy to be familiar with the ceramic substrate, the gold film is used because it is well compatible with the solder, and the nickel film eliminates the incompatibility between the silver-palladium film and the gold film. Therefore, it is used as an intermediate film.
[0008]
In this embodiment, as a positioning method for attaching the metal case 13 to the printed circuit board 12, a convex portion or a concave portion 20 is formed at an appropriate position on the lower edge of the side wall of the metal case 13, and the convex portion or concave portion 20 on the case side is formed. Concave portions or convex portions 21 are provided on the corresponding edge of the printed circuit board, and the respective convex portions and the respective concave portions are fitted to each other. Positioning is completed by fitting one protrusion into the other recess.
After the positioning is completed, solder is poured between the outer surface of the retracting piece 16 retracted inward from the side wall of the metal case and the upper surface of the conductive film 15, thereby electrically and mechanically connecting the retracting piece 16 and the conductive film 15. Secure to.
In this connection operation, the electronic components on the substrate are temporarily fixed on the substrate using cream solder in advance, and the case is covered with cream solder between the retraction piece 16 and the conductor film 15. By heating the entire package after filling, the electronic components and the case can be reflow-connected on the substrate in a lump.
Of course, the case may be connected and fixed on the substrate after the electronic component is fixed on the substrate.
[0009]
The conductor film 15 is connected to the ground of the electronic circuit on the printed circuit board as necessary. By comprising in this way, a metal case can exhibit a shielding effect.
In addition to the metal material, the case 13 may be made of ceramic or heat resistant resin. When a case other than a metal material is used, if it is desired to have a shielding effect, the case surface may be metallized. In particular, the retracting piece 16 portion in contact with the conductor film 15 needs to be processed to have a conductive surface by metallization or the like.
Next, the positioning protrusions or recesses are arranged as described above. In FIGS. 1 (a) and 1 (b), positioning is performed by providing a protrusion and a recess at the center of each of the opposing side walls and edges. However, when configured in this way, a situation in which the front-rear direction of the case and the front-rear direction of the printed board are assembled by mistake is likely to occur.
In order to prevent the occurrence of such erroneous mounting, the convex portions or concave portions 20 formed on the opposing side walls or the concave portions or convex portions 21 respectively formed on the opposing edges are in an asymmetric state. It is effective to vary the position, number, etc. of each.
1B, reference numeral 22 denotes a pad used when the package is surface-mounted on another substrate, and 23 denotes a solder pool.
[0010]
FIGS. 3A, 3B, and 3C are schematic plan views showing examples of configurations for preventing erroneous mounting when a metal case is mounted on a printed circuit board, respectively. First, FIG. 3A shows two sides S1 facing each other. , S2 is provided with one convex portion or concave portion 20, 21 at the center of one side S1, and the other side S2 has two convex portions symmetrically about the center C of the side S2. Or the recessed parts 20 and 21 were arrange | positioned. Since the convex portions or the concave portions 20 and 21 are arranged on the two sides S <b> 1 and S <b> 2 that face each other in the asymmetrical positional relationship and number, the erroneous mounting can be prevented.
Next, in the example of FIG. 3B, one convex portion or concave portion 20, 21 is arranged at the center position of the other side S2, and the convex portion or concave portion 20, 21 is arranged at a non-center position of one side S1. By arranging the, the positional relationship between the convex portions or the concave portions 20 and 21 on both sides S1 and S2 is made asymmetric to prevent erroneous mounting. In this example, the positions of the convex portions or the concave portions 20 and 21 on the side S2 may be provided at a non-center portion of the side S2 and asymmetric.
In the example of FIG. 3 (c), erroneous mounting is prevented by arranging convex portions or concave portions 20, 21 provided on the sides S1, S1 one by one in a facing positional relationship.
[0011]
Next, FIG. 4 is an exploded perspective view of a package according to another embodiment, and FIGS. 5A, 5B, 5C, and 5D are a front sectional view, a side view, and an entire configuration of the package according to this embodiment. It is the block diagram of a case, and the structure of a printed circuit board.
The feature of this embodiment is that a multilayer substrate is used as the printed circuit board 12, and the upper surface of the opposing edges of the multilayer substrate is cut into a groove with a predetermined depth so as to be embedded in the thickness of the substrate and A part of the ground electrode film 25 having an area substantially equal to the substrate area is exposed, and a retraction piece 16 protruding downward from the case 13 is electrically connected and fixed to the exposed ground electrode film 25. The case 13 is located on the multilayer substrate 12.
The retraction piece 16 provided in the case 13 of this embodiment protrudes downward by a predetermined length from the bottom bottom edge of the case, and the protrusion length of the retraction piece 16 is lower when the case 13 is closed on the substrate. The tip of the retracting piece 16 is set so as to be in contact with the electrode film 25 on the bottom surface of the groove 26.
With this configuration, the case positioning is completed simply by covering the case 13 on the substrate in such a positional relationship that each retraction piece 16 enters each groove 26 on the substrate. Fixing is completed by fixing the joint with the electrode film 25 with solder. In this embodiment, the retracting piece 16 and the groove 26 can also serve as positioning means, so that there is no need to provide positioning protrusions or recesses 20, 21 as in the above embodiment.
It should be noted that one or both of the grooves 26 and the retracting pieces 16 may be shifted from the center position in the drawing by a predetermined distance so that the case mounting direction with respect to the substrate is not mistaken, or the widths of the respective retracting pieces 16 are different. In addition, it is preferable that the positions of both grooves and the retracting pieces are asymmetric.
Moreover, in the said example, although the groove | channel and the evacuation piece were provided one by one, you may provide two or more as needed.
[0012]
【The invention's effect】
As described above, according to the present invention, a part of the lower edge portion of the case does not protrude downward beyond the lower surface of the substrate, so that the height of the package can be kept low. Automatic mounting is easy because the case is simply placed on the board and then soldered as it is without turning the board over when soldering. Since the case can be soldered to the board together with the electronic components on the board by reflow, the connecting operation can be realized in one step. Further, the positioning of the case is facilitated by providing the positioning concave and convex portions. Recess for positioning the convex portion, the positional relationship of the non-symmetrical, and by arranging in number, it is possible to prevent the mounting incorrectly orientation of the case relative to the substrate. Furthermore, when applied to a multilayer substrate, the positioning concave portions and convex portions can be omitted, and the configuration and workability can be simplified.
[Brief description of the drawings]
FIGS. 1A and 1B are an exploded perspective view of an electronic component package according to an embodiment of the present invention and a bottom configuration diagram of a printed circuit board.
FIGS. 2A, 2B, and 2C are a perspective view, an enlarged view of a main part, and an AA cross-sectional view showing an assembled state of the package of FIG. 1;
FIGS. 3A, 3B, and 3C are schematic plan views showing configuration examples for preventing erroneous mounting, respectively.
FIG. 4 is an exploded perspective view of a package according to another embodiment of the present invention.
FIGS. 5A, 5B, 5C, and 5D are a front sectional view, a side view, a case configuration diagram, and a printed circuit board configuration diagram showing the overall configuration of the package of the embodiment of FIG.
6A and 6B are a perspective view and a bottom perspective view showing a configuration of a conventional package, respectively.
[Explanation of symbols]
10 package, 11 electronic component, 12 printed circuit board, 13 metal case, 15 conductor film, 16 retracting piece, 20 convex portion or concave portion, 21 concave portion or convex portion, 25 electrode film, 26 groove.

Claims (6)

A printed circuit board having a surface mounting pad on the lower surface, an electronic component mounted on the upper surface of the printed circuit board , and a lower portion for sealing the upper space of the printed circuit board to surround and store the electronic component; In a package comprising a box-shaped metal case having four side walls, conductor films formed respectively at appropriate positions on two opposite edges of the upper surface of the printed circuit board, and lower portions of the two opposite side walls of the metal case. A retracting piece formed by bending and retracting one portion of the side wall portion sandwiched between the two left and right cuts formed respectively in the portion corresponding to each of the conductor films, and the metal case; and place respectively formed projections or recesses opposite the other two side walls of the lower edge of the recess also being formed respectively on the two other edges of the printed circuit board corresponding to the convex portion or concave portion Includes a convex portion,
The side wall portion constituting each retraction piece has a length that does not protrude downward from the lower portions of the two side walls,
The convex portions and the concave portions are fitted to each other, and the lower end edge of each retracting piece is electrically and mechanically connected and fixed with solder in a state of being in contact with each conductive film surface. The convex portions or concave portions provided on the side walls and the edge of the printed circuit board are respectively provided on the other two side walls of the metal case and the other two edge portions of the printed circuit board. Is a package structure of an electronic component, characterized by having an asymmetric positional relationship. One convex portion or concave portion is provided in the central portion of one side wall of the metal case or one end edge of the printed circuit board, and two convex portions or concave portions are provided on the other side wall or the other end edge facing each other. 2. The electronic component package structure according to claim 1 , wherein the other side wall or the central portion of the other end edge is disposed at a symmetrical position. One convex portion or concave portion is provided in the central portion of one side wall of the metal case or one end edge of the printed circuit board, and one convex portion is provided at a non-center position of the opposite side wall or the other edge. The package structure for an electronic component according to claim 1 , wherein a recess is provided. One convex portion or a concave portion is provided on one side wall of the metal case or one end edge of the printed circuit board, and the other side wall or the other end is opposed to a non-center position. The package structure for an electronic component according to claim 1 , wherein one convex portion or concave portion is provided at a position facing one convex portion or concave portion. Claim 1, characterized in that said conductive film is connected to the ground of the electronic circuit on the printed circuit board, according to claim 2, package structure of an electronic component according to claim 3, or claim 4. The conductive film, according to claim 1, characterized in that the surface of the substrate made of non-conductive material is obtained by metallization of a conductive metal, claim 2, claim 3, claim 4, or claim 5 A package structure of an electronic component according to any one of the above.

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