JP2000236155A - Package of surface mount components - Google Patents

Abstract

(57) [Problem] To provide a replaceable package with high density and little electrode damage due to external stress by increasing the number of electrodes and increasing the connection strength of the electrodes. A dead space (component mounting prohibition area) 13 for an exchange jig used when exchanging a package is provided between a package 11 and a peripheral portion of a printed wiring board 10, and a predetermined space is provided in the dead space 13 from the package 11. The projections 14, 16, 18, 20, 22, 24,
26 and 28 are provided. For this reason, the package area can be increased by the amount of the protrusion while leaving a dead space for component replacement, so that the package can be replaced and the dead space can be effectively used.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a package structure of a surface mounting electronic component, and more particularly, to various electronic components including a semiconductor component having an electrode provided on a bottom surface mounted on a printed circuit board or the like. For the package.

[0002]

2. Description of the Related Art Conventionally, a BGA (Ball Grid Array) mounted by soldering or the like on a printed wiring board (a raw board on which no components are mounted, for example, a bare board).
), Etc. when replacing the bottom electrode type package
A jig space has been provided for allowing heat to reach the electrode portions on the lower surface of the package in the peripheral region of the component mounting portion to melt the solder connecting the pads and the electrodes on the substrate. This is because when it is necessary to replace the part for various reasons while completing the mounting on the board,
Printed circuit board (board on which components are mounted) 11
3 This is a measure to repair and use the board only by replacing the problematic parts without discarding the whole, and it is an operation that is arbitrarily performed as necessary in the assembly process of the printed circuit board, etc. is there. That is, FIG. 6 is a plan view showing a state in which a package 112 of a surface-mount component of a bottom electrode type is mounted on a conventional printed wiring board 110.
On the printed circuit board (board on which components are mounted) 113 configured as described above, since the package is to be replaced over a width of about 2 mm around the package 112, mounting of the components is prohibited. A mounting prohibited area (here, also referred to as a dead space) 114 was provided. By using the component mounting prohibited area 114, a jig such as a solder gaunt is inserted into the space between the component and the substrate to melt the solder connecting the electrode and the pad, and to remove the component. Was. The above-mentioned BGA package and printed circuit board are disclosed in Japanese Patent Application Laid-Open No. 9-6452.
No. 9 and Japanese Patent Application Laid-Open No. 9-307225, all of which disclose the repair (replacement) of components using low melting point solder, and are directly related to the present invention. I haven't.

[0003]

As described above, in a conventional package of a surface mounting component, a package 112 such as a BGA having an electrode on the bottom surface of the package is soldered on a pad on a printed wiring board 110. Thus, a printed circuit board 113 is configured. In order to remove and replace the package 112 mounted on the printed circuit board 113, the printed circuit board 1
It was necessary to provide a dead space (component mounting prohibited area) 114 for a replacement jig in a circumference of about 2 mm on the top of the device 10.
However, while it is necessary to provide the dead space 114 on the printed wiring board 110, it is desired to effectively utilize the dead space 114 in order to respond to the recent demand for a higher density of the printed circuit board 113. It is rare. In other words, the number of signals that can be extracted from a fixed area in the printed wiring board is limited to a fixed number mainly by the restrictions on the printed wiring board side, and the layout and the number of electrodes on the package side are determined by these restrictions. It is. Therefore, in order to increase the number of electrodes on the component side in response to a demand for higher density of the printed circuit board, the existence of the dead space described above has been a bottleneck. In addition, a package of a bottom electrode type such as a BGA package receives an external stress compared to a package (for example, QFP) of a type in which an electric signal is extracted through a lead terminal protruding laterally from a package body. In this case, since the structure is difficult to buffer, the connection strength of the bottom electrode in the vicinity of the outer periphery where the direct stress is applied is not improved. In order to prevent this electrode peeling, it is effective to increase the connection strength by increasing the area of each of the package-side electrodes and the substrate-side pads to contribute to the connection.

However, as can be seen from the pad arrangement example of the conventional printed wiring board shown in FIG. 7, in order to increase the pad density, the pads 116, 11 are arranged on the substrate in a plurality of rows.
8, 120 and 122 are arranged, and the wiring 12
4, 126, 128 and 130 are drawn out, respectively. As described above, since the wiring passes between adjacent pads, the wiring hinders the pad size from being further increased, and there is a limit in improving the connection strength of the pad. there were. Therefore, without providing a dead space for the replacement jig used when replacing the package once mounted on the printed circuit board,
If the space is used for increasing the number of electrodes and pads and increasing the size of the electrodes, it is possible to increase the density of the printed circuit board and increase the connection strength of the electrodes and the like. However, on the other hand, the package cannot be replaced, so that if the package needs to be replaced, it must be discarded together with the printed wiring board, which causes a new problem of being uneconomical. The present invention has been made in view of the above,
By making effective use of this while securing the dead space for component replacement, it is possible to increase the number of electrodes and pads, or to increase the electrode size and pad size to increase the connection strength between the electrode and pad, and to increase the density and It is an object of the present invention to provide a replaceable package in which electrodes and the like are less damaged even when external stress is applied.

[0005]

In order to achieve the above-mentioned object, according to the present invention, the position of each pad on the printed wiring board is provided on the bottom surface of the printed wiring board having a plurality of pads. A printed circuit board having a structure in which a surface mount component having a corresponding electrode is mounted, wherein a dead space for component replacement is provided around a portion where the surface mount component is mounted on the printed circuit board, The present invention is characterized in that protrusions are protruded from a peripheral portion of a surface mounting component at predetermined intervals with respect to a dead space provided in a peripheral portion of the printed wiring board, so that the component occupying area is increased while securing the dead space. According to this, the dead space is ensured by forming a package having projections formed at predetermined intervals in a dead space as a component mounting prohibition area provided for component replacement in a peripheral portion of the printed wiring board. Package exchange can be performed. Further, since the package area is increased by the amount corresponding to the formation of the projection, the dead space can be effectively used. Examples of the effective use of this dead space include increasing the number of electrodes along with the increase in package area to increase the density of the printed circuit board, or increasing the size of individual electrodes to improve the connection strength and reduce external stress. Preventing the electrode from being damaged. In addition to the expression that protrusions are formed at predetermined intervals in the dead space described above, a similar package shape can be expressed by the expression that dents are provided at predetermined intervals in a package expanded to the dead space range. is there. Claim 2
According to the invention described in (1), in the package according to (1), the projection direction of the projection is at least each angular direction of the polygon when the component shape without the projection is a polygon. Features. According to this, when the package shape before the projection is provided is a polygon such as a square or a rectangle, the unused wiring area of the printed wiring board is present in the corner direction of the polygon. By projecting the projections on the fin, the dead space can be effectively utilized. According to a third aspect of the present invention, in the package according to the first or second aspect, an electrode is provided also on a bottom surface of the protrusion. According to this, since the electrodes are also provided on the bottom surfaces of the protrusions formed on the package, it is possible to increase the number of connection electrodes and pads between the package and the printed wiring board,
The density of electrodes and pads per unit area can be improved. According to a fourth aspect of the present invention, in the package according to the third aspect, an electrode provided on a bottom surface of the projection is formed larger than an electrode provided on a bottom surface of a component other than the projection. And According to this, the connection strength per electrode pin can be enhanced by forming the electrode size provided on the bottom surface of the protrusion larger than the electrode size provided on the bottom surface of the package portion other than the protrusion. Since the reinforced electrode is located at the outer peripheral portion of the package, it is possible to effectively prevent damage to the electrode when external stress is applied.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the package according to the present invention will be described in detail with reference to the accompanying drawings. (Embodiment 1) FIG. 1 is a view for explaining the relationship between an example of a package having protrusions according to Embodiment 1 and a component mounting prohibited area of a printed wiring board, and FIG. FIG. 9 is a diagram for explaining a relationship between another package example having the protrusion according to (1) and a component mounting prohibited area of a printed wiring board. In the embodiment described below, a BGA having an electrode on a bottom surface for various electronic components including a semiconductor component is described.
This is explained using a package as an example. As shown in FIG. 1, a plurality of electrodes (not shown) are provided on a printed wiring board 10 and wires (not shown) drawn out from the electrodes.
Are formed. Further, on the bottom surface of the package 11 (only the outline is shown) mounted on the printed wiring board 10, electrodes are formed at positions corresponding to the pads on the printed wiring board 10, and the electrodes on the package 11 side are printed. The printed circuit board 12 is formed by connecting the pads on the wiring board 10 side with solder (such as reflow using cream solder). FIG. 1 of the first embodiment
The characteristic configuration of the package in
A dead space (component mounting prohibited area) 13 for a replacement jig used at the time of package replacement is provided on the printed wiring board 10 along the peripheral edge of the package 11. At predetermined intervals, the projections 14, 16, 18, 20, 22, 24, 26, 2
8 is provided.

The package in FIG. 2 is different from the example in FIG.
The protrusions 34, 36, 38, 40, 42, 44, 46, 48,
The point that 50, 52, 54 and 56 are provided is the same. As described above, the printed circuit board 32 is formed by mounting the package 31 by connecting the respective electrodes on the respective pads on the printed wiring board 30 by soldering or the like. 2, the rectangular package is mounted so as to cover the entire dead space 33 of the printed wiring board 30, and then a cut (dent) directed inward is formed at the periphery of the dead space 33 at a predetermined interval. By inserting it, it can be considered that the configuration has a dead space. As described above, although the shape of the package itself is the same, when viewed from the package side, the uneven shape provided on the periphery of the package can be expressed as having protrusions at predetermined intervals, and when viewed from the dead space side, the predetermined shape can be expressed. It can be described that cuts (dents) are made at intervals. The projections or cuts (dents) are made at predetermined intervals, but the intervals need not necessarily be equal. Further, the shape of each concave and convex does not need to be the same. As described above, according to the package of the first embodiment, since the protrusions are formed at predetermined intervals in the dead space, the package area can be increased by the amount of the protrusions while leaving the dead space. Thus, the package can be exchanged and the dead space can be effectively used.

(Embodiment 2) FIG. 3 shows Embodiment 2 of the present invention.
FIG. 2 is a diagram showing a state in which an electrode is arranged on the bottom surface of a projection as an example of effective use of the dead space according to the first embodiment, in which a part of the projection in FIG. As shown in FIG. 3, four electrodes 60 are arranged on the bottom surfaces of the projections 18 and 20 protruding from the peripheral edge of the package 11, respectively. Of course, the printed wiring board 1 on which the package 11 is mounted
On the 0 side, a pad is provided at a position corresponding to the electrode 60, and the electrode and the pad are connected by soldering or the like at the time of mounting. As described above, according to the package of the second embodiment, since the electrodes are formed on the bottom surfaces of the protrusions provided in the dead space, the number of electrodes can be increased without changing the area occupied by the package on the printed circuit board 12. And the density of the printed circuit board can be increased by increasing the number of electrodes per unit area. For example,
In the case of FIG. 3, four electrodes are added to one protrusion, and when considering the printed circuit board 12 of FIG. 1, 4 × 8 = 32 electrodes can be increased.
Considering the printed circuit board 32 of FIG.
2 = 48 electrodes can be increased. Of course, also in this case, since the dead space remains as in the first embodiment, the package can be replaced.

(Embodiment 3) FIG. 4 shows Embodiment 3 of the present invention.
FIG. 4 is a view for explaining positions where the protrusions of the package according to the first embodiment are formed. Here, the pads on the printed wiring board side on which the package is mounted and the wiring state are shown. As shown in FIG. 4, in order to mount the package body 85 on the printed wiring board 70, a plurality of pads 80 are densely arranged along the outer contour of the rectangular package body 85. Wirings 82 for extracting a signal from the pad electrode 80 to the outside are drawn out in the vertical and horizontal directions (four directions) in FIG. Thus, the printed wiring board 70
72, 74, 76, and 78 (rectangular spaces indicated by hatching positioned in the four corners (corners) of rectangular package 80 mounted on printed wiring board 70)
Is an unused space that is not used for wiring etc. for drawing out signal lines, so that at least four corners of the package are provided with protrusions that protrude in the outer diameter direction to utilize this angular space. It is. FIG. 2 described above shows that at least the protrusions 38, 44, 50, 56 (angular spaces 72,
74, 76, and 78) are shown. In the third embodiment, electrodes are provided on the bottom surfaces of the angular projections 38, 44, 50, and 56, and pads are provided at positions on the substrate corresponding to the respective electrodes so that space can be effectively used. . That is, the projections 3 corresponding to the rectangular spaces 72, 74, 76, 78 indicated by hatching are provided at the four corners of the conventional rectangular package body 85.
By integrating 8, 44, 50, and 56, wiring in the angular direction becomes possible. As described above, according to the package of the third embodiment, the protrusions are provided in the corners of the package in order to effectively use the space in the corners of the package that has not been used in the printed wiring board.
By arranging the electrodes on the bottom surface, many signals can be extracted from the package. That is, since the number of connection electrodes and pads can be increased without changing the area occupied by the package on the printed circuit board, the number of pads per unit area increases and the density of the printed circuit board can be increased. Of course, also in this case, as in the first and second embodiments, since a dead space is left in a portion other than the protrusion, the package can be replaced by melting the solder using a jig.

(Embodiment 4) FIG. 5 shows Embodiment 4 of the present invention.
FIG. 4 is a view for explaining the size of the bottom electrode provided on the protruding portion of the package according to the first embodiment. Here, the pad on the printed wiring board connected to the bottom electrode of the protruding portion and its wiring are shown. As shown in FIG. 5, a projection 90 on the package side is mounted at a position shown by a broken line, and a bottom electrode of the projection 90 and a corresponding pad 9 on the printed wiring board side.
2, 94, 96 and 98 are connected by solder. The size of the pads 92, 94, 96, 98 on the printed wiring board side corresponding to the electrodes on the projection (package) 90 side is shown in FIG.
Can be larger than the size of the pad (FIG. 7) connected to the electrode of the conventional package shown in FIG. The reason is that there is no need to draw a wiring between adjacent pads. However, as an example, referring to FIG.
Four pads 92, 9 at positions corresponding to the protrusions 90
Since no other pads exist on both sides of 4, 96, 98, the wirings 100, 1
06 can be formed. In the pad arrangement shown in FIG. 7, since a large number of pads are continuously arranged instead of four, if a wiring is to be drawn from a certain pad, the wiring must be drawn between adjacent pads. Absent. For this reason, the area of each pad must be reduced by the wiring space. For example, even if the inter-pad distance A shown in FIG. 5 and FIG. 7 is the same, it is possible to increase the area of the pad in FIG.

As described above, if the pad size on the printed wiring board side can be increased, the size of the bottom electrode provided on the projecting portion of the package can be set to be large according to the size, so that the connection strength between the electrode and the pad can be reduced. Can be increased. The connection strength between the electrode and the pad is
Since the area of contact and the amount of solder are almost proportional to each other, the larger the electrode size and pad size, the higher the connection strength between the electrode and the pad. Note that the pad size on the printed wiring board side and the electrode size on the package side do not necessarily have to be the same shape and the same diameter, but when both sizes are the same, the connection strength is maximized. It is desirable to set the electrode size and the pad size to substantially the same size in order to improve the size. Further, in the fourth embodiment, the reason why the pad size especially at the protruding portion is increased is the pad located at the outermost peripheral portion of the package as can be seen from FIGS. This is because, by increasing the connection strength, electrode peeling can be prevented as much as possible even when external stress is applied to the package. In the first to fourth embodiments, the BGA package has been described as an example. However, the present invention is not necessarily limited to this.
If the package has a bottom surface electrode, the same advantageous effects as described above can be obtained.

[0012]

As described above, according to the package of the first aspect, the package is formed such that projections are provided at predetermined intervals in a dead space for component replacement provided in the periphery of the printed wiring board. As a result, the package can be exchanged, and the area of the package can be increased by the protruding portion, so that the dead space can be effectively used. According to the package of the present invention, when the package having no projection is a polygon, at least the projection is provided in the corner direction of the polygon, which is often an unused area, so that dead space is provided. Can be used effectively. According to the third aspect of the present invention, since the electrodes are also provided on the bottom surfaces of the projections formed on the package, it is possible to increase the number of connection electrodes between the package and the printed wiring board. Per electrode density can be improved. According to the package of the fourth aspect, the size of the electrode provided on the bottom surface of the protrusion is formed larger than the size of the electrode provided on the bottom surface of the package portion other than the protrusion.
The connection strength of the electrode in the vicinity of the outer periphery is strengthened, so that even when external stress is applied, electrode peeling can be effectively prevented.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating a relationship between an example of a package having a protrusion according to a first embodiment and a component mounting prohibited area of a printed wiring board.

FIG. 2 is a diagram illustrating the relationship between another example of a package having a protrusion according to the first embodiment and a component mounting prohibited area of a printed wiring board.

FIG. 3 is a diagram showing a state where an electrode is arranged on the bottom surface of a protrusion as an example of effective use of a dead space according to the second embodiment.

FIG. 4 is a diagram illustrating positions where protrusions of the package according to the third embodiment are formed.

FIG. 5 is a diagram illustrating the size of a bottom electrode provided on a protruding portion of the package according to the fourth embodiment.

FIG. 6 is a plan view showing a state where a bottom electrode type package is mounted on a conventional printed wiring board.

FIG. 7 is a diagram showing an example of the arrangement of electrodes on a conventional printed wiring board.

[Explanation of symbols]

10 printed wiring board, 11 package, 12 printed circuit board, 13 dead space (component mounting prohibited area), 14, 16, 18, 20, 22, 24, 26,
28 protrusion, 30 printed wiring board, 31 package, 32 printed circuit board, 33 dead space (component mounting prohibited area), 34, 36, 38, 40, 4
2, 44, 46, 48, 50, 52, 54, 56 projections, 60 electrodes (pads), 70 printed wiring board,
72, 74, 76, 78 angular space, 80 electrodes (pads), 82 wirings, 90 protrusions, 92, 94, 9
6,98 electrodes (pads), 100,102,104,
106 wiring.

Claims (4)

[Claims] 1. A printed circuit board having a structure in which a surface mount component having an electrode corresponding to each pad position on the printed wiring board is mounted on a bottom surface of the printed circuit board having a plurality of pads. A dead space for component replacement is provided around a portion where the surface mount component is mounted on the printed circuit board, and the surface mount is performed at predetermined intervals with respect to the dead space provided on the periphery of the printed circuit board. A surface mount component package characterized in that a protrusion is protruded from a peripheral portion of the component to increase a component occupation area while securing a dead space. 2. The surface according to claim 1, wherein the projection direction of the projection is at least each angular direction of the polygon when the component shape without the projection is a polygon. Package of components for mounting. 3. The package according to claim 1, wherein an electrode is also provided on a bottom surface of the projection. 4. The size of an electrode provided on the bottom surface of the projection,
The surface mount component package according to claim 3, wherein the size of the electrode is formed larger than the size of an electrode provided on the bottom surface of the component other than the protrusion.