JPH11297876A - Mounting structure of ball grid array - Google Patents

Abstract

(57) [Problem] To provide an electronic component and a solder ball on the same surface of an interposer substrate, and realize a low-profile BGA mounting structure only by a simple structure. SOLUTION: A BGA in which a BGA 10 provided with an interposer substrate 11, an LSI 12 mounted on the interposer substrate 11, and solder balls 15 is mounted on a motherboard 20.
The LSI 12 and the solder balls 15 are mounted and arranged on the same surface of the interposer substrate 11 that faces the motherboard 20.
The through hole 21 in which the mold resin 14 for sealing the LSI 12 and the bonding wires 13 mounted on the interposer substrate 11 is formed by punching.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a ball having an electronic component such as an LSI and a solder ball on an interposer substrate.
Regarding the mounting structure of the ball grid array for mounting the grid array on the motherboard of the device, in particular, electronic components and solder balls are mounted and arranged on the same surface of the interposer substrate, and the interposer substrate is mounted on the electronic device. By mounting components facing the motherboard, low-profile ball grid array mounting can be effectively achieved with only a simple structure without increasing the number of components or increasing manufacturing costs. The present invention also relates to a ball grid array mounting structure which can be performed very easily.

[0002]

2. Description of the Related Art In recent years, miniaturization of OA equipment has been progressing, and the importance of high-density mounting technology for electronic components such as LSIs has been increasing. Here, as a package that enables high-density mounting of electronic components, a ball grid array (Ball G
rid Array) is known. This ball grid
Arrays (hereinafter, also simply referred to as “BGA”) have been developed as packages capable of mounting electronic components such as multi-pin LSIs on a printed wiring board (motherboard) on the device side with a high yield. In response to the demand for high-density packaging in OA equipment and the like, it has been widely used.

Here, a mounting structure of a conventional general BGA proposed so far will be described with reference to FIG. FIG. 4 is a cross-sectional front view of a main part showing a conventional general BGA mounting structure. As shown in FIG.
In the mounting structure A, the BGA 110 is mounted and mounted on the upper surface of a motherboard 120 formed of a printed wiring board provided on the device side.

The BGA 110 has an interposer substrate 111.
An LSI 112 as an electronic component mounted and mounted on the upper surface of the interposer substrate 111; and a solder ball 11 welded and disposed on the lower surface of the interposer substrate 111.
5 is provided.

The LSI 112 includes an interposer substrate 111
And is connected to the wiring pattern on the interposer substrate 111 side via bonding wires 113 and is resin-sealed by a mold resin 114.

A plurality of solder balls 115 are arranged in a grid pattern (array) on the bottom surface of the interposer substrate 111 opposite to the top surface on which the LSI 112 is mounted, and are welded. The pattern is connected by reflow soldering.

In FIG. 4, reference numeral 117 denotes a heat-dissipating through-hole formed on the bottom surface of the LSI 112 of the interposer substrate 111. Heat generated from the LSI 112 is radiated to the motherboard 120 via the through holes 117 and the solder balls 115.

Here, a conventional B having such a configuration is used.
In the GA mounting structure, as shown in FIG. 4, the LSI 112 mounted on the interposer substrate 111 and the solder balls 115 for external connection are arranged on the opposite surfaces of the interposer substrate 111, respectively.

Therefore, the BGA 110 is connected to the motherboard 12
The mounting height when mounted on the 0 side is the interposer substrate 1
11 and the height of the LSI 112 and the solder balls 115, and the height of the LSI 20 is
Since the height of the bonding wire 113 and the molding resin 114 for sealing and protecting is added, there is a problem that the final mounting height is increased. In particular, the bonding wires 113 for connecting the LSI and the mold resin 114 for sealing the LSIs protrude greatly on the upper surface of the interposer substrate 111, which causes an increase in mounting height.

[0010] Specifically, in the conventional BGA mounting structure, the mounting height of the BGA is usually 2 mm or more. With this mounting height, there is a demand for a recent electronic device which is required to be thinner. Notebook PCs and PDs, which are particularly difficult to apply, are particularly required to be thinner
A. In a small portable information processing device such as an IC card product, a serious problem that BGA cannot be mounted has occurred.

Therefore, an improved BGA mounting structure has been proposed for the purpose of reducing the mounting height of the BGA. Referring to FIG. 5, this improved B
The mounting structure of the GA will be described.

FIG. 5 is a cross-sectional front view of a main part showing a mounting structure of a BGA improved so as to reduce the mounting height proposed so far. As shown in FIG.
The mounting structure of A is the interposer substrate 21 of the BGA 210.
1, an opening 212a capable of accommodating the LSI 212 is formed, and a support substrate 216 is disposed on the bottom side of the interposer substrate 211 so as to cover the opening 212a.

When the BGA 210 having such a configuration is mounted on the motherboard 220, the mounting height of the BGA 210 is, as shown in FIG.
The sum of the height of the LSI 212 and the height of the bonding wire 213 and the mold resin 214 for sealing and protecting is added. Therefore, according to the improved mounting structure, the mounting height of the BGA can be reduced by the thickness of the interposer substrate 211 as compared with the conventional mounting structure of the BGA shown in FIG. .

A technique for providing a thinner mounting structure by providing an opening in a BGA interposer substrate as described above is disclosed, for example, in Japanese Patent Application Laid-Open No. Hei 8-213506, entitled "Low Profile Ball Grid Array Semiconductor Package." And its manufacturing method ", JP-A-8-25052
Japanese Patent Application Laid-Open No. 9-330994, “Resin-sealed semiconductor device and manufacturing method thereof”, Japanese Patent Application Laid-Open No. 9-186272, “Thin Ball Grid Array Semiconductor Package with Externally Exposed Heatsink”, and Japanese Patent Application Laid-Open No. 9-330994. “Semiconductor devices” and the like are known.

[0015]

However, in such a BGA mounting structure in which an opening is provided in the interposer substrate, it is difficult to drill the opening in the interposer substrate, and the support for covering the opening from the bottom side. Since it is necessary to prepare a board separately, there is a problem that the number of parts is increased, the processing and assembling work of these parts are complicated, the entire mounting and assembling process of the BGA is complicated, and the production cost is increased. In particular, the step of forming an opening in an extremely small and thin interposer substrate requires extremely complicated and difficult work, including the accuracy of the formation position of the opening, which may increase the manufacturing cost of the BGA itself. was there.

Even if the production cost is neglected and the BGA is manufactured through such a complicated process, the mounting height can be reduced only by the thickness of the interposer substrate as described above. Therefore, a great effect could not be obtained from the point of thinning the mounting structure itself, which is the original purpose.

That is, even in this improved mounting structure, as shown in FIG. 5, the bonding wires for connecting the LSI and the molding resin for sealing the same largely extend over the upper surface of the interposer substrate as in the conventional case. However, there has been no solution to these points, which have conventionally been the biggest factors in increasing the length of the mounting structure. Therefore,
A slight decrease in the thickness of the interposer substrate could not meet the demand for a thinner portable information terminal device and the like described above.

Further, LS is formed in the opening of the interposer substrate.
Since the structure itself that accommodates I and reduces the thickness is generally the same as or less than the thickness of the LSI, the thickness of the interposer substrate itself is limited, and there is a limit to the reduction in thickness. To do so was structurally impossible.

The present invention has been proposed in order to solve the problems of the prior art, in which electronic components and solder balls are mounted and arranged on the same surface of an interposer substrate. By mounting electronic components facing the motherboard side, it is possible to effectively realize low-profile ball grid array mounting with only a simple structure without increasing the number of components and increasing manufacturing costs, It is an object of the present invention to provide a ball grid array mounting structure in which mounting and assembling work can be performed very easily.

[0020]

According to a first aspect of the present invention, there is provided a ball grid array mounting structure comprising: an interposer substrate; and electronic components and solder balls mounted on the interposer substrate. Ball with
A mounting structure of a ball grid array for mounting a grid array on a motherboard, wherein the electronic components and the solder balls are mounted and arranged on the same surface of the interposer substrate facing the motherboard.

In the ball grid array mounting structure according to a second aspect of the present invention, the motherboard is provided with a component storage portion in which electronic components mounted on the interposer substrate are located. In a third aspect, the component storage portion is a through hole that penetrates the motherboard. In a fourth aspect, the component storage portion is configured by a bottomed recess formed in the motherboard.

The ball of the present invention having such a configuration
According to the mounting structure of the grid array, the electronic components such as the LSI and the solder balls are arranged on the same surface of the interposer substrate, and the electronic components are mounted in the component storage portion on the motherboard side. In addition, the height of the mounting structure of the electronic component can be entirely absorbed by the thickness of the motherboard. Therefore, according to the present invention,
The mounting height of the grid array is only the sum of the thickness of the interposer substrate and the height of the solder balls, and the mounting height can be reduced by almost half as compared with the conventional case.

As described above, according to the present invention, the mounting structure of the ball grid array having a low profile can be realized without increasing the number of parts and the manufacturing cost by only simple drilling on the motherboard. It can be effectively implemented, and the mounting operation itself can be easily performed without any difference from the mounting of a normal ball grid array.

The ball grid according to claim 5
The mounting structure of the array has a configuration in which heat dissipating means is provided on the surface of the interposer substrate opposite to the surface on which the electronic components and the solder balls are provided.

The ball of the present invention having such a configuration
According to the mounting structure of the grid array, since the electronic components are arranged on the same side as the solder balls, the other side of the interposer substrate is in an open state where nothing is present, and the heat sink or the heat sink is mounted. It can be freely mounted and arranged. Thus, heat generated by the electronic component can be radiated to the space above the interposer substrate via the heat radiating means, and more effective heat radiation of the electronic component can be achieved as compared with the related art.

Further, in the ball grid array mounting structure according to claim 6, in a case where the motherboard is formed by punching out a board material, the component storage portion including the through hole is provided in the mother boat. This is a configuration formed by being punched out of a material and simultaneously punched out of the motherboard.

In general, a printed wiring board serving as a motherboard is formed by punching out a substrate material by a press device or the like. Therefore, a motherboard can be formed by forming a die for punching the motherboard together with a die for a through hole. Can be formed by punching a through hole from the motherboard at the same time as the substrate is punched from the substrate material.

Thus, the through-hole according to the present invention can be formed in the same step as the mother board in the same step, and the step of forming only the through-hole is not required at all. The ball grid grid of the present invention can be formed simply and efficiently with accurate positional accuracy, without increasing the production cost.
An array mounting structure can be realized.

[0029]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a ball grid array mounting structure according to the present invention will be described below with reference to the drawings. First Embodiment First, a first embodiment of a mounting structure of a ball grid array according to the present invention will be described with reference to FIG. FIG. 1 is a main part sectional front view showing a mounting structure of a ball grid array according to a first embodiment of the present invention.

As shown in FIG. 1, in this embodiment, an interposer substrate 11, an LSI 12 as electronic components mounted on the interposer substrate 11, and a BGA (ball grid array) 10 having solder balls 15 are provided. This is the mounting structure of the BGA mounted on the motherboard 20, LS
I12 and solder balls 15 are mounted and arranged on the same surface of the interposer substrate 11 facing the motherboard 20. As a result, the BGA 10 is
The mounting height in the state where the BGA 10 is mounted is only the thickness of the interposer substrate 11 and the height of the solder balls 15 constituting the BGA 10.

Specifically, as shown in FIG.
Reference numeral 0 denotes an interposer substrate 11, an LSI 12 as an electronic component mounted and mounted on one surface side (lower surface side in the figure) of the interposer substrate 11, and a solder ball 15 welded and arranged on one surface of the interposer substrate 11. Equipped, LS
The I 12 and the solder balls 15 are provided on the same surface of the interposer substrate 11.

LS mounted on interposer substrate 11
I12 is configured such that an electrode pad on the LSI 12 side is connected to an electrode pad on the interposer substrate 11 by a bonding wire 13, and the LSI 12 is connected to a wiring pattern on the interposer substrate 11 via the bonding wire 13. . The LSI 12 and the bonding wires 13 are sealed and protected by a mold resin 14.

The solder balls 15 include a plurality of solder balls 1.
5,15. . . Are arranged and welded on the same lower surface side of the interposer substrate 11 as the surface on which the LSI 12 is mounted so as to surround the LSI 12 by a reflow soldering method on the wiring pattern on the motherboard 20 side. It is to be connected.

In FIG. 1, reference numeral 17 denotes a heat-dissipating through-hole, which is formed above the LSI 12 of the interposer substrate 11, and generates heat from the LSI 12 to the interposer substrate 11 via the through-hole 17. And
Heat is radiated to the space above and to the motherboard 20 via the interposer substrate 11.

The motherboard 20 on which the BGA 10 is mounted is generally constituted by a printed wiring board, and also in this embodiment is constituted by various printed wiring boards such as a multilayer board and a double-sided board. In the present embodiment, as shown in FIG. 1, a through hole 21 penetrating through the mother board 20 is formed in the mother board 20 so that the LSI 12 mounted and sealed on the interposer substrate 11 can be positioned as shown in FIG. I have.

As shown in FIG. 1, the BGA 10 is connected to the motherboard 20 via the solder balls 15. Normally, the molding resin 14 which seals the LSI 12 projects larger than the height of the solder balls 15. As it is, the mold resin 14 comes into contact with the upper surface of the motherboard 20.

On the other hand, the thickness of the motherboard 20 is
Since the thickness of the mold resin 14 that seals 12 is sufficiently larger than the height of the mother resin 20, the amount of protrusion of the mold resin 14 can be absorbed by utilizing the thickness of the motherboard 20. Therefore, in the present embodiment, a through hole 21 large enough to accommodate the molding resin 14 sealing the LSI 12 is formed on the motherboard 20 side to avoid interference between the motherboard 20 and the molding resin 14.

Here, the method of forming the through hole 21 is as follows.
Any method may be used as long as the hole penetrating the motherboard 20 can be formed at a predetermined position, but in the present embodiment,
The through holes 21 are formed by punching. Generally, a printed wiring board to be the motherboard 20 is formed by punching out a substrate material by a press device.
By forming the mold 1 together, the mother boat 20
Is punched out of the substrate material, and at the same time, the through-hole 21 can be punched out of the motherboard 20.

As a result, the through hole 21 of this embodiment is
Is formed in the same step as the mother board 20, so that no step of forming only the through hole 21 is required, and the through hole 21 can be formed with accurate positional accuracy by punching. Also, the production cost does not increase.

The through holes 21 may be formed by cutting using a router similar to the second embodiment described later, or by dissolving and removing a portion corresponding to the through holes 21 by photoetching. Can be formed.

The size of the through hole 21 is LS
It is sufficient that the mold resin 14 sealing the I12 is of a size that can be accommodated and that can avoid interference between the motherboard 20 and the mold resin 14. For example, electronic components that do not require resin sealing In this case, it is sufficient that the through hole 21 is formed in a size that can accommodate the electronic component. Further, the through hole 21 can be omitted when the amount of the above-described mold resin 14 protruding from the interposer substrate 11 is within the range of the height of the solder ball 15.

The B of the present embodiment having the above configuration
According to the mounting structure of the GA, the height of the mounting structure portion of the LSI 12 including the bonding wires 13 and the mold resin 14 can all be absorbed by the thickness of the motherboard 20. Accordingly, the mounting height of the BGA 10 is only the sum of the thickness of the interposer substrate 11 and the height of the solder balls 15, and it is possible to reduce the mounting height by almost half compared to the above-described conventional BGA mounting structure. This allows the mounting height to be greatly reduced.

Next, a description will be given of a manufacturing and assembling procedure of the mounting structure of the ball grid array of the present embodiment having such a configuration. First, the BGA 10 is manufactured. BG
A10 is L on one surface (lower surface) side of the interposer substrate 11.
The SI 12 is mounted by die mounting, and the electrode pads on the LSI 12 side are connected to the electrode pads on the interposer substrate 11 by the bonding wires 13. Next, the LSI mounted on the interposer substrate 11
12 is sealed with the mold resin 14 including the bonding wires 13.

Further, a plurality of solder balls 15, 1
5. . . Are arranged on the same surface of the interposer substrate 11 as the surface on which the LSI 12 is mounted, in a lattice shape surrounding the LSI 12, and are welded by reflow soldering. Thus, the BGA 10 is completed.

At the same time, a through hole 21 is formed in the motherboard 20. Here, the motherboard 20 is formed by punching from a substrate material by a pressing device or the like. In this embodiment, in the punching step of the motherboard 20, the motherboard 20 is punched from the substrate material, and at the same time, the through holes 21 are formed in the motherboard 20. It is formed by punching out from the material.

Then, the BGA 10 is mounted on the upper surface of the motherboard 20 in which the through holes 21 are formed. At this time,
The BGA 10 is mounted at a predetermined position while the mold resin 14 projecting from the BGA 10 is positioned in the through hole 21 on the motherboard 20 side. Then, the motherboard 20 on which the BGA 10 is mounted is subjected to a reflow process to weld and connect the solder balls 15 to the electrodes on the motherboard 20 side. This completes the mounting of the BGA 10 on the motherboard 20 side.

As described above, according to the mounting structure of the ball grid array of the present embodiment, the LSI 12 and the solder balls 15 are arranged on the same surface of the interposer substrate 11, and the LSI 12 is connected to the through hole on the motherboard 20 side. 2
1, the entire height of the mounting structure portion of the LSI 12 can be absorbed by the thickness of the motherboard 20, and the mounting height of the BGA 10 is
Since only the sum of the thickness of the interposer substrate 11 and the height of the solder balls 15 can be achieved, the mounting height can be reduced by almost half as compared with the related art.

As a result, a low profile BGA mounting structure can be effectively realized without increasing the number of parts or increasing the manufacturing cost by only simple drilling of the motherboard 20. The operation can be easily performed without any difference from the normal BGA mounting operation.

[Second Embodiment] Next, the ball of the present invention
A second embodiment of the mounting structure of the grid array will be described with reference to FIG. FIG. 2 is a sectional front view of a main part showing a mounting structure of a ball grid array according to a second embodiment of the present invention.

Here, the mounting structure of the ball grid array according to the present embodiment is a modified embodiment of the above-described first embodiment, and the motherboard 20 is replaced with a through hole 21 of the first embodiment. A concave portion 22 is provided as a component storage portion, and the other components are the same as those in the first embodiment. Therefore, the same components as those of the first embodiment are denoted by the same reference numerals, and the detailed description is omitted.

That is, in the present embodiment, as shown in FIG. 2, a component housing for avoiding interference between the mold resin 14 sealing the LSI 12 and the motherboard 20 is provided.
A bottomed recess 22 is formed in the motherboard 20.

In the first embodiment described above, the through hole 21 is formed in the portion of the motherboard 20 that interferes with the mold resin 14.
Was provided, but the mold resin 14 and the motherboard 20
As long as the interference of the through holes 21 can be avoided.
Need not be. Therefore, in the present embodiment, the concave portion 22 is formed in the motherboard 20 at a depth where the mold resin 14 sealing the LSI 12 can be located.

Here, as the method of forming the concave portion 22, in the present embodiment, the concave portion 22 is formed by cutting the surface of the motherboard 20 with a router. However, any method may be used as long as the concave portion 22 having a predetermined size can be formed. For example, the upper layer of the motherboard 20 formed of a photosensitive resin is subjected to photo etching,
It can also be formed by dissolving and removing a portion corresponding to the concave portion 22.

As described above, the recess 2 having the bottom as the component storage portion
By forming 2, the protrusion amount of the mounting structure portion of the LSI 12 including the mold resin 14 can be absorbed while avoiding the interference between the mold resin 14 and the motherboard 20, as in the case of the first embodiment described above. Specific effects can be achieved. Moreover, in the present embodiment in which the concave portion 22 is employed as the component storage portion, the bottom side of the motherboard 20 can also be used for wiring.
A further effect that the mounting efficiency of the motherboard 20 can be improved can be obtained.

[Third Embodiment] Next, the ball of the present invention
A third embodiment of the mounting structure of the grid array will be described with reference to FIG. FIG. 3 is a main part sectional front view showing a mounting structure of a ball grid array according to a third embodiment of the present invention.

Here, the mounting structure of the ball grid array according to the present embodiment is obtained by further adding a heat radiating means to the upper surface of the interposer substrate 11 of the BGA 10 described in the first embodiment. Therefore, the other components have the same configuration as that of the first embodiment, and the same components as those of the first embodiment are denoted by the same reference numerals, and detailed description is omitted.

That is, in the present embodiment, as shown in FIG. 3, on the upper surface of the interposer substrate 11 opposite to the lower surface provided with the LSI 12 and the solder balls 15, a heat radiating plate 18 is provided as a heat radiating means for the LSI 12. is there.

Here, the heat radiating plate 18 is desirably formed of a metal plate having high thermal conductivity from the viewpoint of heat radiating effect. Further, the heat radiation means is not limited to the plate-shaped heat radiation plate 18 shown in the present embodiment, and various heat radiation means can be adopted, for example, a heat radiation means such as a comb-shaped heat sink which can be mounted on the interposer substrate 11. Anything may be used.

Further, as shown in FIG. 3, the heat radiating plate 18 has a plate-like member having the same area as the interposer substrate 11 disposed over the entire upper surface of the interposer substrate 11.
It is also possible to provide this on only a part of the upper surface of the interposer substrate 11, or to mount a heat radiating plate having an area larger than that of the interposer substrate 11. It is needless to say that the mounting structure of the BGA including the heat radiating means of the present embodiment can be applied to the above-described second embodiment.

As described above, according to the ball grid array mounting structure of the present embodiment, the LSI 12 is disposed on the same side as the solder balls 15, so that the upper surface of the interposer substrate 11 has no open surface. In this state, the heat radiating plate 18 or a heat radiating means such as a heat sink can be freely mounted and arranged here. As a result, the heat generated by the LSI 12 can be radiated to the space above the interposer substrate 11 via such a heat radiating unit, and the BGA 10 can more effectively radiate heat as compared with the related art.

[0061]

As described above, according to the ball grid array mounting structure of the present invention, electronic components and solder balls are mounted and arranged on the same surface of an interposer substrate, and this interposer substrate is mounted on an electronic device. By mounting components facing the motherboard side, it is possible to effectively realize low-profile ball grid array mounting with only a simple structure without increasing the number of components and increasing manufacturing costs, The mounting operation can be performed very easily.

[Brief description of the drawings]

FIG. 1 is a sectional front view of a main part showing a mounting structure of a ball grid array according to a first embodiment of the present invention.

FIG. 2 is a cross-sectional front view of a main part showing a mounting structure of a ball grid array according to a second embodiment of the present invention.

FIG. 3 is a sectional front view of a main part showing a mounting structure of a ball grid array according to a third embodiment of the present invention.

FIG. 4 is a sectional front view of a main part showing a mounting structure of a conventional general ball grid array.

FIG. 5 is a sectional front view of a main part showing a mounting structure of a conventional improved ball grid array.

[Explanation of symbols]

 Reference Signs List 10 ball grid array 11 interposer substrate 12 LSI 13 bonding wire 14 molding resin 15 solder ball 18 heat sink 20 mother board 21 through hole 22 concave portion

Claims (6)

[Claims] 1. A mounting structure of a ball grid array for mounting a ball grid array including an interposer substrate, an electronic component mounted on the interposer substrate, and a solder ball on a motherboard, the electronic component comprising: A ball grid array mounting structure, wherein solder balls are mounted and arranged on the same surface of the interposer substrate facing the motherboard. 2. The ball grid array mounting structure according to claim 1, wherein said motherboard includes a component storage portion in which electronic components mounted on said interposer substrate are located. 3. The mounting structure of a ball grid array according to claim 2, wherein said component storage portion comprises a through hole penetrating said motherboard. 4. The ball bearing according to claim 2, wherein said component storage portion comprises a concave portion having a bottom formed on said motherboard.
Grid array mounting structure. 5. The ball grid device according to claim 1, wherein a heat radiating means is provided on a surface of the interposer substrate opposite to a surface provided with the electronic components and the solder balls.
Array mounting structure. 6. In the case where the motherboard is formed by punching from a substrate material, the component storage portion including the through hole is formed by punching from the motherboard at the same time that the mother boat is punched from the substrate material. The mounting structure of a ball grid array according to claim 3, wherein