JP2000031315A - Bga package and its manufacture - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the thermal stress which occurs in a BGA package when the package is mounted on a printed board by reducing the size and weight of the package by fixing a metallic sheet to a plastic board so that the metallic plate may cover at least the opening of the plastic board and partially exposing the surface of the plastic board to which the metallic plate is fixed. SOLUTION: On the upper surface of a plastic board 2 having a cavity 6 for housing an IC chip 7, a wiring pattern which is formed by etching copper foil and ball pads 5 are arranged and solder balls 4 are welded to the pads 5. On the lower surface of the board 2, a Cu heat sink 3 is stuck in such a way that the side section 2a of the lower surface of the board 2 is exposed. After wires 8 are connected to the chip 7, the cavity 6 is sealed with a resin 9. Since the heat sink 11 is not stuck to the whole lower surface of the board 2, namely, since the heat sink 11 is stuck in a partially removed state, the volume of the heat sink 11 is reduced and the whole weight of a BGA package can be reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a BGA package and a method of manufacturing the same, and more particularly, to a BGA package mainly used as a package for mounting an LSI and having a metal plate for heat radiation fixed to a resin substrate. And its manufacturing method.

[0002]

2. Description of the Related Art In response to demands for higher density and higher speed in semiconductor devices, a BGA (Ball Grid Arra) capable of increasing the number of pins has been developed.
y) has recently attracted attention. The BGA is most suitable for mounting an IC such as a microprocessor or an ASIC that requires a large number of pins, and has the following features.

(A) Since the balls are arranged two-dimensionally, Q
Many more pins are possible than mounting technology using lead frames such as FP (Quad Flat Package), and PGA
(Pin Grid Array) enables more pins. (B) The lead pitch is larger than the QFP, so that the accuracy of the mounter or the like may be low, and the mounting yield is improved. (C) The cost is relatively low. (D) Excellent heat radiation and low impedance.

Until recently, ceramic BGAs have attracted attention among BGAs from the viewpoint of reliability, but the focus has shifted to plastic array packages from the viewpoint of cost reduction. Broadly interpreting this kind of plastic array package, PBGA (Plastic BGA), TB
GA (Tape BGA), μ-BGA, CSP (Chip Siz
e Package and Chip Scale Package).

A plastic array package is an MPU
(Microprocessor Unit) Used for peripheral devices, MPU mounting, and the like. With the speeding up and miniaturization of arithmetic processing in a computer, the amount of heat generated from an IC chip mounted on the package is increasing. Therefore, there is a type in which a heat radiating plate is attached to the package for the purpose of assisting heat radiation from the IC chip.

FIG. 1 shows an example of a BGA package with a heat sink.
0 is shown. A wiring pattern (not shown) formed by etching a copper foil on the upper surface of the plastic substrate 2 in which the cavity 6 accommodating the IC chip 7 is opened.
And the ball pad 5 are formed, and the solder ball 4 is welded to the ball pad 5. A heat radiating plate 3 made of Cu is adhered to the lower surface of the plastic substrate 2. After connection of the wire 8, the cavity 6 is sealed with a resin 9.

FIG. 11 shows a BGA mounted on a printed circuit board.
Here is an example of a package. The printed circuit board 10 is connected to the BGA package shown in FIG.

[0008]

As shown in FIG. 10, in the case of a conventionally used BGA package with a heat sink, the lower surface of the plastic substrate 2 (the surface on which the wiring pattern and the ball pad 5 are not formed). Has a heat sink 3 attached over the entire surface.

As a result, the entire package becomes heavy, which hinders reduction in size and weight. In addition, since the entire lower surface of the package is covered with the heat sink 3, components such as capacitors cannot be mounted on the lower surface of the package, and it is desired to realize a package form in which the lower surface of the package can be effectively used. I have.

Further, as shown in FIG. 11, when a BGA package having a heat radiating plate 3 stuck over the entire lower surface is mounted on a printed circuit board 10, heat radiation between the heat radiating plate 3 and the plastic substrate 2 and between the printed circuit board 10 and the BGA package. Due to the difference in the expansion coefficient, a large stress is applied to the solder ball 4 and the solder ball 4 is distorted, or the connection between the solder ball 4 and the plastic substrate 2 or the connection between the solder ball 4 and the printed circuit board 10 is broken. May be lost.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and in a BGA package with a heat sink and a method of manufacturing the same, the entire package is reduced in size and weight, and a more effective package form is realized. It is an object of the present invention to provide a BGA package capable of reducing thermal stress generated when mounted on a BGA and a method of manufacturing the BGA package.

[0012]

Means for Solving the Problems and Their Effects To achieve the above object, a BGA package according to the present invention (1)
Is a resin substrate with an open part for housing the semiconductor element,
In a BGA package to which a metal plate for heat radiation is fixed, the metal plate is fixed so as to cover at least the opening, and a surface of the resin substrate fixed to the metal plate is partially exposed. And

[0013] According to the BGA package (1), the metal plate is not fixed so as to cover one side of the resin substrate as in the conventional case. Since the metal plate is removed and the volume of the metal plate is reduced, the weight of the entire package can be reduced. Further, a component such as a capacitor can be mounted on the portion where the metal plate has been removed. Further, by reducing the volume of the metal plate, it is possible to relieve thermal stress caused by a thermal change when mounted on a printed circuit board, and to stably mount the BGA package on the printed circuit board. be able to. Further, since the metal plate is disposed at least on the mounting portion of the semiconductor element, heat radiation from the semiconductor element can be sufficiently assisted.

A BGA package according to the present invention (2)
Is characterized in that in the BGA package (1), a wiring pattern such as a power supply and / or a ground is formed on the exposed portion.

According to the BGA package (2), since a wiring pattern such as a power supply and / or a ground is formed on the exposed portion, mounting of components becomes easy.

The BGA package according to the present invention (3)
In the above BGA package (1) or (2),
A convex or concave portion is formed in the semiconductor element mounting portion of the metal plate such that when the semiconductor element is accommodated, the upper surface of the semiconductor element and the upper surface of the resin substrate are flush with each other. And

According to the BGA package (3), the upper surface of the semiconductor element and the upper surface of the resin substrate are flush with each other, that is, since there is no step between both surfaces, the semiconductor element and the resin substrate are Can be performed more appropriately and easily.

Further, a method of manufacturing a BGA package (1) according to the present invention includes a step of forming a wiring pattern on one or both sides of a resin substrate having an opening for accommodating a semiconductor element; Arranging an alignment jig for mounting a plate on the resin substrate, and mounting the metal plate partially covering the resin substrate on the resin substrate;
Fixing the metal plate to the resin substrate.

According to the BGA package manufacturing method (1), the positioning jig is arranged at a predetermined position on the resin substrate, the metal plate is placed on the resin substrate according to the positioning jig, and fixed. The BG to which the metal plate partially covering the resin substrate is fixed.
A package can be obtained. In addition, by forming the wiring patterns on both surfaces of the resin substrate, it is possible to easily mount components on a portion where the metal plate is removed.

[0020]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of a BGA package according to the present invention will be described with reference to the drawings.

FIG. 1 is a sectional view schematically showing a main part of a BGA package (1) according to an embodiment. A wiring pattern (not shown) formed by etching a copper foil and a ball pad 5 are formed on the upper surface of the plastic substrate 2 in which the cavity 6 accommodating the IC chip 7 is opened. Solder balls 4 are welded. A heat radiating plate 3 made of Cu is attached to the lower surface of the plastic substrate 2 so as to expose the lower side portion 2a of the plastic substrate 2. After connection of the wire 8, the cavity 6 is sealed with a resin 9.

According to the BGA package (1) according to the above-described embodiment, the heat radiating plate 11 is not attached so as to cover one side of the plastic substrate 2 as in the BGA package shown in FIG. Compared with the conventional package, the heat radiating plate 11 is partially removed, and the volume of the heat radiating plate 11 is reduced, so that the weight of the entire package can be reduced. Heat sink 11
Are disposed at least on the mounting portion of the IC chip 7, so that heat radiation from the IC chip 7 can be sufficiently assisted.

FIG. 2 is a lower perspective view of the BGA package (1). On the lower side portion 2a of the plastic substrate 2, a capacitor mounting pad 12 for decoupling and the like can be arranged.

FIG. 3 shows an example of a BGA package on which a decoupling capacitor 13 used for noise removal or the like is mounted. The decoupling capacitor 13 is mounted on the capacitor mounting pad 12.

As described above, components such as the decoupling capacitor 13 can be easily mounted on the portion where the heat radiating plate 11 is not adhered, that is, on the lower side surface (exposed portion) 2a of the plastic substrate 2.

FIG. 4 shows an example of the BGA package (1) mounted on the printed circuit board 10. As shown in FIG. Printed circuit board 1
0 and the BGA package shown in FIG.
Connected through.

Heat sink 11 to be adhered to plastic substrate 2
The thermal stress caused by the difference in the coefficient of thermal expansion between the heat radiating plate 11, the plastic substrate 2, and the printed circuit board 10 can be reduced by reducing the volume of the heat sink 11. The thermal expansion coefficients of the printed board 10 and the plastic board 2 are substantially the same. Therefore, by reducing the volume of the heat sink 11, the thermal stress applied to the solder balls 4 can be reduced, and the printed board 10 of the BGA package can be reduced. It is possible to stabilize the mounting to the.

FIG. 5 is a schematic sectional view showing a part of the manufacturing process of the BGA package (1) according to the above embodiment.

First, a wiring pattern (not shown) is formed on both surfaces of the plastic substrate 2 in which a portion (cavity 6) for accommodating the IC chip 7 (see FIG. 1) is opened (FIG. 5).
(A)) Then, an alignment jig 14 for placing the heat radiating plate 11 on the plastic substrate 2 is arranged at a predetermined position on the plastic substrate 2 (FIG. 5 (b)). An adhesive sheet 15 for thermocompression bonding of the plate 11 is placed (FIG. 5C).

Next, the heat radiating plate 11 covering the cavity 6 of the plastic substrate 2 is placed on the adhesive sheet 15 (FIG. 5).
(D)) After performing the temporary bonding, the positioning jig 14 is removed, and the main heating bonding is performed (FIG. 5E).

The BGA packages manufactured as described above are individually cut (FIG. 5 (f)).
Is mounted, a wire 8 (see FIG. 1) is stretched, a cavity 6 is sealed with a resin 9 (see FIG. 1), and a solder ball 4 (see FIG. 1) is attached, whereby the BGA package shown in FIG. obtain.

FIG. 6 is a sectional view schematically showing a main part of a BGA package (2) according to the embodiment, and FIG. 7 is a lower perspective view. Cavity 6 for accommodating IC chip 7
A wiring pattern (not shown) formed by etching a copper foil and a ball pad 5 are formed on the upper surface of the plastic substrate 2 having an opening.
Is soldered with a solder ball 4. Heat sink 1 having Cu gap 16a on the lower surface of plastic substrate 2
6 is adhered, and a part (exposed portion 2b) of the lower surface of the plastic substrate 2 is exposed. After the connection of wire 8,
The cavity 6 is sealed with a resin 9.

According to the BGA package (2) according to the above embodiment, the volume of the heat radiating plate 16 is reduced as compared with the conventional package, like the BGA package (1) according to the above embodiment. Thus, the weight of the entire package can be reduced. The heat radiating plate 16 is at least IC
Since the IC chip 7 is arranged on the mounting portion, the heat radiation from the IC chip 7 can be sufficiently assisted.

Also, components such as the decoupling capacitor 13 (see FIG. 3) can be mounted on the exposed portion 2b of the plastic substrate 2 exposed by the gap 16a of the heat sink 16. Further, by reducing the volume of the heat radiating plate 16, the thermal stress applied to the solder ball 4 can be reduced.

FIG. 8 is a sectional view schematically showing a main part of a BGA package (3) according to the embodiment. A wiring pattern (not shown) formed by etching a copper foil and a ball pad 5 are formed on the upper surface of the plastic substrate 2 in which the cavity 6 accommodating the IC chip 18 is opened.
Are formed, and the solder ball 4 is welded to the ball pad 5. A heat radiating plate 17 made of Cu is attached to the lower surface of the plastic substrate 2 so as to expose the lower side portion 2a of the plastic substrate 2. Further, a concave portion is formed in the mounting portion of the heat radiating plate 17 on the IC chip 18 so that the upper surface of the IC chip 18 and the upper surface of the plastic substrate 2 are flush with each other. After connection of the wire 8, the cavity 6 is sealed with a resin 9.

FIG. 9 is a sectional view schematically showing a main part of a BGA package (4) according to the embodiment. A wiring pattern (not shown) formed by etching a copper foil and a ball pad 5 are formed on the upper surface of the plastic substrate 2 in which the cavity 6 accommodating the IC chip 20 is opened.
Are formed, and the solder ball 4 is welded to the ball pad 5. A heat radiating plate 19 made of Cu is attached to the lower surface of the plastic substrate 2 so as to expose the lower side portion 2a of the plastic substrate 2. Also, a convex portion is formed on the IC chip 20 mounting portion of the heat sink 19 so that the upper surface of the IC chip 20 and the upper surface of the plastic substrate 2 are flush with each other. After connection of the wire 8, the cavity 6 is sealed with a resin 9.

According to the BGA package (3) or (4) according to the above embodiment, the upper surfaces of the IC chips 18 and 20 and the upper surface of the plastic substrate 2 are flush with each other. Since there is no IC chip 18,
Wire bonding between the substrate 20 and the plastic substrate 2 can be performed more appropriately and easily. The heat radiating plate 17 having the concave shape or the heat radiating plate 19 having the convex shape shown in FIG. 8 or 9 can be obtained at a low cost by drawing a Cu metal plate.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a BGA package (1) according to an embodiment of the present invention.

FIG. 2 is a lower perspective view showing a BGA package (1) according to the embodiment.

FIG. 3 is a lower perspective view showing an example of a BGA package (1) according to an embodiment in which a decoupling capacitor is mounted.

FIG. 4 is a diagram illustrating a B according to the embodiment mounted on a printed circuit board.
It is sectional drawing which showed an example of GA package (1).

FIG. 5 is a schematic cross-sectional view showing a part of the manufacturing process of the BGA package (1) according to the embodiment.

FIG. 6 is a sectional view showing a BGA package (2) according to the embodiment;

FIG. 7 is a lower perspective view showing a BGA package (2) according to the embodiment.

FIG. 8 is a sectional view showing a BGA package (3) according to the embodiment.

FIG. 9 is a sectional view showing a BGA package (4) according to the embodiment.

FIG. 10 is a cross-sectional view showing an example of a conventional BGA package with a radiation plate.

FIG. 11 is a cross-sectional view illustrating an example of a conventional BGA package mounted on a printed circuit board.

[Explanation of symbols]

 2 Plastic substrate 2a, 2b Exposed portion 3, 11, 16, 17, 19 Heat sink 4 Solder ball 5 Ball pad 6 Cavity 7, 18, 20 IC chip 8 Wire 9 Resin 10 Printed circuit board 12 Capacitor mounting pad 13 Decoupling capacitor 14 Positioning jig 15 Adhesive sheet 16a Void

Claims (4)

[Claims] 1. A BGA package in which a metal plate for heat dissipation is fixed to a resin substrate having an opening for accommodating a semiconductor element, wherein the metal plate is fixed so as to cover at least the opening. A BGA package, wherein a side of a fixing surface with the metal plate is partially exposed. 2. The BGA package according to claim 1, wherein a wiring pattern such as a power supply and / or a ground is formed on the exposed portion. 3. The semiconductor element mounting portion of the metal plate is formed with a projection or a recess so that when the semiconductor element is accommodated, an upper surface of the semiconductor element and an upper surface of the resin substrate are flush with each other. The BGA package according to claim 1 or 2, wherein: 4. A step of forming a wiring pattern on one or both sides of a resin substrate having an opening for accommodating a semiconductor element, and a positioning jig for placing a metal plate for heat radiation on the resin substrate. And a step of mounting the metal plate partially covering the resin substrate on the resin substrate, and fixing the metal plate to the resin substrate. .