JP2002217335A - Semiconductor device and its manufacturing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent missing and deformation of a solder ball and adhesion of a foreign matter thereto by preventing the solder balls from touching even if a BGA is placed on flat plane. SOLUTION: A wiring board 1 having a central device hole is bonded to the rear surface of a heat spreader 2, an IC chip 5 is mounted on the heat spreader 2 in the device hole and the external electrodes thereof are connected electrically with a wiring board 1 through a bonding wire 4. In order to protect the IC chip 5 and the bonding wire 4, the device hole part of the wiring board 1 is resin sealed 6. On the other hand, solder balls 3 are bonded as external electrodes to the wiring board 1. At the time of resin sealing, the sealing resin 6 is formed higher than the solder balls 3.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor device and a method of manufacturing the same, and more particularly, to a face-down type BGA (hereinafter referred to as a face-down type) in which a circuit forming surface of a semiconductor element faces downward when mounted on a mounting substrate. BGA) and its manufacturing method.

[0002]

2. Description of the Related Art In recent years, with the demand for high integration and miniaturization of LSI, a BGA which is an area array type package has been
(Ball grid array) is increasingly used. Further, in a case where a semiconductor element requiring heat radiation is mounted, a BGA in which a heat spreader (radiator plate) is fixed to the semiconductor element is often used. In this case, a face-down BGA structure in which the circuit formation surface of the semiconductor element faces downward is often adopted.

FIG. 4 is a sectional view showing a conventional example of this kind. As shown in the figure, the heat spreader 2 has
Wiring board 1 having an opening formed in the center at the center
Is glued. Although not shown, the wiring board 1
Is formed with a multilayer wiring. An IC chip 5 is mounted in the opening of the wiring board 1 on the back surface of the heat spreader 2, and the external electrodes of the IC chip 5 and the wiring of the wiring board 1 are connected by bonding wires 4. The solder balls 3 serving as external terminals are provided on pads provided at one end of the wiring of the wiring board 1. The opening of the wiring board 1 is sealed with a sealing resin 6 to protect the IC chip 5 and the bonding wires 4.

The sealing resin 6 is formed by a potting method or a transfer molding method. Conventionally, the sealing resin 6 is formed lower than the solder balls 3. Therefore, when the package is stored as it is, the solder ball 3 contacts the bottom surface to support the package. In such a state, there is a high possibility that the solder balls will be damaged. Therefore, conventionally, the BGA is stored and transported using a special tray in which the solder balls do not contact the bottom surface.

[0005]

Usually, the height of the BGA solder ball at a pitch of 1.27 mm is about 0.6 mm, and the height of the sealing resin is about 0.35 mm.
Therefore, the bonding wire loop height is 0.2 mm
Therefore, it is difficult to control the wire shape. Further, when sealing is performed by a potting method, there is a large risk that wire exposure or resin leakage failure occurs due to variation in the amount of sealing resin. In addition, the conventional BGA requires a special tray for storage, and the solder ball may come into contact with others during the transport / mounting process, causing chipping, chipping, scratching, and dust adhesion on the solder ball. High in nature.

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems of the conventional example. The object of the present invention is to control the shape of a bonding wire by making the height of a sealing resin higher than that of a solder ball. An object of the present invention is to make it easier to prevent the bonding wire from being exposed and to prevent the solder ball from being damaged. It is another object of the present invention to be able to store and transport BGA without using a special tray.

[0007]

According to the present invention, a first pad connected to an external electrode of a semiconductor device and a second pad connected to an external terminal are set according to the present invention. A wiring board having an opening penetrating through the board, an external terminal provided on the second pad of the wiring board, and electrically connected to the first pad. A semiconductor element having an external electrode, wherein the opening of the wiring board is sealed with a sealing resin from a side of the external terminal, wherein the sealing resin is higher than the external terminal. A semiconductor device characterized by being formed is provided. Preferably, a support substrate is provided so as to close the opening of the wiring substrate from a surface opposite to a surface on which the external terminals are provided, and the semiconductor device is provided with the external terminals on an active element surface. Is mounted on the support substrate. More preferably, the support substrate is formed of a metal plate that covers the entire surface of the wiring substrate.

In order to achieve the above object, according to the present invention, (1) a first pad connected to an external electrode of a semiconductor element and a second pad connected to an external terminal are provided on a supporting substrate. Bonding a surface of the wiring board having a wiring set with the opening opposite to the surface on which the second pad is formed, in which an opening that penetrates the substrate is opened; and Mounting a semiconductor element on a portion of the wiring board exposed by the opening; and (3) connecting a thin metal wire between an external electrode of the semiconductor element and a first pad of the wiring board. (4) a step of resin-sealing the semiconductor element and the fine metal wire; and (5) a step of forming external terminals on the second pads on the wiring board. The height of the sealing resin formed in the step 4) is equal to the height of the (5). Method of manufacturing a semiconductor device, wherein the higher than the height of the external terminals formed in step, is provided. And, preferably, the (4)
In the step (b), after a frame for preventing the flow of the resin surrounding the formation region of the first pad from the outside is provided on the wiring substrate, resin sealing is performed by a potting method.

[0009]

Next, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a sectional view of a face-down BGA showing one embodiment of the present invention. The present embodiment differs from the conventional example shown in FIG. 4 in that the frame 7 is provided on the outer peripheral portion of the sealing resin 6 and the height of the sealing resin 6 is made higher than the solder balls 3. It is that you are.
FIG. 2 is an enlarged view of a portion A in FIG. 1 and shows a portion where the height of the sealing resin 6 is higher than that of the solder ball 3 in a more easily understood manner. Here, the frame 7 functions as a dam at the time of resin potting, and the solder ball is fixed to the pad on which the wire bonding of the wiring board is performed so that the sealing resin 6 does not flow out to the solder ball side. Provided between the pad and the pad.

[0010] In recent years, as the speed and integration of semiconductor elements have increased, the power consumption of the semiconductor elements has increased, and the amount of heat generated per unit area has increased. Therefore, in this embodiment, which is a package for a high-speed, highly integrated LSI,
In order to efficiently diffuse and release the heat generated in the chip 5, a large-area heat spreader 2 made of copper (Cu), a copper alloy or the like is provided on the back surface of the IC chip 5. further,
The wiring substrate 1 is provided with a ground wiring layer to improve the frequency characteristics.

In the present embodiment, which is a face-down BGA, a wiring board 1 having a through hole called a device hole in the center is formed by a heat spreader 2 using an adhesive.
Adhered to. An IC chip 5 is mounted on the heat spreader 2 in a device hole of the wiring board 1 using a silver (Ag) paste or the like. When an IC chip is mounted using an insulating paste instead of the silver paste, it is desirable to use one having high thermal conductivity. In order to further reduce the thermal resistance, it is desirable to perform die bonding using a brazing material. The gold (Au) or aluminum (A)
1) are connected by bonding wires 4. Here, the wiring substrate 1 is a wiring substrate having a multilayer structure, and the pad of the inner lead portion is connected to the pad of the outer lead portion with or without a through hole.

Further, the IC chip 5 and the bonding wires 4 are sealed with a sealing resin 6 in order to protect them from external moisture, foreign matter or impact.
In this embodiment, resin sealing is performed by a potting method, but a transfer molding method may be used instead of this method. It is a feature of the present invention that the height of the sealing resin 6 is made higher than the solder balls during the sealing operation.
Normally, the height of a BGA solder ball having a pitch of 1.27 mm is 0.6 ± 0.1 mm, so that the sealing resin is formed at a height of 0.8 mm or more from the surface of the wiring board 1. A frame 7 is provided on the outer periphery of the sealing resin 6 to prevent the sealing resin 6 from flowing to the solder ball 3 side. The frame 7 is preferably formed of the same or the same material as the sealing resin 6. When the sealing resin 6 is an epoxy resin, the frame 7 is formed using an epoxy resin. The BGA of this embodiment is mounted on a mounting board in which a concave portion or a through hole for allowing a sealing resin portion to escape is formed. Originally, the pattern on the mounting board is almost formed between the solder balls, so that the formation of the concave portion or the through hole does not greatly restrict the wiring pattern on the wiring board.

FIG. 3 is a cross-sectional view showing a method of manufacturing the BGA of this embodiment in the order of steps. First, an adhesive 8 is applied to the back surface of the copper heat spreader 2 in a “B” shape according to the shape of the wiring board [FIG. [Fig. 3
(B)]. Next, a silver paste 9 is applied to the center of the back surface of the heat spreader 2, and the IC chip 5 is mounted thereon (FIG. 3C). Next, the bonding wires 4 connect the external electrodes of the IC chip 5 to the pads set in the inner lead portions of the wiring on the wiring board 1 [FIG.
(D)]. Next, the frame 7 made of epoxy resin is connected to the wiring board 1.
Glue on top. This frame has an annular shape surrounding the pad formation region of the inner lead portion of the wiring board 1, and functions to stop the flow of resin during resin potting. Then, the sealing resin 6 made of epoxy resin is formed by performing resin potting and thermosetting. At this time, the height of the sealing resin 6 on the wiring board is made larger than the diameter of the solder ball to be fixed later. Here, the height of the frame 7 is selected so that the resin does not flow out when an appropriate amount of resin is potted (FIG. 3E). Thereafter, a flux is applied to the surface of the wiring board 1, and the solder balls 3 are placed on the pads set on the outer lead portions of the wiring on the wiring board by a well-known means, and reflowed, and the solder balls 3 are placed on the pads. Is fixed [FIG. 3 (f)]. Finally, a product name, a lot number, and the like are printed on the upper surface of the heat spreader 2, and the manufacturing process of the semiconductor device of this embodiment is completed.

As described above, the BGA according to the present invention
Since the sealing resin is made higher than the solder ball, the solder ball does not come into direct contact with the bottom even on a flat surface of the BGA, and during the transportation and during the mounting process on the mounting board. Solder does not come into contact with other portions, so that the loss and deformation of the solder ball and the attachment of foreign matter to the solder ball are reduced, and the yield can be improved. Further, since the bonding wire loop can be made high, the control of the bonding wire loop shape becomes easy, and the yield of the bonding step can be improved. In addition, it is possible to suppress occurrence of wire short-circuit due to deformation of the wire. Furthermore, it is possible to set a large difference between the height of the bonding wire loop and the height of the sealing resin, and it is possible to more reliably seal the bonding wire and prevent the occurrence of defective wire exposure.

The manufacturing process of the BGA of the present invention is the same as that of the conventional method when the resin sealing is performed by the transfer molding method, and when a potting method of providing a frame is used, a small number of parts and processes are required. Since it only involves addition, the production cost is hardly increased by applying the present invention. Further, in the conventional tray for BGA, a concave portion is formed so that the solder ball does not come into contact with the tray. However, the BGA according to the present invention does not come into contact with the solder ball even if it is placed on a flat surface. It is not necessary to form recesses in the tray, and the shape is simple, making it easier to manufacture molds for tray manufacturing, making it possible to manufacture the tray at low cost. In addition, the tray can be used in common by multiple models become.

Although the preferred embodiment of the present invention has been described above, the present invention is not limited to this embodiment, and can be appropriately modified without departing from the gist of the present invention. Things. For example, the wiring board may have a single wiring layer. The wiring substrate does not need to be a rigid substrate, and may be a substrate using a flexible substrate. Further, although the heat spreader is used in the embodiment, an insulating support substrate may be used instead. Furthermore, eliminating the use of support substrates and heat spreaders,
A wiring board having an opening may be mounted.
In this case, the external electrodes of the IC chip and the pads of the wiring board are connected by bonding wires through the openings of the wiring board. Also, the wiring of the wiring board and I
The connection with the external electrode of the C chip does not necessarily need to depend on the bonding wire. For example, the inner lead formed on the wiring of the flexible substrate may be directly connected to the external electrode of the IC chip.

[0017]

As described above, the face-down BGA according to the present invention has the height of the sealing resin higher than that of the solder balls, so that the following effects can be obtained. During handling such as transporting the BGA or mounting on a mounting board, it is possible to suppress the contact of the solder ball with other members, and it is possible to prevent the solder ball from dropping and deforming and to attach foreign matter to the solder ball. Can be prevented, and the production yield can be improved. Since the solder balls do not come into contact with other parts even on a flat surface of the BGA, there is no need to form a recess in the tray for storing and transporting the BGA, which facilitates the manufacture of a mold for tray manufacturing. Can be used in common by a plurality of models. Since the bonding wire loop can be set high, short circuit with the chip edge due to deformation of the bonding wire can be suppressed. Further, the control of bonding is facilitated, and the yield of wire bonding can be improved. It is possible to increase the difference between the loop height of the bonding wire and the height of the sealing resin, thereby preventing defects such as exposure of the wire due to variation in the amount of the sealing resin, and improving the reliability of the bonding wire. It becomes possible to seal highly. According to the embodiment in which the frame is provided on the outer peripheral portion of the sealing resin,
It is possible to prevent the resin from flowing to the solder ball side during the resin potting.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of one embodiment of the present invention.

FIG. 2 is a partially enlarged view of FIG.

FIG. 3 is a process order sectional view showing a manufacturing process of one embodiment of the present invention.

FIG. 4 is a sectional view of a conventional example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Wiring board 1a Device hole 2 Heat spreader 3 Solder ball 4 Bonding wire 5 IC chip 6 Sealing resin 7 Frame 8 Adhesive 9 Silver paste

Claims (11)

[Claims] A first element connected to an external electrode of the semiconductor element;
And a second pad connected to an external terminal, the wiring board having a wiring set therein, an opening portion penetrating the substrate being opened, and a wiring board provided on the second pad of the wiring board. And a semiconductor element having an external electrode electrically connected to the first pad, wherein the opening of the wiring board is sealed with a sealing resin from a side of the external terminal. Wherein the sealing resin is formed higher than the external terminals. 2. A supporting substrate is provided so as to cover the opening of the wiring substrate from a surface opposite to a surface on which the external terminals are provided, and the semiconductor device has an active element surface provided with the external terminals. The semiconductor device according to claim 1, wherein the semiconductor device is mounted on the support substrate as a support side. 3. The semiconductor device according to claim 2, wherein said support substrate covers an entire surface of said wiring substrate. 4. The semiconductor device according to claim 2, wherein said support substrate is made of metal. 5. The semiconductor device according to claim 1, wherein said external terminal is a solder ball. 6. The semiconductor according to claim 1, wherein the first pad of the wiring board and the external electrode of the semiconductor element are connected by a thin metal wire. apparatus. 7. The frame according to claim 1, wherein a frame is provided on the wiring board so as to prevent the resin from flowing so as to surround the outer periphery of the sealing resin. 13. The semiconductor device according to claim 1. 8. The semiconductor device according to claim 7, wherein said frame is made of the same material as said sealing resin. 9. An opening penetrating a substrate having a wiring in which a first pad connected to an external electrode of a semiconductor element and a second pad connected to an external terminal are set in a support substrate. Adhering a surface of the wiring board having the portion opposite to the surface on which the second pad is formed, and (2) a semiconductor element on a portion of the support substrate exposed by the opening of the wiring substrate. (3) an external electrode of the semiconductor element and a first of the wiring substrate.
(4) a step of resin-sealing the semiconductor element and the thin metal wire, and (5) an external contact on the second pad on the wiring board. Forming a terminal, wherein the height of the sealing resin formed in the step (4) is higher than the height of the external terminal formed in the step (5). Semiconductor device manufacturing method. 10. A semiconductor device comprising: (1 ′) a wiring on a surface of an active element of a semiconductor element in which a first pad connected to an external electrode of the semiconductor element and a second pad connected to an external terminal are set. Bonding a surface of the wiring substrate having an opening through the substrate, the surface being opposite to the surface on which the second pad is formed, such that external electrodes of the semiconductor element are exposed to the opening. (2 ′) a step of connecting between the external electrode of the semiconductor element and the first pad of the wiring board with a thin metal wire; and (3 ′) resin sealing of the semiconductor element and the thin metal wire. (4 ′) forming an external terminal on the second pad on the wiring board, and the height of the sealing resin formed in the (3 ′) th step. Is higher than the height of the external terminal formed in the step (4 ′). A method for manufacturing a semiconductor device. 11. In the step (4) or the step (3 ′), after a frame for preventing a resin from flowing from the outside around the formation region of the first pad is provided on the wiring substrate. 11. The method for manufacturing a semiconductor device according to claim 9, wherein resin sealing is performed by a potting method.