JPH1126635A - Bga type semiconductor device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To providing a thin type package and avoid wire sagging by forming a recess into a substrate to put and settle a chip in the recess. SOLUTION: A recess 3 for housing a chip 2 is formed into a substrate 1 and has a rectangular lower layer recess 3-1 just for fitting the rectangular chip 2 at a depth half the thickness of the substrate 1 and upper recess 3-2 tapered to expand upwards from the recess. The chip 2 chucked to a bonding tool a of a metal or heat-resistive resin collet is fitted into the recess 3-1 of the recess 3 from above. This improves the radiation efficiency, never obstructs when mounting and allows the substrate 1 to be thin.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a BGA type semiconductor device.

[0002]

2. Description of the Related Art Conventionally, as shown in FIG. 9, a BGA type semiconductor device 100 is prepared by applying an Ag paste on a substrate 101, fixing a chip 102, performing wire bonding 103 to form a resin mold 104, and then forming a back surface of the substrate. Is manufactured by transferring a solder ball 105 to the substrate and performing reflow, and welding the solder ball.

[0003]

As described above, the conventional B
The GA type semiconductor device 100 has a chip 102 fixed on a substrate 101, and a wire bonding 103 or a resin mold 104.
However, since the chip is fixed in a state where it protrudes from the substrate, the wire is greatly bent and stretched from the top surface of the chip onto the substrate, causing wire flow during resin molding, The thickness of the mold is increased by the thickness of the mold, and there is a disadvantage that the thickness cannot be reduced.

[0004]

SUMMARY OF THE INVENTION The present invention provides a BGA type semiconductor device in which a recess is formed in a substrate and a chip is housed and fixed in the recess.

Another feature is that the chip in the recess and the inner lead provided on the substrate are electrically connected to each other through bumps projecting from the lower surface of the chip.

Another feature is that a heat-dissipating metal is disposed above the chip in the recess and molded.

[0007]

According to the present invention, the chip is fixed in the concave portion of the substrate, so that the package can be reduced in thickness. In addition, a bump protruding from the lower surface of the chip is provided between the chip and the inner lead. By conducting through, the conventional wire bonding process can be omitted, the wire flow during molding after wire connection can be prevented, and since the chip is embedded in the recess, heat is radiated above the chip. Even if metal is provided, the bulk of the package does not increase, and heat radiation such as copper can prevent heat buildup and improve heat radiation efficiency.

[0008]

FIG. 1 is a plan view of a substrate 1 used in a BGA type semiconductor device M according to the present invention, and FIG. 2 is a sectional side view thereof. Is shown.

The substrate 1 has a recess 3 for accommodating the chip 2.

The shape of the concave portion 3 is such that the rectangular lower layer concave portion 3-1 in which the rectangular chip 2 only fits in the middle of the thickness of the substrate 1.
And a tapered upper concave portion 3-2 which is expanded upward from the concave portion.

As shown in FIGS. 2 and 3, a chip 2 adsorbed by a bonding tool a made of a metal or heat-resistant resin collet is provided in the recess 3 formed in the substrate 1 from above.
In the lower recess 3-1.

If the bonding tool a is made movable, the position can be corrected by the tapered upper concave portion 3-2 even if the bonding position shifts, and finally the lower concave portion 3-1 can be accurately positioned. Can be inserted.

The chip 2 fitted in the lower recess 3-1 is heated from the lower surface of the substrate and fixed by pressure through an adhesive surface.

As shown in FIG. 1, a large number of inner leads 4 are wired on the bottom surface of the concave portion 3 of the substrate 1, and the inner leads 4 connect the conductors 5 in the substrate 1 as shown in FIG. Thus, it is electrically connected to the solder ball 6 on the back surface of the substrate 1.

Here, the conduction structure between the chip 2 and the solder ball 6 in a state where the chip 2 is fitted and stored in the recess 3 will be described in detail.

That is, a bump 7 made of a gold material protrudes from the lower bottom surface of the chip 2 at the position of the bonding pad 8, and an anisotropic conductive film 9 is laid below the bump 7 to form an anisotropic conductive film 9. The film 9 is electrically connected to the inner lead 4.

In the anisotropic conductive film 9, a large number of conductive particles 9-1 are buried in a sheet-like film composition, and the conductive particles 9-1 are brought into contact with each other only in a portion where a certain pressure is applied to conduct. Has properties.

The lower surface of the anisotropic conductive film 9 is in contact with the inner lead 4, and is electrically connected from the inner lead 4 to the solder ball 6 on the back surface of the substrate 1 via the conductor 5.

Therefore, the conventional BGA type semiconductor shown in FIG.
Compared to 100, there is no wire bonding 103 from the conventional chip 102, and it is directly connected to the inner lead 4 via the bump 7 of the chip 2 and the anisotropic conductive film 9.

After the chip 2 is fitted and fixed in the recess 3, the liquid sealing resin 10 is injected into the recess 3 from the dispensing nozzle b to seal the chip, as shown in FIG.

Even if the injection position of the resin is shifted due to the tapered shape of the upper concave portion 3-2, the resin flows in the direction of the lower concave portion 3-1 and accurate sealing work can be performed.

As a pre-process of the resin sealing operation, as shown in FIG.
And the heat radiation plate 11 is also sealed together with the chip 2.

Further, the thickness of the heat radiation plate 11 is set to a thickness located in a gap between the upper surface of the chip 2 and the upper surface of the substrate 1. That is, the upper surface of the heat radiation plate 11 is exposed to the upper surface of the substrate 1 when substantially the same as the upper concave portion 3-2 or approximately half the height of the upper concave portion 3-2 and sealed with resin. Thus, heat generated from the chip 2 is radiated to the atmosphere outside the substrate 1 by direct heat conduction.

As described above, the lower surface of the heat radiation plate 11 is in direct contact with the chip 2 and the upper surface is exposed to the atmosphere.
Since the heat radiation efficiency can be improved and the chip 2 is buried in the recess 3 together with the chip 2, no projection is formed in appearance, so that there is no hindrance at the time of mounting, and the substrate 1 is also made thin.

FIG. 7 shows a state in which solder balls 6 are protruded from the substrate 1.
FIG. 2 is a cross-sectional view of the BGA type semiconductor device M of the present invention showing a state in which the chip 2 and the heat radiation plate 11 are housed in the recess 3 and sealed with a resin.

FIG. 8 shows another modification of the heat radiating plate 11, in which the side end surface of the plate 11 is formed on the tapered side end surface conforming to the tapered shape of the upper layer concave portion 3-2. At times, it is configured to fit into the upper layer concave portion 3-2.

That is, the heat radiation plate 11 is formed in such a shape as to function as a lid of the concave portion 3 in which the chip 2 is stored. Therefore, the molding process is performed after the chip 2 is stored and fixed. The upper concave portion 3-2 is closed while the heat radiating plate 11 is superposed on the upper surface of the chip 2.

By arranging the shape of the heat radiating plate 11 in this manner, a large heat radiating area can be obtained, and the mounting work of the plate 11 can be easily performed by the tapered shape. Only the gap between the chip 3 and the chip 2 is sufficient, and the amount of sealing resin may be small.
As a result, the molding process becomes simpler and the molding resin is smaller, the heat denaturation to the substrate is less, and the heat radiation plate 11 can be fixed with an adhesive through a tapered shape, so that there is no displacement of the fixing position. This has the effect that reliable fixing work can be performed.

As described above, when the fixing of the heat radiation plate 11 and the molding process are completed, the solder balls 6 are transferred to the back surface of the substrate 1 and reflowed to fix the solder balls 6.

[0030]

According to the first aspect of the present invention, since the chip is fixed in the concave portion, the chip does not protrude above the substrate, so that the package can be made thinner. This has the effect of preventing wire drooping due to the molding resin.

According to the second aspect of the present invention, since the chip in the concave portion and the inner lead provided on the substrate are electrically connected to each other through the bumps projecting from the lower surface of the chip, there is no wire bonding step, and the wire during molding is eliminated. This has the effect of eliminating drooping, simplifying the structure, and reducing the cost.

According to the third aspect of the present invention, since the heat-dissipating metal is disposed above the chip in the recess and molded, the thickness of the package does not increase despite the heat-dissipating metal being interposed. The heat dissipation efficiency is improved, and the package can be formed to be thin as a whole despite having a heat dissipation function.

[Brief description of the drawings]

FIG. 1 is a plan view showing a substrate of an apparatus of the present invention.

FIG. 2 is a sectional side view of the same.

FIG. 3 is an explanatory view showing a state in which a chip is mounted on a substrate of the device of the present invention.

FIG. 4 is an enlarged explanatory view showing a state in which a chip is fitted into a substrate of the device of the present invention and a terminal on the back surface of the substrate is electrically connected to a chip bump;

FIG. 5 is an explanatory cross-sectional view of the embodiment of the present invention when a heat sink is mounted.

FIG. 6 is an explanatory diagram showing a state in which a concave portion is sealed in FIG. 5;

FIG. 7 is a sectional view showing a completed state of the embodiment of the present invention.

FIG. 8 is a cross-sectional view of another embodiment showing deformation of a heat sink.

FIG. 9 is an explanatory sectional view of a conventional BGA type semiconductor device.

[Explanation of symbols]

 a bonding tool 1 substrate 2 chip 3 recess 3-1 upper layer recess 3-2 lower layer recess 4 inner lead 5 conductor 6 solder ball 7 bump 8 bonding pad 9 anisotropic conductive film 10 liquid sealing resin 11 heat dissipation plate

Claims (3)

[Claims] 1. A BGA type semiconductor device wherein a recess is formed in a substrate and a chip is housed and fixed in the recess. 2. A BGA type semiconductor device in which a chip in a recess and an inner lead provided on a substrate are electrically connected to each other via a bump protruding from a lower surface of the chip. 3. A BGA type semiconductor device in which a heat-dissipating metal is arranged above a chip in a recess and molded.