JPH09129783A - Resin sealed semiconductor device and manufacturing method thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a resin sealed semiconductor device comprising a low thermal resistance package capable of realizing low cost, high reliability, and to provide a manufacturing method thereof. SOLUTION: This present semiconductor device has an island 14 mounting a semiconductor element 13, a lead frame 22 having an inner lead 15 and a drop-in heat spreader 19 sealed in resin 18. Among components of the lead frame 22, the island 14 and a power supply or ground inner lead are connected to the drop-in heat spreader 19 through a metal plating 20 having a low melting point.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a resin-sealed semiconductor device having a low thermal resistance type package and a method for manufacturing the same.

[0002]

2. Description of the Related Art Generally, since heat is generated in a package during operation of a semiconductor device, a means for improving heat dissipation of the package has been conventionally proposed. One example thereof is Japanese Patent Laid-Open No. 4-249353. A structure of a resin-sealed semiconductor device having a package with high heat dissipation is disclosed.

FIG. 7 (a) is a plan view showing the structure of the resin-sealed semiconductor device, and FIG. 7 (b) is a sectional view taken along the line BB of FIG. 3 (a). In the figure, reference numeral 1 is a semiconductor element, 2 is an island on which the semiconductor element is mounted, 3 is an inner lead arranged so as to surround the island, 4 is an outer lead, 5 is a fine metal wire, 6 is a molding resin, 7 is the entire package A metal radiator plate (hereinafter referred to as a heat spreader) made of a high thermal conductive material so as to spread over
Is an insulating layer for electrically insulating the inner lead and the heat spreader, 9 is an adhesive material for fixing the insulating layer to the heat spreader, and 10 is an adhesive material for connecting the upper and lower high thermal conductive materials.

The lead frame and heat spreader 7 are formed by etching, stamping, or the like, and then an insulating layer 8 is attached to each heat spreader 7, and each heat spreader 7 is connected so as to sandwich the lead frame. Completed as an integrated lead frame.

Alternatively, as another example of improving the heat dissipation of the package, in JP-A-4-6863, 52 alloy material is used for the lead frame and the semiconductor element is bonded on a heat spreader made of copper tungsten alloy material. further,
There is disclosed a resin-sealed semiconductor device in which inner leads of a lead frame are laminated on a peripheral portion of a heat spreader via an adhesive.

On the other hand, there is also a semiconductor device having a structure in which an island and an inner lead are connected by resistance welding in order to stabilize the power supply and the ground potential.

[0007]

In the semiconductor device having the conventional low thermal resistance type package described above, the heat spreader is fixed by using an adhesive. In that case, a phenol / epoxy thermosetting resin, a polyether amide imide thermoplastic resin, or the like is generally used as the adhesive.

However, in the case of using the former, there is a problem that outgas is generated at the time of sticking to contaminate the plated surface of the inner lead and reduce the bonding property of the fine metal wire. Further, when the latter is used, it is necessary to carry out the attachment at a high temperature of 350 ° C. or higher, and oxidation will occur in the copper-based lead frame. Then, there is a problem that the adhesiveness between the oxidized lead frame surface and the sealing resin is lowered, interface peeling is likely to occur, and the reliability of the semiconductor device is deteriorated.

Further, the above-mentioned adhesive has a problem that the cost is generally high, and that the one provided with a power supply and a ground plane uses resistance welding for connection between the island and the inner lead, so that the cost is high. there were.

The present invention has been made to solve the above problems, and provides a resin-sealed semiconductor device having a low thermal resistance type package capable of realizing low cost and high reliability, and a method of manufacturing the same. The purpose is to provide.

[0011]

To achieve the above object, in a resin-sealed semiconductor device of the present invention, an island on which a semiconductor element is mounted, a lead frame having inner leads and a heat sink are sealed in a resin. In the stopped semiconductor device, the lead frame and the heat dissipation plate are joined via a low melting point metal. In particular, of the lead frame, it is preferable to bond the island and the power source or ground inner lead to the heat sink through a low melting point metal. It is good to insert an insulating material between them.

The method of manufacturing a resin-encapsulated semiconductor device of the present invention is a method of manufacturing a semiconductor device in which a lead frame having an island on which a semiconductor element is mounted, inner leads, and a heat sink are encapsulated in resin. A low melting point metal is attached to at least a part of the surface where the lead frame and the heat sink face each other, and the lead frame and the heat sink are placed in contact with each other in a heated encapsulation mold, whereby the low melting point metal is placed. Is melted to bond the lead frame and the heat dissipation plate, and then resin sealing is performed.

In this case, of the two upper and lower molds forming the enclosed mold, the thickness of the mold on the side where the heat dissipation plate is present with respect to the lead frame is the thickness of the mold on the opposite side. It is preferable to perform resin encapsulation using a sealed mold that is thinner than the above, and an insulating material may be attached to a portion of the surfaces of the lead frame and the heat dissipation plate which are not joined by a low melting point metal.

According to the present invention, the manufacturing cost can be reduced by replacing the conventional adhesive with the low melting point metal generally used in the semiconductor manufacturing process as the means for joining the lead frame and the heat sink. , Also, the problem of inner lead contamination due to outgas from the adhesive,
Since the problem of oxidation of the surface of the lead frame due to the high bonding temperature can be eliminated, the reliability of the semiconductor device can be ensured.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a first embodiment of the present invention will be described with reference to FIGS. FIG. 1 is a vertical cross-sectional view of a resin-sealed semiconductor device 12 of the present embodiment, FIG. 2 is a plan view of a drop-in heat spreader used therein, and FIG.
Is the back view of the lead frame. Here, QFP (Qu
A semiconductor device having an ad flat package type resin package will be described as an example. In the figure, reference numeral 13 is a semiconductor element, 14 is an island, 15 is an inner lead, 16 is an outer lead, 17 is a fine metal wire, 18 is a sealing resin, 1
9 is a drop-in heat spreader (heat sink), 20
Is a low melting point metal plating, and 21 is taping (insulating material).

As shown in FIG. 3, the lead frame 22
Is a rectangular island 14, and a plurality of inner leads 15 and outer leads 1 extending toward each side of the island 14 (four on each side in the present embodiment).
6. Then, as shown in FIG. 1, the semiconductor element 13 is mounted on the island 14,
The electrode pad (not shown) and the inner lead 15 or the island 14 are bonded by the fine metal wire 17. The thin metal wire 1 connected to the island 14
Reference numeral 7 is for electrically connecting the power supply or ground electrode pad on the semiconductor element 13 and the island 14 to make the sub-potential of the semiconductor element 13 a more reliable potential.

The wire-bonded lead frame 22 is fixed on the drop-in heat spreader 19 via the low melting point metal plating 20.
The drop-in heat spreader 19 is a radiator plate that is installed by dropping it in a sealed mold. As shown in FIG. 2, the drop-in heat spreader 19 has a rectangular planar shape, and support portions 19b extend downward from each corner of the flat plate portion 19a.

Further, as shown in FIGS. 2 and 3, the low melting point metal plating 20 is formed by the drop-in heat spreader 1.
9 and the surface of the lead frame 22 facing each other are selectively applied. That is, the low melting point metal plating 20
Is provided only on the portion of the lead frame 22 where the island 14 and the power supply or ground lead exist. Further, on the upper surface of the inner lead 15, taping 21 made of an insulating film is provided over the plurality of inner leads 15. And outer lead 1
All the above-mentioned constituent elements except 6 are covered with the sealing resin 18 to form a package.

The resin thickness of the package is a relationship between the upper die thickness (thickness above the lead frame) x and the lower die thickness (thickness below the lead frame) y of a sealed die (not shown). However, x> y.

When manufacturing the semiconductor device 12 having the above structure, first, a brazing material (not shown) is applied on the island 14 of the lead frame 22 to fix the semiconductor element 13.
After that, the electrode pad on the semiconductor element 13 and the inner lead 15, and further the power supply / ground electrode pad and the island 14 are bonded by the fine metal wire 17. In addition, low melting point metal plating 20 is applied in advance to corresponding portions of the back surface of the island 14 of the lead frame 22, the back surface of the inner lead for power supply or ground, and the surface of the drop-in heat spreader 19.

Then, resin sealing is performed. First, the drop-in heat spreader 19 having the supporting portion 19b is placed in the lower die of the enclosed die, the bonded lead frame 22 is placed thereon, and the die is clamped by the upper die. At this time, if the enclosed mold is heated to about 180 ° C., the low melting point metal plating 20 on the back surface of the island 14 of the lead frame 22, the back surface of the inner lead for power supply or ground, and the surface of the drop-in heat spreader 19 is in a molten state. And these low melting point metal plating 2
The lead frame 22 and the drop-in heat spreader 19 are bonded to each other at a position where 0 is provided.

Further, as described above, since the relationship between the upper die thickness x and the lower die thickness y of the encapsulating die is x> y, when the resin 18 flows in from the lower side of the semiconductor element 13. Also, the flow of the resin 18 progresses faster on the upper side. As a result, the semiconductor element 13 and the lead frame 22 receive a downward moment and are pressed against the drop-in heat spreader 19 side, so that peeling of the low melting point metal plating 20 portion at the time of resin encapsulation does not occur.

In the semiconductor device 12 of the present embodiment, the low melting point metal plating 20 is used as the joining means between the semiconductor element 13 and the lead frame 22 and the drop-in heat spreader 19, so that an expensive adhesive is used. The manufacturing cost can be reduced as compared with the semiconductor device described above. Further, regarding the bonding between the power or ground lead and the heat spreader 19, by using the low melting point metal plating, the manufacturing cost can be reduced as compared with the conventional semiconductor device using resistance welding for these bonding. You can

Specifically, comparing the lead frame for a 208-pin QFP, for example, the price of the lead frame and the heat spreader of the semiconductor device of the present invention is higher than that of the conventional lead frame with a heat spreader attached with a polyimide adhesive. Can be reduced to 40-50%.
Also, by using a low melting point metal plating to join the power spreader or ground lead and the heat spreader,
Price ratio with conventional lead frame using welding is 15 ~
The great effect that the cost can be reduced to about 20% can be obtained.

Further, in the case of the semiconductor device 12 of the present embodiment, the problem that the inner leads are contaminated by the outgas from the adhesive and the bondability of the fine metal wire is deteriorated, and the lead frame is formed by sticking at high temperature. The reliability of the semiconductor device can be improved as compared with the conventional case, without the problem that the adhesion of the lead frame surface with the sealing resin is deteriorated due to the oxidation of the semiconductor.

The power or ground lead is connected to the drop-in heat spreader 19 via the low melting point metal plating 20, and the power or ground electrode pad of the semiconductor element 13 is wire-bonded to the island 14. The power supply potential or the ground potential of this semiconductor device 13 can be sufficiently stabilized.

The low melting point metal plating 20 has a certain thickness, and this thickness prevents the inner leads 15 other than the power or ground leads from making electrical contact with the drop-in heat spreader 19. Further, since the upper surface of the inner lead 15 is provided with taping 21 over a plurality of leads, the space between the inner leads 15 is maintained, and the inner leads 15 are prevented from being separated. Therefore, for example, it is possible to prevent a problem that the lead adjacent to the inner lead 15 joined to the low melting point metal plating 20 on the drop-in heat spreader 19 is separated and accidentally comes into contact with the low melting point metal plating 20 to cause a short circuit. be able to.

A second embodiment of the present invention will be described below with reference to FIGS.
This will be described with reference to FIG. FIG. 4 is a vertical cross-sectional view of the semiconductor device of this embodiment, FIG. 5 is a plan view of a drop-in heat spreader used for this, and FIG. 6 is a rear view of the inner leads. The semiconductor device 24 of the present embodiment is different from that of the first embodiment only in that a part of the back surface of the lead frame is taped. Therefore, in FIGS. 4 to 6, the same components as those in FIGS. 1 to 3 are designated by the same reference numerals and the description thereof will be omitted.

As shown in FIGS. 4 and 6, in the semiconductor device 24 of the present embodiment, the back surface of the lead frame 22, that is, the surface on which the low melting point metal plating 20 is applied, is provided with taping 25 by an insulating film. . And
As shown in FIG. 6, the taping 25 is provided over the inner leads 15 other than the power or ground leads.

Regarding the low melting point metal plating 20,
As shown in FIGS. 5 and 6, as in the first embodiment, the surface of the drop-in heat spreader 19 and the lead frame 22 are provided only in the portion of the lead frame 22 where the island 14 and the power or ground lead exist.
It is provided on both sides of the back surface of.

According to the semiconductor device 24 of this embodiment,
In addition to obtaining the same effect as that of the first embodiment, the taping 25 is applied to the inner leads 15 other than the power supply or ground leads on the rear surface side of the lead frame 22, so that the drop-in heat spreader 19 It is possible to more reliably prevent a short circuit between the inner lead 15 and the drop-in heat spreader 19 that do not come into direct contact with.

The technical scope of the present invention is not limited to the above embodiment, and various modifications can be made without departing from the spirit of the present invention. For example, various changes can be made to the number of leads, the package shape, and the like. Further, as the low melting point metal plating, taping material and the like, any of those used in a normal semiconductor manufacturing process can be used.

[0033]

As described above in detail, according to the present invention, the means for joining the lead frame and the heat sink is changed from the conventional adhesive to the low melting point metal generally used in the usual semiconductor manufacturing process. As a result, the manufacturing cost can be reduced. In addition, since the problem of inner lead contamination due to outgas from the adhesive, the problem of oxidation of the lead frame surface due to high bonding temperature, etc. can be eliminated,
The reliability of the semiconductor device can be sufficiently ensured.

Furthermore, when the power source or ground inner lead and the heat sink are connected through a low melting point metal,
It is possible to stabilize the power supply potential or the ground potential at a low cost, and if an insulating material is inserted between the inner lead and the heat sink except for the power or ground inner lead, these inner lead and the heat sink can be used. It is possible to prevent a short circuit.

Further, in the manufacturing method of the present invention, when resin sealing is performed using a sealed mold in which the thickness of the mold on the side where the heat sink is present is smaller than the thickness of the mold on the opposite side, Since the lead frame is pressed against the heat dissipation plate side when the resin flows in, peeling of the low melting point metal portion does not occur when the resin is sealed.

[Brief description of the drawings]

FIG. 1 is a vertical sectional view showing a resin-sealed semiconductor device according to a first embodiment of the present invention.

FIG. 2 is a plan view showing a drop-in heat spreader used in the same resin-sealed semiconductor device.

FIG. 3 is a rear view showing an island and an inner lead portion of the lead frame.

FIG. 4 is a vertical sectional view showing a resin-sealed semiconductor device according to a second embodiment of the present invention.

FIG. 5 is a plan view showing a drop-in heat spreader used in the same resin-sealed semiconductor device.

FIG. 6 is a rear view showing an island and an inner lead portion of the lead frame.

FIG. 7 shows an example of a conventional resin-sealed semiconductor device,
(A) is a plan view, and (b) is a longitudinal sectional view taken along line BB of (a).

[Explanation of symbols]

 12, 24 Resin-encapsulated semiconductor device 13 Semiconductor element 14 Island 15 Inner lead 16 Outer lead 17 Metal fine wire 18 Sealing resin 19 Drop-in heat spreader (heat sink) 20 Low melting point metal plating 21, 25 Taping (insulating material) 22 Lead frame

Claims (6)

[Claims] 1. In a semiconductor device in which a semiconductor device mounted island, a lead frame having inner leads and a heat sink are sealed in a resin, the lead frame and the heat sink are bonded via a low melting point metal. A resin-encapsulated semiconductor device characterized by the above. 2. The resin-encapsulated semiconductor device according to claim 1, wherein in the lead frame, the island and the inner lead for power supply or ground and the heat dissipation plate are joined via a low melting point metal. A characteristic resin-encapsulated semiconductor device. 3. The resin-sealed semiconductor device according to claim 2, wherein an insulating material is inserted between the heat dissipation plate and the inner lead of the lead frame excluding the inner lead for power supply or ground. A resin-sealed semiconductor device characterized by the above. 4. A method for manufacturing a semiconductor device in which a semiconductor device mounted island, a lead frame having inner leads and a heat sink are sealed in a resin, wherein at least a part of a surface where the lead frame and the heat sink face each other. The low melting point metal is adhered to and the lead frame and the heat radiation plate are placed in contact with each other in a heated encapsulation mold to melt the low melting point metal to bond the lead frame and the heat radiation plate. Then, the method for producing a resin-sealed semiconductor device is characterized by performing resin sealing thereafter. 5. The method of manufacturing a resin-encapsulated semiconductor device according to claim 4, wherein a heat radiating plate is provided with respect to the lead frame among two molds which are divided into upper and lower parts and which form the enclosed mold. A method for manufacturing a resin-sealed semiconductor device, characterized in that resin encapsulation is performed by using an encapsulated die in which the thickness of the die on the existing side is smaller than the thickness of the die on the opposite side. 6. The method for manufacturing a resin-encapsulated semiconductor device according to claim 4, wherein an insulating material is provided on a portion of the surfaces of the lead frame and the heat dissipation plate which are not joined by a low melting point metal. A method of manufacturing a resin-encapsulated semiconductor device, comprising the step of attaching.