JPH07283350A - Packaging structure of semiconductor element - Google Patents

Abstract

PURPOSE:To achieve a high-density packaging, facilitate maintenance, and inspect a semiconductor device before packaging alone by efficiently releasing heat to a metal substrate with a metal base as a heat sink and at the same time mounting the semiconductor element to the metal substrate in advance in the form of a chip compactly. CONSTITUTION:A metal substrate 1 is laminated by a metal base 2, its thin part 2a, an insulation layer 5, a die pad 3, and a wiring layer 4, a semiconductor element 6 is die-bonded on the die pad 3 by solder 7, the electrode part is connected to the wiring layer 4 with a wire 8, and then the semiconductor 6 and the wire 8 are sealed by resin 9. In this manner, the chip semiconductor element 6 on the metal substrate 1 is packaged on a substrate 10 by providing a conductor 11 for mounting base and a printed conductor 12 on the surface of the substrate 10, joining the metal base 2 to the conductor 11 for mounting base, and connecting the wiring layer 4 to the printed conductor 12 in a simple packaging structure.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor element mounting structure.

[0002]

2. Description of the Related Art FIG. 12 shows a first mounting structure of a semiconductor device.
The conventional example of is shown. This conventional example has a general bare chip mounting structure, in which the semiconductor element 21 has a heat sink 2
After being soldered to the No. 2 solder 24, the back surface of the heat sink 22 is soldered to the heat sink mounting conductor 25 on the substrate 23. The electrode portion (not shown) of the semiconductor element 21 is electrically connected to the printed conductor 26 on the substrate 23 by the wire 27. A dam ring 28 is bonded to the substrate 23 with an adhesive 29 so as to surround the semiconductor element 21.
A sealing resin 30 is injected for the purpose of protecting the wire 1 and the wire 27.

FIG. 13 shows a second conventional example of a semiconductor element mounting structure. In this conventional example, after packaging the semiconductor element by the transfer molding method,
The semiconductor element 21 has a mounting structure that is surface-mounted on a substrate.
Are soldered onto the heat sink 31 which is a part of the lead frame. The electrode portion (not shown) of the semiconductor element 21 is electrically connected to the lead 32 by the wire 27. Then, in order to protect the semiconductor element 21 and the wire 27, the semiconductor element 21 and the wire 27 and the like are packaged by sealing with a sealing resin 30 by a transfer molding method. After being packaged, the back surface of the heat sink 31 is joined to the heat sink mounting conductor 25 on the substrate 23 by the solder 24, the leads 32 are electrically connected to the printed conductor 26 by the solder 24, and the package is surface-mounted on the substrate 23. Has been done.

[0004]

In the first conventional example, bare chip mounting allows relatively high-density mounting, but since the semiconductor element is resin-sealed integrally with the substrate, repairability after mounting is improved. Is poor, and it is not possible to perform an electrical test on the element alone. Furthermore, the number of parts is large, the parts cost,
There is a problem that the manufacturing cost becomes high.

In the second conventional example, since it is packaged in the lead frame, the weight is heavy and the shape is large, so that high density mounting is difficult, and expensive equipment such as a transfer mold device is required, which is often used. It is not suitable for small-lot production of various varieties, and in the case of small-lot production, there is a problem that the depreciation costs of molds are expensive and the manufacturing cost is high.

The present invention has been made by paying attention to such conventional problems. It has high heat dissipation and enables high-density mounting similar to conventional bare chip mounting, and has good repairability after mounting. It is an object of the present invention to provide a mounting structure for a semiconductor element, which enables electrical inspection of the element after assembly and further enables cost reduction.

[0007]

In order to solve the above-mentioned problems, according to the present invention, firstly, there is a thin portion around a thick metal base serving as a heat sink, and a die pad is provided on the surface of the metal base. Insulation is formed and a wiring layer is formed from the surface of the metal base to the surface of the thin portion such that the surface of the wiring layer at the folded-back end is substantially flush with the back surface of the metal base. The folded metal substrate, a semiconductor element that is die-bonded on the die pad and has an electrode portion appropriately connected to the wiring layer, a base mounting conductor and a printed conductor, and the metal base is soldered to the base mounting conductor. The gist is that the printed conductor has a substrate to which the wiring layer at the folded-back end is soldered and is joined.

Second, a box-shaped heat sink, a semiconductor element that is die-bonded to the inner bottom portion of the heat sink and resin-sealed, and a bonding pad connected to an electrode portion is exposed from the resin sealing, and a heat sink. It is a gist to have a board provided with a mounting conductor and a printed conductor, the back surface of the heat sink being soldered to the heat sink mounting conductor, and the printed conductor being connected to the bonding pad via a wire.

Thirdly, a box-shaped heat sink, a semiconductor element which is die-bonded to the inner bottom portion of the heat sink and is resin-sealed, and a bonding pad connected to an electrode portion is exposed from the resin-sealing, and a heat sink. A gist of the present invention is to have a board having an attachment conductor and a printed conductor, the bonding pad being soldered to the printed conductor, and the peripheral end surface of the heat sink being soldered to the heat sink attachment conductor.

[0010]

In the above structure, firstly, the heat generated in the semiconductor element is efficiently radiated to the substrate because the metal base functions as a heat sink. The semiconductor element is preliminarily mounted on the metal substrate and is made into a small and compact chip carrier. Since the heat dissipation is good as described above, high-density mounting comparable to bare chip mounting becomes possible. Further, since the chip carrier is used, the repairability from the substrate is improved, and it becomes possible to electrically test the semiconductor element by itself before mounting on the substrate.

Secondly, the heat generated in the semiconductor element is efficiently radiated to the substrate via the heat sink. The semiconductor element is preliminarily mounted in the heat sink and is made into a small and compact chip carrier. Since the heat dissipation is good as described above, high density mounting comparable to a bare chip is possible. In addition, since it is made into a chip carrier, the repairability from the board becomes good, and the electrical inspection of the semiconductor element alone before mounting on the board is extremely easy because the bonding pad is exposed from the resin seal. Easier to do.

Thirdly, it is pre-mounted in the heat sink,
Since the semiconductor element, which is made into a small and compact chip carrier, is mounted face down on the substrate, it has an extremely simple mounting structure, which improves heat dissipation and enables high-density mounting comparable to bare chip mounting. Other,
The same effects as those of the second invention can be obtained, such as repairability from the substrate after mounting and easiness of electrical inspection of the semiconductor element alone.

[0013]

Embodiments of the present invention will be described below with reference to the drawings. 1 to 5 are views showing a first embodiment of the present invention. First, the structure of the metal substrate and mounting of the semiconductor element on the metal substrate will be described with reference to FIGS. In the metal substrate 1, a thin portion 2a is formed around a thick metal base 2 serving as a heat sink by a metal such as copper, aluminum or iron, and epoxy, silicone, polyimide An insulating layer 5 made of glass epoxy or the like is formed. The die pad 3 is formed on the insulating layer 5 corresponding to the metal base 2, and the appropriately patterned wiring layer 4 is formed on the insulating layer 5 corresponding to the thin portion 2a from the peripheral portion of the metal base 2. Are formed. In this way, the metal substrate 1 has a laminated structure of the metal base 2, the metal of the thin portion 2a, the insulating layer 5, the die pad 3, and the metal foil of the wiring layer 4. The insulating layer 5 is thinly formed to have a thickness of about 100 μm, and the die pad 3 and the wiring layer 4 are formed.
Is made of copper foil. The thin portion 2a formed thinly with such a material can be bent,
As shown in FIG. 2, the wiring layer 4 is folded back in a U-shape in cross section so that the front surface of the wiring layer 4 at the folded back end is substantially flush with the back surface of the metal base 2. Then, the semiconductor element 6 is die-bonded onto the die pad 3 of the metal substrate 1 thus formed by bonding the solder 7, and its electrode portion (not shown) is electrically connected to the wiring layer 4 by the wire 8. Has been done. The semiconductor element 6, the wire 8 and the like are sealed with a sealing resin 9 for the purpose of protecting from the external environment. If the resin has a high viscosity and a high chicken property, it can be sealed as shown by a bonding method or the like without a guard ring or the like. In the case described above, the thin portion 2a is folded back to assemble the semiconductor element 6 on the metal substrate 1 in the shape of a chip carrier. However, as shown in FIGS. After mounting the semiconductor element 6 and performing wire connection, a step of folding back the thin portion 2a may be taken.

FIG. 1 shows a mounting structure on a substrate 10 of a semiconductor element 6 which is formed into a chip carrier on the metal substrate 1 as described above. The base mounting conductor 1 is provided on the surface of the substrate 10.
1 and an appropriately patterned printed conductor 12 are provided, the metal base 2 is joined to the base mounting conductor 11 by solder 13, and the wiring layer 4 at the folded back end is electrically connected to the printed conductor 12 by solder 13. It is connected to the.

Next, the operation of the semiconductor element mounting structure configured as described above will be described. The metal base 2 functions as a heat sink, and the heat generated in the semiconductor element 6 is efficiently radiated to the substrate 10. Semiconductor element 6 on metal substrate 1
It is possible to easily remove it from the substrate 10 at the time of repair by mounting it in advance and making it into a chip carrier, and to perform the pre-inspection or burn-in of the semiconductor device 6 that has been made into a chip carrier by itself before mounting on the substrate 10. It becomes possible to carry out the screening step. The packaging density can be as high as that of the conventional bare chip packaging, and at the time of packaging, expensive equipment such as a mold and a transfer molding device is not required, and the manufacturing cost can be reduced. In addition, by changing the pattern of the metal substrate 1 etc., it is possible to respond without being influenced by the chip size, the number of terminals of the semiconductor element, etc., and TAT (Turn Around) from design to manufacturing.
Compared with the conventional package (transfer mold), the time required for mold design and manufacturing is also unnecessary and can be made significantly faster.

FIG. 6 and FIG. 7 respectively show modifications of the portion of the metal substrate 1. In the example of FIG. 6, the bent shape of the thin portion 2a is U-shaped in section (bent at right angles) in consideration of occurrence of insulation failure of the insulating layer 5. In the example of FIG. 7, a recess 2b is provided on the surface of the metal base 2, and a semiconductor element is die-bonded to the recess 2b to facilitate the formation of the sealing resin 9. When the sealing resin 9 having a low viscosity and a low chicken property is used, it is advisable to form the recess 2b and pot the sealing resin 9 as described above.

8 to 10 show a second embodiment of the present invention. In this embodiment, as shown in FIGS. 8 and 9, the heat sink 14 is formed in a box shape.
The semiconductor element 6 is die-bonded to the inner bottom of the substrate by bonding the solder 7, and the bonding pads 15 are connected to the respective electrode portions (not shown) by the solder 7. The concave portion of the heat sink 14 is filled with the sealing resin 9 for the purpose of protecting the semiconductor element 6 from the external environment. The bonding pad 15 is formed sufficiently thicker than the electrode film on the semiconductor element 6, and its upper portion is exposed from the sealing resin 9.

FIG. 10 shows a mounting structure of the semiconductor element 6 thus formed into a chip carrier on the heat sink 14 on the substrate 10. A heat sink mounting conductor 11a and an appropriately patterned printed conductor 12 are provided on the front surface of the substrate 10, the back surface of the heat sink 14 is joined to the heat sink mounting conductor 11a with solder 13, and the printed conductor 12 is connected to the wire 8. The bonding pad 15 is connected via.

Next, the operation of the semiconductor element mounting structure configured as described above will be described. The heat generated in the semiconductor element 6 is efficiently radiated to the substrate 10 via the heat sink 14. Since the semiconductor element 6 is mounted in the heat sink 14 to form a chip carrier, and the necessary electrode portions are exposed from the sealing resin 9 by the bonding pad 15, the substrate 10
It is possible to carry out a screening process such as pre-inspection or burn-in of the semiconductor element 6 alone before mounting on the semiconductor device 6. Since the bonding pad 15 can be directly probed any number of times, an electrical test is particularly easy to perform. The repair after mounting on the substrate 10 can be easily performed by melting the solder. Mounting density can be as high as conventional bare chip mounting,
At the time of mounting, expensive equipment such as a mold and a transfer molding device is not required, and the manufacturing cost and material cost are low. There are no restrictions on the chip size, thickness, etc. of the semiconductor element 6 that can be mounted on the heat sink 14, but since the bonding pad 15 is provided on the electrode portion by solder connection,
A semiconductor element such as a transistor or a diode having a small number of electrodes is easier to apply. Connecting the bonding pad (metal pad) to the electrode of the semiconductor element by soldering has been performed for a long time by flip chip or the like, and can be performed by the existing technology. Although the bonding pad is used in this embodiment, a protruding electrode such as a stud bump or a solder bump can be used.

FIG. 11 shows a third embodiment of the present invention.
It is the same as the second embodiment until the semiconductor element 6 is mounted on the box-shaped heat sink 14 and the sealing resin 9 is filled to form a chip carrier. FIG. 11 shows a mounting structure of such a chip carrier semiconductor element 6 on a substrate 10. On the surface of the substrate 10, a heat sink mounting conductor 1
1b and an appropriately patterned printed conductor 12 are provided, and a semiconductor element 6 is mounted face down on such a substrate 10 as in flip chip mounting. That is, the bonding pad 15 is directly connected to the printed conductor 12 by the solder 13, and the peripheral end face portion of the heat sink 14 is joined by the solder 13 to the heat sink mounting conductor 11b.

In this embodiment, as described above, the structure is simple, the semiconductor elements 6 can be mounted on the substrate 10 at a high density, and a mounting structure excellent in heat dissipation is realized. In addition, the present embodiment has substantially the same actions and effects as the second embodiment.

[0022]

As described above, according to the invention described in each claim, the following effects are obtained.

According to the first aspect of the invention, a thin metal base serving as a heat sink has a thin portion around the metal base, and a die pad is formed on the surface of the metal base so as to be insulated from the surface of the metal base. A wiring layer is formed so as to extend over the surface of the thin portion, and the thin portion is folded back so that the surface of the wiring layer at the folded end is substantially flush with the back surface of the metal base, and a die on the die pad. A semiconductor element, which is bonded and whose electrode portion is appropriately connected to the wiring layer, is provided with a base mounting conductor and a printed conductor, the metal base is soldered to the base mounting conductor, and the printed conductor has the folded end. Since the wiring layer in the section is provided with a substrate to which solder connection is made, the heat dissipation is good and the semiconductor element is pre-mounted on the metal substrate. It is possible to realize high-density mounting of bare chip mounting comparable from being chip carrier into a compact size. Further, since the chip carrier is used, the repairability from the substrate after mounting is improved, and the electrical inspection of the semiconductor element alone can be easily performed before mounting on the substrate. Further, when mounting, expensive equipment such as a mold and a transfer molding device is not required, and the manufacturing cost can be reduced.

According to the second aspect of the present invention, the box-shaped heat sink and the bonding pad that is die-bonded to the inner bottom portion of the heat sink and resin-sealed and is connected to the electrode portion are exposed from the resin-sealing. And a substrate having a heat sink mounting conductor and a printed conductor, the back surface of the heat sink being soldered to the heat sink mounting conductor, and the bonding pad being connected to the printed conductor via a wire. Therefore, in addition to the effect of the invention of claim 1, an electrical inspection of the semiconductor element alone after assembly and before mounting on the substrate is further performed because the bonding pad is exposed from the resin sealing. It will be easier.

According to the third aspect of the present invention, the box-shaped heat sink and the bonding pad bonded to the inner bottom portion of the heat sink and sealed with resin and connected to the electrode portion are exposed from the resin seal. Since the semiconductor element and the heat sink mounting conductor and the printed conductor are provided, the bonding pad is soldered to the printed conductor, and the peripheral end face of the heat sink is solder-bonded to the heat sink mounting conductor, In addition to the effect of the invention described in Item 2, in addition, since the semiconductor element which is preliminarily mounted in the heat sink and which is made into a small and compact chip carrier is mounted face down on the substrate, the mounting structure is extremely simple and the heat dissipation is improved. It can be further enhanced. Further, the number of parts is small and the material cost can be reduced.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing a first embodiment of a mounting structure of a semiconductor device according to the present invention.

FIG. 2 is a configuration diagram showing a mounting state of a semiconductor element on a metal substrate in the first embodiment.

FIG. 3 is a perspective view of FIG. 2 excluding a resin sealing portion.

FIG. 4 is a view for explaining the step of folding back the thin portion after mounting the semiconductor element on the metal substrate in the first embodiment.

FIG. 5 is a plan view of FIG.

FIG. 6 is a configuration diagram showing a first modification of the first embodiment.

FIG. 7 is a configuration diagram showing a second modification of the first embodiment.

FIG. 8 is a configuration diagram showing a mounting state of a semiconductor element on a heat sink in the second embodiment of the present invention.

9 is a perspective view of FIG. 8. FIG.

FIG. 10 is a configuration diagram showing a second embodiment of the present invention.

FIG. 11 is a configuration diagram showing a third embodiment of the present invention.

FIG. 12 is a configuration diagram showing a first conventional example of a semiconductor element mounting structure.

FIG. 13 is a configuration diagram showing a second conventional example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Metal substrate 2 Metal base 2a Thin part 3 Die pad 4 Wiring layer 5 Insulating layer 6 Semiconductor element 7,13 Solder 8 Wire 9 Sealing resin 10 Substrate 11 Base mounting conductor 11a, 11b Heat sink mounting conductor 12 Print conductor 14 Heat sink 15 Bonding pad

Claims (3)

[Claims] 1. A thin metal base serving as a heat sink has a thin portion around the metal base, a die pad is formed on the surface of the metal base, and a wiring layer extends from the surface of the metal base to the surface of the thin portion. The thinned portion is insulated and folded back so that the front surface of the wiring layer at the folded back end is substantially flush with the back surface of the metal base; and the electrode portion is die-bonded on the die pad to form the wiring layer. A semiconductor element appropriately connected to the base mounting conductor and a printed conductor, the metal base is soldered to the base mounting conductor, and the printed conductor is soldered to the wiring layer at the folded end. And a mounted substrate for a semiconductor device. 2. A box-shaped heat sink, a semiconductor element which is die-bonded to the inner bottom portion of the heat sink and is resin-sealed, and a bonding pad connected to an electrode portion is exposed from the resin-sealing, and a heat sink mounting member. A semiconductor element comprising a conductor and a printed conductor, the back surface of the heat sink being soldered to the heat sink mounting conductor, and the printed conductor being connected to the bonding pad via a wire. Mounting structure. 3. A box-shaped heat sink, a semiconductor element that is die-bonded to the inner bottom of the heat sink and sealed with resin, and a bonding pad connected to an electrode portion is exposed from the resin sealing, and a heat sink mounting member. A mounting structure for a semiconductor device, comprising: a conductor and a printed conductor; and the bonding pad soldered to the printed conductor, and a substrate to which a peripheral end face of the heat sink is solder-bonded to the heat sink mounting conductor.