JP2726555B2 - Resin-sealed semiconductor device - Google Patents

Description

Description: Object of the Invention (Industrial Application Field) The present invention relates to a resin-encapsulated semiconductor device, and particularly to a semiconductor active element and an external current terminal installed inside a resin envelope. It is suitable for a resin-sealed semiconductor device in which the surface of a resin envelope other than the above is electrically insulated.

(Prior Art) A wide variety of resin-encapsulated semiconductor devices of a type in which a semiconductor active element is sealed and used by a resin envelope have been developed and sold on the market. There are a wide variety of shapes and types. Meanwhile, there is a resin-encapsulated semiconductor device in which a semiconductor active element installed inside a resin envelope and a surface of the resin envelope other than an external current terminal are insulated. The semiconductor active element 3 is mounted on a bed portion 1 of a so-called lead frame via a solder layer 2 and mounted on an electrode (not shown) provided on the semiconductor active element 3. For example, ultrasonic bonding (Bondin
The thin metal wire, for example, the Al or Au thin wire 4 fixed by the method g) is crimped to the lead terminal 5 of the lead frame by the same method and led out of the sealing resin layer 6. This lead terminal led out is usually called an outer lead. The semiconductor active element 3 is a pellet (Pellet) in which, for example, a transistor (Transister) is monolithically (Monolythic) formed on a semiconductor substrate made of silicon (Silicon). As is clear from the figure, since the internal semiconductor element and the surface of the resin envelope other than the external terminals are electrically insulated by the sealing resin layer 6, the user uses the device after purchasing. At this time, electrical insulation can be achieved without using an insulator such as Mika to attach to a heat sink separate from this device. 2 is used in such a model, in addition to FIG. 1, which is used as a part of the mounting substrate instead of the sealing resin layer 6. The semiconductor active element 3 is insulated. The resin-encapsulated semiconductor device in FIG. 1 is described as a mold type (Mold Type) and that in FIG. 2 is described as a module type. Ceramic plate 7 for module type
A mounting substrate is formed by forming metal thin films, that is, copper thin films 8 and 8 'on both sides of which a circuit pattern (Pattern) is formed, and the semiconductor active element 2 is fixed by a solder layer 9 installed here. . Each of the circuit patterns formed on the metal thin film 8 will be described as another portion 11 hereinafter.

The electrodes (not shown) formed on the semiconductor active element 3 have thin metal wires such as Al and Au thin wires 10 as in the mold type.
Is bonded by, for example, an ultrasonic bonding method, and the other end of the fine wire 10 is fixed to the other portion 11 of the metal thin film 8 by so-called 2'nd ultrasonic bonding. By the way, a metal lead holder (Holder) 12 'is used to install the lead 12 on the other part 11 of the metal thin film 8 in order to achieve electrical conduction between the module type and other devices. I do. On the other hand, a heat radiating plate 14 made of copper is fixed to the metal thin film 8 ′ provided on the other surface of the ceramic substrate 7 by a solder layer 13 having a low melting point.

By the way, as shown in the figure, the metal lead 12 is provided so as to protrude through the resin envelope 15 because the resin holder 12 'and the metal lead 12 are integrally molded in advance and then the metal thin film is formed. In this method, a low-melting-point solder layer 13 arranged between the other portion 11 and the metal lead 12 is used. Thus, a module structure is obtained. The relationship with the resin envelope 15 will be described.

As is apparent from FIG. 2, the resin envelope 15 has a side portion A.
And a lid portion B, and a resin holder 12 ′ in which the metal lead 12 of the lid portion B is integrated is fixed to the other portion 11 of the metal thin film 8 via a solder layer 13 and then made of copper. The heat radiating plate 14 and the side portion A are fixed by an adhesive layer 16, and finally, the side portion A and the resin holder 12 'are joined by a thermosetting resin.
Seal with 15 'to complete the module type. As a result, the module type has a structure in which the copper radiator plate 14 is exposed, and covers the Ni plating layer from the viewpoint of preventing oxidation. The type shown in FIG. 3 is known as a resin-encapsulated semiconductor device of a type in which the inside and the surface of the envelope are not electrically insulated, such as a mold type and a module type. Is different.

(Problems to be Solved by the Invention) The problems of the mold type and the module type corresponding to the resin-encapsulated semiconductor device are as follows. As shown in FIG. 3, the bed on which the active element is mounted is not insulated. In comparison, since the envelope has a large saturation thermal resistance value Rth (j−c), when the same active element is mounted, the power loss value Pc allowable as a semiconductor device is reduced. In other words, in the mold type, the thickness of the sealing resin layer covering the back side of the bed portion is inevitably thin, so that the withstand voltage is weak. In addition, nests are easily generated in the thin sealing resin layer, and the reliability is low. Deterioration decreases yield. Therefore, there is a limit even if a thin sealing resin layer is desirable in terms of thermal resistance. Also, the thermal conductivity of the ceramic used for the module type is smaller than that of metal or solder, and the thickness of the ceramic layer can not be thin enough to obtain the same thermal conductivity as that of metal due to manufacturing technology restrictions. Is the cause.

For example, in order to maintain the same thermal conductivity as the 0.5 mm thick copper lead frame currently used, the thickness of the ceramic used must be less than 0.02 mm, but currently the limit is about 0.6 mm .

The present invention has been made in view of such circumstances, and has as its object to improve, in particular, the saturation thermal resistance.

[Structure of the Invention] (Means for Solving the Problems) A resin-encapsulated semiconductor device according to the present invention includes a first silicon radiator plate having front and rear surfaces, and a first silicon radiator plate having a front surface and a back surface. An insulating layer provided, a second silicon radiator provided on the insulating layer, a semiconductor element connected on the second silicon radiator, and a first silicon radiator. Except for the back surface, there is a characteristic in the heat sink and the resin sealing body that covers the semiconductor element.

(Action) DC or AC is often applied to the semiconductor active element applied to the present invention for a long time, and generates about 150 ° C. during operation. Therefore, it is essential to control not the transient thermal resistance but the saturation thermal resistance. Therefore, effective heat dissipation is performed by selecting silicon having good thermal conductivity. Moreover,
DC2500V, AC3 required by forming an electrical isolation layer corresponding to the main surface in the thickness direction of the silicon plate that constitutes the heat sink
It guarantees 500V and is lighter than copper.

Further, a portion exposed to the inside and outside of the silicon plate separated from each other by providing an electrical separation layer is made to function as a heat sink, and on the other side, various circuit components necessary for electronic circuit configuration are provided outside the semiconductor active element. There are also advantages that can be.

(Embodiment) An embodiment according to the present invention will be described with reference to FIGS. 4 and 5, but the same parts as those in the prior art will be given new numbers to facilitate understanding. As shown in both figures, the outer lead (Outer Lead) 21 of the lead frame 20 is extended in the horizontal direction to reduce the height direction of the resin-encapsulated semiconductor device to be compact and attached to other devices. Consideration for convenience.

As shown in FIG. 4 which clarifies the basic structure of the present invention, a lead frame made of a material such as iron, iron-nickel alloy or iron or iron-nickel alloy having a cladding layer.
20 has a bed 22 and an inner lead (Inner
A lead 23 is provided, and a semiconductor active element 24, for example, a power transistor is fixed to the bed 22 via a solder layer 25. Further, a silicon radiator plate is prepared. In the middle of the thickness, the electrical isolation layer 26 made of silicon oxide is set to a thickness of 5 to 6 μm corresponding to the surface. ) Can also be formed. That is, the upper side 27 constituting the silicon radiator plate
The semiconductor active element 24 and the like are formed on -A, and the lower 27-B functions as a heat sink. These can be formed by a so-called bonding step in which a silicon plate and an oxide layer coated on the silicon plate are brought into close contact with each other. This adhesion means that a slightly different structure from the original structure is formed by bringing the clean coated surface into close contact, and the mechanical strength of the integrated structure is sufficient and there is no electrical obstacle at all. is there.

Further, the semiconductor active element 24, for example, an electrode (not shown) of a giant transistor, and the inner lead 23 are fixed to one end of a thin metal wire, for example, Al or Au 28 by ultrasonic bonding. By st bonding, the bonding with the inner lead 23 is performed as 2'nd bonding.

Before and after, the semiconductor active element 24 mounting surface on the upper side 27-A of the silicon radiator plate is subjected to lapping and Ni plating so that soldering is possible, and then the semiconductor active element 24 is soldered. Perform the process.

The lead frame mount structure after the above-described bonding process and the silicon radiating plates 27-A and 27-B on which the electrical isolation layer 26 is formed are integrated with each other by the low melting point solder layer 29. The side surface B of the enclosure 31 is bonded to the silicon radiating plates 27-A and 27-B by the adhesive layer 30. Furthermore, the lid portion C of the resin envelope 28 is sealed on the side surface B together with the protective material 31, for example, a gel-like polymer resin, to complete the resin-encapsulated semiconductor device.

In FIG. 5, the same reference numerals as in FIG. 4 are used, but the difference is that the electrical direction is also applied to the thickness direction of the upper side 27-A of the silicon radiator plate. Separation layer 26
Is formed to form so-called island regions D, E, and F.

That is, for example, a power transistor (not shown) is monolithically formed in the island region D, and the region G divided by the electrical isolation layer 26 is used as a relay point, and a lead frame is formed here.
The 20 inner leads 23 are fixed by the low melting point solder layer 29. Then, a thin metal wire 28 such as Al or Au is fixed between an electrode (not shown) of the power transistor and the inner lead 23 by, for example, an ultrasonic bonding method.

For example, an integrated circuit element may be formed instead of the power transistor, and a so-called individual semiconductor element may be attached to the region G to form a so-called IPD element. Further, a plurality of electrical isolation layers 26 are formed from the vicinity of the center to the periphery when the upper side 27-A of the silicon radiator plate is viewed from above, and various portions are formed on the upper 27-A portion of the divided silicon radiator plate. It is also possible to form circuit components. In this case, the lower side 27-B of the silicon heat radiating plate naturally takes charge of the heat radiating action.

[Effect of the Invention] As described above, the resin-encapsulated semiconductor device according to the present invention can obtain a low saturation thermal resistance characteristic equivalent to that of a non-insulated semiconductor device. This is because the oxide layer constituting the electrical isolation layer can be formed as thin as 5 to 6 μm, so that a saturated thermal resistance characteristic can be obtained as compared with a conventional product. Therefore, in the continuous operation of a motor equipped with a power transistor element as a semiconductor active element, the function of the silicon radiator plate enables low saturation thermal resistance characteristics to be obtained. Life can be extended. The thermal conductivity of silicon oxide used for the electrical isolation layer, for example, silicon dioxide having a thickness of 3 μm is Al _{2 having a} thickness of 0.6 μm.
Note that it is about 20 times that of O ₃ ceramic.

[Brief description of the drawings]

1 to 3 are sectional views of a conventional resin-encapsulated semiconductor device, and FIGS. 4 and 5 are sectional views showing an embodiment of the present invention. 1,22: bed part, 2, 9, 13, 25, 29: solder layer, 3, 24: semiconductor active element, 4, 10, 28: thin metal wire, 7: ceramic plate, 8, 8 ': metal thin film , 14, 27-A, 27-B: heat sink, 12: lead, 12 ': lead holder, 15, 31, B, C: envelope, 15' thermosetting resin, 16, 30: adhesive layer , 26: electrical isolation layer.

Claims (1)

(57) [Claims] 1. A first silicon radiator plate having front and rear surfaces, an insulating layer provided on a surface of the first silicon radiator plate, and a second silicon radiator provided on the insulating layer. A plate, a semiconductor element connected on the second silicon radiator plate, and a resin sealing body covering the radiator plate and the semiconductor element except for the back surface of the first silicon radiator plate. Characteristic resin-encapsulated semiconductor device