JP3314574B2 - Method for manufacturing semiconductor device - Google Patents

Abstract

PURPOSE: To obtain a robust resin sealed multichip IC package having high heat dissipation properties in which a plurality of IC chips are set in a single package. CONSTITUTION: An analog IC chip 11 and a digital IC chip 12 are bonded, on the rear surface thereof, to individual metal plates 21, 22. The metal plates 21, 22 are exposed from sealing resin 1 on the side opposite to the IC chip mounting side. When the metal plates 21, 22 are fed with power and operated, heat is dissipated from the exposed surface into the air. Since the mounting base of the analog IC chip 11, i.e., the metal plate 21, is electrically separated completely from the mounting base of the digital IC chip 12, i.e., the metal plate 22, no noise propagate on the metal plates from the digital IC chip 12 to the analog IC chip 11 to cause deterioration in the performance of the circuit during the operation.

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 semiconductor device in which a plurality of integrated circuit (hereinafter, referred to as IC) chips are resin-sealed as a single package to enhance heat dissipation. And its manufacturing method.

[0002]

2. Description of the Related Art FIG. 2 is a simplified representation of the structure described in JP-A-63-244747. In FIG. 2, two IC chips 10 are metal plates 20 as die pads.
Together with resin sealing. 1 is a sealing resin, 2
Is a lead, 3 is a wiring board, 4 is a thin metal wire for connecting an electrode provided on the surface of the IC chip to an electrode provided on the surface of the wiring board, and 5 is an adhesive. As the adhesive, a conductive material having low heat resistance is generally used. I
One of the C chips 10 is a metal plate 20 which is a die pad.
The other one is insulated from the die pad 20 by the wiring board 3. An example of dividing the chip mounting surface in this way is an analog circuit and a digital circuit. Generally, separate power supplies and grounds are used for the analog circuit and the digital circuit in order to avoid noise. When an analog IC chip and a digital IC chip are resin-encapsulated as a single IC package, the analog IC chip and the digital IC chip are connected to a single metal plate so as to separate power and ground from each other. Since it is not possible to adhere with an adhesive, one of the IC chips has to be adhered to the die pad 20 via the wiring board 3 as shown in FIG. As a result, heat radiation from the IC chip adhered to the die pad 20 via the wiring board 3 deteriorates. Of course, it is possible in terms of packaging technology to bond both IC chips to the die pad 20 without passing through the wiring board 3, but the same power supply or ground is used for the analog circuit and the digital circuit, and a common power supply is used. Alternatively, noise is transmitted from the digital circuit to the analog circuit through the ground, so that the performance of the electric circuit deteriorates.

[0003]

When a plurality of IC chips, in particular, different kinds of IC chips having different one or both of a power supply and a ground are sealed in a single package,
One of the IC chips adheres non-conductively to the metal plate via an insulating substrate such as a printed wiring board. However, there is a problem that heat radiation from the IC chip adhered non-conductively is poor. Further, when one of the IC chips is electrically conductively bonded to a metal plate without passing through an insulating substrate such as a printed wiring board, there is a problem that the performance of an electric circuit is deteriorated due to noise.

[0004] An object of the present invention is to solve such a problem and to incorporate a plurality of different types of IC chips into a single IC package.
An object of the present invention is to provide a resin-sealed IC package that is resistant to noise and has high heat dissipation.

[0005]

A method of manufacturing a semiconductor device according to the present invention comprises a first integrated circuit chip, a second integrated circuit chip, and a first integrated circuit chip bonded to the back surface of the first integrated circuit chip. A metal plate, a second metal plate adhered to the back surface of the second integrated circuit chip, and device holes respectively containing the first integrated circuit chip and the second integrated circuit chip. A wiring board adhered to the first metal plate and the second metal plate; a thin metal wire connecting an electrode group provided on the surface of the integrated circuit chip to an electrode group provided on the surface of the wiring board; And a step of preparing a circuit block including the group, and placing the circuit block in a resin sealing mold so that the surfaces of the first metal plate and the second metal plate are in contact with the inner surface of the mold. And injecting a sealing resin into the mold. The method of manufacturing a device, and wherein the match schematically the direction of flow of the gap sealing resin in the direction of which is formed by the first metal plate and the second metal plate.

[0006]

[0007]

Both of different types of IC chips, such as an analog IC chip and a digital IC chip, are each bonded to a metal plate (mounting table) by a conductive adhesive having a low thermal resistance without passing through an insulating substrate such as a printed wiring board. Since a part of the metal plate is exposed from the sealing resin, it prevents noise transmission between the analog IC chip and the digital IC chip,
The heat generated during the operation of the analog IC chip and the digital IC chip is radiated from the metal plate of the die pad via a conductive adhesive having good heat conductivity.

[0008]

1 is a sectional view of an IC package according to the present invention. In FIG. 1, reference numerals 11 and 12 denote first and second IC chips, respectively. In this example, 11 is an analog IC chip, 12 is a digital IC chip, and 21 is an analog IC chip.
Metal plate for mounting and fixing C chip, 22 is a digital IC
A metal plate on which the chip is mounted and fixed. The analog IC chip 11 is adhered to the metal plate 21 by the adhesive 5.
Similarly, the digital IC chip 12 is bonded to the metal plate 22 by the adhesive 5. Reference numeral 3 denotes a single wiring board. In a region where the analog IC chip 11 and the digital IC chip 12 are mounted, a device hole 6 large enough to mount each chip without difficulty (about 1 mm larger on one side than the chip size) is provided. Is provided. The wiring board 3 is bonded to the metal plates 21 and 22 with the adhesive 5. Therefore, the planar size of the metal plates 21 and 22 is set to a size that overlaps the wiring board 3 at at least three points around the device hole. Around the device hole on the lower surface 7 of the wiring board 3, there are a plurality of electrodes (not shown) formed by nickel plating on a copper foil and further gold plating on the copper foil, and corresponding electrodes (not shown) on an IC chip. ) And a thin metal wire 4.
Although not shown, at least the lower surface 7 of the wiring board 3 has metal wiring designed to realize a desired circuit function, and is electrically connected to the electrode or the lead 2 of the lower surface 7 of the wiring board. ing. Also, metal wiring is provided on the upper surface 8 and the wiring board as necessary, and via holes for electrically connecting these wirings are provided. 2 is a lead for electrically connecting a circuit in the IC package to an external circuit. The lead is made of metal, and is made of 42 alloy or copper alloy. The bending direction of the lead 2 is generally bent in the illustrated direction such that the exposed portions of the metal plates 21 and 22 do not come to the package mounting plate side. Metal plate 21,
When the exposed portion 22 comes to the package mounting plate side, it becomes impossible to further increase the heat radiation performance by adding a heat radiation fin to the exposed portion. Reference numeral 1 denotes a sealing resin;
2. Protect the wiring board 3, the thin metal wires 4 and the like from external mechanical shocks. The surfaces of the metal plates 21 and 22 opposite to the surface on which the IC chip is mounted are exposed from the sealing resin 1. Therefore, the analog IC chip 11, the digital IC chip 1
2 can be easily released into the air when power is applied to the device and the device operates. Further, the metal plate 21 serving as the mounting table for the analog IC chip 11 and the metal plate serving as the mounting table for the digital IC chip 12 are completely separated electrically.
The noise of No. 2 does not propagate to the analog IC chip 11 to lower the performance of the circuit.

The semiconductor device according to the present invention is manufactured as follows.

(1) First, wiring and via holes designed to obtain a desired circuit function, pads for connecting thin metal wires, and pads for connecting leads are provided at the end of the surface, and an analog IC is provided therein. A printed circuit board 3 having a device hole 6 for inserting a chip and a device hole 6 for inserting a digital IC chip therein is prepared. Each of the pads is provided with a nickel plating on a copper foil and a gold plating thereon.
It is desirable that the substrate of the printed circuit board 3 be made of polyimide, BT resin, or the like, which has excellent heat resistance of FR-5 or more. The reason for this is that heating is required in a later step.

(2) Then, as shown in FIG. 4 (a), the inner ends of the tin-plated leads of the lead frame 40 and the gold-plated pads provided on the surface ends of the printed circuit board are heated. Crimp and connect. The gold-tin eutectic alloy has a high melting point so that it can withstand high temperatures in later steps, and has high reliability and high bonding strength. As another connection method, there is a method using a high melting point solder having Sn 90% Pb 10% and a liquidus melting point of about 220 ° C. The reason why the high melting point solder is used is that it is necessary to heat in a later step. As another method, gold plating (when the lead material is 42 alloy) or silver plating (when the lead material is copper alloy) is applied to the inner end of the lead, and the back end of the printed circuit board is bonded to the tab suspension lead. After that, there is also a method of connecting the inner ends of the leads and the pads provided on the surface end of the printed circuit board and provided with gold plating with gold fine wires.

(3) Next, as shown in FIG.
The two metal plates 21 and 22 are attached to the printed circuit board 3 with an adhesive 5
Glue using Epoxy adhesive is applied around the device hole of the printed circuit board, and the metal plate is
After arranging so as to cover the device hole for the C chip and the device hole for the digital IC chip, respectively,
It was dried by heating at 00 to 200 ° C. for about 1 hour to fix it.

(4) Next, an analog IC chip is formed on the surfaces of the printed circuit board 3 where the metal plates 21 and 22 are exposed by the device holes 6 by using a conductive adhesive such as silver paste.
Adhere the digital IC chip.

A silver paste was applied to a portion where the metal plate was exposed by the device hole, and after mounting an analog IC chip and a digital IC chip, it was heated and dried at 100 to 200 ° C. for 1 hour to be fixed.

(5) Next, as shown in FIG.
The electrodes provided on the surfaces of the C chips 11 and 12 and the electrodes provided on the surface of the wiring board are connected by the thin metal wires 4. As a thin metal wire, a gold wire having a diameter of 30 μm was used and connected by a thermocompression bonding method using ultrasonic waves. In addition, there are a method of connecting an aluminum wire by an ultrasonic method and a method of connecting by using a TAB lead.

(6) The lead frame having undergone the above-described steps is mounted on a resin mold 3 as shown in FIG.
0 is mounted so that the surfaces of the metal plates 21 and 22 are in contact with the inner surface of the mold, and are sealed with a resin. At this time, as shown in FIG. 3, the direction of the gap 23 formed between the metal plate 21 and the metal plate 22 matches the direction 24 in which the sealing resin flows. (In FIG. 3, the direction is from the lower left to the upper right.) By doing so, the inflow of the resin can be made smooth and the occurrence of cavities and the like can be suppressed. In FIG. 3, reference numeral 30 denotes a mold, and reference numeral 40 denotes a lead frame. The most common transfer molding method was used as a sealing method, and a cresol novolak-based epoxy resin, which is also commonly used, was used as a molding material. In the case where the package thickness is reduced, a biphenyl-based molding material that is less likely to crack is suitable.

(7) Next, as shown in FIG. 4 (e), the frame and the dam bar are cut and removed from the lead frame by ordinary means, and the external lead 2 is formed into a desired shape.

[0018]

As described above, the analog IC chip and the digital IC chip can be sealed in a single package, and the power supply and the ground are separated in the analog circuit and the digital circuit.
The analog circuit is not affected by the noise of the digital circuit. In addition, even in an IC that operates at high speed and consumes a large amount of power because of its excellent heat dissipation, the operating temperature of the chip does not increase, so that the performance does not decrease.

In the resin sealing step, an analog IC
Since the direction of the gap between the metal plate, which is the die pad of the chip, and the metal plate, which is the die pad of the digital IC chip, is matched with the direction in which the sealing resin flows, the generation of cavities and the like can be suppressed, and reliability can be reduced. A high semiconductor device can be manufactured.

[Brief description of the drawings]

FIG. 1 shows an embodiment of the present invention. FIG. 2 is a cross-sectional view of an IC package.

FIG. 2 is a conventional example. FIG. 2 is a cross-sectional view of an IC package.

FIG. 3 shows an embodiment of the present invention. FIG. 4 is a plan view for explaining inflow of resin in a resin sealing step.

FIG. 4 shows an embodiment of the present invention. The figure explaining a manufacturing process.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Encapsulation resin 2 Lead 3 Wiring board 4 Fine metal wire 5 Adhesive 6 Device hole 7 Lower surface of wiring substrate 8 Upper surface of wiring substrate 11 Analog IC chip 12 Digital IC chip 20 Metal plate which is a die pad 21 A die pad of an analog IC chip Metal plate 22 Metal plate as die pad of digital IC chip 30 Mold 40 Lead frame

Continuation of the front page (58) Field surveyed (Int. Cl. ⁷ , DB name) H01L 21/56 H01L 23/34-23/473 H01L 25/00-25/18

Claims (1)

(57) [Claims] A first integrated circuit chip; a second integrated circuit chip; a first metal plate adhered to a back surface of the first integrated circuit chip; and a back surface of the second integrated circuit chip A second metal plate adhered to the first integrated circuit chip, and device holes respectively containing the first integrated circuit chip and the second integrated circuit chip are provided, and are bonded to the first metal plate and the second metal plate. Preparing a circuit block including a wiring substrate, and an electrode group provided on the surface of the integrated circuit chip and a thin metal wire group connecting the electrode group provided on the surface of the wiring substrate; The circuit block is placed in a mold for resin sealing such that the surfaces of the first metal plate and the second metal plate are in contact with the inner surface of the mold, and the resin for sealing is placed in the mold. Implanting a semiconductor device, the method comprising the steps of: The method of manufacturing a semiconductor device, characterized in that to substantially aligned with the direction of flow of the sealing resin in the direction of the gap formed by the second metal plate.