JPH05259343A - Manufacture of semiconductor module - Google Patents

Abstract

PURPOSE:To provide a method of manufacturing a semiconductor module having a heat radiation capability equivalent to that of a ceramic package by improving the heat radiation of resin mold package. CONSTITUTION:A semiconductor module is produced using a lead frame. A lead frame is punched so that it has fins 17 extending from both sides of a die pad. A semiconductor chip is attached on the lead frame and sealed with resin to form a semiconductor package 22. Then, the fins 17 are bent over the package in such a manner that the extensions of the fins cover the package.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a semiconductor module, and more particularly to a method for manufacturing a semiconductor module having a radiation fin integrated with a lead frame.

[0002]

2. Description of the Related Art Conventionally, as shown in FIG. 4, a semiconductor package of this type has a die pad 2 of a multiple lead frame 1.
A semiconductor chip (IC chip) is mounted on the upper side, and each electrode of the semiconductor chip and the inner lead 3 of the lead frame 1 are electrically connected by wire bonding, and then placed in a mold and transfer molded with resin. Finally, cutting and separating and lead shaping are performed, so-called DIP (Dual Inline Package), QFP (Quad Flat).
Package), SOP (Small Outline Package), etc. In addition, 4 is an outer lead and 5 is a sprocket hole for operating the lead frame 1.

FIG. 5 shows a state in which a semiconductor chip 6 is mounted on the multiple lead frame 1 and wire bonding is performed. The mounted semiconductor chip 6 and the wires 7 are also shown (the electrode pads of the semiconductor chip 6 are omitted to avoid complexity of the drawing). From this state, resin molding is performed to complete a resin molding package.

The development of this method enables continuous automation of mounting of semiconductor chips and wire bonding, and mass processing such as molding and lead shaping, which facilitates mass production. As a result, it is possible to obtain a low-priced semiconductor package due to the fact that the material is inexpensive. In particular, recently, by improving the characteristics of the sealing resin and improving the passivation technology of the element, a highly reliable material has been obtained, and it is also used in important places such as for communications and computers. Under such circumstances, at present, much more packages are used than metal type, ceramic type, cerdep type packages.

[0005]

However, according to the above-mentioned method for manufacturing a semiconductor package, since the resin is used for molding, the heat dissipation is poor, and it is difficult to use it for a semiconductor chip that uses a large amount of electric power. is there.
This is because the molding resin that protects the semiconductor chip has a poor thermal conductivity, so the generated heat is trapped inside and the temperature of the semiconductor chip rises. That is, since the molding resin serves as a heat insulating material for the semiconductor chip, it is said that its thermal resistance is twice or more as large as that of the package using ceramics when the number of terminal pins is the same.

It is an object of the present invention to provide a method of manufacturing a semiconductor module which eliminates the above-mentioned poor heat dissipation of a low-priced resin mold type semiconductor package and has a heat dissipation capability equivalent to that of a ceramic package.

[0007]

In order to achieve the above object, the present invention provides a method of manufacturing a semiconductor module using a lead frame, wherein a radiation fin extending from both ends of a die pad of the lead frame is planned. The frame is die-cut, the semiconductor chip is mounted on the lead frame, the semiconductor chip is resin-sealed to form a semiconductor package, and the predetermined heat radiation fin is bent on the semiconductor package to extend the heat radiation. The fin is formed so as to cover the semiconductor package.

Further, the heat dissipating fins are formed with irregularities.

[0009]

According to the present invention, as described above, the die pad of the lead frame is extended to form the expanded heat radiation fin, and the predetermined heat radiation fin is bent on the semiconductor package. Since it is formed so as to cover the semiconductor package, the heat dissipation effect can be enhanced. In addition, noise can be prevented from entering the semiconductor chip from the outside due to the shielding effect of the heat radiation fins.

[0010]

Embodiments of the present invention will be described in detail below with reference to the drawings. 1 is a plan view showing a state in which a semiconductor chip is mounted on a lead frame for manufacturing a semiconductor module showing a first embodiment of the present invention, and FIG. 2 shows a semiconductor module cut out from a cut line in FIG. FIG. 3 is a development view and FIG. 3 is an external perspective view of the semiconductor module.

First, in FIGS. 1 and 2, 11 is a multiple lead frame, 12 is a tie bar, 13 is an inner lead, 14 is an outer lead, and 15 is a sprocket hole for operating the multiple lead frame 11. Reference numeral 16 is a die pad, and a predetermined radiation fin (expanded portion) 17 is connected to the die pad 16. 18
Is a semiconductor chip bonded on the die pad 16, and 19 is a wire connecting the semiconductor chip 18 and the inner lead 13.

Here, the die pad 16 is made of an iron-based material or a copper-based material, like the ordinary lead frame. As an iron-based alloy, 42 alloy containing 42% of Ni is generally used. The thickness is about 0.8 to 0.2 mm, but it may be thicker or thinner than this. Noble metal plating is applied to the fixed portion of the semiconductor chip 18 and the wire bonding portion of the lead by press working or etching in order to complete the joining. Partial plating with Ag is now commonplace.

In order to realize this embodiment more effectively, it is preferable that the frame material is made of Cu. The thickness, processing method, etc. are the same as those used up to now, as is the case with 42 alloy. As an example, the thermal conductivity of JIS C1020 oxygen-free copper is 0.94 cal / cm · sec · ° C, and 99
%% Al ₂ O ₃ has approximately 0.08 cal / cm
Since it is sec.degree. C., it has a thermal conductivity of 10 times or more, and the object of the present invention can be sufficiently achieved.

Also, one semiconductor module is formed on each of the left and right sides of the rectangular hollow 20 formed in the lead frame 11. Reference numeral 21 is a cutout line of the lead frame 11, which is indicated by a dotted line. The hollow hole 20 is not always necessary. A cut along the cutout line 21 is shown in FIG.

By carrying out resin molding, cutting, lead shaping, etc., a semiconductor module can be obtained as shown in FIG. As shown in this figure, the radiation fins (expanded portion) 17 (the portion where the semiconductor chip 18 is not mounted) extending from both sides of the die pad 16 are taken out of the semiconductor package 22 and the narrow portion 17a of the narrow portion 17a is removed. A vertical portion 17b is formed by being bent upward at the end portion, and a bent horizontal portion 17c is formed at the end portion above the semiconductor package 22. That is, the expanded portions (heat radiation fins) 17 extending from both sides of the die pad 16 are folded inward so that they overlap each other, and the semiconductor package 2
Cover 2

With this structure, the heat in the semiconductor package is expanded on both sides (radiation fins).
It is transmitted from 17 and cooled effectively outside. Further, since the heat radiation fins of the die pad 16 are structured to cover the semiconductor package 22 as described above, the heat radiation fins are compact and have the advantage that the mounting area of the semiconductor module is not enlarged. ..

Further, it can also fulfill the function of shielding noise from the outside. FIG. 6 is a plan view of a main part of a lead frame for manufacturing a semiconductor module showing a second embodiment of the present invention, and FIG. 7 is a perspective view of the main part of the semiconductor module. In this embodiment, the radiation fins connected to the die pad 30 are formed in a striped shape instead of a flat plate, and the radiation fins (radiation frame material) 33 are taken out between the leads 41a and 41b. By doing so, the leads 41a and 41b can be used as leads for electric signals, power supplies, etc., and the radiation fins can be taken out in the same direction as the leads. Further, the heat radiation fin 33 is formed with irregularities to increase the heat radiation area.

That is, a vertical portion 33b bent upward from the end portion of the first portion 33a extending in a stripe shape from the die pad 30 is formed, and the end portion of the vertical portion 33b is positioned above the semiconductor package 50. Horizontal part 33c
To form. Concavities and convexities are formed on the horizontal portion 33c. FIG. 8 is a plan view of an essential part of a lead frame for manufacturing a semiconductor module showing a third embodiment of the present invention.

In this figure, 61 is a connecting lead frame, 62 is a tie bar, 63 is an inner lead, 64 is an outer lead, 65 is a sprocket hole for operating the multiple lead frame 61, 66 is a die pad, and 67 is its die pad. A heat radiation fin continuous with 66, 68 is a semiconductor chip mounted on the die pad 66, and 69 is a wire connecting the semiconductor chip 68 and the inner lead 63.

In this embodiment, the sprocket hole 6
The guide portion of the lead frame 61 including 5 and the like is used as the heat radiation fin 67. Although the width is a little wider, the part to be discarded is usually used as a radiation fin. It is arranged to cut out along a cutout line 71 indicated by a dotted line. As described above, when oxygen-free copper having a thickness of 0.2 mm is used as the lead frame, by providing external extraction fins having the same area as the surface area of the module, a heat radiation effect almost equal to that of the alumina ceramic package can be obtained. I was able to do it.

Furthermore, when the heat radiation fins are air-cooled at a wind speed of 3 m / sec, the thermal resistance of the package is 1/5.
Could be reduced to. In the conventional package for high heat dissipation, the fin is connected to the ceramic with a bonding agent or the like. The thermal resistance of this bonding agent is larger than that of the heat conductive metal, but since it is integrated in the present invention, the heat can be efficiently transferred to the outside.

Various investigations were conducted on the case where the lead frame was made thicker. As a result, the effect of making the lead frame thicker was great even within the range of practical use, and even if a general commercially available lead frame material was used, it was lower than the alumina package. A resin mold package having thermal resistance could be obtained. Also,
By processing the shape of the heat dissipation fin taken out to the unevenness, the heat dissipation effect can be further enhanced.
It was possible to improve the heat dissipation effect by forced air cooling.

The present invention is not limited to DIP, but may be QFP or SO.
It goes without saying that it can be applied to other types of packages such as P. Further, although multiple lead frames are used for clearer explanation, according to the present invention, the portion mounting the semiconductor chip is a good thermal conductor, and the good conductor projects to the outside of the module to dissipate heat. Can act as a fin. The use of multiple leadframes is only one embodiment of the present invention.

The present invention is not limited to the above embodiments, and various modifications can be made within the scope of the present invention, which are not excluded from the scope of the present invention.

[0025]

As described above in detail, according to the present invention, the die pad and the heat radiation fin are directly connected to each other and are made of the same metal substrate, and the heat radiation fin is taken out of the semiconductor package to be mounted on the semiconductor package. Since the predetermined heat dissipation fin is bent and formed so as to cover the semiconductor package with the expanded heat dissipation fin, the temperature of the die pad part is increased by the heat dissipation fin.
That is, the temperature rise of the semiconductor chip mounted on the die pad can be efficiently suppressed.

Further, due to the shielding effect of the heat radiation fin, it is possible to prevent noise from entering the semiconductor chip from the outside.

[Brief description of drawings]

FIG. 1 is a plan view showing a state in which a semiconductor chip is mounted on a lead frame for manufacturing a semiconductor module showing a first embodiment of the present invention.

FIG. 2 is a development view of the semiconductor module cut out from the cutout line in FIG.

FIG. 3 is an external perspective view of the semiconductor module of FIG.

FIG. 4 is a plan view of a lead frame for manufacturing a conventional semiconductor package.

FIG. 5 is a plan view showing a state in which a semiconductor chip is mounted on a lead frame for manufacturing a conventional semiconductor module.

FIG. 6 is a plan view of a main part of a lead frame for manufacturing a semiconductor module showing a second embodiment of the present invention.

FIG. 7 is a perspective view of essential parts of a semiconductor module showing a second embodiment of the present invention.

FIG. 8 is a plan view of a main part of a lead frame for manufacturing a semiconductor module showing a third embodiment of the present invention.

[Explanation of symbols]

 11,61 Multiple lead frame 12,62 Tie bar 13,63 Inner lead 14,64 Outer lead 15,65 Sprocket hole 16,30,66 Die pad 17,33,67 Radiating fin 17a Narrow part 17b Vertical part 17c Bent Horizontal part 18 Semiconductor chip (IC chip) 20 Rectangular hollow hole 22,50 Semiconductor package 33a First part extending in stripes 33b Vertical part 33c Horizontal part 41a, 41b Lead

Claims (2)

[Claims] 1. A method of manufacturing a semiconductor module using a lead frame, comprising the steps of: (a) die-cutting a lead frame with predetermined heat radiation fins extending from both ends of a die pad of the lead frame; A semiconductor chip is mounted on the semiconductor package, (c) the semiconductor chip is resin-sealed to form a semiconductor package, and (d) the predetermined heat dissipation fin is bent on the semiconductor package, and the semiconductor is formed by an expanded heat dissipation fin. A method of manufacturing a semiconductor module, characterized by forming the package so as to cover the package. 2. The method of manufacturing a semiconductor module according to claim 1, wherein unevenness is formed on the heat radiation fin.