JPH10303353A - Method for manufacturing composite lead frame with heat sink - Google Patents

Abstract

PROBLEM TO BE SOLVED: To eliminate the need for pasting a metal layer to an insulation layer for shorter manufacturing process while heat radiation characteristics and electric characteristics are improved, by irradiating an insulating layer of a composite interconnection board comprising a metal layer with a laser beam for removal, and forming a connection hole and an exposed part for metal lead frame connection. SOLUTION: On first and second surfaces of insulating layers 2 and 4, a composite interconnection board 10 comprising first and second metal layers 1 and 3 is prepared, and the first metal layer 1 is worked to form lead patterns 1a and 1b. A residual part of the first metal layer 1 is removed, and by forming connection holes 2a and 2b while a chip mounting region is allowed to remain at the insulating layer 2 from such part as the first metal layer 1 is removed, such an exposed part as exposed on the first surface side of the insulating layer 2 is formed at the second metal layer 3. A semiconductor chip 6 is fixed to a chip formation region 2a of the insulating layer, and the semiconductor chip 6 is connected to the lead patterns 1a and 1b and the exposed part of the second metal layer 3 with a bonding wire 8, and the entire is sealed up with a mold resin.

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 composite lead frame used for a semiconductor device, and more particularly to a method for manufacturing a composite lead frame having a heat sink.

[0002]

2. Description of the Related Art One of lead frames used for a semiconductor package is a QFP (Quad Flat Package) type lead frame. This lead frame is formed by pressing or etching a copper plate having a predetermined thickness, and while having excellent mechanical strength, the electrical characteristics and heat radiation characteristics for the demand for higher integration and higher output of the semiconductor chip. There is an inconvenience of not being able to follow. To meet such demands, a multi-layer lead frame with signal leads on one side of the insulating layer and power or ground leads on the other side, and a heat sink that promotes heat dissipation from the semiconductor chip are provided. Further, a lead frame with a heat sink has been proposed.

However, since these lead frames are formed by metal lead frames, the number of pins is increased,
It is difficult to cope with narrow pitch. In a metal lead frame, it is difficult to form the inner lead with a pitch of 0.2 mm or less, and there is a limit to increasing the number of pins.

In order to solve such a problem, there is a composite lead frame with a heat sink disclosed in Japanese Patent Application Laid-Open No. Hei 5-21690. This composite lead frame with a heat sink is composed of an inner film made of copper foil on one side of an insulating film, a ground layer made of copper foil on the other side, and a heat sink attached to the ground layer. The electrodes of the semiconductor chip are electrically connected to a ground layer and bonding wires via connection holes formed in the insulating film, and the inner leads are connected to outer leads formed of a metal lead frame. ing.

[0005]

However, according to the conventional composite lead frame with a heat sink, the metal layer and the heat sink are bonded after the insulating film is subjected to predetermined processing such as perforation. This requires a punching step and a bonding step of a metal layer, which requires time and effort in manufacturing. Further, as the fineness of the wiring pattern progresses due to the increase in the number of pins and the pitch of the composite lead frame, the positioning accuracy in the above-mentioned bonding is limited. SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a method of manufacturing a composite lead frame with a heat sink having improved heat dissipation characteristics and electrical characteristics, which eliminates the need for attaching a metal layer and an insulating layer, thereby shortening the manufacturing process.

Another object of the present invention is to provide a method of manufacturing a composite lead frame with a heat sink, which can perform a processing such as high-precision drilling on an insulating film even when a wiring pattern is miniaturized.

[0007]

According to the present invention, there is provided a composite wiring board having first and second metal layers on first and second surfaces of an insulating layer. Forming a lead pattern by processing the first metal layer; and
By removing a remaining portion of the first metal layer and forming a connection hole while leaving a chip mounting region in the insulating layer from the portion from which the first metal layer has been removed, the second hole is formed.
Forming an exposed portion exposed on the first surface side of the insulating layer in the metal layer, fixing a semiconductor chip in the chip mounting region of the insulating layer, and attaching the semiconductor chip to the lead pattern and the second pattern. A metal wire is connected to the exposed portion of the metal layer with a bonding wire, a metal lead frame is arranged outside the lead pattern, the metal lead frame is connected to the lead pattern by metal bonding, and a predetermined portion of the metal lead frame is connected. Provided is a method for manufacturing a composite lead frame with a heat sink, which is entirely exposed and sealed with a mold resin.

In the embodiment of the present invention, the formation of the connection hole and the exposed portion may be performed based on laser beam irradiation. The metal bonding is preferably performed based on Au-Sn eutectic bonding of Ni plating Au plating provided on the surface of the lead pattern and Sn plating provided on the surface of the metal lead frame. The second metal layer is
A heat sink made of copper may be fixed to the surface opposite to the surface on which the connection hole and the exposed portion are formed. The heat sink has dimples or through holes formed on the heat dissipation surface and preferably has a thickness of at least 100 μm.

[0009]

FIG. 1 shows a manufacturing process of a composite lead frame with a heat sink according to a first embodiment of the present invention.
First, as shown in FIG. 1A, a metal layer (copper foil) 1 having a thickness of 18 μm for forming a lead pattern and a
μm polyimide layer 2, 105 μm thick metal layer (copper plate) 3 for forming a ground layer and a heat sink, and 1 μm thick
A two-layer copper-attached TAB tape 10 as a composite wiring board constituted by laminating 5 μm polyimide layers 4 is prepared.

Hereinafter, a manufacturing process of a composite lead frame with a heat sink using the TAB tape 10 will be described.

FIG. 1 (b) shows a wiring pattern forming step, in which a known process such as resist coating, mask exposure, development, etching, and resist stripping is performed on the TAB tape 10 to form a lead pattern 1a and a metal layer 1 on the metal layer 1. 1b is formed.

FIG. 1C shows a process of forming an element mounting portion and a lead bonding portion. A laser shielding metal mask (not shown) having an opening at a predetermined position is arranged on a TAB tape 10 to apply a laser beam. Irradiate. The polyimide layer 2 is removed from the portion irradiated with the laser beam, and the metal layer 3 is exposed. As a result, the ground hole 2a and the lead joint 2b are formed. Thereafter, the fine polyimide remaining during the laser processing is removed with potassium permanganate and a sodium hydroxide solution at 50 ° C. In FIG. 1C, the element mounting portion 2A is formed on the polyimide layer 2.

FIG. 1 (d) shows a Ni base Au plating step, in which the surface of the lead patterns 1a and 1b and the metal layer 3 exposed based on the formation of the ground holes 2a and the lead joints 2b have a thickness of 2.0 mm. 0μm Ni plating
An Au plating with a thickness of 0.8 μm is applied to the upper layer to form a Ni base Au plating layer 5. After this plating process, the TAB tape 10 is punched into individual pieces.

FIG. 1 (e) shows a step of connecting to a metal lead frame. A metal lead frame 7 having a Sn plating applied to its tip is prepared, and a lead pattern 1a having a Ni base Au plating layer 5 is formed. Then, it is brought into contact with the lead joint 2b and heated to a predetermined temperature. The plating melts by this heating, and the Au by Ni plating and the Au by Sn plating are melted.
The metal lead frame 7 is joined to the lead pattern 1a and the lead joint 2b based on the / Sn eutectic joining.
The semiconductor chip 6 is mounted on the element mounting portion 2A.

FIG. 1F shows a process of connecting the semiconductor chip 6 to the lead patterns 1a and 1b and the ground hole 2a.
a, 1b and the ground hole 2a are electrically connected by the bonding wire 8. Thereafter, the metal lead frame 7 is sealed with a resin in a state where a predetermined portion of the metal lead frame 7 is exposed.

According to the above-described composite lead frame with a heat sink, a lead frame material in which a metal layer and a polyimide layer are laminated is used, so that the bonding of the metal layer and the polyimide layer becomes unnecessary, and the manufacturing process is shortened. Can be.
In addition, since the ground hole and the lead joint are formed by irradiating the polyimide layer with a laser beam, high-precision processing of the polyimide layer becomes possible irrespective of increasing the number of pins and reducing the pitch of the lead frame. In the first embodiment, by using a lead frame material in which the thickness of the ground layer is larger than the thickness of the inner lead, the electrical characteristics are improved and the heat dissipation of the ground layer is improved.

FIG. 2 shows a manufacturing process of the composite lead frame with a heat sink according to the second embodiment. First, as shown in FIG. 2A, a thickness of 18 μm for forming a lead pattern is formed.
m metal layer (copper foil) 1, a polyimide layer 2 having a thickness of 25 μm, a metal layer (copper plate) 3 having a thickness of 75 μm for forming a ground layer, and a polyimide layer 4 having a thickness of 15 μm. A two-layer copper-bonded TAB tape 20 as a composite wiring board to be configured is prepared. In the following, a description of a part common to the first embodiment will not be repeated, and a part different in the manufacturing process will be described.

FIG. 2F shows a step of connecting the semiconductor chip 6 to the lead patterns 1a and 1b and the ground hole 2a and a step of attaching the heat sink 9 to the semiconductor chip 6.
After the electrodes 6a are electrically connected to the lead patterns 1a and 1b and the ground holes 2a by bonding wires 8, a heat radiating plate 9 having a thickness of 125 μm is attached to the polyimide layer 4. Further, the heat sink 9 can be directly attached to the metal layer 3 after removing the polyimide layer 4.

According to the above-described composite lead frame with a heat radiating plate, the heat radiating characteristics can be further improved by attaching the heat radiating plate 9 later. Further, by performing dimple processing on the surface of the heat radiating plate 9, the adhesion between the heat radiating plate 9 and the sealing resin at the time of resin sealing is improved. Alternatively, the same effect can be obtained by forming a large number of through holes in the heat sink 9 as a method other than the dimple processing.

[0020]

As described above, according to the method for manufacturing a composite lead frame with a heat sink of the present invention, the first of the insulating layers is formed.
And irradiating the insulating layer of the composite wiring substrate having the first and second metal layers on the second surface with a laser beam to remove the insulating layer, thereby forming a connection hole and an exposed portion for connecting a metal lead frame. As a result, it is not necessary to attach the metal layer and the insulating layer, and the manufacturing process can be shortened, the heat radiation characteristics and the electric characteristics can be improved, and even if the wiring pattern is miniaturized, processing such as high-precision drilling is performed on the insulating film. be able to.

[Brief description of the drawings]

FIG. 1 is an explanatory view showing a manufacturing process of a composite lead frame with a heat sink according to a first embodiment of the present invention.

FIG. 2 is an explanatory view showing a manufacturing process of a composite lead frame with a heat sink according to a second embodiment of the present invention.

[Description of Signs] 1, copper foil layer 1a, lead pattern 1b, lead pattern 2, polyimide layer 2A, element mounting portion 2a, ground hole 2b, lead joint portion 3, copper plate layer 4, polyimide layer 5, Ni plating Au plating 6, semiconductor chip 6a, electrode 7, metal lead frame 8, bonding wire 9, heat sink 10, TAB tape 20, TAB tape

Claims (5)

[Claims] 1. A composite wiring board having first and second metal layers on first and second surfaces of an insulating layer is prepared, and the first metal layer is processed to form a lead pattern;
And removing the remaining portion of the first metal layer, and forming a connection hole while leaving a chip mounting region in the insulating layer from the portion from which the first metal layer has been removed. Forming an exposed portion of the insulating layer exposed on the first surface side of the insulating layer, fixing a semiconductor chip to the chip mounting region of the insulating layer, and connecting the semiconductor chip to the lead pattern and the second
Connecting the metal lead frame to the exposed portion of the metal layer with a bonding wire, arranging a metal lead frame outside the lead pattern, connecting the metal lead frame to the lead pattern by metal bonding, and a predetermined portion of the metal lead frame. A method of manufacturing a composite lead frame with a heat sink, wherein the entire structure is sealed with a mold resin while exposing the resin. 2. The method according to claim 1, wherein the formation of the connection hole and the exposed portion is performed based on laser beam irradiation. 3. The method according to claim 1, wherein the metal bonding is performed by Au plating of Ni underlayer provided on the surface of the lead pattern and Au-Sn of Sn plating provided on the surface of the metal lead frame.
The method for manufacturing a composite lead frame with a heat sink according to claim 1, wherein the method is performed based on eutectic bonding. 4. The composite lead frame with a radiator plate according to claim 1, wherein the second metal layer has a radiator plate made of copper fixed to a surface opposite to a surface on which the connection holes and the exposed portions are formed. Manufacturing method. 5. The method for manufacturing a composite lead frame with a heat sink according to claim 4, wherein the heat sink has dimple processing or through holes formed on a heat radiation surface, and has a thickness of at least 100 μm.