JPH07249730A - Lead frame and its manufacture thereof - Google Patents

Abstract

PURPOSE:To provide a lead frame having good transmission characteristics by preventing electromagnetic interference between pins even if the pin count is increased thereby preventing crosstalk when a high frequency signal is transmitted. CONSTITUTION:An island part 11 for mounting a semiconductor integrated circuit element is formed integrally with a large number of leads 12 extending radially outward from the island part 11 and the leads 12 are connected electrically with the semiconductor integrated circuit element. In such metal lead frame 10, the surface of the lead is partially covered with a dielectric layer which is further covered with a conductive layer 15.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lead frame used for mounting a semiconductor integrated circuit device (hereinafter referred to as "semiconductor device") represented by LSI, VLSI, etc. The present invention relates to a lead frame suitable for an element that transmits a signal.

[0002]

2. Description of the Related Art A conventional lead frame used for mounting a semiconductor device is composed of a single metal plate and is generally formed in a shape as shown in FIGS. 6 and 7, for example. That is, the lead frame 10 is located in the center and has an island portion 11 on which a semiconductor element is mounted, and the island portion 11
The main part is composed of a large number of leads 12 provided radially around the frame and a frame 13 that integrally supports them. This lead frame 10 is formed by mechanically punching or etching a single metal plate. It is manufactured by processing into such a shape.

By the way, in recent years, the electrode density of semiconductor elements has tended to increase, and accordingly, the density of leads has also increased and the lead gap has tended to become smaller. And
As the lead gap decreases, the leads come close to each other,
Electromagnetic interference occurs between the mutual leads.
That is, when a high-frequency signal is transmitted, crosstalk occurs, which causes a problem that good transmission characteristics cannot be obtained.

[0004]

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems of the prior art, and an object of the present invention is to provide mutual leads even when the leads come close to each other as the lead gap decreases. To provide a lead frame and a method of manufacturing the same that prevent generation of electromagnetic interference between them, prevent generation of crosstalk when transmitting a high-frequency signal, and obtain good transmission characteristics. It is in.

[0005]

In order to solve the above-mentioned problems, the lead frame of the present invention has an island portion formed so as to mount a semiconductor integrated circuit element and radially outwardly extending around the island portion. In a metal lead frame in which a large number of leads are integrally formed and which electrically connects the leads and the semiconductor integrated circuit element, at least a part of the surface of the lead frame is covered with a dielectric layer, At least part of the surface of the body layer is covered with a conductive layer.

Further, in the lead frame manufacturing method of the present invention, an island portion formed so as to mount a semiconductor integrated circuit element and a large number of leads radially extending outward around the island portion are integrally formed. In a method of manufacturing a metal lead frame for electrically connecting the lead and a semiconductor integrated circuit element, a lead frame in which a single metal plate is processed to integrally form the island portion and a large number of leads. Is prepared, then a dielectric layer covering at least a part of the surface of the lead frame is formed by electrodeposition, and then a conductive layer covering at least a part of the surface of the dielectric layer is formed.

Further, the method for manufacturing a lead frame of the present invention is characterized in that the conductive layer is formed by an electroless plating method or a vapor deposition method.

The structure of the present invention will be described in more detail below.

FIG. 1 is a plan view of a lead frame according to the present invention, and FIG. 2 is a sectional view taken along the line AA 'in FIG.

The basic structure of the lead frame of the present invention is composed of a single metal plate as in the conventional case, and is formed into a shape as shown in FIG. That is, the lead frame 10
Is a centrally located island portion 11 on which a semiconductor element is mounted, a large number of leads 12 radially provided around the island portion 11, and a frame 1 for integrally supporting these.
The lead frame 10 is manufactured by mechanically punching or etching a single metal plate into such a shape.

As shown in FIGS. 1 and 2, the lead frame of the present invention has a characteristic structure in which a part of the surface of each lead 12 is covered with a dielectric layer 14 and the surface of the dielectric layer 14 is covered with a dielectric layer 14. That is, it is covered with the conductive layer 15. That is, the periphery of each lead 12 is covered with the conductive layer 15 via the dielectric layer 14. As described above, the region covered with the dielectric layer 14 and the conductive layer 15 is not particularly limited, but in order to fully exert the effect of the present invention, at least around each lead (later by wire bonding (Excluding the tip portion to be connected) is the dielectric layer 14 and the conductive layer 15
It is desirable to be covered with.

As a method for forming the dielectric layer 14, for example, an electrodeposition method is simple and convenient. When the dielectric layer 14 is formed by electrodeposition, an insulating modified polybutadiene resin or the like can be used.

As a method of forming the conductive layer 15, for example, an electroless plating method or a vapor deposition method is generally and easily used. In this case, Cu or the like is used as the conductive material.

The dielectric layer 14 and the conductive layer 15 are also provided.
The thickness of the dielectric layer 14 is not particularly limited, but for example, the dielectric layer 14 may have a thickness of about 15 to 100 μm, and the conductive layer 15 may have a thickness of about 5 μm in order to prevent the dielectric from being exposed by the mold during outer lead molding. is there.

When the lead frame of the present invention has a so-called dam bar, since the portion is cut after resin sealing, the metal surface of the lead is exposed from the conductive layer and the dielectric layer, and the shield effect is reduced. Therefore, it is desirable to use a form without a dam bar.

[0016]

According to the lead frame of the present invention, as shown in FIGS. 1 and 2, since the periphery of the lead is covered with the conductive layer via the dielectric layer, a shield effect is produced, and the lead and the lead are separated from each other. Even when the two are close to each other, electromagnetic interference between the leads is eliminated, crosstalk is prevented from occurring when a high-frequency signal is transmitted, and good transmission characteristics can be obtained.

[0017]

EXAMPLES The present invention will be described in more detail with reference to the following examples with reference to FIGS.

A lead frame having a Cu alloy material, a plate thickness of 0.150 mm, an inner lead pitch of 0.180 mm, and an outer lead pitch of 0.400 mm was prepared by wet etching. The cross section of the produced lead frame is as shown in FIG.

Next, a mask member 16 made of silicon is used to mask the inner lead tip and the outer lead tip of the lead frame manufactured as described above (see FIG. 3).
Reference), polybutadiene modified product electrodeposition liquid (Nisseki Chemical Co., Ltd.)
Electroplating conditions: low voltage 70V, cure 200 ° C
・ The insulating film 17 having a thickness of 15 μm was provided in 10 minutes (see FIG. 4).
reference).

Then, with the mask member 16 being fixed during electrodeposition, Cu plating 18 having a thickness of 3 μm was applied to the surface of the insulating film 17 by electroless plating (see FIG. 5).

Next, by electroplating, the inner lead and the outer lead were plated with Ni underlayer having a thickness of 3 μm and Pd plating having a thickness of 0.05 μm to produce a lead frame of the present invention.

The produced lead frame had good transmission characteristics when the high frequency signal transmission element was mounted.

[0023]

As described in detail above, according to the lead frame of the present invention, since the periphery of the lead is covered with the conductive layer via the dielectric layer, the shield effect is produced, and the lead and the lead are Even when and are close to each other, electromagnetic interference between the leads is eliminated, crosstalk can be prevented when high-frequency signals are transmitted, and excellent transmission characteristics can be obtained. .

[Brief description of drawings]

FIG. 1 is a plan view of a lead frame according to the present invention.

FIG. 2 is a cross-sectional view taken along the line A-A ′ in FIG.

FIG. 3 is a cross-sectional view showing a lead frame fixed to a mask member in the lead frame according to the embodiment of the present invention.

FIG. 4 is a cross-sectional view of a lead frame according to an embodiment of the present invention, in which a dielectric layer is formed on the lead frame.

FIG. 5 is a cross-sectional view of a lead frame according to an exemplary embodiment of the present invention, in which a conductive layer is formed on a dielectric layer of the lead frame.

FIG. 6 is a plan view of a conventional lead frame.

7 is a cross-sectional view taken along the line B-B ′ of FIG.

[Explanation of symbols]

 10 Lead Frame 11 Island Part 12 Lead 13 Frame 14 Dielectric Layer 15 Conductive Layer 16 Mask Member 17 Insulating Film 18 Cu Plating

Claims (3)

[Claims] 1. An island portion formed so as to mount a semiconductor integrated circuit element and a large number of leads extending radially outwardly around the island portion are integrally formed, and the lead and the semiconductor integrated circuit element are connected to each other. In a metal lead frame to be electrically connected, at least a part of the surface of the lead frame is covered with a dielectric layer, and at least a part of the surface of the dielectric layer is covered with a conductive layer. Lead frame to 2. An island portion formed so as to mount a semiconductor integrated circuit element, and a large number of leads radially extending outward around the island portion are integrally formed, and the lead and the semiconductor integrated circuit element are formed. In a method for manufacturing a metal lead frame to be electrically connected, a single metal plate is processed to produce a lead frame in which the island portion and a large number of leads are integrally formed, and then the lead frame A method of manufacturing a lead frame, comprising forming a dielectric layer that covers at least a part of the surface by electrodeposition, and then forming a conductive layer that covers at least a part of the surface of the dielectric layer. 3. The method of manufacturing a lead frame according to claim 2, wherein the conductive layer is formed by an electroless plating method or a vapor deposition method.