JPH0766346A - Lead frame, composite lead frame using this lead frame, and method of manufacturing composite lead frame - Google Patents

Abstract

(57) [Summary] [Purpose] To improve the lead wettability of the lead frame,
It improves the bondability between the lead pattern and the leads of the lead frame, and improves the reliability. A lead frame in which a bonding layer 19 including at least a tin-plated layer 13 formed on the surface of the tip of the inner lead portion 5 and a gold-plated layer 18 formed on the tin-plated layer 13 is formed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lead frame, a composite lead frame using the lead frame and a method for manufacturing the composite lead frame, and more particularly to a lead frame having improved bonding between the inner lead and the outer lead, The present invention relates to a composite lead frame using this lead frame and a method for manufacturing the composite lead frame.

[0002]

2. Description of the Related Art Generally, semiconductor devices such as IC and LSI are
As shown in FIGS. 3 and 4, the semiconductor chip 12 is bonded to the mounting base 7 of the lead frame 1 and the electrode portion provided on the semiconductor chip 12 and the noble metal plating layer 9 on the tip portion 6 of the inner lead portion 5 are attached. After wire bonding with an ultrafine wire 10 such as gold, it is molded with a plastic resin 11.

In recent years, the number of electrodes on a semiconductor chip has increased with the increase in capacity and multifunction of semiconductor chips. On the other hand, in order to downsize the semiconductor package, it is necessary to narrow the lead width and the pitch between the leads. However, in a package using a lead frame, there is a limit in reducing the pitch between the leads and reducing the size of the package. Therefore, instead of wire bonding, by using a film carrier in which a lead pattern made of a thin copper foil is formed on a film by etching or the like, a mounting method capable of increasing the number of pins and thinning, that is, Tape Automated Bonding
(TAB) has come to be used.

FIG. 5 shows a TAB IC package. In this package, the gold bumps 14 are provided on the electrode terminals of the semiconductor chip 12, and the gold bumps 14 are
The inner lead portion 16 of the lead pattern formed on the film 15 is formed by thermocompression bonding and sealing with the resin 11. Then, the outer lead portion 17 of this package is joined to the printed circuit board.

Since the leads formed on the film carrier used for the package are made of thin copper foil,
Even after the package, the outer lead portion 17 is easily deformed, and it is more difficult to handle at the time of mounting than the package using the lead frame 1. Therefore, as shown in FIG. 6, the outer lead portion 3 is formed of a lead frame,
A composite lead frame has been proposed which mounts a film carrier in which the semiconductor chip 12 is bonded thereto. In this composite lead frame, the lead of the film carrier is gold-plated, and the tip portion 6 of the inner lead portion 5 of the lead frame 1 is tin-plated 13 as shown in FIG. 7 to form the bonding layer 19. The lead of the film carrier and the lead of the lead frame are joined by gold-tin eutectic joining.

[0006]

However, the conventional composite lead frame has a drawback that the surface of the tin plating applied to the lead frame is easily oxidized, and the wettability and the joint strength at the time of gold-tin joining are deteriorated. There was a problem of doing.

Therefore, an object of the present invention is to improve the wettability of the leads of the lead frame and to improve the bondability between the lead pattern and the leads of the lead frame, and a highly reliable lead frame, and a composite using this lead frame. It is to provide a method of manufacturing a lead frame and a composite lead frame.

[0008]

In order to solve the above-mentioned problems, the present invention provides at least a first plating layer containing tin or tin as a main component and formed on the surface of the tip of a lead, and a first plating layer. And a second plating layer containing gold as a component formed on the surface of the lead frame.

Further, according to the present invention, an inner lead having a lead pattern formed on an insulating film and plated with gold, an outer lead having a lead formed from a lead frame, an inner lead and an outer lead are provided. A first plating layer containing tin or tin as a main component formed on at least one end of the outer lead surface for bonding, and a second plating layer containing gold as a component formed on the surface of the first plating layer. A composite lead frame comprising: a bonding layer composed of

Further, according to the present invention, a step of forming tin or a first plating layer containing tin as a main component on at least one end of a surface of an outer lead formed of a lead frame, and the first plating. A step of forming a second plating layer containing gold as a component on the surface of the layer, and an internal lead including a gold-plated lead pattern formed on the insulating film through the second plating layer. And a step of joining with external leads.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the present invention will be described below in detail with reference to the drawings. FIG. 1 shows a lead frame used in the composite lead frame of this embodiment. The lead frame 1 includes an outer frame 2 formed by etching or pressing a metal strip made of a copper-based alloy, an iron-based alloy, or the like based on a predetermined pattern,
The outer lead portion 3, the dam bar 4, the inner lead portion 5, and the pilot hole 8 are included.

FIG. 2 is a sectional view taken along the line AA 'of the lead frame 1 shown in FIG. As shown in FIG. 2, a bonding layer 19 including a tin plating layer 13 and a thin gold plating layer 18 on the surface of the tin plating layer 13 is formed on the surface of the tip portion 6 of the inner lead portion 5. There is.

Then, the lead frame 1 and the TAB
A lead pattern (not shown) formed on the insulating film manufactured by the method through a bonding layer 19;
A composite lead frame as used in the semiconductor package shown in FIG. 6 described in the section of the prior art can be obtained.

The method of manufacturing the above composite lead frame is as follows. First, the inner lead portion 5 is tin-plated, and further gold-plated on the inner lead portion 5 to form the bonding layer 19, and the lead frame 1 is manufactured. Separately from this, a lead pattern plated with gold by the TAB method is manufactured. Next, the lead pattern and the inner lead portion 5 of the lead frame are joined via the joining layer 19. This joining is performed by applying pressure at a predetermined temperature for a predetermined time. As a result, the lead pattern and the inner lead portion 5 of the lead frame 1 are joined. Then, as shown in FIG. 6 described in the section of the prior art, the lead pattern and the inner lead portion 5 of the lead frame 1 are formed.
And form an internal lead covered with the mold resin 11,
The outer lead portion 3 of the lead frame 1 constitutes an external lead connected to an external circuit.

Here, the following Examples 1 and 2 and Comparative Examples 1 and 2 were produced, and the wettability of the ones joined immediately after plating and the ones left to stand for one week after plating were compared to determine the wettability. A joint test of both was performed. Specifically, T
The lead pattern by the AB method and the inner lead portion 5 of the lead frame 1 were joined via the joining layer 19 to manufacture a composite lead frame, and then the lead pattern was peeled off to measure the wetted area of the joined surface.

Example 1 The bonding layer 19 of the lead frame 1 was formed by the tin plating layer 13 having a thickness of 3 μm and the gold plating layer 18 having a thickness of 0.1 μm by the manufacturing method described above, and plating was performed. Immediately after that, a lead pattern manufactured by the TAB method (35 μm thick copper lead with 0.5 μm Ni as the base)
A composite lead frame was obtained by applying a pressure to the surface of a metal plate on which gold plating of 1.0 μm was applied at 350 ° C. for 5 seconds and then cooling.

[Embodiment 2] The bonding layer 19 of the lead frame 1 is formed by the tin plating layer 13 having a thickness of 3 μm and the gold plating layer 18 having a thickness of 0.1 μm by the manufacturing method described above. After leaving for a week, the lead pattern manufactured by the TAB method (35 μm thick copper lead, 0.5 μm N
(i-plated and 1.0 μm gold-plated on the surface) was pressed and bonded at 350 ° C. for 5 seconds, and then cooled to obtain a composite lead frame.

[Comparative Example 1] Bonding layer 1 of lead frame 1
9 is formed by a tin plating layer having a thickness of 3 μm, and a lead pattern manufactured by the TAB method immediately after the plating (35 μm thick copper lead, 0.5 μm Ni plating is applied to the base, and 1.0 μm of the surface is formed). Gold plated) to 350
After pressurizing at 5 ° C. for 5 seconds to bond, cooling was performed to obtain a composite lead frame.

[Comparative Example 2] Bonding layer 1 of lead frame 1
9 was formed by a tin plating layer having a thickness of 3 μm, left for 1 week, and then a lead pattern (35 μm) manufactured by the TAB method was formed.
(m thick copper lead with 0.5 μm Ni plating on the base and 1.0 μm gold plating on the surface), pressurizing and joining at 350 ° C. for 5 seconds, and then cooling to form a composite lead frame Got

From the above four types of composite lead frames, T
Table 1 shows the result of peeling off the lead pattern by the AB method and measuring the wetted area of the joint surface.

[Table 1] In Table 1, the wetted area of Example 1 is 10
0% is compared with others. As is clear from Table 1, in the case of Example 2 which is the lead frame 1 of this Example having the joining layer 19 made of tin plating and gold plating, the wetted area changed even if left for one week after plating. There wasn't. On the other hand, the wettability of the comparative example having the joining layer of only tin plating was slightly lower than that of the example 1 even after the plating, and the comparative example 2 left for one week , Which is half that of Example 1. Thus, it was confirmed that the wettability of Examples 1 and 2 did not change over time, but the wettability of Comparative Examples 1 and 2 decreased over time. .

[0021]

As described above, according to the lead frame of the present invention, the composite lead frame using the lead frame, and the method of manufacturing the composite lead frame, the second plating layer containing gold as a component of the lead of the lead frame. Since the lead frame is provided, the wettability between the lead of the lead frame and the lead pattern can be improved, the bondability between the lead pattern and the lead of the lead frame can be improved, and the reliability can be improved.

[Brief description of drawings]

FIG. 1 is a plan view showing an embodiment of the present invention.

FIG. 2 is a sectional view showing an embodiment of the present invention.

FIG. 3 is a plan view showing a lead frame.

FIG. 4 is a sectional view showing an IC package using a lead frame.

FIG. 5 is a sectional view showing an IC package by the TAB method.

FIG. 6 is a cross-sectional view showing an IC package using a conventional composite lead frame.

FIG. 7 is a cross section of a lead of a lead frame used in a conventional composite lead frame.

[Explanation of symbols]

1 lead frame 2 outer frame part 3 outer lead part of lead frame 4 dam bar 5 inner lead part of lead frame 6 tip of inner lead part 7 IC
Chip mounting part 8 Pilot hole 9 Noble metal plating layer 10 Bonding wire 11 Molding resin 12 Semiconductor chip 13 Tin plating layer 14 Gold bump 15 Film 16 Inner lead part of lead pattern 16 17 Outer lead part of lead pattern 17 18 Gold plating layer 19 Bonding layer

Claims (3)

[Claims] 1. A tin or a first plating layer containing tin as a main component formed on at least a tip surface of a lead, and a second plating layer containing gold as a component formed on the surface of the first plating layer. A lead frame having a plating layer. 2. An inner lead formed of a lead pattern formed on an insulating film and plated with gold, an outer lead formed of a lead frame, and the inner lead and the outer lead are joined together. And a first plating layer containing tin or tin as a main component and formed on at least one end of the outer lead surface, and a second plating layer containing gold as a component formed on the surface of the first plating layer. A composite lead frame comprising: a bonding layer composed of 3. A step of forming tin or a first plating layer containing tin as a main component on at least one end of a surface of an outer lead formed of a lead frame, and a surface of the first plating layer. A step of forming a second plated layer containing gold as a component, and an inner lead formed of a gold-plated lead pattern formed on an insulating film via the second plated layer and the outer side. And a step of joining the leads by applying pressure at a predetermined temperature for a predetermined time.