JPH118340A - Lead frame for semiconductor device and its manufacture - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a lead frame for a resin-sealed semiconductor device with a base from alloys of copper, which does not need expensive Au plating and exhibits good wettability and wire-bond ability and at the same time to provide a method for manufacturing such a lead frame. SOLUTION: A lead frame for a resin-sealed semiconductor device is made of a base 110 from alloys of copper. A layer 120 of Ni or alloys of Ni of 0.5 μm or more, a layer 130 of Ag or an alloy of Ag and Pd of 0.0500.5 μm, a layer 140 of Pd of 0.05-0.5 μm and a layer 150 of Ag or an alloy of Ag and Pd of 5-500 Å are formed on the entire or a specified part of the surface 110S of the base 110 from alloys of copper from the nearest to the surface 110S according to the measurement by X-ray photoelectron spectroscopy.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lead frame for a resin-sealed type semiconductor device, and more particularly to a resin-sealed type which can obtain good solder wettability and wire bonding property without requiring Au plating. The present invention relates to a lead frame for a semiconductor device and a method for manufacturing the same.

[0002]

2. Description of the Related Art Resin-sealed semiconductor devices (plastic lead frame packages) conventionally used.
5A generally has a structure as shown in FIG. 5A, and includes an outer lead portion 51 for making electrical connection with a die pad portion 511 on which a semiconductor element 520 is mounted and surrounding circuits.
3, an inner lead portion 512 integrated with the outer lead portion 513, a wire 530 for electrically connecting a tip end of the inner lead portion 512 and an electrode pad (terminal) 521 of the semiconductor element 520, and the semiconductor element 520. The semiconductor element 520 is formed of a resin 540 or the like which protects the semiconductor element 520 from stress and contamination from the outside by sealing the semiconductor element 520.
After being mounted on the die pad 511 and the like, it is sealed with a resin 540 to form a package.
This requires the number of inner leads 512 corresponding to the number of the electrode pads 521 of zero. The (single-layer) lead frame 510 used as an assembly member of such a resin-sealed semiconductor device generally has a structure as shown in FIG. 5B, and is used for mounting a semiconductor element. A die pad 511, and inner leads 512 for connecting to a semiconductor element provided around the die pad 511;
An outer lead 513 for connecting to an external circuit continuously to the inner lead 512, a dam bar 514 serving as a dam for resin sealing, a frame (frame) portion 515 for supporting the entire lead frame 510 are provided. And usually, Kovar, 42 alloy (42% nickel-iron alloy),
The outer shape has been processed by a pressing method or an etching method using a metal having excellent conductivity such as a copper-based alloy.

In this lead frame, a noble metal plating such as Ag plating or Au plating is required in a wire bonding area of an inner lead 512 for connecting to a semiconductor element. Only the noble metal plating was partially applied. Also,
Noble metal plating is also required and applied to the surface of the die pad 511 on the side where the semiconductor element is die-bonded via paste or the like. In particular, plating only on a region that requires noble metal plating, such as a wire bonding region of the inner lead 512 and a die bonding region of the die pad 511, is referred to as partial plating. Generally, using a mask jig,
A method of injecting a plating solution from a nozzle to perform plating is employed. Also, the outer leads of the lead frame
Good solder wettability is required.

For this reason, as a first form of the lead frame, Ag or Au plating is provided in the wire bonding region between the die pad (chip mounting portion) 511 and the inner lead 512, and the outer lead 513 is provided with S or S plating.
A device provided with an n or Sn alloy layer is known. This form requires a mask jig for partial plating of Ag or Au, and the manufacturing process is complicated. When Au is used, the cost is particularly high. As a second embodiment of the lead frame, a lead frame provided with a Ni plating layer as an intermediate plating layer and a Pd plating layer as an outer layer is known from Japanese Patent No. 1501723 and the like. However, in the case of this lead frame, the Pd of the surface layer is oxidized after the heat treatment step, or the Ni plating of the intermediate layer diffuses into the Pd plating layer of the outer layer to form an oxide of Ni on the surface, thereby improving the wire bonding property and the like. Deterioration of solder wettability has been a problem. As a third form of the lead frame, there is one in which an Au plating layer is provided on the surface of Pd as disclosed in Japanese Patent Application Laid-Open No. 4-115558.
However, in the case of this lead frame, the cost is high because an Au plating layer is used.

[0005]

As described above, a lead frame made of a copper alloy requires noble metal plating on a wire bonding area of an inner lead, a die bonding area of a die pad, and the like. However, there has been a demand for one having good solder wettability, but all have problems in terms of manufacturing and cost. Under such circumstances, the present invention provides a resin-encapsulated semiconductor device lead frame made of a copper alloy base material, which does not require expensive Au plating, and has excellent solder wettability and wire bonding properties. An object of the present invention is to provide a lead frame for a sealed semiconductor device. At the same time, it is intended to provide a method for manufacturing such a lead frame.

[0006]

A lead frame for a semiconductor device according to the present invention is a resin-encapsulated lead frame for a semiconductor device made of a copper alloy base material, wherein the lead frame is provided on the entire surface or a predetermined portion of the surface of the copper alloy base material. In the measurement by X-ray photoelectron spectroscopy, 0.5 μm or more of N
i layer or Ni alloy layer, 0.05 to 0.5 μm A
g layer or alloy layer of Ag and Pd, 0.05 to 0.5
μm Pd layer, 5-500 ° Ag layer or Ag and P
d. An alloy layer with d is formed.

In the method of manufacturing a lead frame for a semiconductor device according to the present invention, the entire or predetermined portion of the surface of the copper alloy base material is measured by X-ray photoelectron spectroscopy, and is 0.5 μm or more in order from the copper alloy base material surface. Ni layer or Ni alloy layer, Ag layer of 0.05 to 0.5 μm or Ag and Pd
Alloy layer, Pd layer of 0.05 to 0.5 μm, 5 to 50
A method for manufacturing a resin-encapsulated semiconductor device lead frame in which a 0 ° Ag layer or an alloy layer of Ag and Pd is formed, the method comprising: Ni layer, Ag layer, Pd layer, Ni layer
After the formation of the layers, the Ag layer, the Pd layer, and the Ag layer, a heat treatment is performed in the air to produce the layer. Then, in the above, the Ni layer, Ag layer, Pd layer, or Ni layer, A on the surface of the copper alloy base material before the heat treatment.
The formation of the g layer, the Pd layer, and the Ag layer may be performed by any one of wet plating, ion plating, and vapor deposition, or 2
The present invention is characterized in that it is performed by a combination of the above methods. Further, the method for manufacturing a lead frame for a semiconductor device of the present invention is characterized in that the entire or predetermined portion of the surface of the copper alloy base material is measured by X-ray photoelectron spectroscopy, and the order of 0.5 μm or more from the copper alloy base material surface. Ni layer or Ni alloy layer, 0.05 to 0.5 μm Ag layer or Ag and Pd
Alloy layer, Pd layer of 0.05 to 0.5 μm, 5 to 50
A method for manufacturing a resin-encapsulated semiconductor device lead frame in which a 0 ° Ag layer or an alloy layer of Ag and Pd is formed, the method comprising: The present invention is characterized in that a Ni layer, an Ag layer, a Pd layer, and an Ag layer are sequentially formed on the surface of the copper alloy substrate in all or a predetermined portion. And
Ni layer, Ag layer, P on the surface of the copper alloy substrate
The method is characterized in that the d layer and the Ag layer are formed by any one of wet plating, ion plating, and vapor deposition, or a combination of two or more methods.

[0008]

According to the lead frame for a semiconductor device of the present invention having the above-described structure, it is a resin-sealed type lead frame for a semiconductor device made of a copper alloy base material and is expensive Au.
It is possible to provide a lead frame for a resin-encapsulated semiconductor device which does not require plating and has excellent solder wettability and wire bonding properties. Further, it is possible to provide a lead frame having good bending workability. More specifically, the entire Ni alloy layer is measured by X-ray photoelectron spectroscopy using a chromium fluoride film as a reference plate on all or a predetermined portion of the surface of the copper alloy substrate. Alternatively, an alloy layer of Ni, an Ag layer of 0.05 to 0.5 μm or an alloy layer of Ag and Pd, a Pd layer of 0.05 to 0.5 μm, an Ag layer of 5 to 500 ° or an alloy layer of Ag and Pd This is achieved by the fact that is formed.

By providing an Ag layer of 5 to 500 ° or an alloy layer of Ag and Pd on the outermost surface, a 0.05 to 0.5 μm P layer can be formed without providing an Au layer as the outermost layer.
The d-layer can be prevented from being oxidized to provide a good wire bonding property.
Ag of 0.05-0.5 μm between Ni layer of μm or more
By providing a layer or an alloy layer of Ag and Pd, the diffusion of Ni into the Pd layer of 0.05 to 0.5 μm due to the heat treatment is suppressed, and deterioration of the wire bonding property is prevented. Further, as described above, in order from the surface of the copper alloy substrate, a Ni layer or a Ni alloy layer of 0.5 μm or more,
Ag layer of 0.05 to 0.5 μm or alloy layer of Ag and Pd, Pd layer of 0.05 to 0.5 μm, 5 to 500 °
In the region where the Ag layer or the alloy layer of Ag and Pd is formed, it is hardly affected by the contamination of the organic gas generated when the organic material is heat-treated, and the solder wettability is at a satisfactory level. Can be maintained. The reason is considered to be that the Ag layer on the outermost surface or the alloy layer of Ag and Pd protects the Pd layer having a catalytic action from the organic gas. Furthermore, from the copper alloy substrate surface such as the outer lead part,
In order, a Ni layer or a Ni alloy layer of 0.5 μm or more,
Ag layer of 0.05 to 0.5 μm or alloy layer of Ag and Pd, Pd layer of 0.05 to 0.5 μm, 5 to 500 °
In the region where the Ag layer or the alloy layer of Ag and Pd is formed, no crack occurs during bending, and the surface of the copper alloy is not exposed by the bending. The reason is considered to be that the Ag layer or the alloy layer of Ag and Pd provided in the middle fills the cracks generated in the Ni layer and prevents the cracks from appearing in the outermost layer.

The method for manufacturing a lead frame for a semiconductor device according to the present invention is a method for manufacturing a lead frame for a semiconductor device according to the present invention. A Ni layer or an Ni alloy layer of 0.5 μm or more, an Ag layer of 0.05 to 0.5 μm or an alloy layer of Ag and Pd, and a 0.05 to 0.
When a 5 μm Pd layer, an Ag layer of 5 to 500 ° or an alloy layer of Ag and Pd is formed, a Ni layer, an Ag layer, a Pd layer, or A Ni layer, an Ag layer, a Pd layer, and an Ag layer are formed, and thereafter, heat treatment only is required in the air, and the operation can be simplified without requiring a mask jig or the like. The formation of the Ni layer, Ag layer, and Pd layer on the surface of the copper alloy substrate before the heat treatment can be performed by a wet plating method, an ion plating method, an evaporation method, or the like.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A lead frame for a semiconductor device according to the present invention will be described below with reference to the drawings. FIG. 1 is a cross-sectional view showing a state of a surface of a copper alloy base material of a lead frame for a semiconductor device of the present invention. In FIG. 1, 110 is a copper alloy substrate, 11
0S is a copper alloy substrate surface, 120 is a Ni layer or an Ni alloy layer, 130 is an Ag layer or an alloy layer of Ag and Pd, 140 is a Pd layer, 150 is an Ag layer or Ag and Pd.
d and an alloy layer. The lead frame for a semiconductor device of the present invention is a resin-sealed lead frame for a semiconductor device made of a copper alloy base material, and the entire region or the wire bonding region of the surface of the copper alloy base material in contact with the sealing resin. In a predetermined region including the die bonding region, as shown in FIG. 1, as measured by X-ray photoelectron spectroscopy, a 0.5 μm or more Ni layer or Ni alloy layer 120, 0 Ag layer or alloy layer 130 of Ag and Pd having a thickness of 0.05 to 0.5 μm.
A Pd layer 140 of 5 μm, an Ag layer of 5 to 500 ° or an alloy layer 150 of Ag and Pd is formed. Since the surface of the copper alloy base material of the lead frame is formed as shown in FIG. 1 in the wire bonding region, the Pd layer 140 can be formed without providing the Au layer as the outermost layer.
Of Pd layer 140 of Ni by heat treatment.
Can be suppressed, and eventually the wire bonding property can be improved.

Ag layer or alloy layer 15 of Ag and Pd
The thickness of 0 is required to be 5 ° or more from the viewpoint of preventing oxidation of the Pd layer 140, but is preferably 500 ° or less from the viewpoint of cost. The thickness of the Pd layer 140 needs to be 0.05 or more from the viewpoint of wire bonding properties, and if it is thicker than 0.5 μm, the cost increases. Ag layer or alloy layer 130 of Ag and Pd
Is required to be 0.05 or more from the viewpoint of preventing the diffusion of Ni into the Pd layer 140 during the heat treatment, and is preferably 0.5 μm or less from the viewpoint of cost. Also, a Ni layer or Ni layer
Is required to have a thickness of 0.5 μm or more in order to ensure the corrosion resistance of the water lead portion.

Next, a method of manufacturing a lead frame for a semiconductor device according to the present invention will be described with reference to FIG. First, a first example of the embodiment will be described. First, Figure 2
As shown in (a), wet-plating or the like is performed on the copper alloy base material 210 (FIG. 2 (a) (a)) of the lead frame whose outer shape has been processed, and in order from the copper alloy base material surface 210S.
A device provided with a Ni layer 220, an Ag layer 230, and a Pd layer 240 (FIG. 2A) is manufactured. The formation of the Ni layer, Ag layer, and Pd layer on the surface of the copper alloy substrate is performed by a wet plating method,
It is performed by any one of ion plating method and vapor deposition method or a combination of two or more methods. Then, this is subjected to a heat treatment in the atmosphere to obtain a cross-sectional structure shown in FIG. 1 for use. As a heat treatment condition, for example, a hot plate heating requires a processing time of about 300 seconds at 170 ° C., or about 30 seconds at 420 ° C. However, the heating temperature and the heating time are appropriately combined. .

Next, a second example of the embodiment will be described.
As shown in FIG. 2 (b), the copper alloy base material 210 (FIG. 2 (b) (a)) of the lead frame whose outer shape has been processed is
Wet plating or the like is performed, and the Ni layer 220A, the Ag layer 230A, and the Pd layer 240 are sequentially formed from the copper alloy substrate surface 210S.
A, provided with Ag layer 235A (FIG. 2 (b) (b))
Was prepared and subjected to a heat treatment in the atmosphere to obtain a mixture shown in FIG.
The sectional structure shown in FIG. The formation of the Ni layer, the Ag layer, the Pd layer, and the Ag layer on the surface 210S of the copper alloy base material is performed by one of wet plating, ion plating, and vapor deposition as in the first example, or It is performed by a combination of two or more methods.

Next, a third example of the embodiment will be described.
In the case of the third example, wet-plating or the like is performed on the copper alloy substrate 210 (FIG. 2 (c) (a)) of the lead frame whose outer shape has been processed, and in order from the copper alloy substrate surface 210S. N
i layer 220B, Ag layer 230B, Pd layer 240B, Ag
A layer 235B is provided (FIGS. 2 (c) and 2 (b)) and directly has the cross-sectional structure shown in FIG. 1, and is directly used without heat treatment. Ni on surface 210S of copper alloy substrate
The layers, the Ag layer, the Pd layer, and the Ag layer are formed in the first example and the second example.
In the same manner as in the above example, the method is performed by any one of wet plating, ion plating, and vapor deposition, or a combination of two or more methods.

[0016]

EXAMPLES The present invention will be further described with reference to examples.
The lead frames of Examples to Examples shown in Table 1 are:
Each layer shown in FIG. 1 is manufactured by the manufacturing method shown in Table 2. In the comparative example shown in Table 1, layers corresponding to the layers shown in FIG. 1 were produced by the manufacturing methods shown in Table 2, respectively. In the comparative example of Table 1, the blank portion of each layer means that the thickness of the corresponding layer is zero, and the blank portion of each layer shown in Table 2 indicates that the thickness of the corresponding layer is zero. It means that Comparative Example 1a and Comparative Example 1b are different from the lead frame of Example 1 in that Ag or the alloy layer 1 of Ag and Pd shown in FIG.
Comparative Example 2a and Comparative Example 2b differ from the lead frame of Example 2 in that Ag or Ag and Pd shown in FIG.
Comparative Example 3 does not include the alloy layer 130 of Ag or Ag and Ag and Pd, and the alloy layer 130 of Ag or Ag and Pd shown in FIG. Ag and Pd alloy layer 15
There is no 0. Lead frame of each of the above embodiments,
The manufacturing conditions of the lead frame of each comparative example were obtained by processing each of the layers shown in FIG. 2 which were wet-plated to the thickness shown in Table 2 under the heat treatment conditions shown in Table 2, respectively. is there. The heat treatment is hot plate heating in the atmosphere. Table 3 shows the results of evaluating the solder wettability, wire bonding property, and W-bendability of the lead frame of each of the above examples and the lead frame of each of the comparative examples. From Table 3, it can be seen that all of the lead frames of Examples were good in solder wettability, wire bonding property, and W-bendability. On the other hand, it is clear that the lead frame of the comparative example is inferior to the example in solder wettability and W bending property, and the one subjected to the heat treatment also has a wire bonding property. It turns out that it is inferior to.

The lead frame of the embodiment and the embodiment is as follows.
In any case, after performing the degreasing and activation treatment on the surface of the lead frame that has been subjected to external processing made of copper alloy by a standard method,
Ni plating, Ag plating, and Pd plating were sequentially formed on the entire surface of the copper alloy to have a predetermined thickness shown in Table 2, respectively, and were prepared by performing a heat treatment shown in Table 2.
The lead frame of the embodiment, the outer surface of the lead frame made of a copper alloy, after degreasing and activating by a conventional method, Ni plating over the entire copper alloy, in order,
Ag plating, Pd plating and Ag plating are shown in Table 2 respectively.
Are formed without heat treatment. The lead frames of Comparative Example 1a and Comparative Example 2a were produced without performing Ag plating and without performing heat treatment in the lead frame production of the example and the example, respectively. The lead frames of Comparative Example 1b and Comparative Example 2b were not subjected to Ag plating in the production of the lead frames of Examples and Examples, respectively.
The heat treatment was performed. The lead frame of Comparative Example 3 was manufactured without performing Ag plating in the manufacture of the lead frame of the example. still,
Ag plating is generally commercially available. Temper resist AGR of a plating solution manufactured by Nippon Kojundo Chemical Co., Ltd., Pb plating was also used with Parabright SST also manufactured by Nippon Kojundo Chemical Co., Ltd., and Ni plating was a standard sulfamic acid bath prepared by self-mixing.

FIG. 3 shows an XPS (X-ray photoelectron beam) obtained by plating the surface of the copper alloy substrate shown in FIG. Spectroscopy)
FIG. 4 is an analysis diagram in the depth direction by XPS (X-ray photoelectron spectroscopy) after heat treatment is performed on the heat treatment. 3 and 4, the horizontal axis represents the depth from the outer surface, and the vertical axis represents the concentration (%). In FIGS. 3 and 4, the influence of noise at the time of measurement is large, and the lower side of the lines L1 and L2 is ignored here. In FIG. 4, (a) is the outermost table, which indicates that Ag or an alloy of Ag and Pd is formed.
(B) is a depth of several thousand square meters from the outermost table.
In the region where only the d layer exists, (c) shows an alloy of Ag and Pd layer, and (d) shows the region where only the Ag layer exists.
(E) is a region of the Ni layer.

Each evaluation was performed as follows. The solder wettability was evaluated by measuring a zero cross time using a meniscograph tester. The wire bonding property is 2
Using a 5 μm gold wire, load 120 g, temperature 250 °
C, wire bonding was performed under ultrasonic conditions of 30 mW and 15 msec, and tensile strength was measured with a peel gauge. The W bendability was evaluated based on the state of occurrence of cracks using a W bend test method according to SEMI G62-94 standard.

[0020]

As described above, the present invention relates to a resin-sealed type lead frame for a semiconductor device made of a copper alloy base material, which does not require expensive Au plating, and has solder wettability, wire bonding property, Has made it possible to provide a lead frame excellent in bending workability. At the same time, it is possible to provide a method for manufacturing a lead frame that can manufacture such a lead frame by a relatively simple method.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a surface portion of a lead frame for a semiconductor device of the present invention.

FIG. 2 is a cross-sectional view for explaining a film formation state on a copper alloy base material surface.

FIG. 3 is an analysis diagram in a depth direction by XPS before a heat treatment.

FIG. 4 is an analysis diagram in a depth direction by XPS after a heat treatment.

FIG. 5 is a diagram illustrating a conventional semiconductor device and a lead frame.

[Explanation of symbols]

Reference Signs List 110 Copper alloy base material 110S Copper alloy base surface 120 Ni layer or Ni alloy layer 130 Ag layer or alloy layer of Ag and Pd 140 Pd layer 150 Ag layer or alloy layer of Ag and Pd 210 Copper alloy base 210S Copper alloy substrate surface 220, 220A, 220B Ni layer 230, 230A, 230B Ag layer 235, 235A, 235B Ag layer 240, 240A, 240B Pd layer 500 Resin-sealed semiconductor device 510 Lead frame 511 Die pad 512 Inner lead 513 Outer Lead 514 Dam bar 515 Frame (frame) 520 Semiconductor element 521 Electrode pad (terminal) 530 Wire 540 Resin

Claims (5)

[Claims] 1. A lead frame for a resin-sealed semiconductor device comprising a copper alloy base material, wherein the entire or predetermined portion of the surface of the copper alloy base material is measured by X-ray photoelectron spectroscopy. 0.5μm or more Ni in order from the material surface
Layer or Ni alloy layer, Ag of 0.05-0.5 μm
Layer or alloy layer of Ag and Pd, 0.05-0.5μ
m Pd layer, 5-500 ° Ag layer or Ag and Pd
A lead frame for a semiconductor device, wherein an alloy layer of 2. The entire or predetermined portion of the surface of the copper alloy substrate is measured by X-ray photoelectron spectroscopy, and the Ni layer or the Ni alloy layer having a thickness of 0.5 μm or more, in order from the copper alloy substrate surface. Ag layer of 0.05 to 0.5 μm or alloy layer of Ag and Pd, Pd layer of 0.05 to 0.5 μm,
A method for manufacturing a resin-encapsulated semiconductor device lead frame in which an Ag layer or an alloy layer of Ag and Pd having a thickness of 500 ° is formed, the method comprising: Ni layer, Ag layer, Pd layer, N layer
A method for manufacturing a lead frame for a semiconductor device, comprising: forming an i-layer, an Ag layer, a Pd layer, and an Ag layer, and then performing a heat treatment in the atmosphere. 3. The Ni layer, Ag layer, Pd layer, or Ni layer on the surface of the copper alloy substrate before the heat treatment according to claim 2.
Layer, Ag layer, Pd layer, and Ag layer are formed by a wet plating method,
A method for manufacturing a lead frame for a semiconductor device, wherein the method is performed by any one of ion plating method and vapor deposition method or a combination of two or more methods. 4. An entire layer or a predetermined portion of the surface of the copper alloy substrate is measured by X-ray photoelectron spectroscopy. Ag layer of 0.05 to 0.5 μm or alloy layer of Ag and Pd, Pd layer of 0.05 to 0.5 μm,
A method for manufacturing a resin-encapsulated semiconductor device lead frame in which an Ag layer or an alloy layer of Ag and Pd having a thickness of 500 ° is formed, the method comprising: A method for manufacturing a lead frame for a semiconductor device, wherein a Ni layer, an Ag layer, a Pd layer, and an Ag layer are sequentially formed on the surface of the copper alloy base material in all or a predetermined portion. 5. The method of claim 4, wherein the formation of the Ni layer, Ag layer, Pd layer, and Ag layer on the surface of the copper alloy substrate is performed by any one of a wet plating method, an ion plating method, and a vapor deposition method.
A method for manufacturing a lead frame for a semiconductor device, wherein the method is performed by one or a combination of two or more methods.