Metal component

Abstract

The metal component of this invention is used in the manufacture of semiconductor devices and comprises a substrate, a nickel layer, and a noble metal layer. The substrate is conductive. The nickel layer is formed on the surface of the substrate and is composed primarily of nickel. A palladium layer is formed on the surface of the nickel layer. Furthermore, the nickel layer comprises a first nickel layer that does not contain phosphorus and a second nickel layer that contains 0.01 (wt%) to 1 (wt%) of phosphorus. According to the metal component disclosed herein, good properties can be maintained while reducing the thickness of the nickel layer.

Description

[Technical Field]

[0001] An embodiment of the present invention relates to a metal component. [Previous Technology]

[0002] It is well known that in the manufacture of semiconductor devices, there is a technique for forming a nickel plating layer on the surface of a metal substrate in metal components such as lead frames. In addition, for example, there is a well known technique called Pd-PPF (Pre Plated lead Frame), in which a nickel plating layer, a palladium plating layer, and a gold plating layer are sequentially formed on the surface of the metal substrate of the lead frame (see Patent Document 1).

[0002] [Previous Technical Documents]

[0002] [Patent Documents]

[0003] Patent Document 1: Japanese Patent Application Publication No. 4-115558

[0004] However, because the nickel layer is relatively thick, there is a problem of increased manufacturing costs.

[0005] One embodiment of the present invention was developed in view of the above, with the aim of providing a metal component used in the manufacture of semiconductor devices that can maintain good properties while reducing the thickness of the nickel layer.

[0006] One embodiment of the metal component includes a substrate, a nickel layer, and a noble metal layer in a metal component used in the manufacture of a semiconductor device. The substrate is conductive. The nickel layer is formed on the surface of the substrate and has nickel as the main component. The noble metal layer is formed on the surface of the nickel layer. Furthermore, the nickel layer has a first nickel layer that does not contain phosphorus and a second nickel layer that contains 0.01 (wt%) to 1 (wt%) of phosphorus.

[0007] According to one embodiment, good properties can be maintained in the metal components used in the manufacture of semiconductor devices while reducing the thickness of the nickel layer. [Simplified Explanation of the Diagram]

[0008] Figure 1 is a schematic diagram of the conductor frame of the relevant implementation type.

[0008] Figure 2 is a cross-sectional view showing an embodiment of the semiconductor device.

[0008] Figure 3 is an enlarged cross-sectional view of the conductor frame of the implementation type and its variations 1 and 2.

[0008] Figure 4 is an enlarged cross-sectional view of the conductor frame of variant examples 3 to 5 of the implementation.

[0008] Figure 5 is a SEM photograph showing the cross-sectional morphology of the conductor frame in Embodiment 4.

[0008] Figure 6 is a SEM photograph showing the cross-sectional morphology of the conductor frame of Embodiment 8.

[0008] Figure 7 is a SEM photograph showing the cross-sectional morphology of the conductor frame of Comparative Example 4.

[0008] Figure 8 is a SEM photograph showing the cross-sectional morphology of the conductor frame of Comparative Example 8.

Implementation Method

[0009] Hereinafter, with reference to the accompanying drawings, an example of a lead frame among the metal components used in the manufacture of the semiconductor device disclosed in this application will be described. Furthermore, this disclosure is not limited to the embodiments shown below. Also, the drawings are illustrative, and the dimensional relationships and ratios of the components may differ from reality; this should be noted. Moreover, there are instances in the drawings where the dimensional relationships or ratios of the components differ from those in reality.

[0010] In the past, it was well known that in the lead frame used in the manufacture of semiconductor devices, there is a technology called Pd-PPF, which involves sequentially forming a nickel plating layer, a palladium plating layer and a gold plating layer on the surface of a metal substrate.

[0011] In this Pd-PPF, since it can have both the wettability of solder and the bonding characteristics of bonding wires, semiconductor devices can be manufactured in a simple process by using such a Pd-PPF.

[0012] However, in the prior art, if the thickness of the nickel plating layer is simply reduced, the copper contained in the substrate can easily diffuse to the surface of the Pd-PPF, resulting in a deterioration in solder wettability. On the other hand, if the thickness of the nickel plating layer is increased, the processing time for forming such a nickel plating layer will be longer, thus raising concerns about increased manufacturing costs.

[0013] Therefore, the realization of a technology that overcomes the above-mentioned problems and can maintain good properties in Pd-PPF while reducing the thickness of the nickel layer is highly anticipated.

[0014] <Conductor Frame and Semiconductor Device>

[0014] First, the lead frame 1 and semiconductor device 100 of the embodiment will be described with reference to Figures 1 and 2. Figure 1 is a schematic diagram of the lead frame 1 of the embodiment, and Figure 2 is a cross-sectional view showing the semiconductor device 100 of the embodiment.

[0015] The lead frame 1 shown in Figure 1 is a lead frame used in the manufacture of a QFP (Quad Flat Package) type semiconductor device 100. Furthermore, the technology disclosed herein can also be applied to lead frames used in the manufacture of other types, such as SOP (Small Outline Package) or QFN (Quad Flat Non-lead package) semiconductor devices with exposed leads on the back side.

[0016] The lead frame 1 in the embodiment has a strip shape when viewed from above, and a plurality of unit lead frames 10 are arranged along the long side direction. Such unit lead frames 10 correspond to various parts of the semiconductor device 100 manufactured using the lead frame 1. Furthermore, a plurality of unit lead frames 10 can be arranged not only along the long side direction of the lead frame 1, but also along the width direction.

[0017] As shown in Figure 1, the unit lead frame 10 has a wafer pad 11, a plurality of wires 12, and a dam bar 13. Furthermore, although not shown in Figure 1, positioning holes may be arranged on the side of the long side of the lead frame 1.

[0018] The wafer pad 11 is provided, for example, in the central portion of the unit lead frame 10. As shown in FIG2, the front surface side of such a wafer pad 11 can be used to mount a semiconductor device 101.

[0019] The chip pad 11 is connected to the outer edge of the cell lead frame 10 by the chip pad support portion 11a and is supported by the cell lead frame 10. Such chip pad support portions 11a are provided at the four corners of the chip pad 11, for example.

[0020] A plurality of wires 12 are arranged around the wafer pad 11, and the front end 12a of each wire extends from the outer edge of the unit lead frame 10 toward the wafer pad 11. As shown in FIG2, such wires 12 function as connection terminals of the semiconductor device 100.

[0021] The lead wire 12 has a front end portion 12a and a base end portion 12b. As shown in FIG2, in the semiconductor device 100, the front end portion 12a of the lead wire 12 is connected to a bonding wire 102, which is made of Cu or Cu alloy, Au, Au alloy, etc. Therefore, the lead frame 1 is required to have high bonding characteristics with the bonding wire 102. The stop bar 13 connects adjacent lead wires 12 to each other.

[0022] In addition to the lead frame 1, semiconductor element 101, and bonding wire 102, the semiconductor device 100 also includes an encapsulating resin 103. The encapsulating resin 103 is made of, for example, epoxy resin, and is molded into a predetermined shape by a molding process or the like. The encapsulating resin 103 encapsulates the semiconductor element 101, bonding wire 102, wafer pad 11, etc.

[0023] Furthermore, the base end 12b of the conductor 12 functions as an external terminal (external conductor) of the semiconductor device 100 and is bonded to the substrate by solder. Also, in semiconductor devices 100 where the back side of the wafer pad 11 is exposed from the encapsulation resin 103 or where a heat sink is provided, the back side of the base end 12b of these conductors 12 is bonded to the substrate by solder. Therefore, the lead frame 1 requires high wettability to solder.

[0024] Furthermore, in the molding step of molding the encapsulating resin 103, the blocking rod 13 has a blocking function to prevent the resin used from leaking to the base end 12b (external wire) side, and is finally cut off in the manufacturing step of the semiconductor device 100.

[0025] <Implementation Type>

[0025] Next, the details of the conductor frame 1 of the embodiment will be described with reference to FIG3(a). FIG3(a) is an enlarged cross-sectional view of the conductor frame 1 of the embodiment.

[0026] As shown in FIG3(a), the lead frame 1 of the embodiment comprises a substrate 2, a nickel layer 3, and a noble metal layer 4. The substrate 2 is made of a conductive material (e.g., a metallic material such as copper or a copper alloy). The noble metal layer 4 is formed on the surface of the nickel layer 3, and the noble metal layer 4 is composed of at least one of palladium, gold, and silver as the main component. Furthermore, the noble metal layer may be a single layer or multiple layers.

[0027] In the lead frame 1, a nickel layer 3 is formed on the surface 2a of the substrate 2. The nickel layer 3 contains nickel (Ni) as the main component and can be formed, for example, by nickel plating.

[0028] Furthermore, the nickel layer 3 comprises a first nickel layer 31 and a second nickel layer 32. The first nickel layer 31 is a nickel layer that does not contain phosphorus (P). Also, in this disclosure, "does not contain phosphorus" also includes cases where phosphorus, which is an unavoidable impurity, is present.

[0029] The second nickel layer 32 is a nickel layer containing a predetermined ratio of phosphorus. The second nickel layer 32 contains, for example, 0.01 (wt%) to 1 (wt%) of phosphorus. Furthermore, the second nickel layer 32 contains, for example, a predetermined ratio of phosphorus and has a columnar crystalline structure. Herein, the unit (wt%) refers to the weight percentage of the substance.

[0030] Furthermore, in this disclosure, the first nickel layer 31 may also contain elements other than nickel, and the second nickel layer 32 may also contain elements other than nickel and phosphorus.

[0031] As shown in FIG3(a), in an embodiment, the nickel layer 3 is composed of two layers: a first nickel layer 31 and a second nickel layer 32. Furthermore, in an embodiment, the first nickel layer 31 is disposed on the surface 2a of the substrate 2, and the second nickel layer 32 is disposed on the surface 31a of the first nickel layer 31.

[0032] Furthermore, a noble metal layer 4 is formed on the surface 3a of the nickel layer 3 (or the surface 32a of the second nickel layer 32 in the embodiment). The noble metal layer 4 comprises a palladium layer 41 and a gold layer 42. The palladium layer 41 comprises palladium (Pd) as the main component, and the palladium layer 41 can be formed, for example, by palladium plating. The gold layer 42 comprises gold (Au) as the main component, and the gold layer 42 can be formed, for example, by gold plating.

[0033] Since the noble metal layer 4 is composed of a noble metal that is not easily oxidized, the lead frame 1 of the embodiment can suppress the formation of oxides on the surface 1a of such a lead frame 1. Therefore, according to the embodiment, a lead frame 1 that combines the wettability of solder and the bonding characteristics of the bonding line 102 (see Figure 2) can be realized.

[0034] Furthermore, the precious metal layer 4 in the embodiment is not limited to being composed of a palladium layer 41 and a gold layer 42, but may also be composed of a silver layer containing silver (Ag) as the main component. Furthermore, the precious metal layer 4 in the embodiment may be composed of only a silver layer.

[0035] Here, in an embodiment, the nickel layer 3 includes a second nickel layer 32 containing 0.01 (wt%) to 1 (wt%) of phosphorus, thereby suppressing the diffusion of copper contained in the substrate 2 within such a second nickel layer 32.

[0036] This is because, inside the second nickel layer 32, concentrated phosphorus nails are embedded at the interface of adjacent crystal grains, and such phosphorus will hinder the diffusion of copper.

[0037] Furthermore, in an embodiment, the nickel layer 3 includes a second nickel layer 32, which contains phosphorus and has a columnar crystalline structure, thereby suppressing the diffusion of copper contained in the substrate 2 within such a second nickel layer 32.

[0038] This is because, inside the second nickel layer 32, nickel is columnar crystal, so the area of ​​the crystal grain boundary is smaller than when nickel is microcrystalline, and the phosphorus present in the smaller crystal grain boundary will hinder the diffusion of copper.

[0039] Moreover, in the embodiment, even if the nickel layer 3 contains a second nickel layer 32, thereby reducing the overall thickness of the nickel layer 3, the diffusion of copper to the surface 1a of the lead frame 1 can be suppressed.

[0040] Therefore, even if the overall thickness of the nickel layer 3 is reduced, the oxidation of copper on the surface 1a can be suppressed, thus achieving a lead frame 1 that combines the wettability of solder and the bonding characteristics of the bonding wire 102.

[0041] That is, in the embodiment, the nickel layer 3 includes a second nickel layer 32, thereby maintaining good properties of Pd-PPF while reducing the thickness of the nickel layer 3.

[0042] Furthermore, in the embodiment, the nickel layer 3 includes a first nickel layer 31 that does not contain phosphorus, thereby reducing the thickness of the second nickel layer 32 compared to the case where the nickel layer 3 is formed only by a second nickel layer 32 containing phosphorus.

[0043] This is because, even if the thickness of the second nickel layer 32 is reduced, the first nickel layer 31 still replaces the function of the portion corresponding to the reduction in thickness, thereby giving the nickel layer 3 the same function as when the nickel layer 3 is constituted by only the second nickel layer 32.

[0044] Furthermore, by reducing the thickness of the second nickel layer 32, the manufacturing cost of the second nickel layer 32, which has a relatively high manufacturing cost, can be reduced. That is, according to the embodiment, by including the first nickel layer 31, which contains no phosphorus, the overall manufacturing cost of the nickel layer 3 can be reduced.

[0045] Furthermore, in an embodiment, as shown in FIG3(a), a first nickel layer 31 may be formed on the surface 2a of the substrate 2, and a second nickel layer 32 may be formed on the surface 31a of the first nickel layer 31. That is, in an embodiment, the second nickel layer 32 may be disposed closer to the surface 1a of the lead frame 1 than the first nickel layer 31.

[0046] In this way, the diffusion of nickel contained in the first nickel layer 31 to the surface 1a of the lead frame 1 can be suppressed by the second nickel layer 32. This is because there is concentrated phosphorus at the interface of adjacent crystal grains inside the second nickel layer 32, and such phosphorus will also hinder the diffusion of nickel.

[0047] That is, in the embodiment, the second nickel layer 32 is disposed closer to the surface 1a of the lead frame 1 than the first nickel layer 31, thereby suppressing the oxidation of nickel on the surface 1a. Therefore, according to the embodiment, a lead frame 1 with high strength and both solder wettability and bonding characteristics of the bonding wire 102 can be realized.

[0048] Furthermore, in an embodiment, the second nickel layer 32 may contain 0.01 (wt%) to 0.5 (wt%) of phosphorus. This further reduces the overall manufacturing cost of the nickel layer 3 and maintains the appearance of the nickel layer 3 well.

[0049] Furthermore, in the embodiment, the thickness ratio of the second nickel layer 32 in the nickel layer 3 can be 50% or less. This further reduces the overall manufacturing cost of the nickel layer 3.

[0050] Furthermore, in the embodiment, the thickness of the second nickel layer 32 can be 0.1 (μm) or more. This further suppresses copper diffusion to the surface 1a of the lead frame 1, thus maintaining good solder wettability on the surface 1a of the lead frame 1.

[0051] <Variant Example 1>

[0051] Next, various variations of the lead frame 1 of the embodiment will be described with reference to Figures 3 and 4. Figure 3(b) is an enlarged cross-sectional view of the lead frame 1 of the embodiment variation 1. The difference between this variation 1 and the embodiment described above is the arrangement of the first nickel layer 31 and the second nickel layer 32 in the nickel layer 3.

[0052] Specifically, as shown in FIG3(b), a second nickel layer 32 is formed on the surface 2a of the substrate 2, and a first nickel layer 31 is formed on the surface 32a of the second nickel layer 32. Furthermore, a palladium layer 41 of a noble metal layer 4 is formed on the surface 31a of the first nickel layer 31.

[0053] In this variant 1, similar to the above embodiment, the nickel layer 3 includes a second nickel layer 32, which contains 0.01 (wt%) to 1 (wt%) of phosphorus, thereby maintaining good properties in Pd-PPF while reducing the thickness of the nickel layer 3.

[0054] Furthermore, in variant example 1, similar to the above-described embodiment, the nickel layer 3 includes a second nickel layer 32, which contains phosphorus and has a columnar crystalline structure, thereby maintaining good properties in Pd-PPF while reducing the thickness of the nickel layer 3.

[0055] Furthermore, in variant example 1, similar to the above-described embodiment, the nickel layer 3 includes a first nickel layer 31 that does not contain phosphorus, thereby reducing the overall manufacturing cost of the nickel layer 3.

[0056] Furthermore, in Variation 1, the second nickel layer 32 may also contain 0.01 (wt%) to 0.5 (wt%) of phosphorus. This further reduces the overall manufacturing cost of the nickel layer 3 and maintains the appearance of the nickel layer 3 well.

[0057] Furthermore, in Variation 1, the thickness ratio of the second nickel layer 32 in the nickel layer 3 can also be 50% or less. This further reduces the overall manufacturing cost of the nickel layer 3.

[0058] Furthermore, in Variation 1, the thickness of the second nickel layer 32 may also be 0.1 (μm) or more. This further suppresses copper diffusion to the surface 1a of the lead frame 1, thus maintaining good solder wettability on the surface 1a of the lead frame 1.

[0059] <Variant Example 2>

[0059] FIG3(c) is an enlarged cross-sectional view of the lead frame 1 of Embodiment Variation 2. The composition of the nickel layer 3 in this Variation 2 is different from that of the Embodiment and Variation 1 described above. Specifically, as shown in FIG3(c), a second nickel layer 32A is formed on the surface 2a of the substrate 2, and a first nickel layer 31 is formed on the surface 32Aa of the second nickel layer 32A.

[0060] Furthermore, a second nickel layer 32B is formed on the surface 31a of the first nickel layer 31, and a palladium layer 41 of the noble metal layer 4 is formed on the surface 32ba of the second nickel layer 32B. The second nickel layer 32B is an example of another second nickel layer.

[0061] Thus, in the technology disclosed herein, the nickel layer 3 is not limited to two layers, but can be composed of three or more layers.

[0062] In this variant 2, similar to the above embodiment, the nickel layer 3 includes second nickel layers 32A and 32B, which contain 0.01 (wt%) to 1 (wt%) of phosphorus, thereby maintaining good properties in Pd-PPF while reducing the thickness of the nickel layer 3.

[0063] Furthermore, in variant example 2, similar to the above embodiment, the nickel layer 3 includes second nickel layers 32A and 32B, which contain phosphorus and have a columnar crystalline structure, thereby maintaining good properties in Pd-PPF while reducing the thickness of the nickel layer 3.

[0064] Furthermore, in variant 2, similar to the above-described embodiment, the nickel layer 3 includes a first nickel layer 31 that does not contain phosphorus, thereby further reducing the overall manufacturing cost of the nickel layer 3.

[0065] Furthermore, in Variation 2, similar to the embodiment described above, the second nickel layer 32B is disposed closer to the surface 1a of the lead frame 1 than the first nickel layer 31, thereby suppressing the oxidation of nickel on the surface 1a. Therefore, according to Variation 2, a lead frame 1 with high strength and both solder wettability and bonding characteristics of the bonding wire 102 (see Figure 2) can be achieved.

[0066] Furthermore, in Variation 2, the second nickel layers 32A and 32B may also contain 0.01 (wt%) to 0.5 (wt%) of phosphorus. This further reduces the overall manufacturing cost of the nickel layer 3 and maintains the appearance of the nickel layer 3 well.

[0067] Furthermore, in Variation 2, the ratio of the total thickness of the second nickel layers 32A and 32B in the nickel layer 3 can be 50% or less. This further reduces the overall manufacturing cost of the nickel layer 3.

[0068] Furthermore, in Variation 2, the combined thickness of the second nickel layers 32A and 32B can be 0.1 μm or more. This further suppresses copper diffusion to the surface 1a of the lead frame 1, thus maintaining good solder wettability on the surface 1a of the lead frame 1.

[0069] <Variant Example 3>

[0069] FIG4(a) is an enlarged cross-sectional view of the lead frame 1 of Embodiment Variation 3. The surface shape of the first nickel layer 31 in this Variation 3 is different from that in the embodiment described above. Specifically, as shown in FIG4(a), the surface 31a of the first nickel layer 31 formed on the surface 2a of the substrate 2 is roughened. The nickel plating process of the first nickel layer 31 can be performed using a suitable plating solution and plating formation conditions to form the aforementioned roughened surface 31a.

[0070] Furthermore, in variant example 3, the surfaces 32a, 41a, and 42a of the second nickel layer 32, palladium layer 41, and gold layer 42 formed sequentially on the aforementioned surface 31a can be roughened, thereby roughening the surface 1a of the lead frame 1.

[0071] Accordingly, in Variation 3, the adhesion between the leadframe 1 and the encapsulating resin 103 (see Figure 2) can be improved through the so-called anchoring effect. That is, according to Variation 3, a leadframe 1 with excellent adhesion to the encapsulating resin 103 can be achieved, and the nickel layer 3 includes a second nickel layer 32, which contains 0.01 (wt%) to 1 (wt%) phosphorus, thereby obtaining good properties in Pd-PPF.

[0072] Furthermore, in variant 3, the nickel layer 3 includes a first nickel layer 31 and a second nickel layer 32. The first nickel layer 31 has a roughened surface 31a, and the second nickel layer 32 contains phosphorus and has a columnar crystalline structure, thereby achieving excellent adhesion to the encapsulating resin 103 and obtaining good properties in Pd-PPF.

[0073] Furthermore, in Variation 3, similar to the above embodiment, the second nickel layer 32 is disposed closer to the surface 1a of the lead frame 1 than the first nickel layer 31, thereby suppressing the oxidation of nickel on the surface 1a. Therefore, according to Variation 3, a lead frame 1 with high strength and both solder wettability and bonding characteristics of the bonding wire 102 (see Figure 2) can be achieved.

[0074] Furthermore, in Variation 3, the thickness ratio of the second nickel layer 32 in the nickel layer 3 can be 50% or less. This further reduces the overall manufacturing cost of the nickel layer 3.

[0075] Furthermore, in Variation 3, the thickness of the second nickel layer 32 can be in the range of 0.1 (μm) to 0.4 (μm). Since the thickness of the second nickel layer 32 is set to 0.1 (μm) or more, copper diffusion to the surface 1a of the lead frame 1 can be further suppressed, and thus the wettability of the solder can be well maintained on the surface 1a of the lead frame 1.

[0076] Furthermore, since the thickness of the second nickel layer 32 is set to 0.4 (μm) or less, the uneven shape of the surface 1a of the lead frame 1 can be well maintained, thereby maintaining good adhesion to the encapsulation resin 103.

[0077] <Variant Example 4>

[0077] Figure 4(b) is an enlarged cross-sectional view of the lead frame 1 of the embodiment variant 4. The arrangement of the first nickel layer 31 and the second nickel layer 32 in the nickel layer 3 in this variant 4 is different from that in the above-described variant 3.

[0078] Specifically, as shown in FIG4(b), a second nickel layer 32 is formed on the surface 2a of the substrate 2, and a roughened first nickel layer 31 is formed on the surface 32a of the second nickel layer 32. Furthermore, a palladium layer 41 of a noble metal layer 4 is formed on the surface 31a of the roughened first nickel layer 31.

[0079] Furthermore, in Variation 4, similar to Variation 3 described above, the surface 31a of the first nickel layer 31 is formed on the rough surface, thus roughening the surface 1a of the lead frame 1. In this way, in Variation 4, a lead frame 1 with excellent adhesion to the encapsulating resin 103 can be achieved.

[0080] Furthermore, in variant example 4, the first nickel layer 31 is disposed closer to the surface 1a of the lead frame 1 than the second nickel layer 32, thereby allowing the surface 31a of the first nickel layer 31, which is a rough surface, to be close to the surface 1a of the lead frame 1.

[0081] Therefore, in Variation 4, the surface 1a of the leadframe 1 can be formed into an uneven shape, and this uneven shape is approximately (i.e., with a larger roughness) the uneven shape formed on the surface 31a of the first nickel layer 31. Therefore, according to Variation 4, a leadframe 1 with better adhesion to the encapsulating resin 103 can be achieved, and the nickel layer 3 includes a second nickel layer 32, which contains 0.01 (wt%) to 1 (wt%) phosphorus, thereby obtaining good properties in Pd-PPF.

[0082] Furthermore, in variant 4, the nickel layer 3 includes a first nickel layer 31 and a second nickel layer 32. The first nickel layer 31 has a roughened surface 31a, and the second nickel layer 32 contains phosphorus and has a columnar crystalline structure, thereby achieving excellent adhesion to the encapsulating resin 103 and obtaining good properties in Pd-PPF.

[0083] Furthermore, in Variation 4, the second nickel layer 32 may contain 0.01 (wt%) to 0.5 (wt%) of phosphorus. This further reduces the overall manufacturing cost of the nickel layer 3 and maintains the appearance of the nickel layer 3 well.

[0084] Furthermore, in Variation 4, the thickness ratio of the second nickel layer 32 in the nickel layer 3 can be 50% or less. This further reduces the overall manufacturing cost of the nickel layer 3.

[0085] Furthermore, in Variation 4, the thickness of the second nickel layer 32 may be 0.1 (μm) or more. This further suppresses copper diffusion to the surface 1a of the lead frame 1, thus maintaining good solder wettability on the surface 1a of the lead frame 1.

[0086] <Variant Example 5>

[0086] FIG4(c) is an enlarged cross-sectional view of the lead frame 1 of embodiment variant 5. The composition of the nickel layer 3 in this variant 5 is different from that of variants 3 and 4 described above. Specifically, as shown in FIG4(c), a second nickel layer 32A is formed on the surface 2a of the substrate 2, and a roughened first nickel layer 31 is formed on the surface 32Aa of the second nickel layer 32A.

[0087] Furthermore, a second nickel layer 32B is formed on the surface 31a of the roughened first nickel layer 31, and a palladium layer 41 of the noble metal layer 4 is formed on the surface 32Ba of the second nickel layer 32B.

[0088] Furthermore, in Variation 5, since the surface 31a of the first nickel layer 31 is formed on the rough surface, the surface 1a of the lead frame 1 can be roughened. Thus, in Variation 5, similar to Variation 3 described above, a lead frame 1 with excellent adhesion to the encapsulating resin 103 can be achieved. The nickel layer 3 includes second nickel layers 32A and 32B, which contain 0.01 (wt%) to 1 (wt%) of phosphorus, thereby obtaining good properties in Pd-PPF.

[0089] In variant 5, the nickel layer 3 includes a first nickel layer 31 and second nickel layers 32A and 32B. The first nickel layer 31 has a roughened surface 31a, and the second nickel layers 32A and 32B contain phosphorus and have a columnar crystalline structure, thereby achieving excellent adhesion to the encapsulating resin 103 and obtaining good properties in Pd-PPF.

[0090] Furthermore, in Variation 5, the second nickel layer 32A may contain 0.01 (wt%) to 0.5 (wt%) of phosphorus. This further reduces the overall manufacturing cost of the nickel layer 3 and maintains the appearance of the nickel layer 3 well.

[0091] Furthermore, in Variation 5, similarly to the above embodiment, the second nickel layer 32B is disposed closer to the surface 1a of the lead frame 1 than the first nickel layer 31, thereby suppressing the oxidation of nickel on the surface 1a. Therefore, according to Variation 5, a lead frame 1 with high strength and both solder wettability and bonding characteristics of the bonding wire 102 (see Figure 2) can be achieved.

[0092] Furthermore, in Variation 5, the ratio of the total thickness of the second nickel layers 32A and 32B in nickel layer 3 can be 50% or less. This further reduces the overall manufacturing cost of nickel layer 3.

[0093] Furthermore, in Variation 5, the combined thickness of the second nickel layers 32A and 32B can be 0.1 μm or more. This further suppresses copper diffusion to the surface 1a of the lead frame 1, thus maintaining good solder wettability on the surface 1a of the lead frame 1.

[0094] Furthermore, in Variation 5, the thickness of the second nickel layer 32A can be 0.1 (μm) or more. This further suppresses copper diffusion to the surface 1a of the lead frame 1, thus maintaining good solder wettability on the surface 1a of the lead frame 1.

[0095] Furthermore, in Variation 5, the thickness of the second nickel layer 32B can be in the range of 0.1 (μm) to 0.4 (μm). Since the thickness of the second nickel layer 32B is formed to be 0.1 (μm) or more, copper diffusion to the surface 1a of the lead frame 1 can be further suppressed, and thus the wettability of the solder can be well maintained on the surface 1a of the lead frame 1.

[0096] Furthermore, since the thickness of the second nickel layer 32B is made to be less than 0.4 (μm), the uneven shape of the surface 1a of the lead frame 1 can be well maintained, thereby maintaining good adhesion to the encapsulation resin 103.

[0096] [Example]

[0097] Hereinafter, the contents of this disclosure will be described in more detail with reference to the embodiments and reference examples, but the present invention is not limited to the following embodiments.

[0098] <Evaluation 1> [Example 1]

[0098] First, a lead frame substrate with copper as the main component is prepared. Next, after degreasing and acid cleaning of the substrate, a first nickel layer without phosphorus is formed on the surface of the substrate with a thickness of 0.1 (μm) by electrolytic plating.

[0099] The first nickel layer was formed using a Watts bath (nickel sulfate: 240 g / L, nickel chloride: 45 g / L, boric acid concentration: 35 g / L, current density: 5 A / dm², bath temperature: 50 °C, pH=3.5, anode: Ni plate). Furthermore, in this disclosure, the first nickel layer was formed under the same conditions in Examples 1 to 48, Reference Examples 1 to 12, and Comparative Examples 1 to 14 below.

[0100] Next, by means of electroplating, a second nickel layer containing 0.1 (wt%) phosphorus is formed on the surface of the first nickel layer with a thickness of 0.1 (μm).

[0101] The second nickel layer was formed using a Watts nickel plating bath (nickel sulfate: 240 g / L, nickel chloride: 45 g / L, boric acid concentration: 35 g / L, phosphorus concentration: 20 mg / L, current density: 5 A / dm², bath temperature: 50 °C, pH=3.5, anode: Ni plate). Furthermore, in this disclosure, in Examples 1 to 48 and Reference Examples 1 to 12 below, the second nickel layer was formed under the same conditions except for the phosphorus concentration.

[0102] Furthermore, the concentration of phosphorus contained in the second nickel layer is determined by the following method. First, about 80 mg of nickel foil on the surface of the sample is measured, and such nickel foil is dissolved in 10 mL of 61% nitric acid (13 mol / L), and the entire volume is filled to 100 mL using a 100 mL volumetric flask.

[0103] Next, 10 mL of 61% nitric acid was added to 5 mL of the prepared phosphorus concentration determination sample solution, and a 100 mL volumetric flask was used to fill the entire volume to 100 mL.

[0104] Furthermore, the phosphorus concentration in the prepared phosphorus concentration test solution was determined using a commercially available ICP luminescence analyzer (manufactured by Horiba Manufacturing Co., Ltd., product name ULTIMA2). Also, in this disclosure, the phosphorus concentration contained in the second nickel layer was determined under the same conditions in Examples 1 to 48 and Reference Examples 1 to 12 below.

[0105] Returning to the description of the manufacturing steps of the lead frame in Example 1. After the formation of the second nickel layer, a palladium layer with a thickness of 0.020 (μm) is formed on the surface of the second nickel layer by electrolytic plating.

[0106] The palladium layer was formed under the following conditions: Pd concentration: 1.6 (g / L), current density: 1.0 (A / dm2), bath temperature: 50 (°C), pH=6.7, and anode: iridium oxide. Furthermore, in this disclosure, the palladium layer was formed under the same conditions in Examples 1 to 48, Reference Examples 1 to 12, and Comparative Examples 1 to 14 below.

[0107] Next, a gold layer is formed on the surface of the palladium layer with a thickness ranging from 0.004 (μm) to 0.006 (μm) by electroplating. In this way, the lead frame of Example 1 is obtained.

[0108] The gold layer was formed under the following conditions: Au concentration: 0.8 (g / L), current density: 3 (A / dm2), bath temperature: 50 (°C), pH=6.4, and anode: iridium oxide. Furthermore, in this disclosure, the gold layer was formed under the same conditions in Examples 1 to 48, Reference Examples 1 to 12, and Comparative Examples 1 to 14 below.

[0109] [Examples 2 to 4]

[0109] The lead frames of Examples 2 to 4 were obtained using the same method as in Example 1 described above. Furthermore, in Examples 2 to 4, the conditions of the electrolytic plating process were adjusted so that the film thicknesses of the first nickel layer and the second nickel layer were as described in Table 1.

[0110] [Example 5]

[0110] First, a lead frame substrate with copper as the main component is prepared. Next, after degreasing and acid cleaning of the substrate, a second nickel layer containing 0.1 wt% phosphorus is formed on the surface of the substrate with a thickness of 0.1 μm by electroplating. Next, a first nickel layer without phosphorus is formed on the surface of the second nickel layer with a thickness of 0.1 μm by electroplating.

[0111] Next, a palladium layer with a thickness of 0.020 μm is formed on the surface of the first nickel layer by electrolytic plating. Then, a gold layer with a thickness ranging from 0.004 μm to 0.006 μm is formed on the surface of the palladium layer by electrolytic plating. Thus, the lead frame of Example 5 is obtained.

[0112] [Examples 6 to 8]

[0112] Using the same method as in Example 5 above, the lead frame of Examples 6 to 8 was obtained. Furthermore, in Examples 6 to 8, the conditions of the electrolytic plating process were adjusted so that the film thickness of the second nickel layer and the first nickel layer became the film thicknesses listed in Table 1.

[0113] [Comparative Example 1]

[0113] First, a lead frame substrate with copper as the main component is prepared. Next, after degreasing and acid cleaning of the substrate, a first nickel layer without phosphorus is formed on the surface of the substrate with a thickness of 0.2 (μm) by electrolytic plating.

[0114] Next, a palladium layer with a thickness of 0.020 μm is formed on the surface of the first nickel layer by electrolytic plating. Then, a gold layer with a thickness ranging from 0.004 μm to 0.006 μm is formed on the surface of the palladium layer by electrolytic plating. Thus, the lead frame of Comparative Example 1 is obtained.

[0115] [Comparative Examples 2 to 4]

[0115] Using the same method as Comparative Example 1 described above, the lead frames of Comparative Examples 2 to 4 were obtained. Furthermore, in Comparative Examples 2 to 4, the conditions of the electrolytic plating process were adjusted so that the thickness of the first nickel layer was as shown in Table 1.

[0116] [Comparative Example 5]

[0116] First, a lead frame substrate with copper as the main component is prepared. Next, after degreasing and acid cleaning of the substrate, a nickel-phosphorus (NiP) layer with a thickness of 0.2 (μm) is formed on the surface of the substrate by electrolytic plating. The nickel-phosphorus (NiP) layer contains a higher proportion of phosphorus (6.7 (wt%) in this disclosure series) than the second nickel layer.

[0117] The nickel-phosphorus layer was formed using a Watts nickel plating bath (nickel sulfate: 150 (g / L), nickel chloride: 150 (g / L), Kizai Co., Ltd. Nypholloy Process: 200 (mL / L), current density: 7.5 (A / dm2), bath temperature: 60 (°C), pH=0.3, anode: Ni plate).

[0118] Furthermore, the concentration of phosphorus contained in the nickel-phosphorus layer was measured using a commercially available X-ray fluorescence measuring device (manufactured by Fischer Instruments Co., Ltd., product name XDV-μ).

[0119] Next, a palladium layer with a thickness of 0.020 μm is formed on the surface of the nickel-phosphorus layer by electrolytic plating. Furthermore, a gold layer with a thickness ranging from 0.004 μm to 0.006 μm is formed on the surface of the palladium layer by electrolytic plating. Thus, the lead frame of Comparative Example 5 is obtained.

[0120] [Comparative Examples 6 to 8]

[0120] Using the same method as Comparative Example 5 described above, the lead frames of Comparative Examples 6 to 8 were obtained. Furthermore, in Comparative Examples 6 to 8, the conditions of the electrolytic plating process were adjusted so that the thickness of the nickel-phosphorus layer was as shown in Table 1.

[0121] Next, for the lead frames of Examples 4 and 8 and Comparative Examples 4 and 8 obtained above, the cross-sectional morphology near the surface was evaluated using a commercially available scanning electron microscope (SEM) (Hitachi High-Tech Fielding Co., Ltd., Hitachi S-4800 Ultra-High Decomposition Energy Electric Field Emission Scanning Electron Microscope).

[0122] Figures 5 to 8 are SEM photographs showing the cross-sectional morphology of the lead frame of Examples 4 and 8 and Comparative Examples 4 and 8.

[0123] As shown in Figures 5 and 6, the second nickel layer system disclosed herein has a columnar crystal structure with relatively large crystal grains. Furthermore, by comparing Examples 4 and 8 shown in Figures 5 and 6 and Comparative Example 4 shown in Figure 7, it can be seen that the second nickel layer system disclosed herein has the same crystal structure as the first nickel layer that does not contain phosphorus (a columnar crystal structure with relatively large crystal grains).

[0124] Furthermore, by comparing Examples 4 and 8 shown in FIG5 and FIG6 with Comparative Example 8 shown in FIG8, it can be seen that the second nickel layer system disclosed herein has a crystal structure that is completely different from that of the nickel-phosphorus layer containing more phosphorus (the nickel-phosphorus layer is a microcrystalline structure with smaller crystal grains).

[0125] Next, for the leadframes of Examples 1 to 8 and Comparative Examples 1 to 8 obtained above, the wettability of the solder was evaluated using a commercially available Solder Checker (manufactured by Lesca Corporation, product name SAT-S100). Specifically, the zero-point crossover time (ZCT) obtained by the meniscograph method was evaluated under the measurement conditions described below: ‧Immersion speed: 5 (mm / s) ‧Immersion depth: 1 (mm) ‧Fluid: Rosin flux (R-type) ‧Solder: Sn-37Pb (230°C) ‧Sample heating device: Heating plate manufactured by AS-ONE Corporation, product name HHP-411 ‧Sample heating conditions: 400 (°C), 30 (seconds)

[0126] The shorter the zero-point crossover time, the better the wettability of the solder on the lead frame. Also, in this disclosure, the term "NG" for zero-point crossover time means that the zero-point crossover time is 10 seconds or more.

[0127] Hereinafter, for Examples 1 to 8 and Comparative Examples 1 to 8, the total thickness of the nickel layer, the thickness of the first nickel layer, the thickness of the second nickel layer and the thickness of the nickel-phosphorus layer, and the measurement results of the zero-point crossover time are shown in Table 1.

[0128] [Table 1]

[0129] It can be seen that the zero-point crossover time of the leadframes in Examples 1 to 8 is all within 1 (second). Therefore, according to the embodiments, a second nickel layer is included in the nickel layer, which contains 0.1 (wt%) phosphorus and has a film thickness of 0.1 (μm) or more, thereby achieving a leadframe with excellent solder wettability.

[0130] Furthermore, comparing Examples 1 to 8 with Comparative Examples 1 to 4, it can be seen that the nickel layer is constructed by using a first nickel layer that does not contain phosphorus and a second nickel layer that contains phosphorus, thereby improving the wettability of the solder.

[0131] Furthermore, comparing Examples 1 to 8 with Comparative Examples 5 to 8, it can be seen that using a second nickel layer with a columnar crystalline structure instead of a nickel-phosphorus layer with a microcrystalline structure improves the wettability of the solder.

[0132] <Evaluation 2> [Example 9]

[0132] First, a lead frame substrate with copper as the main component is prepared. Next, after degreasing and pickling the substrate, a first nickel layer without phosphorus is formed on the surface of the substrate with a thickness of 0.1 μm by electroplating. Next, a second nickel layer containing 0.1 wt% phosphorus is formed on the surface of the substrate with a thickness of 0.1 μm by electroplating.

[0133] Next, a palladium layer with a thickness of 0.020 μm is formed on the surface of the second nickel layer by electrolytic plating. Then, a gold layer with a thickness ranging from 0.004 μm to 0.006 μm is formed on the surface of the palladium layer by electrolytic plating. Thus, the lead frame of Example 9 is obtained.

[0134] [Examples 10 to 12 and Reference Examples 1 and 2]

[0134] Using the same method as in Example 9 above, lead frames for Examples 10 to 12 and Reference Examples 1 and 2 were obtained. Furthermore, in Examples 10 to 12 and Reference Examples 1 and 2, the conditions of the electrolytic plating process were adjusted so that the film thicknesses of the first nickel layer and the second nickel layer were as described in Table 2.

[0135] [Example 13]

[0135] First, a lead frame substrate with copper as the main component is prepared. Next, after degreasing and pickling the substrate, a second nickel layer containing 0.1 wt% phosphorus is formed on the surface of the substrate with a thickness of 0.1 μm by electroplating. Next, a first nickel layer without phosphorus is formed on the surface of the second nickel layer with a thickness of 0.1 μm by electroplating.

[0136] Next, a palladium layer with a thickness of 0.020 μm is formed on the surface of the first nickel layer by electroplating. Then, a gold layer with a thickness ranging from 0.004 μm to 0.006 μm is formed on the surface of the palladium layer by electroplating. Thus, the lead frame of Example 13 is obtained.

[0137] [Examples 14 to 16 and Reference Examples 3 and 4]

[0137] Using the same method as in Example 13 above, lead frames for Examples 14 to 16 and Reference Examples 3 and 4 were obtained. Furthermore, in Examples 14 to 16 and Reference Examples 3 and 4, the conditions of the electrolytic plating process were adjusted so that the film thicknesses of the second nickel layer and the first nickel layer were the film thicknesses listed in Table 2.

[0138] [Comparative Example 9]

[0138] First, a lead frame substrate with copper as the main component is prepared. Next, after degreasing and acid cleaning of the substrate, a first nickel layer without phosphorus is formed on the surface of the substrate with a thickness of 0.05 (μm) by electrolytic plating.

[0139] Next, a palladium layer with a thickness of 0.020 μm is formed on the surface of the first nickel layer by electrolytic plating. Furthermore, a gold layer with a thickness ranging from 0.004 μm to 0.006 μm is formed on the surface of the palladium layer by electrolytic plating. Thus, the lead frame of Comparative Example 9 is obtained.

[0140] [Comparative Examples 10 to 14]

[0140] Using the same method as Comparative Example 9 described above, the lead frames of Comparative Examples 10 to 14 were obtained. Furthermore, in Comparative Examples 10 to 14, the conditions of the electrolytic plating process were adjusted so that the thickness of the first nickel layer was as described in Table 2.

[0141] Next, for the leadframes of Examples 9 to 16, Reference Examples 1 to 4 and Comparative Examples 9 to 14 obtained above, the wettability of the solder (zero cross time obtained by the meniscus method) was evaluated using the same method as Evaluation 1 above.

[0142] Hereinafter, for Examples 9 to 16, Reference Examples 1 to 4 and Comparative Examples 9 to 14, the total thickness of the nickel layer, the thickness of the first nickel layer and the thickness of the second nickel layer, and the measurement results of the zero-point crossover time are shown in Table 2.

[0143] [Table 2]

[0144] It can be seen that the leadframes of Examples 9 to 16 all have a zero-point crossover time of less than 1 second. Therefore, according to the embodiments, a second nickel layer is included in the nickel layer, which contains 0.1 wt% phosphorus and has a film thickness of 0.1 μm or more, thereby achieving a leadframe with excellent solder wettability.

[0145] <Evaluation 3> [Example 17]

[0145] First, a leadframe substrate with copper as the main component is prepared. Next, after degreasing and pickling the substrate, a first nickel layer without phosphorus is formed on the surface of the substrate with a thickness of 0.1 μm by electroplating. Next, a second nickel layer containing 0.01 wt% phosphorus is formed on the surface of the first nickel layer with a thickness of 0.01 μm by electroplating.

[0146] Next, a palladium layer with a thickness of 0.020 μm is formed on the surface of the second nickel layer by electrolytic plating. Then, a gold layer with a thickness ranging from 0.004 μm to 0.006 μm is formed on the surface of the palladium layer by electrolytic plating. Thus, the lead frame of Example 17 is obtained.

[0147] [Examples 18 to 23 and Reference Example 5]

[0147] Using the same method as in Example 17 above, lead frames for Examples 18 to 23 and Reference Example 5 were obtained. Furthermore, in Examples 18 to 23 and Reference Example 5, the conditions of the electrolytic plating process were adjusted so that the phosphorus content in the second nickel layer was as described in Table 3.

[0148] Next, the appearance of the lead frames in Examples 17 to 23 and Reference Example 5 obtained above was evaluated by visual inspection. In terms of appearance, uneven color of the lead frame was considered as poor appearance.

[0149] Hereinafter, for Examples 17 to 23 and Reference Example 5, the total thickness of the nickel layer, the thickness of the first nickel layer and the thickness of the second nickel layer, and the evaluation results of the appearance are presented in Table 3.

[0150] [Table 3]

[0151] It is known that the lead frame of Examples 17 to 23 all have a good appearance. Therefore, according to the embodiments, the second nickel layer is disposed closer to the surface of the lead frame than the first nickel layer, and the second nickel layer contains phosphorus in the range of 0.01 (wt%) to 0.5 (wt%), thereby achieving a lead frame with a good appearance.

[0152] <Evaluation 4> [Example 24]

[0152] First, a leadframe substrate with copper as the main component is prepared. Next, after degreasing and acid cleaning of the substrate, a second nickel layer containing 0.01 wt% phosphorus is formed on the surface of the substrate with a thickness of 1.0 μm by electroplating. Next, a first nickel layer without phosphorus is formed on the surface of the second nickel layer with a thickness of 0.01 μm by electroplating.

[0153] Next, a palladium layer with a thickness of 0.020 μm is formed on the surface of the first nickel layer by electrolytic plating. Then, a gold layer with a thickness ranging from 0.004 μm to 0.006 μm is formed on the surface of the palladium layer by electrolytic plating. Thus, the lead frame of Example 24 is obtained.

[0154] [Examples 25 to 30 and Reference Example 6]

[0154] Using the same method as in Example 24 above, lead frames of Examples 25 to 30 and Reference Example 6 were obtained. Furthermore, in Examples 25 to 30 and Reference Example 6, the conditions of the electrolytic plating process were adjusted so that the phosphorus content in the second nickel layer was as shown in Table 4.

[0155] Next, the appearance of the lead frames in Examples 24 to 30 and Reference Example 6 obtained above is evaluated by visual inspection. In terms of appearance, uneven color of the lead frame is considered as poor appearance.

[0156] Hereinafter, for Examples 24 to 30 and Reference Example 6, the total thickness of the nickel layer, the thickness of the first nickel layer and the thickness of the second nickel layer, and the evaluation results of the appearance are presented in Table 4.

[0157] [Table 4]

[0158] It is known that the leadframes of Examples 24 to 30 all have a good appearance. Therefore, according to the embodiments, the second nickel layer is disposed on the surface side closer to the substrate than the first nickel layer, and the second nickel layer contains phosphorus in the range of 0.01 (wt%) to 0.5 (wt%), thereby achieving a leadframe with a good appearance.

[0159] <Evaluation 5> [Example 31]

[0159] First, a lead frame substrate with copper as the main component is prepared. Next, after degreasing and pickling the substrate, a first nickel layer without phosphorus is formed on the surface of the substrate with a thickness of 1.0 μm by electroplating. Next, a second nickel layer containing 0.01 wt% phosphorus is formed on the surface of the first nickel layer with a thickness of 0.1 μm by electroplating.

[0160] Next, a palladium layer with a thickness of 0.005 μm is formed on the surface of the second nickel layer by electroplating. Then, a gold layer with a thickness ranging from 0.004 μm to 0.006 μm is formed on the surface of the palladium layer by electroplating. Thus, the lead frame of Example 31 is obtained.

[0161] [Examples 32 to 36 and Reference Examples 7 to 9]

[0161] Using the same method as in Example 31 above, lead frames of Examples 32 to 36 and Reference Examples 7 to 9 were obtained. Furthermore, in Examples 32 to 36 and Reference Examples 7 to 9, the conditions of the electrolytic plating process were adjusted so that the film thicknesses of the first nickel layer, the second nickel layer, and the palladium layer were the film thicknesses described in Table 5.

[0162] Next, for the leadframes of Examples 31 to 36 and Reference Examples 7 to 9 obtained above, the wettability of the solder (zero-point cross time obtained by the meniscus method) was evaluated in the same way as Evaluation 1 above.

[0163] Hereinafter, for Examples 31 to 36 and Reference Examples 7 to 9, the total thickness of the nickel layer, the thickness of the first nickel layer, the thickness of the second nickel layer and the thickness of the palladium layer, and the measurement results of the zero-point crossover time are presented in Table 5.

[0164] [Table 5]

[0165] It can be seen that the zero-point crossover time of the leadframes in Examples 31 to 36 is all within 1 second. Furthermore, it can be seen that when the palladium layer is thinned, the wettability of the solder can also be well maintained. Therefore, according to the embodiment, the second nickel layer is disposed closer to the surface side of the leadframe than the first nickel layer, and the second nickel layer contains 0.1 (wt%) phosphorus and has a film thickness of 0.1 (μm) or more, thereby achieving a leadframe with excellent solder wettability.

[0166] <Evaluation 6> [Example 37]

[0166] First, a lead frame substrate with copper as the main component is prepared. Next, after degreasing and pickling the substrate, a second nickel layer containing 0.1 wt% phosphorus is formed on the surface of the substrate with a thickness of 1.0 μm by electroplating. Next, a first nickel layer without 0.1 wt% phosphorus is formed on the surface of the second nickel layer with a thickness of 0.1 μm by electroplating.

[0167] Next, a palladium layer with a thickness of 0.005 μm is formed on the surface of the first nickel layer by electroplating. Then, a gold layer with a thickness ranging from 0.004 μm to 0.006 μm is formed on the surface of the palladium layer by electroplating. Thus, the lead frame of Example 37 is obtained.

[0168] [Examples 38 to 42 and Reference Examples 10 to 12]

[0168] Using the same method as in Example 37 above, lead frames of Examples 38 to 42 and Reference Examples 10 to 12 were obtained. Furthermore, in Examples 38 to 42 and Reference Examples 10 to 12, the conditions of the electrolytic plating process were adjusted so that the film thicknesses of the second nickel layer, the first nickel layer, and the palladium layer were the film thicknesses described in Table 6.

[0169] Next, for the leadframes of Examples 37 to 42 and Reference Examples 10 to 12 obtained above, the wettability of the solder (zero cross time obtained by the meniscus method) was evaluated in the same way as Evaluation 1 above.

[0170] Hereinafter, for Examples 37 to 42 and Reference Examples 10 to 12, the total thickness of the nickel layer, the thickness of the first nickel layer, the thickness of the second nickel layer and the thickness of the palladium layer, and the measurement results of the zero-point crossover time are presented in Table 6.

[0171] [Table 6]

[0172] It can be seen that the leadframes of Examples 37 to 42 all have a zero-point crossover time of less than 1 second. Furthermore, it can be seen that when the palladium layer is thinned, the wettability of the solder can also be well maintained. Therefore, according to the embodiment, the second nickel layer is disposed closer to the surface of the substrate than the first nickel layer, and the second nickel layer contains 0.1 (wt%) phosphorus and has a film thickness of 0.1 (μm) or more, thereby achieving a leadframe with excellent solder wettability.

[0173] Furthermore, comparing Examples 37 and 38 with Examples 31 and 32 shown in Evaluation 5 above, it can be seen that placing the second nickel layer closer to the surface of the lead frame than the first nickel layer can improve the wettability of the solder.

[0174] <Evaluation 7> [Example 43]

[0174] First, a leadframe substrate with copper as the main component is prepared. Next, after degreasing and pickling the substrate, a first nickel layer without phosphorus is formed on the surface of the substrate with a thickness of 1.0 μm by electroplating. Next, a second nickel layer containing 0.1 wt% phosphorus is formed on the surface of the first nickel layer with a thickness of 0.2 μm by electroplating.

[0175] Next, a palladium layer with a thickness of 0.020 μm is formed on the surface of the second nickel layer by electrolytic plating. Then, a gold layer with a thickness ranging from 0.004 μm to 0.006 μm is formed on the surface of the palladium layer by electrolytic plating. Thus, the lead frame of Example 43 is obtained.

[0176] [Examples 44, 45]

[0176] Using the same method as in Example 43 above, the lead frames of Examples 44 and 45 were obtained. Furthermore, in Examples 44 and 45, the conditions of the electrolytic plating process were adjusted so that the film thicknesses of the first nickel layer and the second nickel layer were as described in Table 7.

[0177] Next, for the lead frame of the above-obtained embodiments 43 to 45, the wettability of the solder (zero-point cross time obtained by the meniscus method) is evaluated in the same way as evaluation 1 above.

[0178] Here, for Examples 43 to 45, the film thickness ratio of the second nickel layer, the total film thickness of the nickel layer, the film thickness of the first nickel layer, the film thickness of the second nickel layer and the film thickness of the palladium layer, and the measurement results of the zero-point crossover time are shown in Table 7.

[0179] [Table 7]

[0180] It can be seen that the zero-point crossover time of the leadframes in Examples 43 to 45 is all within 1 second. Therefore, according to the embodiments, the second nickel layer is disposed closer to the surface side of the leadframe than the first nickel layer, and the second nickel layer contains 0.1 wt% phosphorus and has a film thickness ratio in the range of 33% to 67%, thereby achieving a leadframe with excellent solder wettability.

[0181] <Evaluation 8> [Example 46]

[0181] First, a leadframe substrate with copper as the main component is prepared. Next, after degreasing and pickling the substrate, a second nickel layer containing 0.1 wt% phosphorus is formed on the surface of the substrate with a thickness of 1.0 μm by electroplating. Next, a first nickel layer without phosphorus is formed on the surface of the second nickel layer with a thickness of 0.2 μm by electroplating.

[0182] Next, a palladium layer with a thickness of 0.020 μm is formed on the surface of the first nickel layer by electrolytic plating. Then, a gold layer with a thickness ranging from 0.004 μm to 0.006 μm is formed on the surface of the palladium layer by electrolytic plating. Thus, the lead frame of Example 46 is obtained.

[0183] [Examples 47, 48]

[0183] Using the same method as in Example 46 above, the lead frames of Examples 47 and 48 were obtained. Furthermore, in Examples 47 and 48, the conditions of the electrolytic plating process were adjusted so that the film thicknesses of the second nickel layer and the first nickel layer were the film thicknesses listed in Table 8.

[0184] Next, for the lead frame of the above-obtained embodiments 46 to 48, the wettability of the solder (zero-point cross time obtained by the meniscus method) is evaluated using the same method as evaluation 1 above.

[0185] Hereinafter, for Examples 46 to 48, the film thickness ratio of the second nickel layer, the total film thickness of the nickel layer, the film thickness of the first nickel layer, the film thickness of the second nickel layer and the film thickness of the palladium layer, and the measurement results of the zero-point crossover time are presented in Table 8.

[0186] [Table 8]

[0187] It can be seen that the leadframes of Examples 46 to 48 all have a zero-point crossover time of less than 1 second. Therefore, according to the embodiments, the second nickel layer is disposed on the surface side closer to the substrate than the first nickel layer, and the second nickel layer contains 0.1 wt% phosphorus and has a film thickness ratio in the range of 33% to 67%, thereby achieving a leadframe with excellent solder wettability.

[0188] <Evaluation 9> [Example 49]

[0188] First, a lead frame substrate with copper as the main component is prepared. Next, after degreasing and acid cleaning of the substrate, a first nickel layer without phosphorus is formed on the surface of the substrate with a thickness of 0.7 μm by electrolytic plating. This first nickel layer is formed using an aminosulfonic acid bath (Ni concentration: 145 g / L, Cl concentration: 100 g / L, boric acid concentration: 30 g / L, current density: 6 A / dm², bath temperature: 45 °C, pH=3.7, anode: Ni plate). Furthermore, the surface of this first nickel layer is rough.

[0189] Next, by electroplating, a second nickel layer containing 0.1 wt% phosphorus is formed on the surface of the roughened first nickel layer with a thickness of 0.05 μm. This yields the lead frame of Example 49.

[0190] [Examples 50 to 53]

[0190] Using the same method as in Example 49 above, lead frames of Examples 50 to 53 were obtained. Furthermore, in Examples 50 to 53, the conditions of the electrolytic plating process were adjusted so that the film thicknesses of the first nickel layer and the second nickel layer were as described in Table 9.

[0191] [Comparative Example 15]

[0191] Using the same method as in Example 49, a first nickel layer without phosphorus was formed to a thickness of 0.7 μm. This yielded the lead frame of Comparative Example 15.

[0192] [Comparative Example 16]

[0192] First, a leadframe substrate with copper as the main component was prepared. Next, after degreasing and acid cleaning of the substrate, a first nickel layer without phosphorus was formed on the surface of the substrate with a thickness of 0.8 μm by electrolytic plating. This first nickel layer was formed using a Watts nickel plating bath (nickel sulfate: 240 g / L, nickel chloride: 45 g / L, boric acid concentration: 35 g / L, current density: 5 A / dm², bath temperature: 50 °C, pH=3.5, anode: Ni plate). Furthermore, the surface of this first nickel layer was smooth. Thus, the leadframe of Comparative Example 16 was obtained.

[0193] Next, the resin adhesion of the lead frames obtained in Examples 49 to 53 and Comparative Examples 15 and 16 was evaluated using a commercially available testing machine (manufactured by Nordson Advanced Technology Co., Ltd., product name DAGE4000plus). Specifically, the shear force obtained from the cup shear force test was evaluated under the test conditions described below. ‧Molding resin: EME-G631H‧Molding temperature: 175 (°C)‧Post-curing: 175 (°C), 4 (hours)

[0194] The greater the shear force value obtained from the cup shear force test, the better the adhesion of the resin to the conductor frame.

[0195] Next, palladium and gold layers were formed on the surface of the leadframes of Examples 49 to 53 and Comparative Example 15. For these leadframes, the minimum film thickness of the palladium layer with a zero-point crossover time of less than 1 second obtained by the meniscus method was evaluated. Furthermore, the thickness of the gold layer was formed in the range of 0.004 (μm) to 0.006 (μm).

[0196] Hereinafter, for Examples 49 to 53 and Comparative Examples 15 and 16, the film thickness of the first nickel layer and the second nickel layer, the minimum film thickness of the palladium layer with a zero-point crossover time of less than 1 second, the resin adhesion evaluation, and the surface morphology and cross-sectional morphology of the lead frame are shown in Table 9.

[0197] [Table 9]

[0198] Furthermore, comparing Examples 49 to 53 with Comparative Example 15, it can be seen that when the second nickel layer containing 0.1 (wt%) phosphorus is disposed closer to the surface of the lead frame than the first nickel layer, the wettability of the solder can be maintained better when the palladium layer is thinned.

[0199] Furthermore, comparing Examples 49 to 53 with Comparative Example 16, it can be seen that roughening the surface of the first nickel layer can improve the adhesion of the resin to the lead frame.

[0200] <Evaluation 10> [Example 54]

[0200] First, a lead frame substrate with copper as the main component is prepared. Next, after degreasing and acid cleaning of the substrate, a second nickel layer containing 0.1 wt% phosphorus is formed on the surface of the substrate with a thickness of 0.05 μm by electroplating.

[0201] Next, a phosphorus-free first nickel layer is formed on the surface of the second nickel layer with a thickness of 0.7 μm by electrolytic plating. This first nickel layer is formed using an aminosulfonic acid bath (Ni concentration: 145 g / L, Cl concentration: 100 g / L, boric acid concentration: 30 g / L, current density: 6 A / dm², bath temperature: 45 °C, pH=3.7, anode: Ni plate). Furthermore, this first nickel layer has a rough surface. Thus, the lead frame of Example 54 is obtained.

[0202] [Examples 55 to 58]

[0202] Using the same method as in Example 54 above, the lead frame of Examples 55 to 58 was obtained. Furthermore, in Examples 55 to 58, the conditions of the electrolytic plating process were adjusted so that the film thickness of the second nickel layer and the film thickness of the first nickel layer were the film thicknesses listed in Table 10.

[0203] Next, for the lead frame of the above-obtained embodiments 54 to 58, the adhesion of the resin (the shear force obtained by cup shear test) was evaluated in the same way as the evaluation 9 above.

[0204] Next, a palladium layer and a gold layer are formed on the surface of the leadframes of Examples 54 to 58. For these leadframes, the minimum film thickness of the palladium layer with a zero-point crossover time of less than 1 second obtained by the meniscus method is evaluated. Furthermore, the thickness of the gold layer is formed in the range of 0.004 (μm) to 0.006 (μm).

[0205] For Examples 54 to 58 and Comparative Examples 15 and 16, the film thickness of the first nickel layer and the second nickel layer, the minimum film thickness of the palladium layer with a cross-time of less than 1 second, the resin adhesion evaluation, and the surface morphology and cross-sectional morphology of the lead frame are shown in Table 10.

[0206] [Table 10]

[0207] Comparing Examples 54 to 58 with Comparative Example 15, it can be seen that by placing the second nickel layer containing 0.1 (wt%) phosphorus on the surface side closer to the substrate than the first nickel layer, the wettability of the solder can be well maintained even when the palladium layer is thinned.

[0208] Furthermore, comparing Examples 54 to 58 with Comparative Example 16, it can be seen that roughening the surface of the first nickel layer can improve the adhesion of the resin to the lead frame.

[0209] Furthermore, comparing Examples 54 to 58 with Examples 49 to 53 shown in Evaluation 9 above, it can be seen that by placing the roughened first nickel layer closer to the surface of the lead frame than the second nickel layer, the adhesion of the resin can be further improved.

[0210] Furthermore, comparing Examples 54 to 58 with Examples 49 to 53, it can be seen that by placing the second nickel layer closer to the surface of the lead frame than the roughened first nickel layer, the wettability of the solder can be well maintained even when the palladium layer is thinned.

[0211] The embodiments disclosed herein have been described above, but the present invention is not limited to the embodiments described above. Various modifications can be made as long as they do not exceed its intent. For example, after degreasing and acid cleaning of the leadframe substrate with copper as the main component, surface treatments such as chemical polishing or electrolytic polishing can also be performed. Furthermore, another metal layer can also be provided between the leadframe substrate and the nickel layer.

[0212] As described above, the metal component (lead frame 1) of the embodiment, in the metal component used in the manufacture of a semiconductor device, comprises: a substrate 2, a nickel layer 3, and a noble metal layer 4. The substrate 2 is conductive. The nickel layer 3 is formed on the surface 2a of the substrate 2, and nickel is the main component. The noble metal layer 4 is formed on the surface 3a of the nickel layer 3. Furthermore, the nickel layer 3 comprises a first nickel layer 31 and a second nickel layer 32, wherein the first nickel layer 31 does not contain phosphorus, and the second nickel layer 32 contains 0.01 (wt%) to 1 (wt%) of phosphorus. In this way, good properties can be maintained in the metal component used in the manufacture of the semiconductor device 100, while the thickness of the nickel layer 3 is reduced.

[0213] Furthermore, in the metal component (lead frame 1) of the embodiment, the second nickel layer 32 contains 0.01 (wt%) to 0.5 (wt%) of phosphorus. This further reduces the overall manufacturing cost of the nickel layer 3 and maintains the appearance of the nickel layer 3 well.

[0214] Furthermore, the metal component (lead frame 1) of the embodiment, in the metal component used in the manufacture of the semiconductor device, comprises: a substrate 2, a nickel layer 3, and a noble metal layer 4. The substrate 2 is conductive. The nickel layer 3 is formed on the surface 2a of the substrate 2, and nickel is the main component. The noble metal layer 4 is formed on the surface 3a of the nickel layer 3. Furthermore, the nickel layer 3 has a first nickel layer 31 and a second nickel layer 32. The first nickel layer 31 does not contain phosphorus, while the second nickel layer 32 contains phosphorus and has a columnar crystal structure. In this way, good properties can be maintained in the metal component used in the manufacture of the semiconductor device 100, while the thickness of the nickel layer 3 is reduced.

[0215] Furthermore, in the metal component (lead frame 1) of the embodiment, the surface 31a of the first nickel layer 31 is a rough surface. In this way, the lead frame 1 can achieve excellent adhesion to the encapsulating resin 103.

[0216] Furthermore, in the metal component (lead frame 1) of the embodiment, the first nickel layer 31 is formed on the surface 2a of the substrate 2, and the second nickel layer 32 is formed on the surface 31a of the first nickel layer 31. In this way, a lead frame 1 with high strength and solder wettability and bonding characteristics of the bonding wire 102 can be achieved.

[0217] Furthermore, in the metal component (lead frame 1) of the embodiment, the second nickel layer 32 is formed on the surface 2a of the substrate 2, and the first nickel layer 31 is formed on the surface 32a of the second nickel layer 32. In this way, good properties can be maintained in Pd-PPF while reducing the thickness of the nickel layer 3.

[0218] Furthermore, in the metal component (lead frame 1) of the embodiment, another second nickel layer (second nickel layer 32B) is formed on the surface 31a of the first nickel layer 31. In this way, a lead frame 1 with high strength and solder wettability and bonding characteristics of the bonding wire 102 can be achieved.

[0219] Furthermore, in the metal component (lead frame 1) of the embodiment, the thickness of the second nickel layer 32 is 0.1 (μm) or more. Thereby, the wettability of the solder can be well maintained on the surface 1a of the lead frame 1.

[0220] Furthermore, in the metal component (lead frame 1) of the embodiment, the thickness ratio of the second nickel layer 32 in the nickel layer 3 is 50% or less. This further reduces the overall manufacturing cost of the nickel layer 3.

[0221] Furthermore, in the metal component (lead frame 1) of the embodiment, the noble metal layer 4 is composed of at least one layer, and the noble metal layer 4 is composed of at least one of palladium, gold, and silver. In this way, the formation of oxides on the surface 1a of the lead frame 1 can be suppressed.

[0222] Further effects or variations can be readily conceived by those skilled in the art to which the invention pertains. Therefore, the broader scope of the invention is not limited to the specific details and representative embodiments shown and described above. Thus, various modifications can be made without departing from the spirit or scope of the general inventive concept defined by the appended patent application and its equivalents.

Claims

1. A metal component for use in the manufacture of a semiconductor device, the metal component comprising: a conductive substrate; a nickel layer formed on the surface of the substrate, wherein nickel is the main component; and a noble metal layer formed on the surface of the nickel layer; wherein... The aforementioned nickel layer system comprises: a first nickel layer that does not contain phosphorus; and a second nickel layer that contains 0.01 (wt%) to 0.2 (wt%) of phosphorus.

2. The metal component as described in claim 1, wherein, The surface of the aforementioned first nickel layer is rough.

3. The metal component as described in claim 1 or 2, wherein, The aforementioned first nickel layer is formed on the surface of the aforementioned substrate, and the aforementioned second nickel layer is formed on the surface of the aforementioned first nickel layer.

4. The metal component as described in claim 1 or 2, wherein, The aforementioned second nickel layer is formed on the surface of the aforementioned substrate, and the aforementioned first nickel layer is formed on the surface of the aforementioned second nickel layer.

5. The metal component as described in claim 4, wherein, Unlike the aforementioned second nickel layer, another second nickel layer is formed on the surface of the aforementioned first nickel layer.

6. The metal component as described in claim 1 or 2, wherein, The thickness of the aforementioned second nickel layer is 0.1 μm or more.

7. The metal component as described in claim 1 or 2, wherein, The ratio of the thickness of the aforementioned second nickel layer to the thickness of the aforementioned nickel layer is 50% or less.

8. The metal component as described in claim 1 or 2, wherein, The aforementioned precious metal system comprises at least one layer, and the aforementioned precious metal system comprises at least one of palladium, gold, and silver.

9. A metal component for use in the manufacture of a semiconductor device, the metal component comprising: a conductive substrate; a nickel layer formed on the surface of the substrate and having nickel as the main component; and a noble metal layer formed on the surface of the nickel layer; wherein, The aforementioned nickel layer system comprises: a first nickel layer that does not contain phosphorus, and a second nickel layer that contains phosphorus and has a columnar crystalline structure; the aforementioned second nickel layer is formed on the surface of the aforementioned substrate, the aforementioned first nickel layer is formed on the surface of the aforementioned second nickel layer, and the thickness ratio of the aforementioned second nickel layer in the aforementioned nickel layer is 50% or less.

10. The metal component as described in claim 9, wherein, The surface of the aforementioned first nickel layer is rough.

11. The metal component as described in claim 9, wherein, Unlike the aforementioned second nickel layer, another second nickel layer is formed on the surface of the aforementioned first nickel layer.

12. The metal component as described in claim 9 or 10, wherein, The thickness of the aforementioned second nickel layer is 0.1 μm or more.

13. The metal component as described in claim 9 or 10, wherein, The aforementioned precious metal system comprises at least one layer, and the aforementioned precious metal system comprises at least one of palladium, gold, and silver.

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