Metal parts

Abstract

To reduce the thickness of a nickel layer while maintaining good properties in a metal component used in the manufacture of a semiconductor device.SOLUTION: A metal component used in the manufacture of a semiconductor device includes a base material, a nickel layer, and a noble metal layer. The base material has electrical conductivity. The nickel layer is formed on the surface of the base material and contains nickel as a main component. A palladium layer is formed on the surface of the nickel layer. Also, the nickel layer has a first nickel layer containing no phosphorus and a second nickel layer containing 0.01 (wt%) to 1 (wt%) of phosphorus.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The disclosed embodiments relate to metal components. [Background technology]

[0002] Conventionally, there has been known a technique for forming a nickel plating layer on the surface of a metal base material for metal components such as lead frames used in the manufacture of semiconductor devices. One example of this technique is a technique called Pd-PPF (Pre-Plated Lead Frame), in which a nickel plating layer, a palladium plating layer, and a gold plating layer are formed in this order on the surface of the metal base material of a lead frame (see Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 4-115558 Summary of the Invention [Problem to be solved by the invention]

[0004] However, these nickel layers have a relatively large thickness, which increases the manufacturing cost.

[0005] One aspect of the embodiment has been made in consideration of the above, and aims to provide a metal part used in the manufacture of a semiconductor device that can reduce the thickness of the nickel layer while maintaining good characteristics. [Means for solving the problem]

[0006] A metal part according to one aspect of the embodiment is a metal part used in the manufacture of a semiconductor device, and includes a substrate, a nickel layer, and a precious metal layer. The substrate is electrically conductive. The nickel layer is formed on the surface of the substrate and is mainly composed of nickel. The precious metal layer is formed on the surface of the nickel layer. The nickel layer includes a first nickel layer that does not contain phosphorus and a second nickel layer that contains 0.01 (wt%) to 1 (wt%) of phosphorus. [Effects of the Invention]

[0007] According to one aspect of the embodiment, in a metal part used in manufacturing a semiconductor device, the thickness of the nickel layer can be reduced while maintaining good properties. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a schematic diagram of a lead frame according to an embodiment. [Figure 2] FIG. 2 is a cross-sectional view showing the semiconductor device according to the embodiment. [Figure 3] FIG. 3 is an enlarged cross-sectional view of a lead frame according to the embodiment and the first and second modifications of the embodiment. [Figure 4] FIG. 4 is an enlarged cross-sectional view of a lead frame according to modifications 3 to 5 of the embodiment. [Figure 5] FIG. 5 is a diagram showing an SEM photograph of a cross-sectional configuration of the lead frame according to Example 4. As shown in FIG. [Figure 6] FIG. 6 is a diagram showing an SEM photograph of a cross-sectional configuration of the lead frame according to Example 8. As shown in FIG. [Figure 7] FIG. 7 is a diagram showing an SEM photograph of a cross-sectional configuration of the lead frame according to Comparative Example 4. As shown in FIG. [Figure 8] FIG. 8 is a view showing an SEM photograph of a cross-sectional configuration of the lead frame according to Comparative Example 8. As shown in FIG. DETAILED DESCRIPTION OF THE INVENTION

[0009] Hereinafter, with reference to the accompanying drawings, a lead frame will be described as an example of a metal part used in manufacturing a semiconductor device disclosed in the present application. Note that the present disclosure is not limited to the following embodiments. It should be noted that the drawings are schematic, and the dimensional relationships and ratios of each element may differ from reality. Furthermore, the drawings may include parts with different dimensional relationships and ratios.

[0010] BACKGROUND ART Conventionally, for lead frames used in the manufacture of semiconductor devices, a technique called Pd-PPF is known in which a nickel plating layer, a palladium plating layer, and a gold plating layer are formed in this order on the surface of a metal base material.

[0011] This Pd-PPF can achieve both good solder wettability and good bonding wire bonding properties, so by using this Pd-PPF, semiconductor devices can be manufactured using a simple process.

[0012] However, with conventional technology, simply reducing the thickness of the nickel plating layer can lead to copper in the base material diffusing more easily to the surface of the Pd-PPF, which can result in poor solder wettability, etc. On the other hand, increasing the thickness of the nickel plating layer can lengthen the takt time required to form the nickel plating layer, which can increase manufacturing costs.

[0013] Therefore, it is hoped that a technology will be developed that can overcome the above-mentioned problems and reduce the thickness of the nickel layer while maintaining the good properties of Pd-PPF.

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

[0015] 1 shows a lead frame 1 used in manufacturing a QFP (Quad Flat Package) type semiconductor device 100. Note that the technology of the present disclosure may also be applied to lead frames used in manufacturing other types of semiconductor devices, such as an SOP (Small Outline Package) or a QFN (Quad Flat Non-lead package) in which leads are exposed on the back surface of the semiconductor device.

[0016] The lead frame 1 according to the embodiment has, for example, a band shape in a plan view, and is formed with a plurality of unit lead frames 10 arranged along the longitudinal direction. Each unit lead frame 10 corresponds to one of the semiconductor devices 100 manufactured using the lead frame 1. Note that the plurality of unit lead frames 10 may be arranged not only along the longitudinal direction of the lead frame 1 but also along the width direction.

[0017] 1, a unit lead frame 10 has a die pad 11, a plurality of leads 12, and a dam bar 13. Although not shown in FIG. 1, pilot holes may be provided in a row on the side surface of the long side of the lead frame 1.

[0018] The die pad 11 is provided, for example, in the center of the unit lead frame 10. A semiconductor element 101 can be mounted on the front surface side of the die pad 11, as shown in FIG.

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

[0020] The leads 12 are arranged side by side around the die pad 11, with their respective tips 12a extending from the outer edge of the unit lead frame 10 toward the die pad 11. As shown in FIG. 2, the leads 12 function as connection terminals of the semiconductor device 100.

[0021] The leads 12 have a tip end 12a and a base end 12b. As shown in Fig. 2, in the semiconductor device 100, a bonding wire 102 made of Cu, a Cu alloy, Au, an Au alloy, or the like is connected to the tip end 12a of the lead 12. Therefore, the lead frame 1 is required to have high bonding characteristics with the bonding wire 102. The dam bar 13 connects adjacent leads 12 together.

[0022] The semiconductor device 100 includes a lead frame 1, a semiconductor element 101, and bonding wires 102, as well as a sealing resin 103. The sealing resin 103 is made of, for example, epoxy resin, and is formed into a predetermined shape by a molding process or the like. The sealing resin 103 seals the semiconductor element 101, the bonding wires 102, the die pad 11, etc.

[0023] Base ends 12b of leads 12 function as external terminals (outer leads) of semiconductor device 100 and are solder-bonded to the substrate. In semiconductor device 100 in which the back surface of die pad 11 is exposed from sealing resin 103 or in which a heat slug is provided, the back surface is solder-bonded to the substrate. Therefore, lead frame 1 is required to have high wettability with respect to solder.

[0024] The dam bar 13 functions as a dam to prevent the resin used in the molding process for forming the sealing resin 103 from leaking out toward the base end portion 12b (outer lead), and is finally cut off during the manufacturing process of the semiconductor device 100.

[0025] <Embodiment> Next, the lead frame 1 according to the embodiment will be described in detail with reference to (a) of Fig. 3. (a) of Fig. 3 is an enlarged cross-sectional view of the lead frame 1 according to the embodiment.

[0026] As shown in (a) of FIG. 3, the lead frame 1 according to the embodiment includes a substrate 2, a nickel layer 3, and a precious metal layer 4. The substrate 2 is made of a conductive material (for example, a metal material such as copper or a copper alloy). The precious metal layer 4 is formed on the surface of the nickel layer 3 and contains at least one of palladium, gold, and silver as its main component. The precious metal layer may be a single layer or multiple layers.

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

[0028] The nickel layer 3 includes 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). In the present disclosure, "does not contain phosphorus" also includes the case where phosphorus, which is an inevitable impurity, is contained.

[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. The second nickel layer 32 also contains, for example, a predetermined ratio of phosphorus and has a columnar crystal structure.

[0030] In the present disclosure, the first nickel layer 31 may contain an element other than nickel, and the second nickel layer 32 may contain an element other than nickel and phosphorus.

[0031] 3(a), the nickel layer 3 is composed of two layers: a first nickel layer 31 and a second nickel layer 32. In the 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 precious metal layer 4 is formed on the surface 3a of the nickel layer 3 (in the embodiment, the surface 32a of the second nickel layer 32). The precious metal layer 4 includes a palladium layer 41 and a gold layer 42. The palladium layer 41 contains palladium (Pd) as a main component and can be formed, for example, by a palladium plating process. The gold layer 42 contains gold (Au) as a main component and can be formed, for example, by a gold plating process.

[0033] Since the precious metal layer 4 is made of a precious metal that is resistant to oxidation, the lead frame 1 according to the embodiment can suppress the formation of oxides on the surface 1a of the lead frame 1. Therefore, according to the embodiment, it is possible to realize a lead frame 1 that achieves both the wettability of the solder and the bonding characteristics of the bonding wire 102 (see FIG. 2).

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

[0035] Here, in the embodiment, the nickel layer 3 includes a second nickel layer 32 containing 0.01 (wt%) to 1 (wt%) of phosphorus, thereby making it possible to suppress the diffusion of copper contained in the base material 2 within the second nickel layer 32.

[0036] This is because, inside the second nickel layer 32, concentrated phosphorus is pinned at the interfaces between adjacent crystal grains, and such phosphorus inhibits the diffusion of copper.

[0037] Furthermore, in the embodiment, the nickel layer 3 includes the second nickel layer 32 containing phosphorus and having a columnar crystal structure, thereby making it possible to suppress the diffusion of copper contained in the base material 2 within the second nickel layer 32.

[0038] This is because, since the nickel inside the second nickel layer 32 is in the form of columnar crystals, the area of the crystal grain boundaries is smaller than when the nickel is microcrystalline, and the phosphorus present in the small area of the crystal grain boundaries inhibits the diffusion of copper.

[0039] In the embodiment, since the nickel layer 3 includes the second nickel layer 32, it is possible to prevent copper from diffusing to the surface 1a of the lead frame 1 even if the overall thickness of the nickel layer 3 is reduced.

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

[0041] That is, in the embodiment, the nickel layer 3 includes the second nickel layer 32, so that the thickness of the nickel layer 3 can be reduced while maintaining good properties in Pd-PPF.

[0042] Furthermore, in the embodiment, since the nickel layer 3 includes the first nickel layer 31 that does not contain phosphorus, the thickness of the second nickel layer 32 can be reduced compared to when the nickel layer 3 is composed only of the second nickel layer 32 that contains phosphorus.

[0043] This is because even if the thickness of the second nickel layer 32 is reduced, the function of the reduced thickness can be replaced by the first nickel layer 31, thereby imparting the nickel layer 3 with the same function as when the nickel layer 3 is composed only of the second nickel layer 32.

[0044] Furthermore, by reducing the thickness of the second nickel layer 32, it is possible to reduce the manufacturing cost of the second nickel layer 32, which is relatively expensive to manufacture. That is, according to the embodiment, the nickel layer 3 includes the first nickel layer 31 which does not contain phosphorus, so that the manufacturing cost of the nickel layer 3 as a whole can be reduced.

[0045] 3(a), the first nickel layer 31 may be formed on the surface 2a of the base material 2, and the second nickel layer 32 may be formed on the surface 31a of the first nickel layer 31. That is, in the 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] As a result, the second nickel layer 32 can prevent nickel contained in the first nickel layer 31 from diffusing to the surface 1a of the lead frame 1. This is because concentrated phosphorus is present at the interfaces between adjacent crystal grains inside the second nickel layer 32, and this phosphorus also inhibits the diffusion of nickel.

[0047] That is, in the embodiment, the second nickel layer 32 is disposed closer to the front surface 1a of the lead frame 1 than the first nickel layer 31, thereby preventing the nickel from being oxidized on the front surface 1a. Therefore, according to the embodiment, it is possible to realize a lead frame 1 that achieves both high levels of solder wettability and high levels of bonding characteristics of the bonding wire 102.

[0048] In addition, in the embodiment, the second nickel layer 32 may contain 0.01 (wt%) to 0.5 (wt%) of phosphorus, which can further reduce the manufacturing cost of the entire nickel layer 3 and maintain the good appearance of the nickel layer 3.

[0049] In addition, in the embodiment, the ratio of the thickness of the second nickel layer 32 to the thickness of the nickel layer 3 may be 50(%) or less, which allows the manufacturing cost of the nickel layer 3 as a whole to be further reduced.

[0050] In addition, in the embodiment, the thickness of the second nickel layer 32 may be 0.1 μm or more, which further suppresses copper from diffusing to the surface 1 a of the lead frame 1, thereby maintaining good solder wettability on the surface 1 a of the lead frame 1.

[0051] <Variation 1> Next, various modified examples of the lead frame 1 according to the embodiment will be described with reference to Fig. 3 and Fig. 4. Fig. 3(b) is an enlarged cross-sectional view of the lead frame 1 according to Modification 1 of the embodiment. Modification 1 differs from the above-described embodiment in the arrangement of the first nickel layer 31 and the second nickel layer 32 in the nickel layer 3.

[0052] 3(b), a second nickel layer 32 is formed on the surface 2a of the base material 2, and a first nickel layer 31 is formed on the surface 32a of the second nickel layer 32. Then, a palladium layer 41 of the precious metal layer 4 is formed on the surface 31a of the first nickel layer 31.

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

[0054] Furthermore, in the first modification, similar to the above-described embodiment, the nickel layer 3 includes the second nickel layer 32 containing phosphorus and having a columnar crystal structure, thereby making it possible to reduce the thickness of the nickel layer 3 while maintaining good characteristics in the Pd-PPF.

[0055] Furthermore, in the first modification, as in the above-described embodiment, the nickel layer 3 includes the first nickel layer 31 that does not contain phosphorus, so that the manufacturing cost of the nickel layer 3 as a whole can be reduced.

[0056] In addition, in Modification 1, the second nickel layer 32 may contain 0.01 (wt%) to 0.5 (wt%) of phosphorus, which can further reduce the manufacturing cost of the entire nickel layer 3 and maintain the good appearance of the nickel layer 3.

[0057] In addition, in the first modification, the ratio of the thickness of the second nickel layer 32 to the thickness of the nickel layer 3 may be 50(%) or less. This allows the manufacturing cost of the nickel layer 3 as a whole to be further reduced.

[0058] In addition, in Modification 1, the thickness of second nickel layer 32 may be 0.1 μm or more, which further suppresses copper from diffusing to surface 1 a of lead frame 1, thereby maintaining good solder wettability on surface 1 a of lead frame 1.

[0059] <Variation 2> Fig. 3(c) is an enlarged cross-sectional view of a lead frame 1 according to Modification 2 of the embodiment. Modification 2 differs from the above-described embodiment and Modification 1 in the configuration of the nickel layer 3. Specifically, as shown in Fig. 3(c), a second nickel layer 32A is formed on the surface 2a of the base material 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 precious 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] As described above, in the technique of the present disclosure, the nickel layer 3 is not limited to a two-layer structure, but may be a three-layer or more structure.

[0062] In this variant 2, similar to the above-described embodiment, the nickel layer 3 includes second nickel layers 32A, 32B containing 0.01 (wt%) to 1 (wt%) of phosphorus, thereby making it possible to reduce the thickness of the nickel layer 3 while maintaining good characteristics in Pd-PPF.

[0063] Furthermore, in the second modification, as in the above-described embodiment, the nickel layer 3 contains second nickel layers 32A, 32B containing phosphorus and having a columnar crystal structure, thereby making it possible to reduce the thickness of the nickel layer 3 while maintaining good characteristics in Pd-PPF.

[0064] Furthermore, in the second modification, as in the above-described embodiment, the nickel layer 3 includes the first nickel layer 31 that does not contain phosphorus, so that the manufacturing cost of the nickel layer 3 as a whole can be reduced.

[0065] Furthermore, in Modification 2, similar to the above-described embodiment, the second nickel layer 32B is disposed closer to the front surface 1a of the lead frame 1 than the first nickel layer 31, thereby preventing the nickel from oxidizing on the front surface 1a. Therefore, Modification 2 makes it possible to realize a lead frame 1 that achieves both high levels of solder wettability and high levels of bonding characteristics of the bonding wire 102 (see FIG. 2).

[0066] In addition, in Modification 2, the second nickel layers 32A, 32B may contain 0.01 (wt%) to 0.5 (wt%) of phosphorus, which can further reduce the manufacturing cost of the nickel layer 3 as a whole and maintain the good appearance of the nickel layer 3.

[0067] In addition, in the second modification, the ratio of the total thickness of the second nickel layers 32A, 32B to the nickel layer 3 may be 50(%) or less. This allows the manufacturing cost of the nickel layer 3 as a whole to be further reduced.

[0068] In addition, in Modification 2, the total thickness of second nickel layers 32A, 32B may be 0.1 μm or more, which further suppresses copper from diffusing to surface 1 a of lead frame 1, thereby maintaining good solder wettability on surface 1 a of lead frame 1.

[0069] <Variation 3> Fig. 4(a) is an enlarged cross-sectional view of a lead frame 1 according to a third modification of the embodiment. This third modification differs from the above-described embodiment in the surface shape of the first nickel layer 31. Specifically, as shown in Fig. 4(a), the first nickel layer 31 formed on the surface 2a of the substrate 2 has a roughened surface 31a. This roughened surface 31a can be formed by nickel plating the first nickel layer 31 using an appropriate plating solution under appropriate plating conditions.

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

[0071] As a result, in Modification 3, the adhesion between the lead frame 1 and the sealing resin 103 (see FIG. 2) can be improved by a so-called anchor effect. That is, according to Modification 3, it is possible to realize a lead frame 1 that has excellent adhesion to the sealing resin 103, and since the nickel layer 3 includes the second nickel layer 32 containing 0.01 (wt%) to 1 (wt%) of phosphorus, good characteristics can be obtained in Pd-PPF.

[0072] Furthermore, in variant 3, the nickel layer 3 includes a first nickel layer 31 having a roughened surface 31a and a second nickel layer 32 containing phosphorus and having a columnar crystal structure, thereby providing excellent adhesion to the sealing resin 103 and achieving good characteristics in Pd-PPF.

[0073] Furthermore, in the third modification, similarly to the above-described embodiment, the second nickel layer 32 is disposed closer to the front surface 1a of the lead frame 1 than the first nickel layer 31, thereby preventing the nickel from oxidizing on the front surface 1a. Therefore, according to the third modification, it is possible to realize a lead frame 1 that achieves both high levels of solder wettability and high levels of bonding characteristics of the bonding wire 102 (see FIG. 2).

[0074] In addition, in the third modification, the ratio of the thickness of the second nickel layer 32 to the thickness of the nickel layer 3 may be 50(%) or less. This allows the manufacturing cost of the nickel layer 3 as a whole to be further reduced.

[0075] In addition, in Modification 3, the thickness of the second nickel layer 32 may be in the range of 0.1 (μm) to 0.4 (μm). By making the thickness of the second nickel layer 32 0.1 (μm) or more, it is possible to further suppress the diffusion of copper to the surface 1a of the lead frame 1, and therefore it is possible to maintain good solder wettability on the surface 1a of the lead frame 1.

[0076] Furthermore, by making the thickness of the second nickel layer 32 0.4 μm or less, the uneven shape of the surface 1 a of the lead frame 1 can be maintained well, thereby maintaining good adhesion with the sealing resin 103.

[0077] <Variation 4> 4(b) is an enlarged cross-sectional view of the lead frame 1 according to Modification 4 of the embodiment. Modification 4 differs from Modification 3 described above in the arrangement of the first nickel layer 31 and the second nickel layer 32 in the nickel layer 3.

[0078] 4(b), a second nickel layer 32 is formed on the surface 2a of the base material 2, and a roughened first nickel layer 31 is formed on the surface 32a of the second nickel layer 32. Then, a palladium layer 41 of the precious metal layer 4 is formed on the roughened surface 31a of the first nickel layer 31.

[0079] In the fourth modification, similarly to the third modification, the surface 31a of the first nickel layer 31 is roughened, so that the surface 1a of the lead frame 1 can be roughened. As a result, in the fourth modification, the lead frame 1 can have excellent adhesion to the sealing resin 103.

[0080] In addition, in variant example 4, the first nickel layer 31 is positioned closer to the surface 1a of the lead frame 1 than the second nickel layer 32, so that the surface 31a of the first nickel layer 31, which is a rough surface, can be brought closer to the surface 1a of the lead frame 1.

[0081] Therefore, in Modification 4, the surface 1a of the lead frame 1 can be made to have an uneven shape similar to (i.e., greater roughness than) the uneven shape formed on the surface 31a of the first nickel layer 31. Therefore, Modification 4 makes it possible to realize a lead frame 1 with even better adhesion to the sealing resin 103, and since the nickel layer 3 includes the second nickel layer 32 containing 0.01 (wt%) to 1 (wt%) of phosphorus, good characteristics can be obtained in Pd-PPF.

[0082] Furthermore, in variant 4, the nickel layer 3 includes a first nickel layer 31 having a roughened surface 31a and a second nickel layer 32 containing phosphorus and having a columnar crystal structure, thereby providing excellent adhesion to the sealing resin 103 and achieving good characteristics in Pd-PPF.

[0083] In addition, in Modification 4, the second nickel layer 32 may contain 0.01 (wt%) to 0.5 (wt%) of phosphorus, which can further reduce the manufacturing cost of the entire nickel layer 3 and maintain the good appearance of the nickel layer 3.

[0084] In addition, in the fourth modification, the ratio of the thickness of the second nickel layer 32 to the thickness of the nickel layer 3 may be 50(%) or less. This allows the manufacturing cost of the nickel layer 3 as a whole to be further reduced.

[0085] In addition, in Modification 4, the thickness of second nickel layer 32 may be 0.1 μm or more. This further prevents copper from diffusing to surface 1 a of lead frame 1, thereby maintaining good solder wettability on surface 1 a of lead frame 1.

[0086] <Variation 5> Fig. 4(c) is an enlarged cross-sectional view of a lead frame 1 according to Modification 5 of the embodiment. Modification 2 differs from the above-described Modifications 3 and 4 in the configuration of the nickel layer 3. Specifically, as shown in Fig. 4(c), a second nickel layer 32A is formed on the surface 2a of the base material 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 roughened surface 31a of the first nickel layer 31, and a palladium layer 41 of the precious metal layer 4 is formed on a surface 32Ba of the second nickel layer 32B.

[0088] In the fifth modification, the surface 31a of the first nickel layer 31 is formed to be a rough surface, thereby roughening the surface 1a of the lead frame 1. As a result, in the fifth modification, similar to the third modification, the lead frame 1 can be realized with excellent adhesion to the sealing resin 103, and the nickel layer 3 includes the second nickel layers 32A, 32B containing 0.01 (wt%) to 1 (wt%) of phosphorus, thereby achieving good characteristics in Pd-PPF.

[0089] Furthermore, in variant 5, the nickel layer 3 includes a first nickel layer 31 having a roughened surface 31a and second nickel layers 32A, 32B containing phosphorus and having a columnar crystal structure, thereby providing excellent adhesion to the sealing resin 103 and achieving good characteristics in Pd-PPF.

[0090] In addition, in Modification 5, the second nickel layer 32A may contain 0.01 (wt%) to 0.5 (wt%) of phosphorus, which can further reduce the manufacturing cost of the entire nickel layer 3 and maintain the good appearance of the nickel layer 3.

[0091] Furthermore, in the fifth modification, similarly to the above-described embodiment, the second nickel layer 32B is disposed closer to the front surface 1a of the lead frame 1 than the first nickel layer 31, thereby preventing the nickel from being oxidized on the front surface 1a. Therefore, according to the fifth modification, it is possible to realize a lead frame 1 that achieves both high levels of solder wettability and high levels of bonding characteristics of the bonding wire 102 (see FIG. 2).

[0092] In addition, in the fifth modification, the ratio of the total thickness of the second nickel layers 32A, 32B in the nickel layer 3 may be 50(%) or less. This allows the manufacturing cost of the nickel layer 3 as a whole to be further reduced.

[0093] In addition, in Modification 5, the total thickness of second nickel layers 32A, 32B may be 0.1 μm or more, which further suppresses copper from diffusing to surface 1 a of lead frame 1, thereby maintaining good solder wettability on surface 1 a of lead frame 1.

[0094] In addition, in Modification 5, the thickness of second nickel layer 32A may be 0.1 μm or more, which further suppresses copper from diffusing to surface 1 a of lead frame 1, thereby maintaining good solder wettability on surface 1 a of lead frame 1.

[0095] In addition, in Modification 5, the thickness of the second nickel layer 32B may be in the range of 0.1 (μm) to 0.4 (μm). By making the thickness of the second nickel layer 32B 0.1 (μm) or more, it is possible to further suppress the diffusion of copper to the surface 1a of the lead frame 1, and therefore it is possible to maintain good solder wettability on the surface 1a of the lead frame 1.

[0096] Furthermore, by making the thickness of the second nickel layer 32B 0.4 (μm) or less, the uneven shape of the surface 1a of the lead frame 1 can be maintained well, thereby maintaining good adhesion with the sealing resin 103. [Example]

[0097] The present disclosure will be described in more detail below with reference to examples and reference examples, but the present disclosure is not limited to the following examples.

[0098] <Rating 1> [Example 1] First, a lead frame substrate made primarily of copper was prepared. After degreasing and acid cleaning of the substrate, a phosphorus-free first nickel layer was formed on the surface of the substrate by electroplating to a thickness of 0.1 μm.

[0099] This first nickel layer was formed in a Watts bath (nickel sulfate: 240 (g / L), nickel chloride: 45 (g / L), boric acid concentration: 35 (g / L), current density: 5 (A / dm 2 ), bath temperature: 50°C, pH = 3.5, anode: Ni plate). In the present disclosure, the first nickel layer was formed under similar conditions in the following Examples 1 to 48, Reference Examples 1 to 12, and Comparative Examples 1 to 14.

[0100] Next, a second nickel layer containing 0.1 (wt %) of phosphorus was formed to a thickness of 0.1 (μm) on the surface of the first nickel layer by electrolytic plating.

[0101] This second nickel layer was formed in a Watts bath (Ni sulfate: 240 (g / L), Ni chloride: 45 (g / L), boric acid concentration: 35 (g / L), P concentration: 20 (mg / L), current density: 5 (A / dm 2 ), bath temperature: 50°C, pH = 3.5, anode: Ni plate). In the present disclosure, the second nickel layer was formed under similar conditions except for the P concentration in the following Examples 1 to 48 and Reference Examples 1 to 12.

[0102] The phosphorus concentration in this second nickel layer was measured as follows: First, approximately 80 mg of the nickel foil on the surface of the sample was weighed out, and this nickel foil was dissolved in 10 mL of 61% nitric acid (13 mol / L), and the total volume was adjusted to 100 mL using a 100 mL measuring flask.

[0103] Next, 10 mL of 61% nitric acid is added to 5 mL of the sample solution for measuring phosphorus concentration prepared above, and the total volume is adjusted to 100 mL using a 100 mL measuring flask.

[0104] Next, the phosphorus concentration of the sample solution for measuring the phosphorus concentration prepared above was measured using a commercially available ICP optical emission spectrometer (product name ULTIMA2, manufactured by Horiba, Ltd.) In the present disclosure, the phosphorus concentration contained in the second nickel layer was measured under the same conditions in the following Examples 1 to 48 and Reference Examples 1 to 12.

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

[0106] This palladium layer had a Pd concentration of 1.6 (g / L) and a current density of 1.0 (A / dm 2 ), bath temperature: 50°C, pH = 6.7, anode: iridium oxide. In the present disclosure, the palladium layer was formed under similar conditions in the following Examples 1 to 48, Reference Examples 1 to 12, and Comparative Examples 1 to 14.

[0107] Next, a gold layer was formed on the surface of the palladium layer by electrolytic plating to a thickness in the range of 0.004 (μm) to 0.006 (μm), thereby obtaining the lead frame of Example 1.

[0108] This gold layer was formed at an Au concentration of 0.8 (g / L) and a current density of 3 (A / dm 2 ), bath temperature: 50°C, pH = 6.4, anode: iridium oxide. In the present disclosure, the gold layers were also formed under similar conditions in the following Examples 1 to 48, Reference Examples 1 to 12, and Comparative Examples 1 to 14.

[0109] [Examples 2 to 4] The lead frames of Examples 2 to 4 were obtained using a method similar to that of Example 1. In Examples 2 to 4, the conditions of the electrolytic plating treatment were adjusted so that the film thicknesses of the first nickel layer and the second nickel layer were as shown in Table 1.

[0110] [Example 5] First, a lead frame substrate composed primarily of copper was prepared. After degreasing and acid cleaning of the substrate, a second nickel layer containing 0.1 wt% phosphorus was formed on the surface of the substrate by electroplating to a thickness of 0.1 μm. Next, a first nickel layer not containing phosphorus was formed on the surface of the second nickel layer by electroplating to a thickness of 0.1 μm.

[0111] Next, a palladium layer was formed on the surface of the first nickel layer by electroplating to a thickness of 0.020 μm. Then, a gold layer was formed on the surface of the palladium layer by electroplating to a thickness in the range of 0.004 μm to 0.006 μm. This produced the lead frame of Example 5.

[0112] [Examples 6 to 8] The lead frames of Examples 6 to 8 were obtained using a method similar to that of Example 5. In Examples 6 to 8, the conditions of the electrolytic plating treatment were adjusted so that the film thicknesses of the second nickel layer and the first nickel layer were as shown in Table 1.

[0113] [Comparative Example 1] First, a copper-based lead frame substrate was prepared. After degreasing and acid cleaning of the substrate, a phosphorus-free first nickel layer was formed on the surface of the substrate by electroplating to a thickness of 0.2 μm.

[0114] Next, a palladium layer was formed on the surface of the first nickel layer by electroplating to a thickness of 0.020 μm. Then, a gold layer was formed on the surface of the palladium layer by electroplating to a thickness in the range of 0.004 μm to 0.006 μm. This produced the lead frame of Comparative Example 1.

[0115] [Comparative Examples 2 to 4] The lead frames of Comparative Examples 2 to 4 were obtained using the same method as in Comparative Example 1. In Comparative Examples 2 to 4, the conditions for the electrolytic plating treatment were adjusted so that the film thickness of the first nickel layer would be as shown in Table 1.

[0116] Comparative Example 5 First, a copper-based lead frame substrate was prepared. After degreasing and acid cleaning, a nickel-phosphorus (NiP) layer containing a higher phosphorus content (6.7 wt%) than the second nickel layer was formed on the substrate surface by electroplating to a thickness of 0.2 μm.

[0117] This nickel phosphorus layer was formed in a Watts bath (Ni sulfate: 150 (g / L), Ni chloride: 150 (g / L), Niholloy process (manufactured by Kizai Corporation): 200 (mL / L), current density 7.5 (A / dm 2 ), bath temperature: 60 (°C), pH = 0.3, anode: Ni plate).

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

[0119] Next, a palladium layer was formed on the surface of the nickel phosphorus layer by electroplating to a thickness of 0.020 μm. Then, a gold layer was formed on the surface of the palladium layer by electroplating to a thickness in the range of 0.004 μm to 0.006 μm. This resulted in the lead frame of Comparative Example 5.

[0120] [Comparative Examples 6 to 8] The lead frames of Comparative Examples 6 to 8 were obtained using the same method as in Comparative Example 5. In Comparative Examples 6 to 8, the conditions for the electrolytic plating treatment were adjusted so that the thickness of the nickel phosphorus layer would be the thickness shown in Table 1.

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

[0122] 5 to 8 are SEM photographs of the cross-sectional shapes of the lead frames according to Examples 4 and 8 and Comparative Examples 4 and 8. FIG.

[0123] As shown in Figures 5 and 6, it can be seen that the second nickel layer of the present disclosure has a columnar crystal structure with relatively large crystal grains. Furthermore, a comparison between Examples 4 and 8 shown in Figures 5 and 6 and Comparative Example 4 shown in Figure 7 shows that the second nickel layer of the present disclosure has a crystal structure similar to that of 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 FIGS. 5 and 6 with Comparative Example 8 shown in FIG. 8, it can be seen that the second nickel layer of the present disclosure has a crystal structure that is completely different from that of a nickel phosphorus layer that contains more phosphorus (the nickel phosphorus layer has a microcrystalline structure with small crystal grains).

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

[0126] The shorter this zero cross time, the better the wettability of the solder to the lead frame. In addition, in this disclosure, a zero cross time of "NG" means that the zero cross time is 10 seconds or longer.

[0127] Here, for Examples 1 to 8 and Comparative Examples 1 to 8, Table 1 shows 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, as well as the measurement results of the zero cross time.

[0128] [Table 1]

[0129] It can be seen that the zero cross time is within 1 second for all of the lead frames of Examples 1 to 8. Therefore, according to the embodiment, by including a second nickel layer containing 0.1 wt % phosphorus and having a film thickness of 0.1 μm or more in the nickel layer, a lead frame with excellent solder wettability can be realized.

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

[0131] Furthermore, a comparison between Examples 1 to 8 and Comparative Examples 5 to 8 shows that the solder wettability is improved by using the second nickel layer having a columnar crystal structure instead of the nickel phosphorus layer having a microcrystalline structure.

[0132] <Rating 2> [Example 9] First, a lead frame substrate composed primarily of copper was prepared. The substrate was then degreased and acid-washed, and a first nickel layer containing no phosphorus was formed on the surface of the substrate by electroplating to a thickness of 0.1 μm. Next, a second nickel layer containing 0.1 wt% phosphorus was formed on the surface of the first nickel layer by electroplating to a thickness of 0.1 μm.

[0133] Next, a palladium layer was formed on the surface of the second nickel layer by electroplating to a thickness of 0.020 μm. Then, a gold layer was formed on the surface of the palladium layer by electroplating to a thickness in the range of 0.004 μm to 0.006 μm. This produced the lead frame of Example 9.

[0134] [Examples 10 to 12 and Reference Examples 1 and 2] The lead frames of Examples 10 to 12 and Reference Examples 1 and 2 were obtained using a method similar to that of Example 9. In Examples 10 to 12 and Reference Examples 1 and 2, the conditions of the electrolytic plating treatment were adjusted so that the film thicknesses of the first nickel layer and the second nickel layer would be as shown in Table 2.

[0135] [Example 13] First, a lead frame substrate composed primarily of copper was prepared. After degreasing and acid cleaning of the substrate, a second nickel layer containing 0.1 wt% phosphorus was formed on the surface of the substrate by electroplating to a thickness of 0.1 μm. Next, a first nickel layer not containing phosphorus was formed on the surface of the second nickel layer by electroplating to a thickness of 0.1 μm.

[0136] Next, a palladium layer was formed on the surface of the first nickel layer by electroplating to a thickness of 0.020 μm. Then, a gold layer was formed on the surface of the palladium layer by electroplating to a thickness in the range of 0.004 μm to 0.006 μm. This produced the lead frame of Example 13.

[0137] [Examples 14 to 16 and Reference Examples 3 and 4] The lead frames of Examples 14 to 16 and Reference Examples 3 and 4 were obtained using a method similar to that of Example 13 described above. In Examples 14 to 16 and Reference Examples 3 and 4, the conditions of the electrolytic plating treatment were adjusted so that the film thicknesses of the second nickel layer and the first nickel layer would be as shown in Table 2.

[0138] Comparative Example 9 First, a lead frame substrate made primarily of copper was prepared. After degreasing and acid cleaning of the substrate, a phosphorus-free first nickel layer was formed on the surface of the substrate by electroplating to a thickness of 0.05 μm.

[0139] Next, a palladium layer was formed on the surface of the first nickel layer by electroplating to a thickness of 0.020 μm. Then, a gold layer was formed on the surface of the palladium layer by electroplating to a thickness in the range of 0.004 μm to 0.006 μm. This resulted in the lead frame of Comparative Example 9.

[0140] [Comparative Examples 10 to 14] The lead frames of Comparative Examples 10 to 14 were obtained using the same method as in Comparative Example 9. In Comparative Examples 10 to 14, the conditions for the electrolytic plating treatment were adjusted so that the film thickness of the first nickel layer would be as shown in Table 2.

[0141] Next, the solder wettability (zero cross time by meniscograph method) of the lead frames of Examples 9 to 16, Reference Examples 1 to 4, and Comparative Examples 9 to 14 obtained above was evaluated in the same manner as in Evaluation 1 above.

[0142] Table 2 shows the total thickness of the nickel layers, the thickness of the first nickel layer, the thickness of the second nickel layer, and the measurement results of the zero cross time for Examples 9 to 16, Reference Examples 1 to 4, and Comparative Examples 9 to 14.

[0143] [Table 2]

[0144] It can be seen that the zero cross time was within 1 second for all of the lead frames of Examples 9 to 16. Therefore, according to the embodiment, by including a second nickel layer containing 0.1 wt % phosphorus and having a film thickness of 0.1 μm or more in the nickel layer, a lead frame with excellent solder wettability can be realized.

[0145] <Rating 3> [Example 17] First, a lead frame substrate primarily composed of copper was prepared. The substrate was then degreased and acid-washed, and a first nickel layer containing no phosphorus was formed on the surface of the substrate by electroplating to a thickness of 1.0 μm. Next, a second nickel layer containing 0.01 wt% phosphorus was formed on the surface of the first nickel layer by electroplating to a thickness of 1.0 μm.

[0146] Next, a palladium layer was formed on the surface of the second nickel layer by electroplating to a thickness of 0.020 μm. Then, a gold layer was formed on the surface of the palladium layer by electroplating to a thickness in the range of 0.004 μm to 0.006 μm. This produced the lead frame of Example 17.

[0147] [Examples 18 to 23 and Reference Example 5] The lead frames of Examples 18 to 23 and Reference Example 5 were obtained using a method similar to that of Example 17. In Examples 18 to 23 and Reference Example 5, the conditions of the electrolytic plating treatment were adjusted so that the phosphorus content in the second nickel layer was the content shown in Table 3.

[0148] Next, the appearance of the lead frames obtained above in Examples 17 to 23 and Reference Example 5 was visually evaluated as to whether they were good or not. Lead frames with uneven color tone were judged to have poor appearance.

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

[0150] [Table 3]

[0151] It can be seen that the lead frames of Examples 17 to 23 all had good appearances. Therefore, according to the embodiment, by arranging the second nickel layer containing phosphorus in the range of 0.01 (wt%) to 0.5 (wt%) closer to the surface of the lead frame than the first nickel layer, a lead frame with good appearance can be realized.

[0152] <Rating 4> [Example 24] First, a lead frame substrate primarily composed of copper was prepared. After degreasing and acid cleaning of the substrate, a second nickel layer containing 0.01 wt% phosphorus was formed on the surface of the substrate by electroplating to a thickness of 1.0 μm. Next, a first nickel layer not containing phosphorus was formed on the surface of the second nickel layer by electroplating to a thickness of 1.0 μm.

[0153] Next, a palladium layer was formed on the surface of the first nickel layer by electroplating to a thickness of 0.020 μm. Then, a gold layer was formed on the surface of the palladium layer by electroplating to a thickness in the range of 0.004 μm to 0.006 μm. This resulted in the lead frame of Example 24.

[0154] [Examples 25 to 30 and Reference Example 6] The lead frames of Examples 25 to 30 and Reference Example 6 were obtained using a method similar to that of Example 24. In Examples 25 to 30 and Reference Example 6, the conditions of the electrolytic plating treatment were adjusted so that the phosphorus content in the second nickel layer was the content shown in Table 4.

[0155] Next, the appearance of the lead frames obtained above in Examples 24 to 30 and Reference Example 6 was visually evaluated to determine whether they were good or not. Lead frames with uneven color tone were judged to have poor appearance.

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

[0157] [Table 4]

[0158] It can be seen that the lead frames of Examples 24 to 30 all had good appearances. Therefore, according to the embodiment, by arranging the second nickel layer containing phosphorus in the range of 0.01 (wt%) to 0.5 (wt%) closer to the surface of the base material than the first nickel layer, a lead frame with good appearance can be realized.

[0159] <Rating 5> [Example 31] First, a lead frame substrate composed primarily of copper was prepared. The substrate was then degreased and acid-washed, and a first nickel layer containing no phosphorus was formed on the surface of the substrate by electroplating to a thickness of 0.1 μm. Next, a second nickel layer containing 0.1 wt% phosphorus was formed on the surface of the first nickel layer by electroplating to a thickness of 0.1 μm.

[0160] Next, a palladium layer was formed on the surface of the second nickel layer by electroplating to a thickness of 0.005 μm. Then, a gold layer was formed on the surface of the palladium layer by electroplating to a thickness in the range of 0.004 μm to 0.006 μm. This produced the lead frame of Example 31.

[0161] [Examples 32 to 36 and Reference Examples 7 to 9] The lead frames of Examples 32 to 36 and Reference Examples 7 to 9 were obtained using a method similar to that of Example 31. In Examples 32 to 36 and Reference Examples 7 to 9, the conditions for the electrolytic plating treatment were adjusted so that the film thicknesses of the first nickel layer, second nickel layer, and palladium layer would be as shown in Table 5.

[0162] Next, the solder wettability (zero cross time by the meniscograph method) of the lead frames of Examples 31 to 36 and Reference Examples 7 to 9 obtained above was evaluated in the same manner as in Evaluation 1 above.

[0163] Here, for Examples 31 to 36 and Reference Examples 7 to 9, Table 5 shows 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, as well as the measurement results of the zero cross time.

[0164] [Table 5]

[0165] It can be seen that the lead frames of Examples 31 to 36 all had zero-cross times of 1 second or less. Furthermore, it can be seen that good solder wettability can be maintained even when the palladium layer is thin. Therefore, according to the embodiment, by arranging a second nickel layer containing 0.1 wt % phosphorus and having a film thickness of 0.1 μm or more on the surface side of the lead frame relative to the first nickel layer, a lead frame with excellent solder wettability can be realized.

[0166] <Rating 6> [Example 37] First, a lead frame substrate composed primarily of copper was prepared. After degreasing and acid cleaning of the substrate, a second nickel layer containing 0.1 wt% phosphorus was formed on the surface of the substrate by electroplating to a thickness of 0.1 μm. Next, a first nickel layer not containing phosphorus was formed on the surface of the second nickel layer by electroplating to a thickness of 0.1 μm.

[0167] Next, a palladium layer was formed on the surface of the first nickel layer by electroplating to a thickness of 0.005 μm. Then, a gold layer was formed on the surface of the palladium layer by electroplating to a thickness in the range of 0.004 μm to 0.006 μm. This produced the lead frame of Example 37.

[0168] [Examples 38 to 42 and Reference Examples 10 to 12] The lead frames of Examples 38 to 42 and Reference Examples 10 to 12 were obtained using a method similar to that of Example 37. In Examples 38 to 42 and Reference Examples 10 to 12, the conditions for the electrolytic plating treatment were adjusted so that the film thicknesses of the second nickel layer, the first nickel layer, and the palladium layer would be as shown in Table 6.

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

[0170] Table 6 shows the total thickness of the nickel layer, the thickness of the first nickel layer, the thickness of the second nickel layer, the thickness of the palladium layer, and the measurement results of the zero cross time for Examples 37 to 42 and Reference Examples 10 to 12.

[0171] [Table 6]

[0172] It can be seen that the lead frames of Examples 37 to 42 all had a zero-cross time of 1 second or less. Furthermore, it can be seen that good solder wettability can be maintained even when the palladium layer is thin. Therefore, according to the embodiment, by arranging a second nickel layer containing 0.1 wt % phosphorus and having a film thickness of 0.1 μm or more closer to the surface of the base material than the first nickel layer, a lead frame with excellent solder wettability can be realized.

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

[0174] <Rating 7> [Example 43] First, a lead frame substrate primarily composed of copper was prepared. After degreasing and acid cleaning of the substrate, a first nickel layer containing no phosphorus was formed on the surface of the substrate by electroplating to a thickness of 0.1 μm. Next, a second nickel layer containing 0.1 wt% phosphorus was formed on the surface of the first nickel layer by electroplating to a thickness of 0.2 μm.

[0175] Next, a palladium layer was formed on the surface of the second nickel layer by electroplating to a thickness of 0.020 μm. Then, a gold layer was formed on the surface of the palladium layer by electroplating to a thickness in the range of 0.004 μm to 0.006 μm. This produced the lead frame of Example 43.

[0176] [Examples 44 and 45] The lead frames of Examples 44 and 45 were obtained using a method similar to that of Example 43. In Examples 44 and 45, the conditions of the electrolytic plating treatment were adjusted so that the film thicknesses of the first nickel layer and the second nickel layer would be as shown in Table 7.

[0177] Next, the lead frames of Examples 43 to 45 obtained above were evaluated for solder wettability (zero cross time by the meniscograph method) using the same method as in Evaluation 1 above.

[0178] Here, for Examples 43 to 45, Table 7 shows the film thickness ratio of the second nickel layer, the total film thickness of the nickel layers, the film thickness of the first nickel layer, the film thickness of the second nickel layer, and the film thickness of the palladium layer, as well as the measurement results of the zero cross time.

[0179] [Table 7]

[0180] It can be seen that the zero cross time was within 1 second for all of the lead frames of Examples 43 to 45. Therefore, according to the embodiment, by arranging the second nickel layer containing 0.1 wt% phosphorus and having a film thickness ratio in the range of 33% to 67% closer to the surface of the lead frame than the first nickel layer, a lead frame with excellent solder wettability can be realized.

[0181] <Rating 8> [Example 46] First, a lead frame substrate composed primarily of copper was prepared. After degreasing and acid cleaning of the substrate, a second nickel layer containing 0.1 wt% phosphorus was formed on the surface of the substrate by electroplating to a thickness of 0.1 μm. Next, a first nickel layer not containing phosphorus was formed on the surface of the second nickel layer by electroplating to a thickness of 0.2 μm.

[0182] Next, a palladium layer was formed on the surface of the first nickel layer by electroplating to a thickness of 0.020 μm. Then, a gold layer was formed on the surface of the palladium layer by electroplating to a thickness in the range of 0.004 μm to 0.006 μm. This resulted in the lead frame of Example 46.

[0183] [Examples 47 and 48] The lead frames of Examples 47 and 48 were obtained using a method similar to that of Example 46. In Examples 47 and 48, the conditions of the electrolytic plating treatment were adjusted so that the film thicknesses of the second nickel layer and the first nickel layer would be as shown in Table 8.

[0184] Next, the lead frames of Examples 46 to 48 obtained above were evaluated for solder wettability (zero cross time by the meniscograph method) using the same method as in Evaluation 1 above.

[0185] Here, for Examples 46 to 48, Table 8 shows the film thickness ratio of the second nickel layer, the total film thickness of the nickel layers, the film thickness of the first nickel layer, the film thickness of the second nickel layer, and the film thickness of the palladium layer, as well as the measurement results of the zero cross time.

[0186] [Table 8]

[0187] It can be seen that the zero cross time was within 1 second for all of the lead frames of Examples 46 to 48. Therefore, according to the embodiment, by arranging a second nickel layer containing 0.1 wt% phosphorus and having a film thickness ratio in the range of 33% to 67% closer to the surface of the base material than the first nickel layer, a lead frame with excellent solder wettability can be realized.

[0188] <Rating 9> [Example 49] First, a lead frame substrate composed primarily of copper was prepared. The substrate was then degreased and acid-washed, and a phosphorus-free first nickel layer was formed on the surface of the substrate by electroplating to a thickness of 0.7 μm. This first nickel layer was formed using a sulfamic 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). The first nickel layer had a rough surface.

[0189] Next, a second nickel layer containing 0.1 wt % phosphorus was formed on the roughened surface of the first nickel layer by electroplating to a thickness of 0.05 μm, thereby obtaining the lead frame of Example 49.

[0190] [Examples 50 to 53] The lead frames of Examples 50 to 53 were obtained using a method similar to that of Example 49. In Examples 50 to 53, the conditions of the electrolytic plating treatment were adjusted so that the film thickness of the first nickel layer and the film thickness of the second nickel layer would be as shown in Table 9.

[0191] [Comparative Example 15] A first nickel layer not containing phosphorus was formed to a thickness of 0.7 μm using the same method as in Example 49. In this way, a lead frame of Comparative Example 15 was obtained.

[0192] [Comparative Example 16] First, a lead frame substrate composed primarily of copper was prepared. Next, the substrate was degreased and acid-washed, and then a phosphorus-free first nickel layer was formed on the surface of the substrate by electroplating to a thickness of 0.8 μm. This first nickel layer was formed using a Watts bath (Ni sulfate: 240 g / L, Ni 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). The first nickel layer had a smooth surface. This resulted in the lead frame of Comparative Example 16.

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

[0194] The larger the shear force value in this cup shear test, the better the adhesion of the resin to the lead frame.

[0195] Next, a palladium layer and a gold layer were formed on the surface of the lead frames of Examples 49 to 53 and Comparative Example 15. For these lead frames, the minimum film thickness of the palladium layer that would achieve a zero cross time of 1 second or less using the meniscograph method was evaluated. The gold layer was formed to a thickness in the range of 0.004 (μm) to 0.006 (μm).

[0196] Table 9 shows the film thicknesses of the first nickel layer and the second nickel layer, the minimum film thickness of the palladium layer that achieves a zero cross time of 1 second or less, resin adhesion evaluation, and SEM photographs of the surface and cross-sectional morphology of the lead frame for Examples 49 to 53 and Comparative Examples 15 and 16.

[0197] [Table 9]

[0198] Comparing Examples 49 to 53 with Comparative Example 15, it can be seen that by placing the second nickel layer containing 0.1 (wt%) phosphorus closer to the surface of the lead frame than the first nickel layer, good solder wettability can be maintained even when the palladium layer is made thin.

[0199] Furthermore, a comparison between Examples 49 to 53 and Comparative Example 16 reveals that roughening the surface of the first nickel layer can improve the adhesion of the resin to the lead frame.

[0200] <Rating 10> [Example 54] First, a lead frame substrate made primarily of copper was prepared. After degreasing and acid cleaning of the substrate, a second nickel layer containing 0.1 wt% phosphorus was formed on the surface of the substrate by electroplating to a thickness of 0.05 μm.

[0201] Next, a phosphorus-free first nickel layer was formed on the surface of the second nickel layer by electroplating to a thickness of 0.7 μm. This first nickel layer was formed using a sulfamic 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). The first nickel layer had a rough surface. This resulted in the lead frame of Example 54.

[0202] [Examples 55 to 58] The lead frames of Examples 55 to 58 were obtained using a method similar to that of Example 54. In Examples 55 to 58, the conditions for the electrolytic plating treatment were adjusted so that the film thickness of the second nickel layer and the film thickness of the first nickel layer would be as shown in Table 10.

[0203] Next, the lead frames of Examples 54 to 58 obtained above were evaluated for resin adhesion (shear force by cup shear test) using the same method as in Evaluation 9 above.

[0204] Next, a palladium layer and a gold layer were formed on the surface of the lead frames of Examples 54 to 58. For these lead frames, the minimum film thickness of the palladium layer that would achieve a zero cross time of 1 second or less using the meniscograph method was evaluated. The gold layer was formed to a thickness in the range of 0.004 (μm) to 0.006 (μm).

[0205] For Examples 54 to 58 and the above-mentioned Comparative Examples 15 and 16, Table 10 shows the film thicknesses of the first nickel layer and the second nickel layer, the minimum film thickness of the palladium layer that achieves a zero-cross time of 1 second or less, resin adhesion evaluation, and SEM photographs of the surface morphology and cross-sectional morphology of the lead frame.

[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 closer to the surface of the substrate than the first nickel layer, good solder wettability can be maintained even when the palladium layer is made thin.

[0208] Furthermore, a comparison between Examples 54 to 58 and Comparative Example 16 shows that the adhesion of the resin to the lead frame can be improved by roughening the surface of the first nickel layer.

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

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

[0211] Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and various modifications are possible without departing from the spirit of the present invention. For example, a copper-based lead frame substrate may be degreased and acid-washed, and then subjected to surface treatment such as chemical polishing or electrolytic polishing. Furthermore, another metal layer may be present between the lead frame substrate and the nickel layer.

[0212] As described above, the metal component (lead frame 1) according to the embodiment is a metal component used in the manufacture of a semiconductor device, and includes the base material 2, the nickel layer 3, and the precious metal layer 4. The base material 2 is conductive. The nickel layer 3 is formed on the surface 2a of the base material 2 and contains nickel as its main component. The precious metal layer 4 is formed on the surface 3a of the nickel layer 3. The nickel layer 3 also includes a first nickel layer 31 that does not contain phosphorus, and a second nickel layer 32 that contains 0.01 (wt%) to 1 (wt%) of phosphorus. This allows the thickness of the nickel layer 3 to be reduced while maintaining good properties in the metal component used in the manufacture of the semiconductor device 100.

[0213] Furthermore, in the metal component (lead frame 1) according to the embodiment, the second nickel layer 32 contains 0.01 (wt%) to 0.5 (wt%) of phosphorus, which can further reduce the overall manufacturing cost of the nickel layer 3 and maintain the good appearance of the nickel layer 3.

[0214] Furthermore, the metal component (lead frame 1) according to the embodiment is a metal component used in the manufacture of a semiconductor device, and includes a base material 2, a nickel layer 3, and a precious metal layer 4. The base material 2 is electrically conductive. The nickel layer 3 is formed on a surface 2a of the base material 2 and contains nickel as a main component. The precious metal layer 4 is formed on a surface 3a of the nickel layer 3. The nickel layer 3 includes a first nickel layer 31 that does not contain phosphorus, and a second nickel layer 32 that contains phosphorus and has a columnar crystal structure. This allows the thickness of the nickel layer 3 to be reduced while maintaining good characteristics in a metal component used in the manufacture of a semiconductor device 100.

[0215] Furthermore, in the metal component (lead frame 1) according to this embodiment, the surface 31a of the first nickel layer 31 is a rough surface. This makes it possible to realize the lead frame 1 with excellent adhesion to the sealing resin 103.

[0216] Furthermore, in the metal component (lead frame 1) according to the embodiment, the first nickel layer 31 is formed on the surface 2a of the base material 2, and the second nickel layer 32 is formed on the surface 31a of the first nickel layer 31. This makes it possible to realize a lead frame 1 that achieves both high levels of solder wettability and high levels of bonding characteristics of the bonding wire 102.

[0217] Furthermore, in the metal component (lead frame 1) according to the embodiment, the second nickel layer 32 is formed on the surface 2a of the base material 2, and the first nickel layer 31 is formed on the surface 32a of the second nickel layer 32. This allows the thickness of the nickel layer 3 to be reduced while maintaining good properties in Pd-PPF.

[0218] Furthermore, in the metal component (lead frame 1) according to the embodiment, another second nickel layer (second nickel layer 32B) is formed on the surface 31a of the first nickel layer 31. This makes it possible to realize a lead frame 1 that achieves both high levels of solder wettability and high levels of bonding characteristics of the bonding wire 102.

[0219] In the metal part (lead frame 1) according to this embodiment, the thickness of the second nickel layer 32 is 0.1 μm or more, which allows the surface 1a of the lead frame 1 to maintain good solder wettability.

[0220] Furthermore, in the metal component (lead frame 1) according to the embodiment, the ratio of the thickness of the second nickel layer 32 to the thickness of the nickel layer 3 is 50% or less. This allows the manufacturing cost of the nickel layer 3 as a whole to be further reduced.

[0221] Furthermore, in the metal component (lead frame 1) according to the embodiment, the precious metal layer 4 is made of at least one layer, and the precious metal layer 4 is made of at least one of palladium, gold, and silver. This makes it possible to suppress the formation of oxides on the surface 1a of the lead frame 1.

[0222] Further advantages and modifications will readily occur to those skilled in the art. Therefore, the invention in its broader aspects is not limited to the specific details and representative embodiments shown and described above. Accordingly, various modifications may be made without departing from the spirit or scope of the general inventive concept as defined by the appended claims and their equivalents. [Explanation of symbols]

[0223] 1. Lead frame (an example of a metal part) 2 Base material 2a surface 3 Nickel layer 4 Precious metal layer 31 First nickel layer 31a surface 32 Second nickel layer 32a surface 41 Palladium layer 42 gold layer

Claims

1. In metal parts used in the manufacture of semiconductor devices, a conductive substrate; a nickel layer formed on the surface of the substrate and containing nickel as a main component; a noble metal layer formed on the surface of the nickel layer; Equipped with The nickel layer is a phosphorus-free first nickel layer; a second nickel layer containing 0.01 (wt%) to 0.2 (wt%) phosphorus and having a columnar crystal structure; and the first nickel layer is formed on a surface of the substrate; The second nickel layer is formed on the surface of the first nickel layer. Metal parts.

2. The surface of the first nickel layer is rough. The metal part according to claim 1 .

3. The thickness of the second nickel layer is 0.1 (μm) or more. The metal part according to claim 1 or 2.

4. The ratio of the thickness of the second nickel layer to the thickness of the nickel layer is 50(%) or less. The metal part according to any one of claims 1 to 3.

5. The noble metal layer is made up of at least one layer, and the noble metal layer is made up of at least one of palladium, gold, and silver. The metal part according to any one of claims 1 to 4.

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