Material for electronic component and method for producing same, lead frame material and method for producing same, and semiconductor package

Abstract

Provided is a material for an electronic component which has high solder wettability even when heated at, e.g., 400°C while anticipating assembly of a semiconductor package, and with which it is possible to suppress deterioration of connection reliability resulting from Ni atoms constituting an Ni-containing layer diffusing to the surface and reacting with solder or a wire, even when the material for an electronic component is used in a high-temperature environment of around 120°C.　A material 1 for an electronic component includes a base body 2 composed of an electroconductive material, and a surface coating film 3 formed on at least part of a surface 21 of the base body 2. The surface coating film 3 has an Ni-containing layer 31 that contains Ni. The Ni-containing layer 31 has an average crystal grain size within the range of 0.10-0.50 μm when viewed in a cross-section including the thickness direction t. The average value of GAM in the cross-section, obtained from crystal orientation analysis performed using an electron backscatter diffraction (EBSD) method, is within the range of 0.95-2.00°, and the mode value of GAM in the cross-section is 0.7° or higher.

Description

Materials for electronic components and manufacturing method thereof, lead frame materials and manufacturing method thereof, and semiconductor packages

[0001] The present invention relates to a material for electronic components and a method for manufacturing the same, a lead frame material and a method for manufacturing the same, and a semiconductor package.

[0002] Many resin-sealed semiconductor devices are incorporated into electronic devices, electrical devices, and the like. These resin-sealed semiconductor devices are formed by electrically connecting a lead frame material, which is formed by pressing or bending a plate-shaped material for electronic components, to a semiconductor element via wires or the like, and then sealing the resulting structure with a molded resin. In these resin-sealed semiconductor devices, the lead frame material is often coated with an exterior plating such as gold (Au), silver (Ag), or tin (Sn) to impart functions such as bonding properties, heat resistance, and sealing properties.

[0003] In recent years, in order to simplify the assembly process and reduce costs, lead frame materials (pre-plated leadframes) have been used in which the surface of the lead frame material is pre-plated with plating (e.g., Ni / Pd / Au) that can increase wettability with solder when mounted on a printed circuit board.

[0004] For example, Patent Document 1 describes a lead frame material for a semiconductor device having a plurality of layers of metal film formed on the surface of a material (substrate), in which a Pd or Pd alloy film with a thickness of 0.3 μm or less is formed on the entire surface of the material directly or via an underlying metal film such as a Ni plating film, and an Au plating film with a thickness of 0.001 to 0.1 μm is formed on the Pd or Pd alloy film formed on the outer leads of the lead frame material, and it is claimed that this makes it possible to provide a lead frame material for a semiconductor device with particularly improved solderability.

[0005] On the other hand, as semiconductor packages become lighter, thinner, shorter, and smaller, there is a demand for lead frame materials to be thinner and have a smaller surface area, and there is a demand for joints and connection terminals with high solder wettability to maintain a good bond even when subjected to thermal history such as heating to around 400°C during assembly of the semiconductor package, for example, during resin molding.

[0006] In this regard, Patent Document 2 describes an electronic component in which a germanium-containing nickel plating film is formed on the surface of a conductive substrate (base) in the connection terminal portion, and claims that this makes it possible to provide an electronic component in which a plating film that allows for good bonding even when subjected to high-temperature thermal history, has excellent heat resistance and solder wettability, and can be made thinner is formed in the connection terminal portion.

[0007] Patent No. 2543619 Patent No. 5042894

[0008] The nickel plating films used in these lead frame materials and electronic components can improve heat resistance and solder wettability. However, when used in a high-temperature environment of around 120°C, which has recently become required for in-vehicle applications, etc., Ni atoms constituting a Ni-containing layer such as a Ni plating film diffuse to the surface of the lead frame and react with solder or wire to form a compound, which can cause voids or cracks to occur in the soldered portion or reduce the tensile strength of the wire-bonded portion. Therefore, it has been found that there is still room for improvement in terms of preventing a decrease in the connection reliability between the solder and wire in such a high-temperature environment.

[0009] An object of the present invention is to provide a material for electronic components and a manufacturing method thereof, a lead frame material and a manufacturing method thereof, and a semiconductor package, which have high solder wettability even when heated at, for example, 400°C in anticipation of the assembly of a semiconductor package, and which are capable of preventing a decrease in connection reliability caused by Ni atoms constituting a Ni-containing layer diffusing to the surface and reacting with solder or wire even when used in a high-temperature environment of around 120°C.

[0010] As a result of intensive research and development to address the above-mentioned conventional problems, the inventors have found that an electronic component material having at least a substrate made of a conductive material and a surface coating formed on at least a portion of the substrate, the surface coating includes a Ni-containing layer containing Ni, and that the Ni-containing layer has an average crystal grain size in the thickness direction cross section of the Ni-containing layer in the range of 0.10 μm to 0.50 μm, an average GAM in the thickness direction cross section obtained by crystal orientation analysis using electron backscatter diffraction (EBSD) in the range of 0.95° to 2.00°, and a mode of GAM in the thickness direction cross section of 0.7° or greater, can be obtained. This electronic component material has high solder wettability even when heated to, for example, 400° C., assuming the assembly of a semiconductor package, and exhibits little diffusion of Ni atoms constituting the Ni-containing layer to the lead frame surface even when used in a high-temperature environment of around 120° C. Based on this finding, the present invention was completed.

[0011] In order to achieve the above object, the gist of the present invention is as follows: (1) A material for electronic components having a substrate made of a conductive material and a surface coating formed on at least a part of the surface of the substrate, wherein the surface coating has a Ni-containing layer containing Ni, and the Ni-containing layer has an average crystal grain size in the range of 0.10 μm to 0.50 μm when viewed in a cross section including the thickness direction of the material for electronic components, and the average value of GAM in the cross section obtained by crystal orientation analysis using electron backscatter diffraction (EBSD) is in the range of 0.95° to 2.00°, and the mode of GAM in the cross section is 0.7° or more. (2) The material for electronic components according to (1) above, wherein the Ni-containing layer is made of a Ni alloy, and the Ni alloy contains one or more additive elements selected from the group consisting of germanium (Ge), manganese (Mn), zinc (Zn), phosphorus (P), cobalt (Co), molybdenum (Mo), and tungsten (W), with the balance being Ni and unavoidable impurities. (3) The material for electronic components according to (2) above, wherein the Ni alloy contains the additive elements in a total amount of 0.01% by mass or more and 10.0% by mass or less. (4) The material for electronic components according to any one of (1) to (3) above, wherein the surface coating further includes at least one surface coating layer on the Ni-containing layer. (5) The material for electronic components according to (4) above, wherein the surface coating layer is made of copper, a copper alloy, cobalt, a cobalt alloy, palladium, a palladium alloy, rhodium, a rhodium alloy, ruthenium, a ruthenium alloy, platinum, a platinum alloy, iridium, an iridium alloy, gold, a gold alloy, silver, a silver alloy, tin, a tin alloy, indium, or an indium alloy. (6) The material for electronic components according to any one of (1) to (5) above, wherein the substrate is made of copper, a copper alloy, iron, an iron alloy, aluminum, or an aluminum alloy. (7) A method for producing the material for electronic components according to any one of (1) to (6) above, comprising a coating formation step of forming the surface coating on at least a part of the surface of the substrate by electroplating.(8) A leadframe material having a base made of a conductive material and a surface coating formed on at least a portion of the surface of the base, the surface coating having a Ni-containing layer containing Ni, the Ni-containing layer having an average crystal grain size in the range of 0.10 μm to 0.60 μm when viewed in a cross section including the thickness direction of the leadframe material, and an average GAM in the cross section obtained by crystal orientation analysis using electron backscatter diffraction (EBSD) is in the range of 0.90° to 1.90° and a mode of GAM in the cross section is 0.6° or more. (9) A method for producing the leadframe material described in (8) above, comprising: a coating formation step of forming the surface coating on at least a portion of the surface of the base by electroplating to obtain a material for electronic components; and a heat treatment step of subjecting the material for electronic components to heat treatment to obtain a leadframe material. (10) A semiconductor package having a leadframe formed using the leadframe material described in (8) above.

[0012] According to the present invention, it is possible to provide a material for electronic components and a manufacturing method thereof, a lead frame material and a manufacturing method thereof, and a semiconductor package, which have high solder wettability even when heated at, for example, 400°C in anticipation of assembling a semiconductor package, and which are capable of making it difficult for a decrease in connection reliability to occur due to Ni atoms constituting the Ni-containing layer diffusing to the surface and reacting with solder or wire even when used in a high-temperature environment of around 120°C.

[0013] 1 is a schematic cross-sectional view showing an example of a material for electronic components according to an embodiment of the present invention, and FIG. 2 is a schematic cross-sectional view showing another example of a material for electronic components according to an embodiment of the present invention.

[0014] Preferred embodiments of the material for electronic components and the method for producing the same, the lead frame material and the method for producing the same, and the semiconductor package of the present invention will be described in detail below.

[0015] <Regarding the Material for Electronic Components> As shown in FIG. 1 , the material for electronic components 1 according to the present invention has a substrate 2 made of a conductive material and a surface coating 3 formed on at least a part of a surface 21 of the substrate 2. The surface coating 3 has a Ni-containing layer 31 that contains Ni. The Ni-containing layer 31 has an average crystal grain size in the range of 0.10 μm or more and 0.50 μm or less, as viewed in a cross section including the thickness direction t of the material for electronic components 1 (hereinafter, may be simply referred to as the "thickness direction t"). The average value of GAM in the cross section, obtained from crystal orientation analysis by electron backscatter diffraction (EBSD), is in the range of 0.95° or more and 2.00° or less, and the mode of GAM in the cross section is 0.7° or more.

[0016] In the electronic component material 1 of the present invention, by controlling the average crystal grain size in the cross section of the Ni-containing layer 31 including the thickness direction t to a range of 0.10 μm or more and 0.50 μm or less, high solder wettability can be achieved even when heated at, for example, 400° C., assuming the assembly of a semiconductor package. At the same time, by controlling the average value of GAM in the cross section of the Ni-containing layer 31 including the thickness direction t to a range of 0.95° or more and 2.00° or less, and controlling the mode value of GAM in the cross section to 0.7° or more, even when used in a high-temperature environment of around 120° C., as required for automotive applications, Ni atoms constituting the Ni-containing layer 31 are unlikely to diffuse to the surface of the lead frame, which can cause voids or cracks in the soldered portion or damage to the wire-bonded portion, thereby making it less likely that a decrease in connection reliability will occur. Therefore, by using the material for electronic components 1 of the present invention, it is possible to provide a material for electronic components and a manufacturing method thereof, a lead frame material and a manufacturing method thereof, and a semiconductor package, which have high solder wettability even when heated at, for example, 400°C, assuming the assembly of a semiconductor package, and which are capable of making it difficult for a decrease in connection reliability to occur due to Ni atoms constituting the Ni-containing layer diffusing to the surface and reacting with solder or wire, even when used in a high-temperature environment of around 120°C.

[0017] The material for electronic components 1 according to the present invention has a substrate 2 made of a conductive material and a surface coating 3 formed on at least a part of the surface 21 of the substrate 2 .

[0018] [Regarding the Base] The base 2 is preferably made of a metal or alloy containing copper (Cu), iron (Fe), or aluminum (Al). More specifically, from the viewpoint of improving electrical conductivity and heat dissipation, the base 2 is preferably made of copper, a copper alloy, iron, an iron alloy, aluminum, or an aluminum alloy, and more preferably made of copper, a copper alloy, iron, or an iron alloy.

[0019] When the base 2 is made of an alloy, the alloy composition is not particularly limited and can be appropriately selected depending on the characteristics required of the lead frame material. Examples of copper alloys that make up the base 2 include pure copper (oxygen-free copper (OFC): C1020 or tough pitch copper (TPC): C1100, etc.), as well as alloys listed in the Copper Development Association (CDA), such as C18045 (Cu-0.3Cr-0.25Sn-0.52Zn) and C19400 (Cu-2.3Fe-0.03P-0.15Zn). An example of an iron alloy that makes up the base 2 is 42 alloy (Fe-42Ni). The number before each element indicates the content in mass% of the alloy.

[0020] The base 2 is preferably in the form of a metal foil or alloy foil, and examples of such metal foil or alloy foil include rolled foil, electrolytic foil, etc. In particular, from the viewpoint of configuring the base 2 to have anisotropic mechanical properties, a rolled foil formed by press working or the like may be used for the base 2.

[0021] The thickness of the substrate 2 is not particularly limited, but is, for example, in the range of 1 μm to 500 μm, preferably 5 μm to 200 μm.

[0022] [Regarding the Surface Coating] The material for electronic components 1 has a surface coating 3 formed on at least a portion of the surface 21 of the substrate 2. Examples of the surface coating 3 include, in order from closest to the substrate 2, a Ni-containing layer 31 and a surface coating layer 32. The material for electronic components 1 of the present invention has at least the Ni-containing layer 31 as the surface coating 3. The surface coating 3 may be formed on the entire surface 21 of the substrate 2 as shown in FIG. 1 , or may be formed on only a portion of the surface 21 of the substrate 2.

[0023] (Ni-containing layer) The Ni-containing layer 31 is a layer containing nickel (Ni). When viewed in a cross section including the thickness direction t of the material for electronic components 1, the Ni-containing layer 31 has an average crystal grain size and an average and mode of GAM within predetermined ranges. This reduces the diffusion of Ni atoms constituting the Ni-containing layer 31 to the surface of the lead frame, thereby making it less likely that Ni atoms will diffuse to the surface of the lead frame and react with the solder or wire, thereby reducing the deterioration of connection reliability with the solder or wire.

[0024] The average crystal grain size of the Ni-containing layer 31 of the electronic component material 1, more specifically, the average crystal grain size of the crystalline phase contained in the Ni-containing layer 31 when viewed in a cross section including the thickness direction t of the electronic component material 1, is in the range of 0.10 μm to 0.50 μm. Here, if the average crystal grain size of the Ni-containing layer 31 is less than 0.10 μm, the Ni-containing layer 31 becomes hard, making it difficult to process the electronic component material 1 into a lead frame material, etc. On the other hand, if the average crystal grain size of the Ni-containing layer 31 exceeds 0.50 μm, the Ni atoms constituting the Ni-containing layer 31 tend to diffuse from the grain boundaries of the Ni-containing layer 31 to the surface of the lead frame, which makes it easier for the Ni atoms to react with solder or wire on the surface of the lead frame to form compounds. Therefore, when heated at, for example, 400°C, assuming the assembly of a semiconductor package, the solder wettability of the Ni-containing layer 31 deteriorates. Furthermore, when used in a high-temperature environment of around 120°C, wire bonding properties deteriorate. Therefore, by controlling the average crystal grain size in the Ni-containing layer 31 of the electronic component material 1 to be in the range of 0.10 μm or more and 0.50 μm or less, the electronic component material 1 can be easily processed into a lead frame material or the like, and can have high solder wettability even when heated at, for example, 400° C., assuming the assembly of a semiconductor package, and can provide high wire bondability even when the lead frame is used in a high-temperature environment of around 120° C. Furthermore, even when the lead frame is used in a high-temperature environment of around 120° C., the occurrence of voids or cracks in the soldered portion and breakage of the wire-bonded portion are made less likely, thereby making it less likely that a decrease in connection reliability due to the formation of compounds on the surface of the lead frame will occur.

[0025] The average grain size of the crystalline phase contained in the Ni-containing layer 31 can be determined by a cutting method. More specifically, a cross section of the substrate 2, which is finished using a cross-section polisher (manufactured by JEOL Ltd.) or the like and includes the thickness direction t and the rolling direction of the substrate 2, is observed using a scanning electron microscope (SEM). In the resulting SEM image, ten 5 μm-long line segments parallel to the surface of the substrate 2 are drawn, and the total number of intersections between each line segment and the boundaries of the crystal grains is counted. The average length of each line segment defined by the boundaries of the crystal grains is calculated using the following formula (I), thereby determining the average grain size, which is the average length of each line segment. Average length per line segment [μm] = 5 [μm] × 10 / (total number of intersections between line segments and crystal grain boundaries) ... (I)

[0026] Furthermore, the Ni-containing layer 31 of the electronic component material 1 has an average grain average misorientation (GAM) value (hereinafter sometimes simply referred to as the "average GAM value") in a cross section including the thickness direction t of the electronic component material 1, obtained by crystal orientation analysis using electron backscatter diffraction (EBSD), in the range of 0.95° to 2.00°. Here, if the average GAM value is less than 0.95°, the strain in the Ni-containing layer 31 is reduced, and Ni atoms constituting the Ni-containing layer 31 diffuse from the Ni-containing layer 31 to the surface of the lead frame, making it easier to react with solder or wire to form compounds. On the other hand, if the average GAM value is greater than 2.00°, excessive strain in the Ni-containing layer 31 may harden the Ni-containing layer 31, potentially reducing processability. Furthermore, if the average GAM value is greater than 2.00°, the solder wettability of the Ni-containing layer 31 is likely to decrease, especially when the lead frame material 10 is formed. Furthermore, especially when the lead frame is used in a high-temperature environment of around 120°C, excessive strain in the Ni-containing layer 31 makes it easier for Ni atoms to migrate from within the Ni-containing layer 31. When this occurs, the Ni atoms diffuse from the Ni-containing layer 31 to the surface of the lead frame, reacting with the solder or wire to form compounds, which reduces wire bonding properties and increases the likelihood of voids or cracks occurring in the soldered portion or damage to the wire-bonded portion. Therefore, in the Ni-containing layer 31 of the electronic component material 1, by setting the average GAM value in the range of 0.95° to 2.00°, the strain in the Ni-containing layer 31 is appropriately increased, thereby reducing the diffusion of Ni atoms constituting the Ni-containing layer 31 to the surface of the lead frame and improving solder wettability.

[0027] Furthermore, the Ni-containing layer 31 of the electronic component material 1 has a GAM mode (hereinafter, sometimes simply referred to as the "GAM mode") of 0.7° or more in a cross section including the thickness direction t of the electronic component material 1, which is obtained by crystal orientation analysis using an electron backscatter diffraction (EBSD) method. Here, if the GAM mode is less than 0.7°, the amount of strain within each crystal grain contained in the Ni-containing layer 31 decreases, making it easier for Ni atoms to migrate from within the Ni-containing layer 31. Therefore, particularly when the lead frame is used in a high-temperature environment of around 120°C, the Ni atoms constituting the Ni-containing layer 31 diffuse to the surface of the lead frame and react with the solder or wire to form a compound, which results in reduced wire bondability and makes it easier for voids and cracks to occur in the soldered portion and for the wire-bonded portion to break. Therefore, in the Ni-containing layer 31 of the material for electronic components 1, by setting the mode of GAM to 0.7° or more, the movement of Ni atoms is suppressed by strain within the crystal grains, and therefore, a decrease in connection reliability due to the formation of compounds on the surface of the lead frame can be made less likely to occur.

[0028] The average and mode values ​​of the GAM of the Ni-containing layer 31 can be obtained from crystal orientation analysis data calculated using analysis software (OIM Analysis, manufactured by TSL Solutions) from crystal orientation data continuously measured using an EBSD detector (OIM5.0 HIKARI, manufactured by TSL Solutions) attached to a high-resolution scanning analytical electron microscope (JSM-7001FA, manufactured by JEOL Ltd.) for a cross section including the thickness direction t. Here, "EBSD" stands for Electron Backscatter Diffraction, and refers to a crystal orientation analysis technique that utilizes reflected electron Kikuchi diffraction that occurs when an electron beam is irradiated on a copper alloy sheet sample in a scanning electron microscope (SEM). "OIM Analysis" refers to analysis software for data measured by EBSD. The measurement can be performed on a cross section including the thickness direction t, which has been finished using a cross-section polisher (manufactured by JEOL Ltd.). The measurement magnification of the cross section can be 30,000 times, and measurements can be performed at measurement intervals of 50 nm or less. Among these measurement points, measurement points for which the reliability index (CI) value is 0.1 or less as analyzed using analysis software are excluded from the analysis. The boundary where the orientation difference between adjacent measurement points is 5.00° or more is considered to be a grain boundary. The average GAM value representing the orientation difference between a measurement point and its surrounding measurement points within the same grain can be calculated for each measurement area. This measurement is performed on five different measurement areas within the same cross section of the Ni-containing layer 31, and the average of the five GAM values ​​obtained for each measurement area can be calculated to calculate the average GAM value of the Ni-containing layer 31. Furthermore, by rounding off the GAM of all measurement points to be analyzed that are included in these five measurement areas to the nearest tenth, and obtaining a frequency distribution in increments of 0.1°, the most frequent value in this frequency distribution can be taken as the most frequent value of the GAM.

[0029] Here, the CI value is a value used as an index for indexing a crystal orientation analysis pattern obtained by the EBSD method and for evaluating whether the calculated crystal orientation is correct. In other words, the CI value is a value reflecting the reliability of the crystal orientation measured by the EBSD method in the cross section of the Ni-containing layer 31 described above. This CI value can be calculated from the Map-Confidence Index of the analysis software (manufactured by TSL, OIM Analysis) by analyzing the crystal orientation data obtained in the cross section by the EBSD detector as described above.

[0030] The Ni-containing layer 31 is preferably made of a material containing Ni, and is preferably made of a Ni-based material such as metallic Ni or a Ni alloy. In particular, the Ni-containing layer 31 is preferably made of a Ni alloy. From the viewpoint of further improving the heat resistance of the electronic component material 1 and enhancing the corrosion resistance of the Ni-containing layer 31, the Ni alloy preferably contains one or more additive components selected from the group consisting of germanium (Ge), manganese (Mn), zinc (Zn), phosphorus (P), cobalt (Co), molybdenum (Mo), and tungsten (W), with the balance consisting of Ni and inevitable impurities. On the other hand, the additive component contained in the alloy composition of the Ni alloy may be one or more additive components selected from the group consisting of germanium (Ge), manganese (Mn), zinc (Zn), and phosphorus (P).

[0031] The Ni alloy constituting the Ni-containing layer 31 preferably has an alloy composition containing one or more additive elements selected from the group consisting of germanium (Ge), manganese (Mn), zinc (Zn), phosphorus (P), cobalt (Co), molybdenum (Mo), and tungsten (W) in a total amount ranging from 0.01% by mass to 10.0% by mass. In particular, by setting the total content of these additive elements to 0.01% by mass or more, the Ni alloy is sufficiently alloyed, further improving the heat resistance of the electronic component material 1 and the corrosion resistance of the Ni-containing layer 31. Furthermore, by setting the total content of these additive elements to 0.01% by mass or more, when the lead frame material 10 is formed, Ni atoms are less likely to diffuse to the surface of the lead frame, which also makes it less likely that the Ni atoms diffused to the surface of the lead frame are oxidized, thereby further improving the solder wettability of the Ni-containing layer 31. Furthermore, when used in a high-temperature environment, particularly around 120°C, the formation of compounds of Ni atoms diffused on the surface of the lead frame is further suppressed, thereby further suppressing the occurrence of voids and cracks in the soldered joints and damage to the wire-bonded joints. On the other hand, by setting the total content of these additive components to 10.0 mass% or less, the diffusion of the additive components to the surface of the lead frame is suppressed, thereby reducing the formation of intermetallic compounds on the surface of the lead frame, and as a result, the occurrence of voids and cracks in the soldered joints and damage to the wire-bonded joints are suppressed. Note that when the additive component contained in the alloy composition of the Ni alloy is one or more selected from the group consisting of germanium (Ge), manganese (Mn), zinc (Zn), and phosphorus (P), from the same viewpoint, the total content of these additive components is preferably in the range of 0.01 mass% to 10.0 mass%.

[0032] Among the additive components, the content of germanium (Ge) is preferably 0.01% by mass or more from the viewpoint of sufficiently alloying the Ni alloy and further enhancing the heat resistance of the electronic component material 1. Furthermore, the content of germanium (Ge) is preferably 10.0% by mass or less, more preferably 5.0% by mass or less, and even more preferably 2.0% by mass or less, from the viewpoint of making it difficult for germanium to diffuse to the surface of the lead frame and thereby making it difficult for an intermetallic compound to form on the surface of the lead frame.

[0033] The manganese (Mn) content is preferably 0.01% by mass or more from the viewpoint of sufficiently alloying the Ni alloy and further enhancing the heat resistance of the electronic component material 1. Furthermore, the manganese (Mn) content is preferably 7.0% by mass or less, and more preferably 4.0% by mass or less, from the viewpoint of making it difficult for the manganese (Mn) to diffuse to the surface of the lead frame, thereby making it difficult for an intermetallic compound to be formed on the surface of the lead frame.

[0034] The zinc (Zn) content is preferably 0.01% by mass or more from the viewpoint of sufficiently alloying the Ni alloy and further enhancing the heat resistance of the electronic component material 1. Furthermore, the zinc (Zn) content is preferably 10.0% by mass or less, and more preferably 8.0% by mass or less, from the viewpoint of making it difficult for zinc to diffuse to the surface of the lead frame, thereby making it difficult for an intermetallic compound to be formed on the surface of the lead frame.

[0035] The phosphorus (P) content is preferably 0.01% by mass or more from the viewpoint of sufficiently alloying the Ni alloy and further enhancing the heat resistance of the electronic component material 1. The phosphorus (P) content is preferably 5.0% by mass or less from the viewpoint of making it difficult for the phosphorus (P) to diffuse to the surface of the lead frame, thereby making it difficult for an intermetallic compound to be formed on the surface of the lead frame.

[0036] The content of cobalt (Co) is preferably 0.01% by mass or more from the viewpoint of sufficiently alloying the Ni alloy and further enhancing the heat resistance of the electronic component material 1. The content of cobalt (Co) is preferably 10.0% by mass or less from the viewpoint of making it difficult for cobalt (Co) to diffuse to the surface of the lead frame, thereby making it difficult for an intermetallic compound to be formed on the surface of the lead frame.

[0037] The content of molybdenum (Mo) is preferably 0.01% by mass or more from the viewpoint of sufficiently alloying the Ni alloy and further enhancing the heat resistance of the material for electronic components 1. The content of molybdenum (Mo) is preferably 7.0% by mass or less from the viewpoint of making it difficult for diffusion of Mo to the surface of the lead frame to occur, thereby making it difficult for an intermetallic compound to form on the surface of the lead frame.

[0038] The tungsten (W) content is preferably 0.01% by mass or more from the viewpoint of sufficiently alloying the Ni alloy and further enhancing the heat resistance of the electronic component material 1. Furthermore, the tungsten (W) content is preferably 5.0% by mass or less from the viewpoint of making it difficult for tungsten (W) to diffuse to the surface of the lead frame, thereby making it difficult for an intermetallic compound to be formed on the surface of the lead frame.

[0039] The Ni alloy consists of nickel (Ni) and inevitable impurities, other than the above-mentioned additive components. The term "unavoidable impurities" as used herein refers to impurities present in raw materials or unavoidably mixed in during the manufacturing process. These impurities are essentially unnecessary but are tolerated in trace amounts that do not affect the properties of the alloy. The upper limit of the content of the components constituting the inevitable impurities is less than 0.01% by mass for each component, and the total amount of the inevitable impurities can be 0.10% by mass.

[0040] The thickness of the Ni-containing layer 31 is not particularly limited, but can be, for example, in the range of 0.1 μm to 5.0 μm. Here, by making the thickness of the Ni-containing layer 31 0.1 μm or more, the Ni-containing layer 31 acts as a barrier layer that reduces the diffusion of base material components to the surface of the lead frame, making it possible to prevent deterioration of solder wettability and wire bonding properties due to the diffusion of base material 2 components to the surface. On the other hand, by making the thickness of the Ni-containing layer 31 5.0 μm or less, it is possible to make the electronic component material 1 less likely to crack when bent.

[0041] (Surface Coating Layer) The surface coating 3 preferably further includes at least one surface coating layer 32 on the Ni-containing layer 31. The surface coating layer 32 has a surface that contacts the outside of the electronic component material 1, and the presence of the surface coating layer 32 can further enhance the solder wettability of the electronic component material 1 and the lead frame. Furthermore, since the surface coating layer 32 covers the surface of the Ni-containing layer 31, the diffusion of Ni atoms constituting the Ni-containing layer 31 to the surface of the lead frame is further reduced, making it more unlikely that cracks will occur in the soldered joints or that wire-bonded joints will be damaged due to the formation of compounds on the surface of the lead frame. Additionally, since the surface coating layer 32 covers the surface of the Ni-containing layer 31, the surface of the Ni-containing layer 31 is protected, making it more unlikely that oxidation of the base 2 or the Ni-containing layer 31 will occur.

[0042] The surface coating layer 32 is composed of a layer of a metal or alloy having a different composition from the Ni-containing layer 31. More specifically, the surface coating layer 32 is preferably composed of copper, a copper alloy, cobalt, a cobalt alloy, palladium, a palladium alloy, rhodium, a rhodium alloy, ruthenium, a ruthenium alloy, platinum, a platinum alloy, iridium, an iridium alloy, gold, a gold alloy, silver, a silver alloy, tin, a tin alloy, indium, or an indium alloy. Since the surface coating layer 32 is the surface that comes into contact with the outside of the electronic component material 1, by forming the surface coating layer 32 from at least one of these materials, the surface coating layer 32 is less susceptible to oxidation and the solder wettability and wire bondability can be further improved.

[0043] Here, the surface coating layer 32 may be composed of one layer or two or more layers. For example, as shown in the material for electronic components 1A in Fig. 2 , when the surface coating layer 32 of the surface coating 3A is composed of two layers, the layer closer to the substrate 2 may be the first surface coating layer 32a, and the layer farther from the substrate 2 may be the second surface coating layer 32b. Furthermore, as shown in Fig. 2 , the surface coating layer 32 may be formed on a part of the surface of the Ni-containing layer 31, or may be formed on the entire surface.

[0044] The surface coating layer 32 has a surface that comes into contact with the outside of the electronic component material 1, and is preferably resistant to oxidation and has excellent wettability with solder, etc. Therefore, the surface coating layer 32 is preferably made of gold, a gold alloy, palladium, a palladium alloy, silver, a silver alloy, tin, or a tin alloy. In particular, from the viewpoint of further enhancing wettability with solder, the surface coating layer 32 is preferably made of a gold-palladium laminate, gold, silver, tin, or a gold-cobalt alloy. Here, when the surface coating layer 32 is composed of two or more layers, the layer farthest from the base 2 (for example, when the surface coating layer 32 is composed of two layers, the second surface coating layer 32b) is preferably made of gold, silver, tin, or a gold-cobalt alloy.

[0045] <Regarding the Manufacturing Method of the Material for Electronic Components> The manufacturing method of the material for electronic components 1 described above is not particularly limited, but from the viewpoint of easily controlling the average crystal grain size of the Ni-containing layer 31 and the average and mode values ​​of the GAM, and from the viewpoint of easily controlling the content of the additive components of the Ni alloy, particularly when the Ni-containing layer 31 is made of a Ni alloy, it is preferable that the method include a coating formation step of forming the surface coating 3 on at least a part of the surface of the base 2 by electroplating.

[0046] One example of a method for manufacturing the electronic component material 1 includes preparing a conductive substrate 2 whose size and thickness have been adjusted by press working, performing cathodic electrolytic degreasing and pickling as pretreatments, and then performing a coating formation step in which a surface coating 3 is formed on the substrate 2. Specific methods for forming the surface coating 3 in the coating formation step include electroplating, sputtering, and vapor deposition. Among these, electroplating is particularly preferred to form an electroplated layer as the surface coating 3. In this case, it is more preferred to use pulse current in the electroplating. For example, examples of conditions for forming an electroplated layer, which is a Ni-containing layer 31, as the surface coating 3 in the coating formation step are shown below.

[0047] [Example of conditions for forming an electroplated layer] Plating bath: 50 g / L to 110 g / L (Ni (atom) equivalent) of Ni salt excluding nickel chloride, 30 g / L to 40 g / L of boric acid, 30 g / L to 60 g / L of nickel chloride Plating conditions: bath temperature 30°C to 40°C, current density 15 A / dm ２ ~80A / dm ２ , Pulse current duty ratio 0.05 to 0.20, Pulse current pulse count 0.5 pps to 100 pps

[0048] As a method for controlling the average crystal grain size and the average and mode values ​​of the GAM of the Ni-containing layer 31, for example, when forming the Ni-containing layer 31 by electroplating, the bath temperature of the plating bath may be adjusted to a range of 30°C to 40°C, and pulsed current may be used to form the Ni-containing layer 31. Here, pulsed current may be used to apply a pulse current with a duty ratio of 0.05 to 0.20. By adjusting the bath temperature of the plating bath and performing pulsed current electroplating in this manner, it is possible to obtain a material for electronic components 1 in which, when viewed in a cross section including the thickness direction t, the average crystal grain size of the crystalline phase contained in the Ni-containing layer 31 is in the range of 0.10 μm to 0.50 μm, the average GAM value in the cross section including the thickness direction t is in the range of 0.95° to 2.00°, and the mode GAM value in the cross section is 0.7° or more.

[0049] <Regarding the Lead Frame Material> Similar to the electronic component material 1 shown in Fig. 1 , the lead frame material 10 according to the present invention has a base 2 made of a conductive material and a surface coating 3 formed on at least a portion of the surface 21 of the base 2, with the surface coating 3 having a Ni-containing layer 31 containing Ni. On the other hand, similar to the electronic component material 1 described above, the Ni-containing layer 31 of the lead frame material 10 is composed of a Ni-based material that is metallic Ni or a Ni alloy, but has a different crystalline state from that of the electronic component material 1 because it is mainly produced by subjecting the electronic component material 1 to heat treatment. Therefore, in this specification, the configuration of the lead frame material 10 other than the Ni-containing layer 31 is the same as that of the electronic component material 1, so description thereof will be omitted, and only the Ni-containing layer 31 will be described.

[0050] The Ni-containing layer 31 of the lead frame material 10 is a layer containing nickel (Ni), and by setting the average crystal grain size and the average and mode values ​​of the GAM within a predetermined range when viewed in a cross section including the thickness direction t of the lead frame material 10, the diffusion of Ni atoms constituting the Ni-containing layer 31 to the surface of the lead frame material 10 is reduced, making it less likely that the connection reliability with the solder or wire will decrease due to the Ni atoms reacting with the solder or wire.

[0051] The average crystal grain size of the Ni-containing layer 31 of the lead frame material 10, more specifically, the average crystal grain size of the crystalline phase contained in the Ni-containing layer 31 when viewed in a cross section including the thickness direction t of the lead frame material 10, is in the range of 0.10 μm to 0.60 μm. Here, Ni-containing layers 31 having an average crystal grain size of less than 0.10 μm are difficult to obtain in practice because the Ni-containing layer 31 becomes hard, making it difficult to process the electronic component material 1 into the lead frame material 10. On the other hand, if the average crystal grain size of the Ni-containing layer 31 exceeds 0.60 μm, when used in a high-temperature environment of around 120° C., Ni atoms constituting the Ni-containing layer 31 are likely to diffuse from the grain boundaries of the Ni-containing layer 31 to the surface of the lead frame, and therefore the Ni atoms are likely to react with solder or wire on the surface of the lead frame to form compounds. Therefore, by controlling the average crystal grain size of the Ni-containing layer 31 of the lead frame material 10 to a range of 0.10 μm or more and 0.60 μm or less, and preferably to a range of 0.20 μm or more and 0.50 μm or less, it is possible to reduce the occurrence of voids or cracks in the soldered joints and the damage to the wire-bonded parts, even when the lead frame is used in a high-temperature environment of around 120°C, thereby reducing the likelihood of a decrease in connection reliability due to the formation of compounds on the surface of the lead frame.

[0052] Furthermore, the Ni-containing layer 31 of the lead frame material 10 has an average GAM value in a cross section of the lead frame material 10 including the thickness direction t, obtained by crystal orientation analysis using electron backscatter diffraction (EBSD), in the range of 0.90° to 1.90°. Here, if the average GAM value is less than 0.90°, the strain in the Ni-containing layer 31 is reduced, and Ni atoms constituting the Ni-containing layer 31 diffuse from the Ni-containing layer 31 to the surface of the lead frame, making it easier to react with solder or wire to form compounds. Furthermore, if the average GAM value is less than 0.90°, crystal grains with less strain become dominant among the crystal grains contained in the Ni-containing layer 31. Therefore, when the lead frame is used in a high-temperature environment, particularly at around 120°C, the Ni atoms constituting the Ni-containing layer 31 diffuse to the surface of the lead frame, reacting with solder or wire to form compounds, which may result in a decrease in the connection reliability of the lead frame. On the other hand, if the average value of GAM is greater than 1.90°, excessive strain in the Ni-containing layer 31 may cause the Ni-containing layer 31 to harden, potentially resulting in reduced workability. Furthermore, if the average value of GAM is greater than 1.90°, the solder wettability of the Ni-containing layer 31 is likely to be reduced. Furthermore, particularly when the lead frame is used in a high-temperature environment of around 120°C, excessive strain in the Ni-containing layer 31 may cause Ni atoms to migrate from within the Ni-containing layer 31. In this case, the Ni atoms diffuse from the Ni-containing layer 31 to the surface of the lead frame, reacting with the solder or wire to form compounds, which reduces wire bondability and may lead to the generation of voids or cracks in the soldered portion or damage to the wire-bonded portion. Therefore, in the Ni-containing layer 31 of the lead frame material 10, by setting the average value of the GAM to be 0.90° or more and 1.90° or less, the strain in the Ni-containing layer 31 becomes moderately large, thereby reducing the diffusion of Ni atoms that make up the Ni-containing layer 31 to the surface of the lead frame and improving solder wettability.

[0053] Furthermore, the Ni-containing layer 31 of the lead frame material 10 has a GAM mode of 0.6° or more in a cross section including the thickness direction t of the lead frame material 10, as obtained by crystal orientation analysis using electron backscatter diffraction (EBSD). Here, if the GAM mode is less than 0.6°, less strained crystal grains will predominate among the crystal grains contained in the Ni-containing layer 31. Therefore, particularly when the lead frame is used in a high-temperature environment of around 120°C, the Ni atoms constituting the Ni-containing layer 31 will diffuse to the surface of the lead frame, reacting with the solder or wire to form compounds, which will result in reduced wire bonding properties and the likelihood of voids or cracks occurring in the soldered portion or breakage of the wire-bonded portion. Therefore, by making the GAM mode of the Ni-containing layer 31 of the lead frame material 10 0.6° or more, the influence of less strained crystal grains can be reduced, making it less likely that a decrease in connection reliability will occur due to the formation of compounds on the surface of the lead frame.

[0054] The material constituting the Ni-containing layer 31 of the lead frame material 10 is composed of a material containing Ni, similar to the above-mentioned electronic component material 1, and is preferably composed of a Ni-based material such as metallic Ni or a Ni alloy. The alloy composition of the Ni alloy is the same as that of the above-mentioned electronic component material 1, and therefore will not be described here.

[0055] The thickness of the Ni-containing layer 31 of the lead frame material 10 is not particularly limited, but can be, for example, in the range of 0.1 μm to 5.0 μm. Here, by making the thickness of the Ni-containing layer 31 0.1 μm or more, the Ni-containing layer 31 acts as a barrier layer that reduces the diffusion of base material components to the surface of the lead frame, making it possible to prevent deterioration of solder wettability and wire bonding properties due to the diffusion of components of the base 2 to the surface. On the other hand, by making the thickness of the Ni-containing layer 31 5.0 μm or less, it is possible to make the lead frame material 10 less likely to crack when bent.

[0056] <Regarding the Manufacturing Method of Lead Frame Material> The manufacturing method of the above-described lead frame material 10 is not particularly limited, but from the viewpoint of facilitating control of the average crystal grain size of the Ni-containing layer 31 and the average and mode values ​​of the GAM, and from the viewpoint of facilitating control of the content of additive components of the Ni alloy, particularly when the Ni-containing layer 31 is made of a Ni alloy, it is preferable that the method include a coating formation step of forming a surface coating 3 on at least a part of the surface of the base 2 by electroplating to obtain the electronic component material 1, and a heat treatment step of subjecting the electronic component material 1 to heat treatment to obtain the lead frame material 10.

[0057] Of these, the film forming step can be carried out in the same manner as in the manufacturing method of the material for electronic components 1 .

[0058] On the other hand, the heat treatment process may be performed in conjunction with forming a resin mold on the surface to fix and protect the semiconductor element. The heating temperature in the heat treatment process is preferably in the range of 100°C to 300°C. When a typical lead frame material undergoes such a thermal history, the average crystal grain size of the Ni-containing layer 31 increases and the GAM value decreases, which tends to reduce solder wettability and connection reliability when solder or wire is fixed and connected to the lead frame material. In this regard, the lead frame material 10 of the present invention forms the Ni-plated layer, which is the Ni-containing layer 31, using the above-mentioned electroplated layer formation conditions in the coating process. This suppresses grain boundary migration within the Ni-containing layer 31 even when heated in the heat treatment process, thereby maintaining the average crystal grain size and the average and mode values ​​of the GAM within desired ranges.

[0059] The heating time of the heat treatment in the heat treatment step is not particularly limited, but can be, for example, in the range of 10 seconds to 5 minutes.

[0060] The heat treatment in the heat treatment step is preferably carried out in a non-oxidizing atmosphere from the viewpoint of preventing oxidation of the metals constituting the substrate 2 and the surface coating 3 of the material for electronic components 1, and more specifically, is preferably carried out in an inert gas atmosphere or a reducing gas atmosphere. ２In addition to Ar, He, etc., a mixed gas of two or more of these can be used. ２ , CO, CH ４ In addition to the above, a mixed gas of two or more of these, for example, H ２ A mixed gas of HCl and CO can be used.

[0061] In this way, by adjusting the bath temperature of the plating bath to the range of 30°C to 40°C in the coating formation process and performing electroplating using pulse current to form the Ni-containing layer 31 on the electronic component material 1, it is possible to obtain a lead frame material 10 in which the average grain size of the crystalline phase contained in the Ni-containing layer 31, when viewed in a cross section including the thickness direction t, is in the range of 0.10 μm to 0.60 μm, the average value of GAM in the cross section including the thickness direction t is in the range of 0.90° to 1.90°, and the most frequent value of GAM in the cross section is 0.6° or more.

[0062] <Uses of Lead Frame Material> The lead frame material 10 of the present invention is used as a connection terminal for supporting and fixing a semiconductor element and exchanging electricity and signals with the outside via wires, a printed circuit board, etc., and is preferably used, for example, in a semiconductor package having a lead frame formed using the lead frame material. Here, examples of semiconductor elements that can be mounted in the semiconductor package include, but are not limited to, transistors, capacitors, LEDs, etc.

[0063] Furthermore, the electronic component material 1 of the present invention has high solder wettability even when heated at, for example, 400° C., assuming the assembly of a semiconductor package, and therefore can be preferably used for semiconductor packages equipped with such lead frames. Furthermore, even when used in a high-temperature environment of around 120° C., the electronic component material 1 and lead frame material 10 of the present invention are unlikely to cause a decrease in the connection reliability of the lead frame due to the Ni atoms constituting the Ni-containing layer 31 diffusing to the surface of the lead frame and reacting with the solder or wire, and therefore can achieve high reliability, particularly in semiconductor packages for automotive applications.

[0064] Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, but includes all aspects encompassed by the concept of the present invention and the scope of the claims, and can be modified in various ways within the scope of the present invention.

[0065] Next, in order to further clarify the effects of the present invention, examples of the present invention and comparative examples will be described, but the present invention is not limited to these examples of the present invention.

[0066] <Pretreatment of Base> A conductive base 2 made of a metal or alloy of the type shown in Table 1 and having a thickness of 0.1 mm and a size of 50 mm length x 50 mm width was prepared by pressing in advance, and cathodic electrolytic degreasing and pickling were performed as pretreatment.

[0067] Here, the cathodic electrolytic degreasing is carried out by heating an aqueous solution of sodium hydroxide with a concentration of 60 g / L as a degreasing solution in an electrolytic cell, immersing the substrate 2 in the degreasing solution heated to 60°C and connecting it to the anode of the electrolytic cell, and applying a current of 2.5 A / dm ２ The treatment was carried out by passing a current at a current density of 1000 kJ / min for 60 seconds.

[0068] The pickling was carried out by immersing the substrate 2 after cathodic electrolytic degreasing in 10 mass % sulfuric acid at room temperature for 30 seconds. Here, for Inventive Example 3 using 42 alloy as the substrate 2, the substrate 2 after pickling was immersed in 10 mass % hydrochloric acid at room temperature for 30 seconds.

[0069] <Formation of Ni-Containing Layer> Thereafter, the Ni-containing layer 31 was formed on all surfaces (front, back and side surfaces) of the base 2 by electroplating under the conditions shown below.

[0070] [Ni-Ge Plating (when the "type of added element" of the Ni-containing layer listed in Table 1 is Ge)] For Inventive Examples 1 to 3, an aqueous solution containing nickel sulfamate with a nickel (Ni) metal concentration of 90 g / L to 110 g / L, 30 g / L nickel chloride, 30 g / L boric acid, and 100 mg / L germanium oxide was prepared as the electroplating solution. 1 L of the electroplating solution was placed in a cylindrical plating electrolytic cell with an inner diameter of 80 mm, and the electroplating was conducted at a temperature of 30°C to 40°C and a current of 15 A / dm ２The Ni-containing layer 31 was formed by electroplating by applying pulse current at a current density of 0.05 to 0.20 and a pulse number of 1 pps to 10 pps.

[0071] On the other hand, for Comparative Example 3, an aqueous solution containing nickel sulfamate at a concentration of 90 g / L of nickel (Ni) metal, 30 g / L of nickel chloride, 30 g / L of boric acid, and 100 mg / L of germanium oxide was prepared as an electroplating solution. 1 L of the electroplating solution was placed in a cylindrical plating electrolytic cell with an inner diameter of 80 mm, and the electroplating solution was heated at 50° C. and 3 A / dm ２ The Ni-containing layer 31 was formed by electroplating by continuously passing a current at a current density of 1000 kJ / cm 2 .

[0072] [Ni-Mn Plating (when the "type of added element" of the Ni-containing layer listed in Table 1 is Mn)] For Inventive Examples 4 and 5, an aqueous solution containing, in terms of nickel (Ni) metal concentration, 90 g / L of nickel sulfamate, 30 g / L of nickel chloride, 30 g / L of boric acid, and 5 g / L of manganese sulfamate was prepared as the electroplating solution. 1 L of the electroplating solution was placed in a cylindrical plating electrolytic cell with an inner diameter of 80 mm, and the plating was conducted at a temperature of 30 to 40°C and a current of 15 A / dm ２ The Ni-containing layer 31 was formed by electroplating by applying pulse current at a current density of 0.05 to 0.20 and a pulse number of 1 pps to 10 pps.

[0073] On the other hand, for Comparative Example 4, an aqueous solution containing nickel sulfamate at a concentration of 90 g / L of nickel (Ni) metal, 30 g / L of nickel chloride, 30 g / L of boric acid, and 5 g / L of manganese sulfamate was prepared as an electroplating solution. 1 L of the electroplating solution was placed in a cylindrical plating electrolytic cell with an inner diameter of 80 mm, and the electroplating solution was heated at a temperature of 50° C. and a current of 3 A / dm ２ The Ni-containing layer 31 was formed by electroplating by continuously passing a current at a current density of 1000 kJ / cm 2 .

[0074] [Ni-Zn Plating (when the "type of added element" of the Ni-containing layer listed in Table 1 is Zn)] An aqueous solution containing nickel sulfate with a nickel (Ni) metal concentration ranging from 75 g / L to 110 g / L, 30 g / L of boric acid, and 10 g / L of zinc sulfate was prepared as an electroplating solution. 1 L of the electroplating solution was placed in a cylindrical plating electrolytic cell with an inner diameter of 80 mm, and the electroplating was conducted at a temperature of 30°C to 40°C and a current of 15 A / dm ２ The Ni-containing layer 31 was formed by electroplating by applying pulse current at a current density of 0.05 to 0.20 and a pulse number of 1 pps to 10 pps.

[0075] [Ni-P Plating (when the "type of added element" of the Ni-containing layer listed in Table 1 is P)] An aqueous solution containing nickel sulfate at a nickel (Ni) metal concentration of 75 g / L, 30 g / L of boric acid, and 10 g / L of sodium hypophosphite was prepared as an electroplating solution. 1 L of the electroplating solution was placed in a cylindrical plating electrolytic cell with an inner diameter of 80 mm, and the electroplating was conducted at a temperature of 30 to 40°C and a current of 15 A / dm ２ The Ni-containing layer 31 was formed by electroplating by applying pulse current at a current density of 0.05 to 0.20 and a pulse number of 1 pps to 10 pps.

[0076] [Ni-Zn-P Plating (when the "type of added element" of the Ni-containing layer listed in Table 1 is Zn and P)] An aqueous solution containing, in terms of nickel (Ni) metal concentration, 75 g / L of nickel sulfate, 30 g / L of boric acid, 10 g / L of zinc sulfate, and 5 g / L of sodium hypophosphite was prepared as an electroplating solution. 1 L of the electroplating solution was placed in a cylindrical plating electrolytic cell with an inner diameter of 80 mm, and the electroplating was conducted at a temperature of 40°C and a current of 15 A / dm ２ A pulse current was applied at a current density of 0.10, a duty ratio of 0.10, and a pulse number of 1 pps to 10 pps, thereby forming a Ni-containing layer 31 by electroplating.

[0077] [Ni Plating (When the "Type of Added Element" of the Ni-Containing Layer in Table 1 is No Added Element)] For Inventive Examples 11 and 12, an aqueous solution containing nickel sulfamate at a nickel (Ni) metal concentration of 90 g / L, nickel chloride at 30 g / L, and boric acid at 30 g / L was prepared as the electroplating solution. 1 L of the electroplating solution was placed in a cylindrical plating electrolytic cell with an inner diameter of 80 mm, and the plating was conducted at a temperature of 30 to 40°C and a current of 15 A / dm ２ The Ni-containing layer 31 was formed by electroplating by applying pulse current at a current density of 0.05 to 0.20 and a pulse number of 1 pps to 10 pps.

[0078] On the other hand, for Comparative Example 1, an aqueous solution containing nickel sulfamate at a concentration of 90 g / L of nickel (Ni) metal, 30 g / L of nickel chloride, and 30 g / L of boric acid was prepared. 1 L of the electroplating solution was placed in a cylindrical plating electrolytic cell with an inner diameter of 80 mm, and the electroplating solution was heated at a temperature of 50°C and a current of 15 A / dm ２ The Ni-containing layer 31 was formed by electroplating by continuously passing a current at a current density of 1000 kJ / cm 2 .

[0079] For Comparative Example 2, an aqueous solution containing nickel sulfamate at a concentration of 90 g / L, nickel chloride at a concentration of 30 g / L, and boric acid at a concentration of 30 g / L was prepared. 1 L of the electroplating solution was placed in a cylindrical plating electrolytic cell with an inner diameter of 80 mm, and the electroplating solution was heated at a temperature of 55°C and a current of 10 A / dm ２ The Ni-containing layer 31 was formed by electroplating by continuously passing a current at a current density of 1000 kJ / cm 2 .

[0080] <Formation of Surface Coating Layer> Next, for Inventive Examples 1 to 9, 11, and 12 and Comparative Examples 2 to 4, a surface coating layer 32 was formed. In this case, the surface coating layer 32 was formed on all surfaces (front, back, and side) of the Ni-containing layer 31 by electroplating under the conditions shown below to the thickness shown in Table 1. Of these, for Inventive Examples 1 to 6, 10 to 12, and Comparative Examples 2 to 4, the surface coating layer 32 was composed of two layers, with a first surface coating layer 32a as the lower layer and a second surface coating layer 32b as the upper layer. For Inventive Examples 7 to 9, the surface coating layer 32 was formed as a single layer. The electroplating conditions and the thickness of the surface coating layer 32 at this time are listed in the lower layer column in Table 1, and no upper layer was formed. In this manner, the coating film formation step of forming a surface coating 3 on the surface of the substrate 2 was performed, thereby obtaining materials for electronic components 1 for the Inventive Examples and Comparative Examples.

[0081] [Pd plating (when the "type of metal or alloy" of the lower layer described in Table 1 is Pd)] As an electroplating solution, dichlorotetraamminepalladium (Pd(NH ３ ) ４ Cl ２ ), 90 mL / L of 25% by mass ammonia water, 50 g / L of ammonium sulfate, and 10 g / L of Palla Sigma LN brightener (trade name, manufactured by Matsuda Sangyo Co., Ltd.). 1 L of the electroplating solution was placed in a cylindrical plating electrolytic cell with an inner diameter of 80 mm, and the electroplating solution was heated at 60°C and 5 A / dm ２ The first surface coating layer 32a, which is the lower layer, was formed by electroplating by passing a current at a current density of 1000 kJ / cm2.

[0082] [Au Plating (when the "type of metal or alloy" of the lower or upper layer listed in Table 1 is Au)] An aqueous solution containing potassium gold cyanide with a gold (Au) metal concentration of 14.6 g / L, 150 g / L of citric acid, and 180 g / L of potassium citrate was prepared as an electroplating solution. 1 L of the electroplating solution was placed in a cylindrical plating electrolytic cell with an inner diameter of 80 mm, and the plating was conducted at a temperature of 40° C. and a current of 1 A / dm ２By passing a current at a current density of 1000 kJ / cm, a first surface coating layer 32a as a lower layer or a second surface coating layer 32b as an upper layer was formed by electroplating.

[0083] [AuCo Plating (when the "Type of Metal or Alloy" of the Lower Layer in Table 1 is AuCo)] An aqueous solution containing potassium gold cyanide with a gold (Au) metal concentration of 10 g / L, cobalt carbonate with a cobalt (Co) metal concentration of 0.1 g / L, citric acid at 100 g / L, and dipotassium hydrogen phosphate at 20 g / L was prepared as an electroplating solution. 1 L of the electroplating solution was placed in a cylindrical plating electrolytic cell with an inner diameter of 80 mm, and the plating was conducted at a temperature of 40° C. and a current of 1 A / dm ２ The first surface coating layer 32a, which is the lower layer, was formed by electroplating by passing a current at a current density of 1000 kJ / cm2.

[0084] [Ag Plating (when the "type of metal or alloy" of the lower layer listed in Table 1 is Ag)] An aqueous solution containing silver cyanide with a silver (Ag) metal concentration of 93 g / L and potassium cyanide at 132 g / L was prepared as an electroplating solution. 1 L of the electroplating solution was placed in a cylindrical plating electrolytic cell with an inner diameter of 80 mm, and the plating was conducted at a temperature of 20°C and a current of 1 A / dm ２ The first surface coating layer 32a, which is the lower layer, was formed by electroplating by passing a current at a current density of 1000 kJ / cm2.

[0085] <Production of lead frame material> The obtained electronic component material 1 was subjected to a heat treatment process in which it was heated on a hot plate at a heating temperature of 400°C for a heating time of 30 seconds, assuming the thermal history during assembly of a semiconductor package, particularly during resin molding, to produce a lead frame material 10.

[0086] <Various Measurement and Evaluation Methods> Next, the properties of the obtained electronic component material 1 and the lead frame material 10 obtained by subjecting the electronic component material 1 to a heat treatment process were measured and evaluated as follows. Note that the properties of each layer constituting the electronic component material 1 and the lead frame material 10 were measured at any time during or after the production of the electronic component material 1 and the lead frame material 10.

[0087] [1] Measurement of Average Crystal Grain Size of Ni-Containing Layer The average crystal grain size of the crystalline phase contained in the Ni-containing layer 31 of the electronic component material 1 and the lead frame material 10 was determined by a cross-section method. More specifically, cross sections of the electronic component material 1 and the lead frame material 10, which were finished using a cross-section polisher (manufactured by JEOL Ltd.) or the like and included the thickness direction t and the rolling direction of the substrate 2, were observed using a scanning electron microscope (SEM). In the resulting scanning electron microscope (SEM) image, ten 5 μm-long line segments parallel to the surface of the substrate 2 were drawn, and the total number of intersections between each line segment and the boundaries of the crystal grains was counted. The average length of each line segment defined by the boundaries of the crystal grains was calculated using the following formula (I), thereby determining the average crystal grain size, which is the average length of each line segment. The results are shown in Table 1. Average length per line segment [μm] = 5 [μm] × 10 / (total number of intersections between the line segments and the crystal grain boundaries) (I)

[0088] [2] Measurement of the average and mode values ​​of GAM in the Ni-containing layer The average and mode values ​​of GAM in the Ni-containing layer 31 of the electronic component material 1 and the lead frame material 10 were obtained from crystal orientation analysis data calculated using analysis software (TSL Solutions, OIM Analysis) from crystal orientation data continuously measured using an EBSD detector (TSL Solutions, OIM5.0 HIKARI) attached to the microscope, for each cross section including the thickness direction t, which was finished using a cross-section polisher (JEOL Ltd.). The measurement magnification of the cross section was 30,000 times, and the measurement was performed at measurement intervals of 50 nm or less. Among these measurement points, measurement points with a reliability index CI value of 0.1 or less were excluded from the analysis, and boundaries where the orientation difference between adjacent measurement points was 5.00° or more were considered to be grain boundaries. The average GAM value for each measurement region was calculated. This measurement was performed on five different measurement regions within the cross section of the same Ni-containing layer 31, and the average of the five measurement regions was calculated from the average GAM values ​​obtained for each measurement region. This resulted in the calculation of the average GAM value of the Ni-containing layer 31 for each of the electronic component material 1 and the lead frame material 10. Furthermore, the GAM values ​​of all measurement points included in these five measurement regions to be analyzed were rounded to the nearest tenth to obtain a frequency distribution in 0.1° increments, and the most frequent value in this frequency distribution was determined as the most frequent GAM value. The results are shown in Table 1.

[0089] [3] Evaluation of Solder Wettability For each of the obtained electronic component materials 1 and lead frame materials 10, the solder wetting time was measured using a solder checker (SAT-5100 (trade name, manufactured by Rhesca Corporation)) by the wetting balance method specified in JIS Z3198-4, Lead-Free Solder Test Methods - Part 4: Wetting Balance and Contact Angle Methods. The solder bath temperature was 250°C, Sn-3Ag-0.5Cu solder was used for the solder bath, the immersion speed was 10 mm / sec, the immersion depth was 2 mm, and the immersion time was 10 seconds. Isopropyl alcohol containing 25% by mass of rosin was used as the flux. Among the examples and comparative examples of the present invention, for those having a surface coating layer 32, the solder wettability on the surface of the surface coating layer 32 was evaluated.

[0090] The zero cross time (the time t when wetting begins) was measured for each of the electronic component material 1 and the lead frame material 10. ０ When the measured zero cross time was less than 2.0 seconds, the solder wettability was evaluated as excellent and marked with a "◎". When the measured zero cross time was 2.0 seconds or more and less than 10.0 seconds, the solder wettability was evaluated as good and marked with a "◯". On the other hand, when the measured zero cross time was 10.0 seconds or more, the solder wettability was evaluated as poor and marked with a "×". The results are shown in Table 2.

[0091] [4] Evaluation of Wire Bondability (Evaluation before High-Temperature Holding Test described later) For the obtained electronic component material 1, a bonding wire was fixed to the surface of the surface coating under the following wire bonding conditions, and the pull strength after a 10-point test was measured. Wire bonder: SWB-FA-CUB-10 (trade name, manufactured by Shinkawa Co., Ltd.) Wire: 25 μm Gold wire bonding temperature: 150° C. Capillary: 1820-15-437GM (model number, manufactured by Coorstek Inc.) 1st conditions: 10 msec., 45 bits, 45 g 2nd conditions: 10 msec., 100 bits, 130 g

[0092] When the measured pull strength of the bonding wire was 0.080 N or more, the wire bonding property was evaluated as "◎" as being particularly excellent. When the pull strength was 0.070 N or more but less than 0.080 N, the wire bonding property was evaluated as "◯" as being good. On the other hand, when the pull strength was less than 0.070 N, the wire bonding property was evaluated as "×" as being poor. The results are shown in Table 2.

[0093] [5] Evaluation of reliability of solder connection after high-temperature retention test A solder layer of 10 μm in thickness was formed on the surface of the obtained material for electronic components 1 using a solder checker (SAT-5100 (trade name, manufactured by Rhesca Corporation)). A high-temperature retention test was carried out on the test material by heating it at a temperature of 125° C. for 1,000 hours in a thermostatic chamber containing air at normal pressure.

[0094] After the high-temperature retention test, the test material having a solder layer formed on the material for electronic components 1 was finished at the position where the solder layer was cut using a cross-section polisher (manufactured by JEOL Ltd.) or the like to form a cross section including the thickness direction t and the rolling direction of the base 2. This cross section was observed using a scanning electron microscope (SEM), and for any 10 fields of view in the cross section, the direction parallel to the surface of the base 2 was defined as the width direction, and the total number of voids and cracks present in specific regions of the solder layer defined by a width of 50 μm was counted, and the average number for the 10 fields of view was calculated.

[0095] When the average total number of voids and cracks calculated was less than 0.7, the solder layer had particularly few defects due to compound formation when used in a high-temperature environment of around 120°C, and the reliability of the solder connection was evaluated as "Excellent". When the average total number of voids and cracks was 0.7 or more but less than 3.0, the solder layer had few defects due to compound formation when used in a high-temperature environment of around 120°C, and the reliability of the solder connection was evaluated as "Good". On the other hand, when the average total number of voids and cracks was 3.0 or more, the solder layer had many defects due to compound formation when used in a high-temperature environment of around 120°C, and the reliability of the solder connection was evaluated as "Poor". The results are shown in Table 2.

[0096] [6] Evaluation of Wire Bondability After High-Temperature Holding Test A test material was prepared by bonding wires attached to the surface of the surface coating of the obtained electronic component material 1 under the following wire bonding conditions. The test material was heated at 125°C for 1000 hours in a thermostatic chamber containing atmospheric air. After the high-temperature holding test, the test material was measured for pull strength after a 10-point test. Wire bonder: SWB-FA-CUB-10 (trade name, manufactured by Shinkawa Co., Ltd.) Wire: 25 μm Gold wire bonding temperature: 150°C Capillary: 1820-15-437GM (model number, manufactured by Coorstek Inc.) 1st condition: 10 msec, 45 bits, 45 g 2nd condition: 10 msec, 100 bits, 130 g

[0097] When the measured pull strength of the bonding wire was 0.080 N or more, the wire bonding property was evaluated as "◎" as being particularly excellent. When the pull strength was 0.070 N or more but less than 0.080 N, the wire bonding property was evaluated as "◯" as being good. On the other hand, when the pull strength was less than 0.070 N, the wire bonding property was evaluated as "×" as being poor. The results are shown in Table 2.

[0098] [7] Overall Evaluation Among these evaluation results, for the five evaluation results regarding the solder wettability of the electronic component material, the solder wettability of the lead frame material, the wire bondability before and after the high-temperature test, and the reliability of the solder connection after the high-temperature test, if all five were evaluated as "◎", the electronic component material had excellent solder wettability even when heated to about 400°C, simulating the assembly of a semiconductor package, and had excellent connection reliability even when used in a high-temperature environment of about 120°C. Furthermore, if all three of these five evaluation results were evaluated as "◎" or "○" (excluding cases where all five were evaluated as "◎"), the electronic component material had good or excellent solder wettability even when heated to about 400°C, simulating the assembly of a semiconductor package, and had good or excellent connection reliability even when used in a high-temperature environment of about 120°C, and was evaluated as "○". On the other hand, if at least one of these five evaluation results was "x", it was evaluated as "x" because the solder wettability was poor at least either before or after heating, which is assumed to occur during assembly of a semiconductor package, or the connection reliability was poor when placed in a high-temperature environment of around 120°C. The results are shown in Table 2.

[0099]

[0100]

[0101] From the results in Table 1, the average crystal grain size of the Ni-containing layer 31 when viewed in a cross section including the thickness direction t, and the average and mode values ​​of the GAM in this cross section, were all within the appropriate ranges of the present invention for the electronic component materials and lead frame materials of Examples 1 to 12. At this time, the electronic component materials and lead frame materials of Examples 1 to 12 were evaluated as "◎" or "◯" in five categories: the solder wettability of the electronic component material, the solder wettability of the lead frame material, the wire bondability before and after the high-temperature retention test, and the reliability of the solder connection after the high-temperature retention test.

[0102] In contrast, the electrical contact material of Comparative Example 1, in which the bath temperature of the electroplating solution was 50°C, which is higher than the preferred range, and in which the Ni-containing layer 31 was formed by continuous current application, had an average crystal grain size when viewed in a cross section including the thickness direction t, which was larger than the appropriate range of the present invention, and the three evaluation results regarding the solder wettability of the lead frame material, the reliability of the solder connection after the high-temperature retention test, and the wire bondability after the high-temperature retention test were all evaluated as ``X.''

[0103] In addition, the bath temperature of the electroplating solution was 55°C, which was higher than the preferred range, and 10 A / dm ２ The electrical contact material of Comparative Example 2, in which a Ni-containing layer 31 was formed by continuous current flow at a current density of 0.05, had an average GAM value in a cross section including the thickness direction t that was greater than the appropriate range of the present invention, and the three evaluation results regarding the solder wettability of the lead frame material, the reliability of the solder connection after the high-temperature retention test, and the wire bonding property after the high-temperature retention test were all evaluated as "X".

[0104] In addition, the bath temperature of the electroplating solution was 50°C, which was higher than the preferred range, and 3 A / dm ２ In the electrical contact material of Comparative Example 3, in which a Ni-containing layer 31 was formed by continuous current flow at a current density of 0.05, the average value and the mode of the GAM in the cross section including the thickness direction t were smaller than the appropriate range of the present invention, and both the results of the evaluation of the reliability of the solder connection after the high-temperature holding test and the wire bonding property after the high-temperature holding test were evaluated as "X".

[0105] In addition, the bath temperature of the electroplating solution was 50°C, which was higher than the preferred range, and 3 A / dm ２ The electrical contact material of Comparative Example 4, in which a Ni-containing layer 31 was formed by continuous current flow at a current density of 0.15, had an average crystal grain size when viewed in a cross section including the thickness direction t that was larger than the appropriate range of the present invention, and the results of the evaluation of the solder wettability of the lead frame material, the reliability of the solder connection after the high-temperature retention test, and the wire bonding property after the high-temperature retention test were all evaluated as "X".

[0106] Therefore, it was revealed that the electronic component material 1 and the lead frame material 10 of Examples 1 to 12 of the present invention have high solder wettability even when heated at, for example, 400°C, assuming the assembly of a semiconductor package, and that even when used in a high-temperature environment of around 120°C, the Ni atoms constituting the Ni-containing layer are less likely to diffuse to the surface and react with solder or wire, resulting in a decrease in connection reliability.

[0107] REFERENCE SIGNS LIST 1, 1A Electronic component material 10, 10A Lead frame material 2 Base 21 Surface of base 3, 3A Surface coating 31 Ni-containing layer 32 Surface coating layer 32a First surface coating layer (or lower layer) 32b Second surface coating layer (or upper layer) t Thickness direction of electronic component material (or lead frame material)

Claims

1. A material for electronic components having a substrate made of a conductive material and a surface coating formed on at least a portion of the surface of the substrate, wherein the surface coating has a Ni-containing layer containing Ni, and the Ni-containing layer has an average crystal grain size in the range of 0.10 μm to 0.50 μm when viewed in a cross section including the thickness direction of the material for electronic components, and wherein the average value of GAM in the cross section obtained by crystal orientation analysis using electron backscatter diffraction (EBSD) is in the range of 0.95° to 2.00°, and the most frequent value of GAM in the cross section is 0.7° or more.

2. The material for electronic components according to claim 1, wherein the Ni-containing layer is made of a Ni alloy, and the Ni alloy has an alloy composition containing one or more additive components selected from the group consisting of germanium (Ge), manganese (Mn), zinc (Zn), phosphorus (P), cobalt (Co), molybdenum (Mo) and tungsten (W), with the balance consisting of Ni and unavoidable impurities.

3. The material for electronic components according to claim 2, wherein the Ni alloy has an alloy composition containing the additive components in a total range of 0.01 mass % to 10.0 mass %.

4. The material for electronic components according to claim 1, wherein the surface coating further comprises at least one surface coating layer on the Ni-containing layer.

5. The material for electronic components according to claim 4, wherein the surface coating layer is made of copper, copper alloy, cobalt, cobalt alloy, palladium, palladium alloy, rhodium, rhodium alloy, ruthenium, ruthenium alloy, platinum, platinum alloy, iridium, iridium alloy, gold, gold alloy, silver, silver alloy, tin, tin alloy, indium or indium alloy.

6. The material for electronic components according to claim 1, wherein the substrate is made of copper, a copper alloy, iron, an iron alloy, aluminum, or an aluminum alloy.

7. A method for producing a material for electronic components according to any one of claims 1 to 6, comprising a coating formation step of forming the surface coating on at least a part of the surface of the substrate by electroplating.

8. A lead frame material having a substrate made of a conductive material and a surface coating formed on at least a portion of the surface of the substrate, wherein the surface coating has a Ni-containing layer containing Ni, and the Ni-containing layer has an average crystal grain size in the range of 0.10 μm to 0.60 μm when viewed in a cross section including the thickness direction of the lead frame material, and the average value of GAM in the cross section obtained by crystal orientation analysis using electron backscatter diffraction (EBSD) is in the range of 0.90° to 1.90°, and the most frequent value of GAM in the cross section is 0.6° or more.

9. A method for producing a lead frame material as set forth in claim 8, comprising: a coating formation step of forming the surface coating on at least a portion of the surface of the base by electroplating to obtain a material for electronic components; and a heat treatment step of subjecting the material for electronic components to heat treatment to obtain a lead frame material.

10. A semiconductor package having a lead frame formed using the lead frame material according to claim 8.

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