Al connecting material

Abstract

Provided is an Al connection material which can suppress generation of internal cracks when being manufactured and which exhibits excellent temperature cycle reliability. This Al connection material contains 3.0-12.0 mass% of Si and contains at least one of Sr, Na, Eu, and Ca in a total amount of 5-800 mass ppm.

Description

Technical Field

[0001] The present invention relates to an Al connection material.

Background Art

[0002] In a semiconductor device, the electrodes formed on a semiconductor chip are connected to the electrodes on a lead frame or a substrate by bonding wires (wires) or bonding ribbons (strips). In a power semiconductor device, bonding wires and bonding ribbons mainly made of aluminum (Al) are used. The wire diameter of an Al bonding wire is mainly in the range of 100 μm to 600 μm, and for an Al bonding ribbon, the width is mainly in the range of 100 μm to 3000 μm and the thickness is mainly in the range of 50 μm to 600 μm. Here, Al bonding wires and Al bonding ribbons are collectively referred to as Al connection materials.

[0003] In a power semiconductor device, silicon (Si) is often used as the material of a semiconductor chip, and Al-Si alloys and Al-Cu alloys are often used as the materials of the electrodes formed on the semiconductor chip. Also, power semiconductor devices using Al connection materials are often used as large power equipment such as air conditioners and solar power generation systems, and semiconductor devices for vehicles.

[0004] Regarding the bonding method of the Al connection material, there are a first bonding with the electrodes on the semiconductor chip and a second bonding with the electrodes on the lead frame or the substrate, and in both cases, wedge bonding is used. Wedge bonding is a method in which ultrasonic vibration and a load are applied to the Al connection material through a metal jig (tool) to break the surface oxide film of the Al connection material and the electrode material to expose a fresh surface, and solid-phase diffusion bonding is performed. This connection method is characterized by connecting in a solid state without melting the connection material, and is a bonding technique different from welding techniques that melt the connection material.

[0005] Next-generation power semiconductor devices are required to operate stably over longer periods compared to general-purpose power semiconductor devices. Power semiconductor devices operate by repeatedly switching the current on and off. When current is supplied to a silicon semiconductor chip through an Al connector, the temperature of the first junction rises. Conversely, when the current supply is stopped, the temperature of the first junction decreases. In this way, the first junction repeatedly heats up and cools down during the operation of the power semiconductor. As a result, thermal stress is repeatedly applied to the first junction due to the difference in thermal expansion between the Al connector and the semiconductor chip. When a connector made only of high-purity Al is used, the Al connector breaks down relatively quickly due to thermal stress, making it difficult to satisfy the performance required for next-generation power semiconductor devices. Therefore, next-generation power semiconductors require improved junction life (hereinafter also referred to as "temperature cycle reliability") in relation to the heating and cooling of the first junction.

[0006] In response to the requirements for temperature cycling reliability, aluminum (Al) connectors have been proposed that focus primarily on improving mechanical strength. As a method to improve the mechanical properties of Al connectors, a technique involving the addition of specific elements to Al has been proposed.

[0007] Patent Document 1 discloses a bonding wire made of an Al alloy containing at least magnesium (Mg) and silicon (Si), wherein the total content of Mg and Si is 0.03% by mass or more and 0.3% by mass or less. This patent document discloses that the decrease in bonding strength of the 1st joint in a cold temperature cycle test in the temperature range of 70°C to 120°C is delayed due to the effect of increased strength through solid solution strengthening of Mg and Si and the crack propagation suppression effect of precipitated magnesium silicide (Mg2Si).

[0008] Patent Document 2 discloses a bonding wire characterized by being made of an alloy containing 0.01 to 0.2 mass% iron (Fe), 1 to 20 mass ppm silicon (Si), and the remainder being Al with a purity of 99.997 mass% or higher, having a solid solution amount of Fe of 0.01 to 0.06%, a precipitation amount of Fe of 7 times or less the solid solution amount of Fe, and a microstructure with an average crystal grain diameter of 6 to 12 μm. This patent document discloses that by uniformly dispersing intermetallic compound particles of Fe and Al in Al to improve the mechanical strength of the matrix, and further refining the recrystallized grains, the decrease in bonding strength of the 1st joint in thermal shock tests in the temperature range of -50°C to 200°C can be suppressed.

[0009] Patent Document 3 discloses a bonding wire made by melting an Al-Si alloy containing 0.1 to 5 mass% silicon (Si) with the remainder being Al and impurities, and then ejecting and rapidly cooling it to form a fine wire. This patent document also discloses that the mechanical strength is improved by rapidly cooling the molten Al-Si alloy to finely and uniformly disperse the Si. [Prior art documents] [Patent Documents]

[0010] [Patent Document 1] Japanese Patent Publication No. 2014-131010 [Patent Document 2] Japanese Patent Publication No. 2014-129578 [Patent Document 3] Japanese Patent Application Publication No. 59-57440 [Overview of the Initiative] [Problems that the invention aims to solve]

[0011] As mentioned above, next-generation power semiconductor devices are required to withstand longer operating times compared to general-purpose power semiconductor devices. During operation of a power semiconductor device, the temperature of the 1st junction repeatedly rises and falls. As a result, because the Al connector has a larger coefficient of thermal expansion than the semiconductor chip, thermal stress occurs at the 1st junction due to the difference in the coefficients of thermal expansion between the two, and in some cases the Al connector may ultimately suffer fatigue failure. One test to accelerate the evaluation of the lifespan (temperature cycle reliability) of the 1st junction in relation to such temperature rises and falls is the temperature cycle test. Al connectors used in next-generation power semiconductors are required to exhibit excellent temperature cycle reliability in temperature cycle tests. However, when using Al connectors with increased strength due to the addition of Si, etc., as disclosed in Patent Documents 1 to 3, it has been confirmed that in temperature cycle tests intended for use in next-generation power semiconductor devices, cracks propagate at a relatively fast rate within the Al alloy electrode, which has lower strength than the Al connector, making it difficult to stably obtain good temperature cycle reliability.

[0012] Furthermore, Al alloys containing high concentrations of alloying elements can lead to hardening, resulting in reduced workability, decreased manufacturing yield, and lower quality, hindering practical application. We have found that in Al connectors strengthened by the addition of Si, etc., cracks (hereinafter referred to as "internal cracks") may occur within the Al connector during wire drawing. This is thought to be due to the formation of coarse Si precipitates and non-uniform plastic deformation of the Al phase. Since internal cracks can induce defects such as reduced temperature cycle reliability and melting fracture when high currents are applied, it is necessary to suppress the occurrence of internal cracks.

[0013] The present invention aims to provide an Al connector that can suppress the occurrence of internal cracks during manufacturing and exhibits excellent temperature cycling reliability. [Means for solving the problem]

[0014] As a result of diligent research into the above-mentioned problems, the inventors of the present invention have found that an Al connecting material containing 3.0% to 12.0% by mass of Si and one or more of Sr, Na, Eu, and Ca in a total amount of 5 ppm to 800 ppm by mass can solve the above-mentioned problems. Based on this finding, the inventors have completed the present invention through further research.

[0015] In other words, the present invention includes the following: <1> It contains 3.0% by mass or more and 12.0% by mass or less of Si, and An aluminum binder containing one or more of the following elements in a total amount of 5 ppm by mass or more and 800 ppm by mass or less. <2> When the crystal orientation of the Si phase in the L-shaped cross-section (cross-section in the direction of the central axis including the central axis) of the Al connecting material is measured, the angular difference with respect to the central axis is 15° or less. <111> Crystal orientation and <110> The sum of the orientation ratios of the crystal orientations is between 20% and 70%. <1> Al connecting material as described above. <3> The average diameter of the Si phase in the L section is between 0.8 μm and 4 μm. <1> or <2> Al connecting material as described above. <4> Furthermore, it contains one or more of Ti, B, or Zr in a total amount of 10 ppm by mass or more and 500 ppm by mass or less. <1> ~ <3> Al connecting material as described in any of the following. <5> Furthermore, it contains one or more of Ni, Y, Yb, and Sc in a total amount of 5 ppm by mass or more and 500 ppm by mass or less. <1> ~ <4> Al connecting material as described in any of the following. [Effects of the Invention]

[0016] According to the present invention, it is possible to provide an Al connector that can suppress the occurrence of internal cracks during manufacturing and exhibits excellent temperature cycle reliability. [Brief explanation of the drawing]

[0017] [Figure 1]FIG. 1 is a schematic diagram for explaining a measurement target surface (inspection surface) when measuring the crystal orientation and average diameter of Si phases for an Al connection material. The measurement target surface is a cross-section (L cross-section) in the central axis direction including the central axis of the Al connection material. [Figure 2] FIG. 2 is a schematic diagram for explaining the void defect in the 1st joint. [Figure 3] FIG. 3 is an example of an internal crack of an Al connection material observed by a soft X-ray transmission device.

Embodiments for Carrying Out the Invention

[0018] Hereinafter, the present invention will be described in detail according to its preferred embodiments. Although the drawings may be referred to in the description, each drawing only schematically shows the shape, size, and arrangement of the components to an extent that the invention can be understood. The present invention is not limited to the following embodiments and examples, and can be arbitrarily modified and implemented without departing from the scope of the claims of the present invention and its equivalent scope.

[0019] [Al Connection Material] The Al connection material of the present invention is characterized by containing 3.0 mass% or more and 12.0 mass% or less of Si, and containing 5 mass ppm or more and 800 mass ppm or less in total of any one or more of Sr, Na, Eu, and Ca

[0020] As described above, in the temperature cycle test (TCT), when using a connection material composed only of high-purity Al, it was difficult to obtain good temperature cycle reliability because cracks propagated relatively quickly inside the connection material. On the other hand, when using an Al connection material strengthened by adding Si or the like, it was confirmed that it was difficult to obtain the temperature cycle reliability required for next-generation power semiconductor devices because cracks propagated inside the Al alloy electrode with relatively low strength. Furthermore, for Al connection materials strengthened by adding Si or the like, internal cracks sometimes occurred during their manufacture.

[0021] As a result of diligent research to solve the above problems, the inventors of the present invention have found that an Al connector containing 3.0% to 12.0% by mass of Si and one or more of Sr, Na, Eu, and Ca in a total amount of 5 ppm to 800 ppm by mass can suppress the occurrence of internal cracks during manufacturing and provide excellent temperature cycle reliability. The Al connector of the present invention thus makes a significant contribution to achieving the temperature cycle reliability required for next-generation power semiconductor devices.

[0022] The Al connector of the present invention contains 3.0% to 12.0% by mass of Si and is composed of an Al phase in which Si is solid-dissolved in Al and a Si phase formed by crystallization or precipitation of Si. Here, the Al phase may contain solid-dissolved elements other than Si. Furthermore, the Si phase is a general term for Si crystals and Si precipitates. Si crystals are formed from the dissolved solution during solidification and are coarse in size, about 1 to 20 μm, while Si precipitates are formed from the solid state and are small in size, about 0.1 to several μm.

[0023] The reason why the Al connector of the present invention can suppress the occurrence of internal cracks during manufacturing and provide excellent temperature cycle reliability is presumed to be as follows.

[0024] Regarding temperature cycling reliability, the Si phase has a lower coefficient of thermal expansion than Al, which contributes to reducing the difference in coefficients of thermal expansion between the Al connector and the semiconductor chip, and consequently, can reduce the thermal stress generated. Furthermore, the particulate Si phase can suppress the growth of cracks generated at the bonding interface into the Al connector.

[0025] Furthermore, regarding internal cracks, it is thought that the adhesion to the Al phase decreases or delamination occurs on the surface of the Si phase, which consists of coarse Si precipitates, and that this becomes the starting point for cracks. In this regard, it is thought that by containing a high concentration of Si and also containing a predetermined amount of one or more of Sr, Na, Eu, and Ca (hereinafter also referred to as the "first element group"), the adhesion at the interface between the Si phase and the Al phase is improved, and the occurrence of internal cracks can be suppressed. Possible reasons for this include the concentration of some of the first element group on the surface of the Si phase, improving adhesion, or the addition of the first element group causing the shape of the Si phase to become granular or closer to spherical, thus improving adhesion.

[0026] As described above, the Al connector of the present invention is presumed to suppress the occurrence of internal cracks during manufacturing and provide excellent temperature cycle reliability, as a result of appropriately controlling factors that contribute to suppressing internal cracks and improving temperature cycle reliability.

[0027] -Si concentration- A Si concentration in the range of 3.0 mass% to 12.0 mass% helps reduce thermal strain at the joint and improve temperature cycling characteristics. If it is less than 3.0 mass%, the improvement effect is small, and if it is greater than 12.0 mass%, problems arise such as a decrease in initial joint strength due to hardening and damage to the semiconductor chip. From the viewpoint of obtaining good temperature cycling reliability, the Si concentration in the Al connector of the present invention is 3.0 mass% or more, preferably 3.5 mass% or more, more preferably 3.6 mass% or more, 3.8 mass% or more, 4.0 mass% or more, 4.2 mass% or more, 4.4 mass% or more, 4.5 mass% or more, 4.6 mass% or more, 4.8 mass% or more, or 5.0 mass% or more. On the other hand, if the hardness of the Al connector is excessive, damage to the semiconductor chip is more likely to occur during the first bonding under commonly used ultrasonic vibration and load bonding conditions. From the viewpoint of obtaining good bonding strength when performing 1st bonding under general bonding conditions, the Si concentration in the Al connecting material of the present invention is 12.0 mass% or less, preferably 11.5 mass% or less or 11.0 mass% or less, more preferably 10.8 mass% or less, 10.6 mass% or less, 10.5 mass% or less, 10.4 mass% or less, 10.2 mass% or less or 10.0 mass% or less.

[0028] For analyzing the elemental concentrations contained in the Al connector of the present invention, for example, an ICP (Inductively Coupled Plasma) emission spectrometer or an ICP mass spectrometer can be used. If elements derived from atmospheric contaminants such as oxygen and carbon are adsorbed on the surface of the Al connector, it is effective to wash the surface with an acid or alkali depending on the adsorbed substance before performing the analysis.

[0029] -Concentrations of the first element group- From the viewpoint of suppressing the occurrence of internal cracks during manufacturing and obtaining good temperature cycle reliability, the total concentration of the first element group in the Al connector of the present invention is 5 ppm by mass or more, preferably 10 ppm by mass or more, more preferably 20 ppm by mass or more, 30 ppm by mass or more, 40 ppm by mass or more, or 50 ppm by mass or more, even more preferably 60 ppm by mass or more, 80 ppm by mass or more, or 100 ppm by mass or more, with an upper limit of 800 ppm by mass or less, preferably 750 ppm by mass or less or 700 ppm by mass or less, more preferably 650 ppm by mass or less or 600 ppm by mass or less, even more preferably 580 ppm by mass or less, 560 ppm by mass or less, or 550 ppm by mass or less. When the total concentration of the first element group is within the above preferred range, it is also beneficial from the viewpoint of easily achieving good 1st bond strength while suppressing damage to semiconductor chips.

[0030] -Crystal orientation of the Si phase in the L section- From the perspective of obtaining even better temperature cycle reliability and reducing the frequency of wire breakage during wire drawing, when the crystal orientation of the Si phase in the L-section of the Al connecting material is measured, the angular difference with respect to the central axis is 15° or less. <111> Crystal orientation and <110> The sum of the orientation ratios of the crystal orientations (hereinafter referred to as "Si phase") <111> + <110> Also called the "total ratio," the ratio is preferably in the range of 20% to 70%. In the present invention, the L-section of the Al connector, that is, the section in the direction of the central axis including the central axis of the Al connector, is as will be explained later in the "(Method for measuring the crystal orientation of the Si phase)" section with reference to Figure 1.

[0031] In addition to controlling the Al alloy composition as described above, the Si phase <111> + <110> By setting the total ratio within this range, effects such as extending the number of tests until a defect occurs that reduces bonding strength, and adapting to the widening of the temperature difference in temperature cycling tests can be obtained, thereby achieving even better temperature cycling reliability. This is because the Si phase <111> Crystal orientation and <110> It is thought that the alignment of crystal orientations improves the adhesion at the interface between the Si phase and the Al phase, and reduces deformation in the central axis direction of the Al connecting material, thereby suppressing defects such as crack propagation at the joint caused by thermal strain during temperature cycling tests. Furthermore, Al alloys containing high concentrations of Si (3.0% to 12.0% by mass) tend to experience an increased frequency of wire breakage during the wire drawing process. One possible reason is that Si phase particles crystallized during solidification cause stress concentration during wire drawing, inducing wire breakage. In this regard, by containing a predetermined amount of the first element group, and the Si phase <111> + <110> It is presumed that adjusting the total ratio to the above-mentioned preferred range will reduce wire breakage due to effects such as mitigating stress concentration during wire drawing. Si phase <111> + <110> The total ratio is more preferably 25% or more, even more preferably 26% or more, 28% or more, or 30% or more, from the viewpoint of obtaining even better temperature cycle reliability and reducing the frequency of wire breakage during wire drawing, and its upper limit is more preferably 65% ​​or less, even more preferably 60% or less, 58% or less, 56% or less, 55% or less, 54% or less, 52% or less, or 50% or less.

[0032] Si phase in the L-section of the Al connecting material <111> + <110> For measuring the total ratio, a method can be used that combines information on Al and Si concentrations obtained by SEM-EDS with information on crystal orientation obtained by backscattered electron diffraction (EBSD). Specifically, in a measurement area where the L-section of the Al connecting material is the inspection surface, Al and Si concentration measurements using EDS and crystal orientation analysis using EBSD are performed simultaneously. Subsequently, the Al phase and Si phase are separated and extracted from the EDS measurement results using analysis software attached to the instrument. Specifically, it is preferable to use the Chi Scan function of the analysis software OIM Data Collection or OIM Analysis (both manufactured by TSL Solutions) attached to the FE-SEM instrument. Then, for the region identified as the Si phase, the Si phase is separated using the analysis software attached to the instrument. <111> Crystal orientation and <110> The orientation ratio of crystal orientations can be calculated. In calculating this orientation ratio, a partial ratio is used, which is calculated using the area of ​​only the crystal orientations that could be identified within the measurement area based on a certain level of confidence as the population. Therefore, in one embodiment, the orientation ratio of the crystal orientations of the Si phase in the L cross section of the Al connecting material of the present invention is calculated by the following steps (1) to (3). (1) In a measurement area where the L-shaped cross-section of the Al connecting material is used as the inspection surface, the concentrations of Al and Si are measured using EDS and the crystal orientation is measured using EBSD simultaneously. (2) Use the Chi Scan function to separate and extract Al and Si. Specifically, by setting a Tolerance corresponding to the Si threshold from the Si EDS measurement results, Al and Si can be separated and identified. Using the crystal information of Al and Si from the material file, the crystal orientation can be analyzed. (3) For the region identified as the Si phase, the crystal orientation was analyzed, and the Si phase <111> The orientation ratio of the crystal orientation and <110> Calculate the orientation ratio of the crystal orientation.

[0033] In the procedure described in (2) above, the Tolerance (%) setting can be selected within the range of 20-40%, and for standard analysis of the L-section of the Al connector, it is preferable to compare at approximately 30%. A supplementary explanation of the procedure for adjusting this Tolerance is provided below. It is preferable to select or confirm the Tolerance value such that the shape and size of the Si phase extracted and identified by the Chi Scan function are equivalent to the shape and size of the Si phase identified from the EDS map, which displays the Si element concentration of the EDS analysis in two dimensions.

[0034] In the present invention, the Si phase in the L cross section <111> The orientation ratio of the crystal orientation and <110> The orientation ratio of the crystal orientation was taken as the average value of each value obtained by measuring at three or more locations. When selecting the measurement area, from the viewpoint of ensuring the objectivity of the measurement data, it is preferable to obtain the sample for measurement from the Al connector to be measured at intervals of 50 cm or more in the direction of the central axis of the Al connector and use it for measurement. Furthermore, in this invention, the measurement area for the crystal orientation by EBSD method is preferably such that the length in the direction of the central axis of the Al connector is 300 μm or more and less than 800 μm, and the entire Al connector is included in the direction perpendicular to the central axis of the Al connector. However, if the size is large and it is difficult to measure the entire thing, it may be adjusted to a range of less than 600 μm.

[0035] -Average diameter of the Si phase in the L-section- In the present invention, the Al connecting material preferably has an average diameter of the Si phase in its L cross-section of 0.8 μm or more and 4 μm or less.

[0036] In the case of Al connectors whose strength has been increased by the addition of Si, etc., semiconductor chips are easily damaged during the first bonding stage. When ultrasonic vibration and load are adjusted to reduce such damage, a phenomenon may occur in which areas with insufficient metal bonding are formed near the center of the bonding area between the Al connector and the electrode (hereinafter also referred to as "hollow areas"). Because the metal bonding in the hollow areas is insufficient, the bonding strength decreases and these areas become the starting point for defects in temperature cycling tests.

[0037] When the average diameter of the Si phase in the L-section is in the range of 0.8 μm to 4 μm, the gap in the 1st joint can be suppressed. By controlling the average diameter of the Si phase, it is thought that effects such as promoting the deformation of the Al phase that contributes to the joint and improving the transmission efficiency of ultrasonic vibrations to the center of the joint region can be obtained, thereby suppressing the gap.

[0038] From the viewpoint of further suppressing hollowing in the 1st joint, the average diameter of the Si phase in the L cross-section of the Al connecting material of the present invention is more preferably 3.5 μm or less, even more preferably 3.4 μm or less, 3.2 μm or less, or 3 μm or less, and the lower limit is more preferably 1 μm or more, and even more preferably 1.2 μm or more.

[0039] This section describes a method for measuring the average diameter of the Si phase in an L-shaped cross-section of an Al connecting material. The measurement of the average diameter of the Si phase in an L-shaped cross-section involves the Si phase as described above. <111> + <110> Similar to the measurement of total ratios, a method can be used that combines information on Al and Si concentrations obtained by SEM-EDS with information on crystal orientation obtained by EBSD. The detailed procedure is for the Si phase. <111> + <110> The measurement of the total ratio can be carried out in the same manner as described above; that is, the crystal orientation can be analyzed for the region identified as the Si phase by using the analysis software attached to the device. If the orientation difference between measurement points is 15° or more, it is determined to be a grain boundary and the equivalent circle diameter is calculated. The average value of the equivalent circle diameter of each Si phase is defined as the average diameter of the Si phase. In the process of determining the average diameter of the Si phase, parts where the crystal orientation cannot be measured, or parts where the reliability of the orientation analysis is low even if it can be measured, were excluded from the calculation. Therefore, in one embodiment, the average diameter of the Si phase in the L cross section of the Al connecting material of the present invention is calculated by the following steps (1) to (3). (1) The L-shaped cross section of the Al connecting material is used as the inspection surface, and the concentrations of Al and Si are measured using EDS, and the crystal orientation is measured using EBSD simultaneously. (2) Use the Chi Scan function to separate and extract Al and Si. Specifically, by setting a Tolerance corresponding to the Si threshold from the Si EDS measurement results, Al and Si can be separated and identified. Using the crystal information of Al and Si from the material file, the crystal orientation can be analyzed. (3) For the region identified as the Si phase, the crystal orientation is analyzed, and if the orientation difference between measurement points is 15° or more, it is determined to be a grain boundary, and the equivalent circular diameter of each crystal grain is determined. Then, the average of the equivalent circular diameters of each crystal grain is calculated to determine the average diameter of the Si phase. Here, for the average calculation, the average value obtained by area averaging, which can be selected in the software attached to the instrument, is used. By using the average value obtained by area averaging, it is possible to accurately measure and determine whether the conditions related to the average diameter of the Si phase are suitable for suppressing gaps in the 1st junction. In the area averaging calculation, the average is calculated from the average of the values ​​obtained by multiplying the area of ​​each particle by the ratio of the area of ​​each particle to the area of ​​all particles, and the software performs the calculation automatically.

[0040] In this invention, when calculating the average diameter of the Si phase in the L-section, only Si phases with a diameter (equivalent to a circle diameter) of 0.5 μm or more were considered. This allows for accurate determination of whether the requirements related to the average diameter of the Si phase in the L-section, which are suitable for suppressing hollowing in the 1st joint, are met.

[0041] When measuring the average diameter of the Si phase in the L section, the setting range of Tolerance in the procedure in (2) above, the method of obtaining the sample for measurement, and the measurement area of ​​the crystal orientation by the EBSD method are as follows: <111> + <110> The measurement of the total ratio is as described above.

[0042] In addition to the above, there are several methods for measuring the average diameter of the Si phase, including binarization processing from observation images of the L cross section. However, in the present invention, many measurement functions are provided, and the above Si phase can be measured in a single measurement. <111> + <110> For reasons such as the ability to determine multiple characteristics including the total ratio and the average diameter of the Si phase, the possibility of automated analysis, and the ease of measurement due to the widely available equipment and analysis techniques, the method described above combines Al and Si concentration information obtained by SEM-EDS with crystal orientation information obtained by EBSD.

[0043] -Average diameter of the Al phase in the L section- In the present invention, the Al connecting material preferably has an average diameter of the Al phase in its L-section of 5 μm or more and 40 μm or less.

[0044] By having an average diameter of the Al phase in the L cross-section between 5 μm and 40 μm, a high effect is obtained in reducing variations in bonding strength in the 2nd bond. This is thought to be due to the synergistic effect of two factors: the effect of promoting deformation of the Al connector by ultrasonic vibration by containing a predetermined concentration of Si and one or more of the first element group Sr, Na, Eu, and Ca, and the effect of homogenizing the deformation of the Al connector in both directions parallel and perpendicular to the central axis of the Al connector by setting the average diameter of the Al phase between 5 μm and 40 μm.

[0045] To measure the average diameter of the Al phase in the L-section of the Al connecting material, a method can be used that combines information on Al and Si concentrations obtained by SEM-EDS with information on crystal orientation obtained by EBSD, similar to the measurement of the average diameter of the Si phase. Therefore, in one embodiment, the average diameter of the Al phase in the L-section of the Al connecting material of the present invention is calculated according to the following procedure (3) after performing the procedures (1) and (2) above. (3) For the region identified as the Al phase, the crystal orientation is analyzed, and if the orientation difference between measurement points is 15° or more, it is determined to be a grain boundary, and the equivalent circular diameter of each crystal grain is determined. Then, the average diameter of the Al phase is calculated by averaging the equivalent circular diameters of each crystal grain. For the average calculation, the average value obtained by area averaging, which can be selected in the software attached to the instrument, is used, similar to the measurement of the average diameter of the Si phase.

[0046] When calculating the average diameter of the Al phase in the L section, only Al phases with a diameter (equivalent circle diameter) of 0.5 μm or more are considered. Furthermore, when measuring the average diameter of the Al phase in the L section, the tolerance setting range in the procedure in (2) above, the method of obtaining the sample for measurement, and the measurement area of ​​the crystal orientation by EBSD method are for the Si phase. <111> + <110> The measurement of the total ratio is as described above.

[0047] -Addition of Ti, B, and Zr- The Al connecting material of the present invention may further contain one or more of Ti, B, and Zr (hereinafter also referred to as the "second element group") in a total amount of 10 ppm by mass or more and 500 ppm by mass or less.

[0048] When joining aluminum (Al) connectors using ultrasonic vibration and load, controlling the joint shape is crucial. The joint shape of the Al connector can be evaluated by the length of the indentation in the central axis direction of the Al connector (hereinafter referred to as "joint length") at the fracture site during a shear strength test of the joint. Reducing and stabilizing this joint length contributes to improving temperature cycle reliability. In this regard, for Al connectors with increased strength due to the addition of Si, etc., it is effective to join them under conditions of high ultrasonic output in the initial stages of joining time to improve bondability. However, under such joining conditions, there is a concern that the strong ultrasonic vibration applied in the initial stages of deformation will make the sliding between the joining tool and the Al connector unstable, increasing the variation in joint length.

[0049] In the process of investigating an Al connector containing 3.0% to 12.0% by mass of Si and a predetermined amount of the first element group, the inventors discovered that by further including a total of 10 ppm to 500 ppm of the second element group, it is possible to reduce variations in the bonded length of the Al connector when bonding the Al connector by applying ultrasonic vibration and load. It is believed that the second element group concentrates on the surface of the Al connector or affects the oxide film on the surface of the Al connector, thereby controlling the friction, crystalline structure, and hardness of the Al connector surface.

[0050] From the viewpoint of reducing variations in bonding length during bonding and achieving even better temperature cycle reliability required for next-generation power semiconductor devices, the total concentration of the second element group in the Al connector of the present invention is more preferably 20 ppm by mass or more, even more preferably 30 ppm by mass or more, 40 ppm by mass or more, or 50 ppm by mass or more, and the upper limit is preferably 450 ppm by mass or less, more preferably 440 ppm by mass or less, 420 ppm by mass or less, or 400 ppm by mass or less, from the viewpoint of easily achieving good 1st bonding strength while suppressing damage to semiconductor chips.

[0051] - Addition of Ni, Y, Yb, and Sc - The Al connector of the present invention may further contain one or more of Ni, Y, Yb, and Sc (hereinafter also referred to as the "third element group") in a total amount of 5 ppm by mass or more and 500 ppm by mass or less.

[0052] Furthermore, by including one or more of Ni, Y, Yb, and Sc in a total amount of 5 ppm to 500 ppm by mass, it is possible to suppress the occurrence of scratches and abrasion on the surface of the Al connector and form a smooth surface. Al alloys containing a high concentration of Si, between 3.0% and 12.0% by mass, may result in surface hardening and detachment of the Si phase and Al oxide present on the surface, leading to scratches and abrasion on the surface during wire drawing and resulting in an Al connector with large surface irregularities. It is presumed that the addition of the third group of elements promotes the stabilization of Al oxide on the surface of the Al connector and reduces friction between the Al connector and the die, thereby reducing scratches and abrasion during wire drawing. It is thought that adding the third group of elements in combination with the first group of elements enhances the effect of suppressing the occurrence of scratches and abrasion on the surface of the Al connector and forming a smooth surface.

[0053] From the viewpoint of suppressing the occurrence of surface scratches and abrasions and forming an Al connector having a smooth surface, the total concentration of the third element group in the Al connector of the present invention is more preferably 10 ppm by mass or more, even more preferably 20 ppm by mass or more, 30 ppm by mass or more, 40 ppm by mass or more, or 50 ppm by mass or more, and the upper limit is more preferably 450 ppm by mass or less, even more preferably 440 ppm by mass or less, 420 ppm by mass or less, or 400 ppm by mass or less, from the viewpoint of easily achieving good 1st bond strength while suppressing damage to semiconductor chips.

[0054] When manufacturing the Al connector of the present invention, it is preferable to use Al with a purity of 4N (Al: 99.99% by mass or higher) as the aluminum raw material, and it is even more preferable to use Al with a purity of 5N (Al: 99.999% by mass or higher) or higher, which has a lower impurity content.

[0055] Within a range that does not impede the effects of the present invention, the Al connector of the present invention may further contain elements other than Al, Si, the first element group, the second element group, and the third element group (hereinafter also referred to as "other elements"). The total concentration of other elements in the Al connector is not particularly limited within a range that does not impede the effects of the present invention. The total concentration of other elements may be, for example, 0.5% by mass or less, 0.4% by mass or less, 0.3% by mass or less, 0.2% by mass or less, 0.15% by mass or less, 0.1% by mass or less, 0.08% by mass or less, 0.06% by mass or less, 0.05% by mass or less, 0.04% by mass or less, 0.03% by mass or less, 0.025% by mass or less, 0.02% by mass or less, 0.018% by mass or less, 0.016% by mass or less, 0.015% by mass or less, 0.014% by mass or less, 0.012% by mass or less, or 0.01% by mass or less. The lower limit of the total concentration of other elements is not particularly limited and may be 0% by mass.

[0056] In one embodiment, the remainder of the Al connector of the present invention consists of Al and unavoidable impurities. Therefore, in one preferred embodiment, the Al connector of the present invention consists of Al, Si, one or more elements from the first element group, and unavoidable impurities. In another preferred embodiment, the Al connector of the present invention consists of Al, Si, one or more elements from the first element group, one or more elements from the second element group, and unavoidable impurities. In yet another preferred embodiment, the Al connector of the present invention consists of Al, Si, one or more elements from the first element group, one or more elements from the third element group, and unavoidable impurities. In yet another preferred embodiment, the Al connector of the present invention consists of Al, Si, one or more elements from the first element group, one or more elements from the second element group, one or more elements from the third element group, and unavoidable impurities.

[0057] In one preferred embodiment, the Al connector of the present invention does not have a coating on its outer circumference that is mainly composed of a metal other than Al. Here, "coating mainly composed of a metal other than Al" means a coating in which the content of a metal other than Al is 50% by mass or more.

[0058] The Al connecting material of the present invention may be an Al bonding wire or an Al bonding ribbon. When the Al connecting material of the present invention is an Al bonding wire, its wire diameter is not particularly limited and may be in the range of 100 to 600 μm, for example. When the Al connecting material of the present invention is an Al bonding ribbon, the dimensions (W × T) of its rectangular or substantially rectangular cross-section are not particularly limited and may be, for example, W may be 100 to 3000 μm and T may be 50 to 600 μm.

[0059] The Al connector of the present invention can suppress the occurrence of internal cracks during manufacturing and can provide excellent temperature cycle reliability. Therefore, the Al connector of the present invention can be suitably used as an Al connector for semiconductor devices, and in particular as an Al connector for power semiconductor devices.

[0060] -Manufacturing method for aluminum connecting material- An example of a manufacturing method for the Al connecting material of the present invention will be described below. The following example will focus on the manufacturing of Al bonding wires with a diameter of 200 to 400 μm.

[0061] The raw materials, Al and alloying elements, should preferably have high purity. For Al, a purity of 99.99% by mass or higher, with the remainder being unavoidable impurities, is preferable. For Si, the first element group, the second element group, and the third element group used as alloying elements, a purity of 99.9% by mass or higher, with the remainder being unavoidable impurities, is preferable. Al alloys used in bonding wires can be manufactured by loading Al raw materials and alloying element raw materials into a graphite or alumina crucible processed to obtain a cylindrical ingot, and melting them using an electric furnace or high-frequency heating furnace. The diameter of the cylindrical ingot is preferably Φ6 mm or more and less than 8 mm, considering machinability in subsequent processing steps. The atmosphere inside the furnace during melting is preferably an inert or reducing atmosphere to prevent excessive oxidation of the Al and other elements constituting the wire. The maximum temperature reached by the molten metal during melting is preferably in the range of 800°C to less than 1050°C, considering factors such as ensuring the fluidity of the molten metal while easily controlling the shape and size of the Si phase during solidification. Cooling methods after melting include water cooling, furnace cooling, and air cooling.

[0062] After melting down a cylindrical ingot, a solution treatment is performed by heating it at a high temperature. Following this, wires of the desired diameter can be produced by repeatedly drawing them using dies. The drawn wires can then be used as aluminum alloy bonding wires after a final heat treatment using an electric furnace.

[0063] To control the crystal orientation and grain size of the Si phase in the L-section, it is effective to control heat treatment conditions such as solution treatment, homogenization treatment, and final heat treatment, as well as wire drawing conditions. During wire drawing, it is effective to use a lubricating fluid to ensure lubrication at the contact interface between the wire and the die.

[0064] Regarding the Al binder of the present invention containing the first group of elements (Sr, Na, Eu, Ca), the particle size of the Si phase tends to be easier to control. Since the first group of elements affects the morphology of the Si phase, the appropriate range of manufacturing conditions may vary depending on the type and concentration of the first group of elements.

[0065] Si phase in L section <111> + <110> An example of manufacturing conditions for controlling the total ratio within the range of 20% to 70% is shown below.

[0066] To adjust the crystal orientation of the Si phase, it is effective to perform a two-stage heat treatment on the ingot and to control the reduction ratio during wire drawing.

[0067] The solution treatment temperature range should be between 400°C and 550°C, and the duration between 1 hour and 6 hours. Following this solution treatment, a homogenization treatment should be performed at a temperature between 250°C and 350°C, and for a duration between 2 hours and 10 hours. This promotes the fragmentation and growth of the Si phase crystallized during the solidification process, thereby improving the crystal orientation of the Si phase. <111> and <110> This can promote orientation.

[0068] Regarding the wire drawing process conditions, it is effective to set the wire reduction ratio per die used during wire drawing to a range of 10% or more and less than 30%. Here, if the wire reduction ratio per die is P1, P1 is expressed by the following formula.

[0069] P1={(R2 2 -R1 2 ) / R2 2}×100 In the formula, R2 represents the diameter of the wire before processing (mm), and R1 represents the diameter of the wire after processing (mm).

[0070] By adjusting the wire reduction ratio to the above-mentioned high range (high reduction ratio) compared to normal wire drawing conditions, the entire wire is significantly deformed during die processing, increasing processing strain even within the wire. This causes the Si phase to align along the wire's central axis while simultaneously adjusting the processing strain within the Si phase. Subsequent heat treatment from this wire drawing state results in a wire with high atomic density. <111> Crystal orientation and <110> This makes it possible to increase the orientation ratio of the crystal orientation.

[0071] To adjust the average diameter of the Si phase in the L-section to a range of 0.8 μm to 4 μm, it is effective to adjust the melting temperature to between 800°C and 1000°C, the casting temperature to between 700°C and 780°C, and the solution treatment temperature to between 400°C and 550°C, with a duration of between 1 hour and 6 hours. The casting temperature is the temperature at which the molten material is poured into a mold, and corresponds to the solidification start temperature. If the casting temperature is high, the Si phase crystallized during solidification tends to become coarser and columnar, and the average diameter of the Si phase tends to increase. If the solution treatment temperature is high, the columnar Si phase tends to be fragmented and granulated, which tends to decrease the average diameter of the Si phase. To further reduce the average diameter of the Si phase, it is effective to increase the cooling rate during solidification, for example, by using water cooling.

[0072] To control the average diameter of the Al phase in the L-section to a range of 5 μm to 40 μm, it is effective to control the growth of crystal grains due to recrystallization of the Al phase by adjusting the temperature and time of the heat treatment at the final wire diameter.

[0073] As mentioned above, the above is an example of manufacturing Al bonding wire, which is a wire, as a representative example of Al connecting material. Al bonding ribbon, which is a strip material, can be manufactured using basically the same procedure. The temperature and time for heat treatment can be approximately the same as described above. Furthermore, when manufacturing Al bonding ribbon by rolling, the die reduction ratio should be replaced with the reduction ratio for adjustment.

[0074] [Semiconductor device] By using the Al connector of the present invention, semiconductor devices can be manufactured by connecting electrodes on a semiconductor chip to external electrodes on a lead frame or substrate. As mentioned above, wedge bonding is used for both the first connection with the electrodes on the semiconductor chip and the second connection with the electrodes on the lead frame or substrate.

[0075] In one embodiment, the semiconductor device of the present invention includes a circuit board, a semiconductor chip, and an Al connector for making electrical connections between the circuit board and the semiconductor chip, wherein the Al connector is the Al connector of the present invention.

[0076] In the semiconductor device of the present invention, the circuit board and semiconductor chip are not particularly limited, and known circuit boards and semiconductor chips that can be used to constitute a semiconductor device may be used. Alternatively, a lead frame may be used instead of a circuit board. For example, the semiconductor device may be configured to include a lead frame and a semiconductor chip mounted on the lead frame, as described in Japanese Patent Application Publication No. 2020-150116.

[0077] Examples of semiconductor devices include various types of semiconductor devices used in electrical products (e.g., computers, mobile phones, digital cameras, televisions, air conditioners, solar power generation systems, etc.) and vehicles (e.g., motorcycles, automobiles, trains, ships, and aircraft, etc.), with power semiconductor devices being particularly preferred. [Examples]

[0078] The present invention will be described in detail below with reference to examples. However, the present invention is not limited to the examples shown below.

[0079] (sample) The sample preparation method is described below. The raw material, Al, had a purity of 4N (99.99% by mass or higher), with the remainder consisting of unavoidable impurities. The alloying elements used, Si, the first element group (Sr, Na, Eu, Ca), the second element group (Ti, B, Zr), and the third element group (Ni, Y, Yb, Sc), had a purity of 99.99% by mass or higher, with the remainder consisting of unavoidable impurities. The Al alloy used for the Al connector was manufactured by loading the Al raw material and the alloying element raw materials into an alumina crucible and melting them using a high-frequency heating furnace. The atmosphere inside the furnace during melting was an Ar atmosphere, the maximum temperature of the molten metal during melting was set to 800°C or higher and less than 1000°C, and the casting temperature was set to 700°C or higher and less than 780°C. The cooling method after melting was either air cooling in the atmosphere or water cooling in water.

[0080] A cylindrical ingot with a diameter of Φ6 mm was obtained by melting. After solution treatment and homogenization treatment of the ingot, wire drawing using a die and intermediate heat treatment were performed to produce a Φ300 μm Al connecting material (Al bonding wire). The temperature range for the solution treatment was 400°C to less than 550°C, and the duration was 1 hour to less than 4 hours. After the completion of the solution treatment, a homogenization treatment was performed continuously during the cooling process. The temperature range for the homogenization treatment was 250°C to less than 350°C, and the duration was 4 hours to less than 10 hours. The cooling method after the homogenization treatment was air cooling in the atmosphere.

[0081] During the wire drawing process, a commercially available lubricant was used, and the wire reduction ratio per die during wire drawing was set to 14% or more and less than 30%. The temperature range for the final heat treatment was 250°C or more and less than 350°C, and the duration of the final heat treatment was 4 hours or more and less than 18 hours.

[0082] (Method for measuring elemental content) The elemental concentrations in the Al connector were analyzed using either ICP-OES (Hitachi High-Tech Science Co., Ltd. "PS3520UVDDII") or ICP-MS (Agilent Technologies, Inc. "Agilent 7700x ICP-MS") as the analytical instrument.

[0083] (Method for measuring the crystal orientation of the Si phase) The L-section (a cross-section in the direction of the central axis including the central axis) of the Al connector was used as the inspection surface, and the crystal orientation of the Si phase was measured. In this invention, the central axis of the Al connector and the cross-section in the direction of the central axis including the central axis (L-section) are as shown in Figure 1. Figure 1 shows the case where the Al connector is an Al bonding wire having a circular cross-sectional shape. However, if the Al connector is an Al bonding ribbon having a rectangular or substantially rectangular cross-sectional shape with width W and thickness T, the central axis refers to the axis that is at the center of the width W and passes through the center of the thickness T, and the L-section refers to the cross-section in the direction of the central axis including the central axis and in the direction of thickness T. When processing the cross-section to expose the L-section of the Al connector, it may deviate from the central axis of the Al connector. In this case, if the length of the L-section in the direction perpendicular to the central axis is 90% or more of the wire diameter (thickness T in the case of a ribbon) of the Al connector, it can be considered a cross-section including the central axis.

[0084] Furthermore, an FE-SEM (Hitachi High-Tech SU-70) was used for measurement, and TSL Solutions' APEX (for data acquisition), OIM Data Collection (for KaiScan), and OIM Analysis (for data analysis) were used for analysis software. Three measurement areas were randomly selected at intervals of 50 cm or more along the central axis of the Al connector, and measurements were taken in these three areas. The measurement areas were determined to be between 300 μm and 800 μm along the central axis of the Al connector, and to include the entire Al connector in the direction perpendicular to the central axis. The main conditions for EDS and EBSD measurements were set to an acceleration voltage of 15 kV, a measurement magnification of 350x, a scan speed of 30 to 120 points / second, and a measurement interval of 0.1 to 0.3 μm. Here, while a faster scan speed can shorten the measurement time, there is a concern that the measurement accuracy of EDS may decrease. It is desirable to select an appropriate scan speed within the above range.

[0085] To measure the orientation ratio of the Si phase crystal orientation in the L-section of the Al connecting material, a method was used that combined information on Al and Si concentrations obtained by SEM-EDS with information on crystal orientation obtained by EBSD. In detail, the measurements were carried out according to the following procedures (1) to (3). (1) In a measurement area where the L-shaped cross-section of the Al connecting material was used as the inspection surface, the concentrations of Al and Si were measured using EDS and the crystal orientation was measured using EBSD simultaneously. (2) Al and Si were separated and extracted using the Chi Scan function of the EBSD analysis software. Specifically, Al and Si were separated and identified by setting a Tolerance corresponding to the Si threshold from the EDS measurement results of Si. The crystal information of Al and Si from the material file was used for crystal orientation analysis. Here, the Tolerance condition was mainly set to 30%, and can be adjusted as needed. (3) For the region identified as the Si phase, the crystal orientation was analyzed, and the Si phase <111> The orientation ratio of the crystal orientation and <110> The orientation ratios of the crystal orientations were calculated. Partial ratios were used for calculating the orientation ratios of the crystal orientations.

[0086] Si phase <111> The orientation ratio of the crystal orientation and <110> The orientation ratio of the crystal orientation was calculated as the average of the values ​​obtained from the three measurement areas using the procedures (1) to (3) described above.

[0087] (Method for measuring the average diameter of the Si phase) The average diameter of the Si phase in the L-section of the Al connecting material was measured using a method that combined information on Al and Si concentrations obtained by SEM-EDS with information on crystal orientation obtained by EBSD, similar to the measurement of the crystal orientation of the Si phase. Specifically, after performing the procedures in (1) and (2) above, the measurement was carried out according to the procedure in (3) below. (3) For the regions identified as the Si phase, the crystal orientation was analyzed, and if the orientation difference between measurement points was 15° or more, it was determined to be a grain boundary, and the equivalent circular diameter of each crystal grain was determined. The average diameter of the Si phase was then calculated by averaging the equivalent circular diameters of each crystal grain. Here, the average value obtained by area averaging was used for the average calculation. Furthermore, when calculating the average diameter of the Si phase in the L section, only Si phases with a diameter (equivalent circular diameter) of 0.5 μm or more were considered.

[0088] The average diameter of the Si phase was calculated as the average of the values ​​obtained from the three measurement areas using the procedures described in (1) to (3) above. The average diameter of the Al phase in the L-shaped cross-section of the Al connecting material was also measured using the same procedure.

[0089] (Evaluation method for aluminum connecting material) This section describes the evaluation method for Al connectors. The wire diameter of the Al connector (Al bonding wire) used for evaluation was Φ300 μm. A silicon semiconductor chip was used, and the electrodes on the semiconductor chip were made of an Al-0.5%Cu alloy with a thickness of 4 μm. The substrate was an Al alloy with a 15 μm Ni film. A commercially available wire bonder (manufactured by Ultrasonics Co., Ltd.) was used to bond the Al connectors, and both the 1st and 2nd bonds were wedge bonds.

[0090] (Method for evaluating temperature cycle reliability) A commercially available thermal shock test apparatus was used to evaluate the temperature cycling test. In the temperature cycling test, the sample chamber moved between a low-temperature chamber and a high-temperature chamber, repeatedly raising and lowering the temperature. The temperature of the low-temperature chamber was set to -40°C, and the temperature of the high-temperature chamber was set to 175°C. One cycle was defined as starting the test with the sample chamber in the high-temperature chamber, moving to the low-temperature chamber, and returning to the high-temperature chamber. The sample chamber stayed in the low-temperature and high-temperature chambers for 20 minutes each. The sample used for the temperature cycling test had a structure in which a semiconductor chip was mounted on a substrate, and the electrodes on the semiconductor chip and the electrodes on the substrate were connected with an aluminum connector. After the start of the test, the sample was removed every 250 cycles, and a shear test was performed on the 1st joint. The shear strength value of the 1st joint used to evaluate the temperature cycling reliability was the average value of the shear strength of five randomly selected 1st joints. The number of cycles at which the shear strength decreased to 70% or less of the value before the temperature cycling test was defined as the joint life. A joint life of less than 500 cycles was judged to be practically problematic and rated as "0", a joint life of 500 cycles or more but less than 750 cycles was judged to be practically problem-free and rated as "1", a joint life of 750 cycles or more but less than 1000 cycles was judged to be excellent and rated as "2", and a joint life of 1000 cycles or more was judged to be particularly excellent and rated as "3". "0" is a failure, and "1", "2", and "3" are passes. The evaluation results are listed in the "Temperature Cycling Reliability" column in the table.

[0091] (Method for evaluating internal cracks) This section describes the evaluation method for internal cracks in Al connectors. The manufactured Al connectors were evaluated by observation using a soft X-ray projection inspection device (Matsusada Precision, μB2600) (hereinafter referred to as X-ray observation). The measurement conditions for X-ray observation can be appropriately determined according to the wire diameter of the Al connector, but in the case of the Al connector with a wire diameter of 300 μm manufactured in this example, the voltage was adjusted to 50-80 kV and the current to 60-90 μA. Three locations were randomly selected at intervals of 1 m or more along the central axis of the Al connector, and three samples of approximately 8 cm in length were selected from each of the three locations, for a total of nine samples to be measured. Figure 3 shows an example of X-ray observation of an Al connector with a wire diameter of 300 μm, in which internal cracks are observed. If the length of the internal crack was 0.3 mm or more, it was judged to be a problematic defect and scored with a score of "2", and if it was between 0.1 mm and 0.3 mm, it was judged to require attention and scored with a score of "0.5". The sum of the scores from the measurement points was defined as the "crack index." For the crack index of the entire sample, a score of zero was judged as good and was rated as "3," a range of 0.1 to 2.0 was judged as practically acceptable and was rated as "2," a range of 2.0 to 5.0 was judged as needing improvement and was rated as "1," and a score above 6.0 was judged as difficult to use and was rated as "0." The evaluation results are recorded in the "Internal Cracks" column in the table.

[0092] (Method for evaluating wire breakage during processing) This section describes the evaluation method for wire breakage during processing. Wire drawing was performed on wires ranging from 6mmφ to 0.3mmφ, and the number of breakages was recorded. The wire drawing processing conditions, such as feed rate and reduction ratio, were selected from the previously mentioned conditions, and the appropriate manufacturing conditions were adjusted and modified for each wire. The length of the drawn Al connectors ranged from 100 to 200m, and the number of breakages was calculated per 100m. A score of "3" was given if the number of breakages was 0, indicating good performance; a score of "2" was given if the number of breakages was 1, indicating that it could be addressed by improving the manufacturing conditions; a score of "1" was given if the number of breakages was 2 to 4, indicating that the decrease in productivity was problematic; and a score of "0" was given if the number of breakages was 5 or more, indicating that it would be difficult to use in practice. The evaluation results are recorded in the "Breakage During Processing" column of the table.

[0093] (Evaluation method for gaps in the 1st joint) This section describes the evaluation method for defects in the 1st joint. After performing the shear strength test of the 1st joint as described above, the indentation on the fracture surface on the electrode side was observed using an optical microscope or SEM, and areas within the fracture region where metal bonding was not achieved were identified as defects. Areas where defects occurred are areas where bonding did not occur even when the electrode deformed, and can be distinguished from areas where metal bonding was achieved. The shear strength test was performed under the conditions described above, and the fracture surfaces of 10 1st joints were observed. The ratio of the total length of the defects in the joint width direction (K) to the joint length (J) perpendicular to the central axis of the Al connector (joint width direction) was calculated as the defects ratio (K / J) (Figure 2). The defects ratio was checked for 10 fracture surfaces, and the maximum value was defined as the "defect rate of defects in defects". A defect rate of less than 5% was judged as good and rated as "3," a rate of 5% to less than 15% was judged as acceptable for practical use and rated as "2," a rate of 15% to less than 25% was judged as requiring improvement and rated as "1," and a rate exceeding 25% was judged as an obstacle to mass production and rated as "0." The evaluation results are recorded in the "Defect Rate at 1st Joint" column in the table.

[0094] (Method for evaluating the stability of the joint length) This section describes the evaluation method for joint length stability. After conducting the shear strength test of the 1st joint as described above, the joint length was evaluated based on the indentation length (joint length) at the fracture surface on the electrode side. Specifically, the joint length (μm) in the direction of the central axis of the Al connector was measured for the indentation at the fracture surface, and the population standard deviation (σ) was calculated. If σ was 15 or higher, it was judged to have a practical problem and was evaluated as "1". If σ was between 5 and 15, it was judged to be good and was evaluated as "2". If σ was less than 5, it was judged to be excellent and was evaluated as "3". "1" is a failure, and "2" and "3" are passing. The evaluation results are recorded in the "Joint Length Stability" column in the table.

[0095] (Method for evaluating surface scratches and abrasions) The surface properties of the aluminum connector were evaluated focusing on scratches and abrasions. The wire diameter of the aluminum connector was set to 0.3 mmφ. Three measurement areas were randomly selected at intervals of 1 m or more along the central axis of the aluminum connector. Three samples of approximately 2 cm in length were taken from each of the three areas, and a total of nine samples were observed. The surface was observed at a magnification range of 50 to 500 times using an SEM. Scratches longer than 50 μm and abrasions longer than 30 μm were judged as defective. The number of scratches and abrasions was counted, and a score of "3" was given if there were 0, a score of "2" was given if there were 2 or fewer, a score of "1" was given if there were 3 to 7, a score of "1" was given if the surface properties were not good, and a score of "0" was given if there were 8 or more, making it difficult to use. The evaluation results are recorded in the "Surface Properties" column of the table.

[0096] The evaluation results for the examples and comparative examples are shown in Tables 1 to 3.

[0097] [Table 1]

[0098] [Table 2]

[0099] [Table 3]

[0100] All of the Al connectors in Examples No. 1 to 47 contained 3.0% to 12.0% by mass of Si, and a total of 5 ppm to 800 ppm by mass of one or more elements from the first element group (Sr, Na, Eu, Ca). It was confirmed that these materials could suppress the occurrence of internal cracks during manufacturing and exhibited good temperature cycle reliability. In addition, the Si phase in the L cross section <111> + <110> In Examples No. 1-3, 5-24, 26-37, and 39-47, where the total ratio was between 20% and 70%, the Al connecting materials tended to exhibit even better temperature cycle reliability and were found to reduce the frequency of wire breakage during processing. In Examples No. 1-11, 13, 14, 16-27, and 29-47, the Al connecting material, in which the average diameter of the Si phase in the L-section was 0.8 μm or more and 4 μm or less, was confirmed to suppress hollowing out of the 1st joint. Furthermore, it was confirmed that the Al connecting material, in which the average diameter of the Al phase in the L-section was 5 μm or more and 40 μm or less, tended to yield better results in terms of joint strength stability of the 2nd joint. Furthermore, it was confirmed that the Al connecting materials of Examples No. 20-23, 25-27, and 41-47, which contain one or more elements from the second element group (Ti, B, Zr) in a total amount of 10 ppm to 500 ppm by mass, can reduce variations in the bonded length during bonding and stabilize the bonded length. The Al connectors of Examples No. 29-36, 38, 39, and 41-47, which contain one or more elements from the third element group (Ni, Y, Yb, Sc) in a total amount of 5 ppm to 500 ppm by mass, were confirmed to have a smooth surface with suppressed surface scratches and abrasions. On the other hand, in Comparative Examples No. 1 to 7, the Al connecting materials had Si concentration or the concentration of the first element group outside the range of the present invention, and it was confirmed that neither the effect of suppressing the occurrence of internal cracks during manufacturing nor the temperature cycle reliability could be sufficiently obtained.

Claims

1. It contains 3.0% by mass or more and 12.0% by mass or less of Si, and It contains one or more of Sr, Na, Eu, and Ca in a total amount of 5 ppm by mass or more and 800 ppm by mass or less. Al connector, the remainder consisting of Al and unavoidable impurities.

2. Contains 3.0% by mass or more and 12.0% by mass or less of Si, It contains one or more of Sr, Na, Eu, and Ca in a total amount of 5 ppm by mass or more and 800 ppm by mass or less. Furthermore, it contains one or more of Ti, B, and Zr in a total amount of 600 ppm by mass or less. Al connector, the remainder consisting of Al and unavoidable impurities.

3. It contains 3.0% by mass or more and 12.0% by mass or less of Si, and It contains one or more of Sr, Na, Eu, and Ca in a total amount of 5 ppm by mass or more and 800 ppm by mass or less. Furthermore, it contains one or more of Ni, Y, Yb, and Sc in a total amount of 600 ppm by mass or less. Al connector, the remainder consisting of Al and unavoidable impurities.

4. It contains 3.0% by mass or more and 12.0% by mass or less of Si, and It contains one or more of Sr, Na, Eu, and Ca in a total amount of 5 ppm by mass or more and 800 ppm by mass or less. Furthermore, it contains one or more of Ti, B, and Zr in a total amount of 600 ppm by mass or less. Furthermore, it contains one or more of Ni, Y, Yb, and Sc in a total amount of 600 ppm by mass or less. Al connector, the remainder consisting of Al and unavoidable impurities.

5. An Al connecting material according to any one of claims 1 to 4, wherein when the crystal orientation of the Si phase in the L-shaped cross section (cross section in the direction of the central axis including the central axis) of the Al connecting material is measured, the total ratio of the crystal orientations of the <111> crystal orientation and the <110> crystal orientation, which have an angular difference of 15° or less with respect to the central axis, is 20% or more and 70% or less, An Al connecting material in which the sum of the orientation ratios of the <111> crystal orientation and the <110> crystal orientation is the sum of the average values ​​obtained by measuring at three or more locations.

6. The Al connecting material according to any one of claims 1 to 4, wherein the average diameter of the Si phase in the L cross section, determined by area average, is 0.8 μm or more and 4 μm or less.

7. The Al connector according to any one of claims 1 to 4, wherein the total concentration of Sr, Na, Eu, and Ca is 250 ppm by mass or less.

8. The Al connector according to any one of claims 1 to 4, wherein the total concentration of Sr, Na, Eu, and Ca is 180 ppm by mass or less.

9. The Al connector according to any one of claims 1 to 4, wherein the total concentration of Sr, Na, Eu, and Ca is 50 ppm by mass or less.

10. An Al connector according to any one of claims 1 to 4, comprising at least Na, Eu, or Ca.

11. The Al connector according to claim 2 or 4, wherein the total concentration of Ti, B, and Zr is 10 ppm by mass or more.

12. The Al connector according to claim 3 or 4, wherein the total concentration of Ni, Y, Yb, and Sc is 5 ppm by mass or more.

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