Solder compositions and electronic components

Abstract

To provide a solder composition that is suitable for high-density mounting, and to provide an electronic component.SOLUTION: A solder composition includes Sn. The composition includes 1.0-5.0 mass% Cu, 0.1-0.5 mass% Ni, and more than 0.01 mass% and 0.5 mass% or less Ge.SELECTED DRAWING: Figure 1A

Description

Technical Field

[0001] The present invention relates to a solder composition and an electronic component.

Background Art

[0002] Examples of lead-free solders substantially free of lead include Sn-Cu-Ni-P-Ga systems (Patent Document 1).

[0003] However, when these lead-free solders are used at a high temperature of 300 to 450°C in the manufacture of electronic components, etc., there is a problem that solder horns (a phenomenon in which solder protrudes in a horn shape from the tip toward the solder joint) are likely to occur during soldering. And when solder horns occur, it is necessary to design the electronic components considering the solder horns, and there is a problem that the outer dimensions of the electronic components become large and it is not suitable for high-density mounting.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] In view of such circumstances, the present invention has been made, and an object thereof is to provide a solder composition and an electronic component suitable for high-density mounting.

Means for Solving the Problems

[0006] In order to achieve the above object, the solder composition according to the present invention is a solder composition containing Sn, characterized by containing 1.0 mass% or more and 5.0 mass% or less of Cu, 0.1 mass% or more and 0.5 mass% or less of Ni, and more than 0.01 mass% and 0.5 mass% or less of Ge.

[0007] The solder composition of the present invention contains Sn, and further contains Cu, Ni, and Ge, thereby enabling a substantially lead-free solder composition. Furthermore, the solder composition of the present invention can suppress the formation of solder horns during soldering in high-temperature ranges (e.g., 300-450°C). By suppressing the formation of solder horns, it is possible to prevent short circuits caused by solder horns coming into contact with other terminals (other circuit patterns or other electronic components).

[0008] Furthermore, by suppressing the formation of solder horns, it becomes unnecessary to lengthen the terminal mounting area to account for the formation of solder horns, making it easier to reduce the size of electronic components, including the terminal mounting area. This facilitates high-density mounting of electronic components. For example, when solder horns are formed, when connecting wire leads to the terminal joint with a solder composition, the terminal mounting area located below the joint needs to be longer than the joint to account for the formation of solder horns.

[0009] By using the solder composition of the present invention, the formation of solder horns can be suppressed, which allows for a shorter length of the terminal mounting area on electronic components, and thus a smaller overall size of the electronic component, including the terminal mounting area. Furthermore, inspection of the mounting condition at the terminal mounting area becomes easier, facilitating automated mounting inspection, contributing to the automation of inspection and the reduction of costs for electronic components.

[0010] Furthermore, heating the solder to a high temperature can suppress the scattering of solder balls into the surrounding area. Therefore, it is possible to effectively prevent short circuits between other circuits or between electronic components caused by solder balls scattering onto other circuit patterns or electronic components. Consequently, this solder composition is suitable for high-density mounting of electronic components. Moreover, this solder composition is suitable for use in high-temperature mounting applications.

[0011] Furthermore, this solder composition can effectively suppress the wire thinning phenomenon, where metals such as copper in the wire dissolve into the solder, causing the wire to become thinner, even when used on the lead portion of a wire.

[0012] Preferably, the solder composition further contains 0.001 to 0.5% by mass of P. More preferably, it contains 0.001 to 0.5% by mass of Ga. Such a solder composition can further suppress the scattering of solder balls. It can also effectively prevent oxidation of the solder.

[0013] The electronic component according to the present invention has a solder portion containing the solder composition described above. The electronic component also has terminal electrodes, and the terminal electrodes have a connecting portion to which the lead portion of a wire is connected, and the lead portion may be electrically connected to the connecting portion at the solder portion. The lead portion of the wire may also be wrapped around the connecting portion.

[0014] The terminal electrode may further have a mounting portion, and the connecting portion may be positioned on the side opposite to the mounting portion. In a soldered portion using the solder composition of the present invention, the generation of solder horns can be suppressed when soldering in a high-temperature range such as 300 to 450°C. For this reason, even if the connecting portion is positioned above the mounting portion, the length of the mounting portion can be kept to the minimum necessary length, and the bonding state of the mounting portion (e.g., solder joint) can be observed from above the connecting portion with a camera for automated mounting inspection, making it suitable for automated mounting inspection. [Brief explanation of the drawing]

[0015] [Figure 1A] Figure 1A is a schematic front view of an electronic component according to one embodiment of the present invention. [Figure 1B] Figure 1B is a magnified view of the main parts of the electronic component shown in Figure 1A. [Figure 2] Figure 2 is a top view of the electronic component shown in Figure 1A. [Figure 3] Figure 3 is a schematic perspective view of an electronic component according to another embodiment of the present invention. [Figure 4]FIG. 4 is a schematic diagram related to the measurement of solder length. [Figure 5A] FIG. 5A is a graph showing the change in the distance between the connection parts of the terminal electrodes before and after solder connection of the coil device according to an embodiment of the present invention. [Figure 5B] FIG. 5B is a graph showing the change in the distance between the connection parts of the terminal electrodes before and after solder connection of the coil device according to a comparative example of the present invention. [Figure 6] FIG. 6 is a graph showing the relationship between the solder immersion time and the change in wire diameter in the embodiment and the comparative example of the present invention. [Figure 7A] FIG. 7A is a cross-sectional view of an apparatus related to the evaluation of the amount of solder balls. [Figure 7B] FIG. 7B is a top view of the apparatus related to the evaluation of the amount of solder balls shown in FIG. 7A. [Figure 8] FIG. 8 is a schematic diagram showing the state of attachment of solder balls related to the evaluation of the amount of solder balls.

MODE FOR CARRYING OUT THE INVENTION

[0016] Hereinafter, the present invention will be described based on the embodiments shown in the drawings.

[0017] First Embodiment As shown in FIG. 1A, a coil device 1 as an electronic component according to an embodiment of the present invention has two coil parts 19, 19 and functions as a transformer. Each coil part 19 is formed by winding a wire 22 around a bobbin part 20. Further, a middle leg part (not shown) of the core part 16 is inserted into the axis of each coil part 19. Also, the respective coil parts 19, 19 are separated by flange parts 18. A cover 15 is attached to the upper part of the coil parts 19, 19.

[0018] The wire that constitutes the coil part 19 and is connected to each terminal part is not particularly limited, and for example, conductive wires such as copper, copper alloy, iron, iron alloy, and CP wire are used. The insulating material that constitutes the insulating coating for coating the wire is not particularly limited, but urethane, polyamideimide, ETFE, etc. are used.

[0019] The material of the core portion 16 is not particularly limited, but is a magnetic material, and is composed of a ferrite composition, a metal composition, or a composite composition of the same with a resin, and is manufactured by methods such as compression molding followed by firing, or general powder compaction molding.

[0020] The bobbin portion 20 is formed, for example, by injection molding, and its material is not particularly limited, but can be made of PBT, PET, LCP, PA, or phenolic resin from the viewpoint of heat resistance, etc. The cover plate 15 can also be made of the same material as the bobbin, but may be made of an insulating material other than resin. The bobbin portion 20 may also be made of an insulating material other than resin if it is possible to mold it.

[0021] Terminal blocks 17, 17 are integrally formed at both ends of the bobbin portion 20 in the Y-axis direction. As shown in Figure 2, multiple terminal electrodes 11 are insert-molded into each terminal block 17 and are arranged in a line along the X-axis direction.

[0022] As shown in Figure 1A, the terminal electrode 11 has a U-shape with a mounting portion 12 and a connecting portion 14. The connecting portion 14 protrudes outward from the end face 17y of the terminal block 17 in the Y-axis direction. The mounting portion 12 extends downward in the Z-axis direction from the bottom surface of the terminal block 17 and further protrudes outward in the Y-axis direction. The mounting portion 12 protrudes slightly longer outward in the Y-axis direction than the connecting portion 14. The connecting portion 14 is positioned on the opposite side (above) of the mounting portion 12 along the Z-axis. Note that in the drawing, the X-axis, Y-axis, and Z-axis are perpendicular to each other.

[0023] As shown in Figure 1B, the lead portion 13 of the wire 22 is wrapped around the splice portion 14. A solder portion 10 is formed to cover the lead portion 13 and the splice portion 14. The splice portion 14 and the lead portion 13 are electrically connected by the solder portion 10.

[0024] The solder portion 10 is composed of a solder composition, which may contain flux or other components, for example. The solder composition of this embodiment is substantially lead-free. The liquidus temperature of the solder composition of this embodiment is lower than the soldering temperature, for example, 220 to 380°C. In this embodiment, "substantially lead-free" means that the lead content of the solder composition is preferably 0.10% by mass or less, more preferably 0.05% by mass or less, and particularly preferably 0.01% by mass or less.

[0025] The solder composition of this embodiment contains Sn as its main component. The Sn content in the solder composition is not particularly limited, but is preferably 90% by mass or more, more preferably 93% by mass or more, and especially preferably 94% by mass or more. A lead-free solder composition is easily realized when the Sn content is within this range.

[0026] Furthermore, the Cu content in the solder composition of this embodiment is 1.0% by mass or more and 5.0% by mass or less, preferably 2.0% by mass or more, more preferably 2.5% by mass or more, and preferably 3.5% by mass or less. By setting the Cu content within this range, the effect of suppressing wire diameter thinning is enhanced without causing a decrease in solderability.

[0027] The Ni content in the solder composition of this embodiment is 0.1% by mass or more and 0.5% by mass or less, preferably 0.15% by mass or more, more preferably 0.2% by mass or more, preferably 0.4% by mass or less, and even more preferably 0.3% by mass or less. By setting the content within this range, the effect of suppressing wire diameter thinning is enhanced.

[0028] In this embodiment, the total content of Cu and Ni is preferably more than 1.2% by mass, more preferably 2.0% by mass or more, and even more preferably 3.0% by mass or more.

[0029] The Ge content in the solder composition of this embodiment is more than 0.01% by mass and 0.5% by mass or less, preferably 0.015% by mass or more, more preferably 0.02% by mass or more, particularly preferably 0.04% by mass or more, or 0.05% by mass or more, preferably 0.3% by mass or less, more preferably 0.1% by mass or less, and particularly preferably 0.08% by mass or less. By setting the content within this range, the effect of suppressing the solder horn phenomenon is enhanced.

[0030] The P content in the solder composition of this embodiment may be substantially zero, but is preferably more than 0.001% by mass and 0.5% by mass or less, more preferably 0.01% by mass or more, 0.02% by mass or more, preferably 0.3% by mass or less, and even more preferably 0.1% by mass or less. By keeping it within this range, the effect of suppressing solder ball scattering is enhanced.

[0031] In this embodiment, since the solder composition contains Sn, and further contains Cu, Ni, and Ge, a lead-free solder composition that is substantially lead-free can be realized. Furthermore, according to the solder composition of this embodiment, the generation of solder horns can be suppressed when soldering in a high-temperature range (for example, 300 to 450°C). By suppressing the generation of solder horns, it is possible to prevent short circuits caused by solder horns coming into contact with other terminals (other circuit patterns or other electronic components).

[0032] Furthermore, by suppressing the generation of solder horns, as shown in Figure 1B, the mounting portion of the terminal electrode 11 is designed to anticipate the generation of solder horns. 12 This eliminates the need to lengthen the coil along the Y-axis. As a result, it becomes easier to reduce the total length Ly0 along the Y-axis of the coil device 1, including the mounting portion 12 of the terminal electrode 11 shown in Figure 1A. Consequently, high-density mounting of the coil device 1 becomes easier.

[0033] For example, as shown in Figure 1B, if a solder horn forms on the solder tip 52 of the solder portion 10 that protrudes outward along the Y-axis from the tip 14a of the joint portion 14 of the terminal electrode 11, the solder length ΔL1 will be longer. Therefore, when connecting the lead portion 13 of the wire 22 to the joint portion 14 of the terminal electrode 11 with the solder portion 10 made of a solder composition, the mounting portion 12 of the terminal electrode 11 located below the joint portion 14 needs to be longer along the Y-axis than the joint portion 14 to account for the formation of a solder horn.

[0034] In other words, the length Ly3 of the mounting portion 12 along the Y-axis from the end face 17y of the terminal block 17 needs to be longer than the length Ly2, which is the length Ly1 of the connecting portion 14 along the Y-axis from the end face 17y, with the solder length ΔL1 taken into account. Otherwise, the solder tip 52 shown in Figure 1B will get in the way, making it difficult to observe the mounting state of the mounting portion 12 with a camera 23 or the like, which is located above the connecting portion 14 along the Z-axis, as shown in Figure 1A. In other words, it becomes difficult to automatically inspect with a camera 23 or the like whether the tip of the mounting portion 12 along the Y-axis is joined to a circuit pattern on a circuit board (not shown).

[0035] In the solder portion 10 made of the solder composition of this embodiment, the generation of solder horns can be suppressed, so the length of the solder tip Ly2 from the end face 17y of the terminal block can be shortened. As a result, the length Ly3 of the mounting portion 12 of the terminal electrode 11 shown in Figure 1B can be shortened, and the length along the Y axis of the coil device 1 including the mounting portion 12 of the terminal electrode 11 (especially the distance between the terminal electrodes 11) Ly0 shown in Figure 1A can be reduced. Furthermore, inspection of the mounting state of the terminal electrode 11 at the mounting portion 12 becomes easier, making it easier to support automated mounting inspection, and contributing to the automation of inspection and the cost reduction of the coil device 1.

[0036] Furthermore, in this embodiment, the solder (solder composition) constituting the solder portion 10 can be heated to a high temperature to suppress the scattering of solder balls into the surroundings. Therefore, it is possible to effectively prevent short circuits with other circuits or short circuits between multiple coil devices 1 caused by solder balls scattering onto other circuit patterns or electronic components. Accordingly, the solder composition of this embodiment can be suitably used for high-density mounting of coil devices 1 and the like. In addition, this solder composition can be suitably used for mounting at high temperatures.

[0037] Furthermore, according to the solder composition constituting the solder portion 10 of this embodiment, even when used on the lead portion 13 of the wire 22, 22 This also effectively suppresses the wire thinning phenomenon that occurs when metals such as copper dissolve into the solder, causing the lead portion 13 to become thinner. As a result, the reliability of the mechanical and electrical connection between the lead portion 13 and the connecting portion 14 is improved.

[0038] Furthermore, it is preferable that the liquidus temperature (or melting point) of the solder used when connecting the mounting portion 12 of the terminal electrode 11 to a circuit board or the like is equal to or lower than the liquidus temperature (or melting point) of the solder composition of this embodiment.

[0039] Furthermore, the solder composition of this embodiment may contain other components, such as Ag, Zn, Sb, Au, etc., to the extent that they do not impair its effect. The solder composition of this embodiment also contains unavoidable impurities. It is preferable that the amount of unavoidable impurities be as small as possible, and it is even more preferable that their total content be 1% by mass or less.

[0040] Second Embodiment As shown in Figure 3, the coil device 2 of this embodiment functions, for example, as a surface-mount inductor in a power supply circuit. The coil device 2 has a core 33 and a coil 31, and a mounting portion 32 is formed on the coil portion 31, and a solder portion 10 is formed on the surface of the mounting portion 32. The configuration of the solder portion 10 is the same as in the previously described embodiment and provides the same effects.

[0041] As shown in Figure 3, the core 33 has a main core 33a which is roughly rectangular in shape, and a sub-core 33b which is roughly rectangular in shape and is positioned above it in the Z-axis direction.

[0042] The coil 31 is obtained by press-forming a plate-shaped conductor. The intermediate coil portion 31a of the coil 31 extends linearly in the Y-axis direction. Both ends of the intermediate coil portion 31a in the Y-axis direction are connected to end coil portions 31b. The end coil portion 31b extends linearly downward in the Z-axis direction. At the lower end of the end coil portion 31b in the Z-axis direction, a mounting portion 32 is formed which extends downward in the Z-axis direction and is further bent outward in the Y-axis direction.

[0043] The intermediate coil portion 31a is sandwiched between the cores 33a and 33b and positioned in a groove extending linearly in the Y-axis direction, formed on the upper surface of the main core 33a in the Z-axis direction. In this embodiment, the upper surface of the main core 33a in the Z-axis direction is fixed and integrated with the lower surface of the subcore 33b in the Z-axis direction with an adhesive (not shown), and the intermediate coil portion 31a of the coil 31 is sandwiched between them. The end coil portions 31b are positioned in grooves extending linearly downward in the Z-axis direction, formed on both end surfaces of the main core 33a in the Y-axis direction.

[0044] The plate-shaped conductors constituting the coil 31 and the mounting portion 32 are not particularly limited, but metals such as copper, copper alloys, silver, and gold can be used. The surface of the plate-shaped conductor is, for example, plated with metal. Examples of metal plating include nickel plating, tin plating, solder plating, and silver plating, and the plating may be a single layer or multiple layers. It is preferable that metal plating is formed on the surface of the plate-shaped conductor, at least on the mounting surface of the mounting portion 32.

[0045] A solder portion 10 is formed on the surface of the mounting portion 32. The method for forming the solder portion 10 is not particularly limited, but examples include immersion method and reflow method. The solder portion 10 may be formed after assembling the coil device 2, before assembling the coil device 2, or when connecting the coil device 2 to a circuit board or the like.

[0046] It should be noted that the present invention is not limited to the embodiments described above, and can be modified in various ways within the scope of the present invention.

[0047] For example, the solder composition of the present invention can be used in electronic components that are not limited to coil devices such as transformers, but can also be applied to coil devices for other applications, or to other electronic components having terminal electrodes, such as capacitors, varistors, and resistors. [Examples]

[0048] The present invention will be described below based on more detailed examples, but the present invention is not limited to these examples.

[0049] Examples and Comparative Examples Solder compositions were prepared by blending various elements. Various solder materials were prepared by mixing these solder compositions with flux (SR-209, manufactured by Senju Metal Industry Co., Ltd.). The content ratios of the components of each solder composition are shown in Tables 1 to 3. The solder compositions were evaluated using the following method.

[0050] [Measuring solder length] As shown in Figure 4, a test wire 40 made of insulated copper wire (AIEIW) with an outer diameter of 1.0 mm was prepared, and its tip 40a was polished to be flat. Various soldering materials were heated to a temperature above liquidus and below 440°C. The wire tip 40a was pointed downwards along the vertical axis and immersed from a direction perpendicular to the soldering surface, and then cooled by being pulled up in the opposite direction at a speed of 1 mm / s to 15 mm / s.

[0051] As shown in Figure 4, the solder length ΔL2 (mm) from the wire tip 40a to the solder tip 40b was measured. This was repeated four times with different wires, and the maximum and minimum values ​​of the solder length ΔL2 are shown in Table 1.

[0052] [Table 1]

[0053] As shown in Table 1, in Examples 1 to 7, where the content of each component was within the specified range, the solder length ΔL2 was 0.2 to 0.4 mm in all cases. Furthermore, as shown by the dashed line in Figure 4, in Examples 1 to 7, the solder end 52 had a gentle curve, and there were almost no solder horns.

[0054] In contrast, in Comparative Examples 1 to 5, where the Ni and Ge content was outside the specified range, the minimum solder length ΔL2 (mm) was 0.5 mm and the maximum was 0.9 mm. Furthermore, in Comparative Examples 1 to 5, as shown by the solid line in Figure 4, the solder tip 40b was conical, and the formation of solder horns was confirmed.

[0055] Furthermore, in Examples 11-15, the solder length ΔL2 was 0.2-0.7 mm, which was inferior to Examples 1-7 but better than Comparative Examples 1-5. Also, as shown by the dashed line in Figure 4, in Examples 11-15, the solder end 52 had a gentle curve, and there were almost no solder horns.

[0056] Furthermore, using the solder composition of Example 1 described above, the soldered portion 10 of the coil device 1 shown in Figure 1A was actually formed, and the distance (lead length) LyOa between the joint portions 14 located at both outer ends of the Y-axis, including the soldered portion 10, was measured to investigate the change in length (mm) before and after soldering. The measurement was performed on 20 pairs of test joint portions 14, and the frequency and length change were measured. The results are shown in Figure 5A. In Figure 5A, the horizontal axis represents frequency, and the vertical axis represents length change.

[0057] Similarly, the solder portion 10 of the coil device 1 shown in Figure 1A was actually formed using the solder composition of Comparative Example 1, and the distance (lead length) LyOa between the joint portions 14 located at both outer ends of the Y-axis, including the solder portion 10, was measured to investigate the change in length (mm) before and after soldering. Measurements were performed on 20 pairs of test joint portions 14, and the frequency and length change were measured. The results are shown in Figure 5B.

[0058] As shown in Figures 5A and 5B, it was confirmed that the change in lead length was significantly less in Example 1 compared to Comparative Example 1.

[0059] [Evaluation of thinness] Two types of polyurethane copper wire (2UEW Φ0.16) with an outer diameter of 0.16 mm were prepared. Multiple wires were immersed for 10 seconds in solder material consisting of the solder compositions and flux described above for Example 2, Comparative Example 6, and Comparative Example 7, heated to 405-415°C. The wire diameter after immersion was measured, and the decrease rate from the wire diameter before immersion was calculated and defined as wire tapering. The results are shown in Table 2.

[0060] [Table 2]

[0061] As shown in Table 2, it was confirmed that wire thinning was significantly suppressed in Example 2 compared to Comparative Examples 6 and 7. To reduce wire thinning, it is expected that it is preferable to include at least a predetermined proportion of Ni in the solder composition. Figure 6 shows the relationship between immersion time and wire diameter when using the solder compositions of Example 1 and Comparative Example 1.

[0062] [Evaluation of solder ball quantity] As shown in Figures 7A and 7B, a 40 x 40 mm square substrate 43 was prepared, and a 20 x 25 mm square double-sided tape 44 was attached to the lower center of it. A test wire 40, consisting of 1000 strands of 0.05 mm outer diameter polyurethane copper wire (2UAE) twisted together, was passed through a through hole 46 in the center of the substrate.

[0063] Before and after the above, a solder bath 41 was prepared containing the solder baths 42 shown in Figure 7A, each containing the solder compositions of Example 1, Example 2, and Comparative Example 1, respectively. Next, the wire 40 and substrate 43 were fixed to the holder 45 and immersed in the solder bath 42 at a temperature of 380-390°C for 5 seconds at a position where the solder immersion depth Lz1 was 10 mm and the distance Lz2 from the solder surface of the double-sided tape 44 was 5 mm, thereby adhering solder to the tip of the wire 40. The flux used was SR-209 manufactured by Senju Metal Industry Co., Ltd. After that, as shown in Figure 8, the number of solder balls adhering to the surface of the double-sided tape 44 was counted. This test was performed a total of four times, and the average value was calculated. The results are shown in Table 3.

[0064] [Table 3]

[0065] As shown in Table 3, compared to Comparative Example 1, which does not contain Ni and Ge, it was confirmed that the generation of solder balls was suppressed in Examples 1 and 2, in which the content of each component was within a predetermined range. [Explanation of symbols]

[0066] 1, 2… Coil device 10... Soldering section 11...Terminal electrode 12…Implementation Section 13…Lead section 14...Connection section 15…Cover plate 16…Core section 17...Terminal block 18... Tsuba (sword guard) 19... Coil section 20... Bobbin section 22... Wire 23... Camera 31... Coil section 31a...Intermediate coil section 31b...End coil section 32…Implementation Section 33... Core 33a... Main core 33b... Subcore 40…Test wire 40a... Wire tip 40b...Solder tip 41... Soldering bath 42... Solder bath 42a...solder side 43... Circuit board 44…Double-sided tape 45... Holder 46…Through hole 47... Solder ball

Claims

1. A solder composition containing 90% by mass or more of Sn, It contains Cu in an amount of 2.5% to 5.0% by mass, Ni in an amount of 0.1% to 0.5% by mass, and Ge in an amount of 0.02% to 0.5% by mass. It contains P in an amount of 0.001% by mass or more and 0.5% by mass or less. A solder composition comprising 0.001% by mass or more and 0.5% by mass or less of Ga.

2. An electronic component having a solder portion containing the solder composition described in claim 1.

3. The electronic component according to claim 2, wherein the terminal electrode has a connecting portion to which a lead portion of a wire is connected, and the lead portion is electrically connected to the connecting portion by the solder portion.

4. The electronic component according to claim 3, wherein the lead portion of the wire is wrapped around the connecting portion.

5. The electronic component according to claim 3 or 4, wherein the terminal electrode further comprises a mounting portion.

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