WO2024034689A1 - はんだ合金、はんだペースト及びはんだ継手 - Google Patents
はんだ合金、はんだペースト及びはんだ継手 Download PDFInfo
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- WO2024034689A1 WO2024034689A1 PCT/JP2023/029383 JP2023029383W WO2024034689A1 WO 2024034689 A1 WO2024034689 A1 WO 2024034689A1 JP 2023029383 W JP2023029383 W JP 2023029383W WO 2024034689 A1 WO2024034689 A1 WO 2024034689A1
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- solder
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- solder alloy
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Classifications
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
- B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
- B23K35/00—Rods, electrodes, materials, or media, for use in soldering, welding, or cutting
- B23K35/22—Rods, electrodes, materials, or media, for use in soldering, welding, or cutting characterised by the composition or nature of the material
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
- B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
- B23K35/00—Rods, electrodes, materials, or media, for use in soldering, welding, or cutting
- B23K35/22—Rods, electrodes, materials, or media, for use in soldering, welding, or cutting characterised by the composition or nature of the material
- B23K35/24—Selection of soldering or welding materials proper
- B23K35/26—Selection of soldering or welding materials proper with the principal constituent melting at less than 400 degrees C
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C13/00—Alloys based on tin
- C22C13/02—Alloys based on tin with antimony or bismuth as the next major constituent
Definitions
- the present invention relates to solder alloys, solder pastes, and solder joints.
- Hybrid vehicles are equipped with inverters that handle large amounts of power, and require solder joints that can withstand the operating temperatures of the inverters.
- inverters that handle large amounts of power, and require solder joints that can withstand the operating temperatures of the inverters.
- high reliability of the solder alloys forming the solder joints is required, and various studies are being conducted.
- Patent Document 1 discloses a solder alloy suitable for a solder paste that requires high reliability at high usage or operating temperatures of 150° C. or higher.
- the solder alloy described in this document is a Sn-Ag-Cu-Ni-Bi-Sb-Co solder alloy whose liquidus temperature is 220° C. or higher.
- Patent Document 2 discloses a Sn-Ag-Cu-Ni-Sb-Bi-Co-P solder alloy containing P in order to improve creep resistance.
- a solder alloy whose liquidus temperature is within a range of 250° C. or lower is considered.
- Patent Document 3 discloses a solder alloy that can withstand being left at 150° C. for 480 hours.
- a Sn-Ag-Cu-Ni-Sb-Bi-Co-In solder alloy containing In is considered.
- Patent Document 4 discloses a solder alloy that exhibits a relatively high melting point in order to allow long-term operation at, for example, 150° C. or higher in the fields of automobiles, high-power electronics, energy, LED lighting, etc.
- a Sn-Ag-Cu-Ni-Bi-Sb-Co-Ge solder alloy having a melting temperature of 220° C. or higher has been disclosed.
- Patent No. 6730999 Patent No. 6836040 China Patent Application Publication No. 112475664 International Publication No. 2021/043437
- Patent Documents 1 to 4 disclose that a Sn-Ag-Cu-Ni-Bi-Sb-Co based solder alloy with a liquidus temperature of 200°C or higher is used to achieve the purpose of the invention described in each document. Disclosed. For example, some SiC semiconductor devices are capable of high temperature operation at 200° C. or higher. If the melting point of the solder alloy is lower than 200° C., the solder alloy will melt during operation and cannot be used in high-performance electronic components. The solder alloys described in Patent Documents 1 to 4 are considered to be applicable to the connection of electronic components that operate at high temperatures, as described above. However, as a solder joint, even if it satisfies the heat resistance, other properties may be inferior.
- the above-mentioned Sn-Ag-Cu-Ni-Bi-Sb-Co solder alloy disclosed in Patent Document 1 has a reduced Bi content for the purpose of improving the tensile strength after being left at high temperatures. This results in poor wettability.
- Patent Document 2 discloses a P-containing Sn-Ag-Cu-Ni-Sb-Bi-Co-P solder alloy.
- Patent Document 2 is an excellent invention containing P in order to improve creep resistance.
- the invention described in Patent Document 2 is mainly used for preforms. Solder powder made of a solder alloy containing P is rarely used as a solder paste because there is a risk of agglomeration. Moreover, when a large amount of P is contained, the liquidus temperature increases.
- Patent Document 2 discloses Comparative Example 12, a solder alloy that does not contain P.
- Comparative Example 12 of Patent Document 2 is a Sn-Ag-Cu-Ni-Sb-Bi-Co solder alloy that has the same constituent elements as Patent Document 1, it has poor wettability due to the low Bi content. It will be inferior.
- An object of the present invention is to provide a solder alloy, a solder paste, and a solder joint that exhibit a suitable melting temperature, excellent wettability, high tensile strength and shear strength, and also excellent drop impact resistance.
- Patent Document 1 discloses a Sn-3.54Ag-1.04Cu-0.05Ni-3.46Sb-0.29Bi-0.05Co solder alloy (numerical values represent mass %. The same applies hereinafter). There is. Patent Document 1 discloses that the liquidus temperature of this solder alloy is 226° C., which is an appropriate temperature. However, as mentioned above, it was found that this solder alloy has a low Bi content and poor wettability.
- Comparative Example 12 of Patent Document 2 discloses a Sn-3.4Ag-0.70Cu-0.06Ni-6.0Sb-0.5Bi-0.008Co solder alloy. It was found that this solder alloy, like the solder alloy disclosed in Patent Document 1, has poor wettability because it has a low Bi content.
- Example 7 of Patent Document 3 discloses a Sn-3Ag-0.5Cu-0.05Ni-3.5Sb-7Bi-0.03Co-0.2In solder alloy.
- Example 38 of Patent Document 4 discloses a Sn-3.5Ag-0.7Cu-0.05Ni-4Sb-3.1Bi-0.05Co-0.01Ge solder alloy. All of these solder alloys are considered to have poor drop impact resistance. This is presumed to be due to the high Bi content in both cases, which caused Bi to segregate and become brittle.
- the Sn-Ag-Cu-Ni-Bi-Sb-Co solder alloys that have been studied so far focus on specific effects, making it difficult to adapt to the actual situation in consideration of the usage environment.
- the same constituent elements as conventional solder alloys, there is a single alloy composition that exhibits a suitable melting temperature, excellent wettability, high tensile strength and shear strength, and also has excellent drop impact resistance. It seems that there is.
- the drop impact resistance includes all factors such as the strength of the board and the bonding strength between the wiring and the board. In this way, the cause of breakage in drop impact resistance is not necessarily the solder alloy.
- the inventors of the present invention focused on evaluating under conditions that are more severe than the drop impact resistance, separately from the drop impact resistance, and conducted a shear strength test at a much faster speed than conventional ones. This evaluation is very different from the conventional test conditions for shear strength, and is an evaluation that allows you to confirm the failure mode when a solder joint breaks instantly.
- the present invention was completed based on the findings that showed an appropriate failure mode in a high-speed shear test in which solder joints instantaneously break under conditions more severe than drop impact resistance. .
- the present invention obtained based on these findings is as follows.
- the alloy composition further contains at least one of In, Ga, As, Fe, Pd, Mn, Zn, Zr, and Mg in a total amount of 0.1% or less in mass%. (0) or the solder alloy described in (1) above.
- the alloy composition includes at least one of the following formulas (1) to (4). ) to the solder alloy according to any one of (2) above. 426 ⁇ (Ag ⁇ Cu)/(Ni ⁇ Co) ⁇ 8530 (1) 0.10 ⁇ Bi/Sb ⁇ 0.28 (2) 10.8 ⁇ Sn/Sb ⁇ 18.0 (3) 0.00004 ⁇ Bi ⁇ Sb ⁇ Ni ⁇ Co ⁇ 0.00254 (4) In the above formulas (1) to (4), Sn, Ag, Cu, Bi, Sb, Ni, and Co are each contained in mass % of the solder alloy.
- a solder paste comprising the solder alloy according to any one of (0) to (3) above.
- a solder joint characterized by comprising the solder alloy according to any one of (0) to (3) above.
- FIG. 1 is an optical micrograph of the surface of the PCB substrate after the HSS shear test of Example 5.
- FIG. 2 is an optical micrograph of the surface of the PCB substrate after the HSS shear test of Comparative Example 8.
- Solder alloy (1) 0.1-3.9% Ag improves the wettability of molten solder and suppresses the rise in melting point. Furthermore, Ag prevents joint interface failure and drop impact resistance from decreasing in high speed shear tests (hereinafter simply referred to as "HSS").
- HSS high speed shear tests
- the lower limit of the Ag content is 0.1% or more, preferably 0.5% or more, more preferably 1.0% or more, more preferably 1.4% or more, and still more preferably It is 2.0% or more, even more preferably 3.3% or more, particularly preferably 3.4% or more.
- the upper limit of the Ag content is 3.9% or less, preferably 3.7% or less, and more preferably 3.5% or less.
- Cu 0.1-1.0%
- Cu improves the wettability of molten solder. Furthermore, Cu contributes to increasing the tensile strength by precipitation strengthening of the solder alloy. Furthermore, bonding interface destruction due to HSS can be suppressed. In addition to this, share strength will also improve.
- the lower limit of the Cu content is 0.1% or more, preferably 0.3% or more, more preferably 0.5% or more, and still more preferably 0.6% or more.
- the Cu content exceeds 1.0%, wettability deteriorates. Moreover, since coarse Cu 6 Sn 5 compounds that crystallize as primary crystals are precipitated in the bulk, the tensile strength is significantly deteriorated. Furthermore, since the Cu 6 Sn 5 intermetallic compound and the Cu 3 Sn intermetallic compound grow coarsely at the bonding interface, the shear strength deteriorates. In addition, HSS causes bond interface failure.
- the upper limit of the Cu content is 1.0% or less, preferably 0.9% or less, more preferably 0.8% or less, and still more preferably 0.7% or less.
- Bi 0.6-1.4% Bi improves wettability.
- amount of Bi 0.6-1.4% Bi improves wettability.
- amount of Bi brittleness does not occur, and bond interface fracture due to HSS can be suppressed.
- the lower limit of the Bi content is 0.6% or more, preferably 0.7% or more, more preferably 0.8% or more, and still more preferably 0.9% or more.
- the upper limit of the Bi content is 1.4% or less, preferably 1.3% or less, more preferably 1.2% or less, still more preferably 1.1% or less, particularly preferably It is 1.0% or less.
- Sb is a solid solution-strengthening element that penetrates into the Sn matrix, and the amount exceeding the solid solubility limit in Sn forms a precipitation dispersion-strengthening solder alloy that forms fine SnSb intermetallic compounds. Therefore, the tensile strength is improved. Furthermore, since it is less likely to become brittle than Bi, it is possible to suppress bond interface fracture due to HSS. It also prevents a drop in drop impact resistance.
- the lower limit of the Sb content is 5.1% or more, more preferably 5.3% or more, even more preferably 5.5% or more, particularly preferably 5.7% or more, and most preferably It is 6.0% or more.
- the upper limit of the Sb content is 7.9% or less, more preferably 7.5% or less, even more preferably 7.0% or less, particularly preferably 6.5% or less, and most preferably is 6.3% or less.
- Ni 0.01-0.30%
- SnNi compound produced is dispersed and precipitated in the solder alloy, and the structure of the solder alloy becomes fine, so that the tensile strength can be adjusted. Furthermore, drop impact resistance and shear strength are improved, and joint interface failure due to HSS is suppressed. Furthermore, Ni is uniformly dispersed in the intermetallic compound that precipitates near the bonding interface between the electrode and the solder alloy, modifies the intermetallic compound layer, and suppresses breakage at the bonding interface between the electrode and the solder alloy. Therefore, share strength will improve.
- the lower limit of the Ni content is 0.01% or more, preferably 0.02% or more, more preferably 0.03% or more, still more preferably 0.04% or more, and particularly preferably It is 0.05% or more, most preferably 0.06% or more.
- the upper limit of the Ni content is 0.30% or less, preferably 0.25% or less, more preferably 0.20% or less, still more preferably 0.15% or less, and particularly preferably It is 0.10% or less, most preferably 0.08% or less.
- Co 0.001-0.100%
- SnCo compound produced by reacting with Sn is dispersed and precipitated in the solder alloy, resulting in a finer structure of the solder alloy. Therefore, the intermetallic compound formed at the bonding interface also becomes fine, improving the shear strength.
- the lower limit of the Co content is 0.001% or more, preferably 0.003% or more, more preferably 0.004% or more, still more preferably 0.005% or more, particularly preferably 0. It is .006% or more, most preferably 0.007% or more.
- the upper limit of the Co content is 0.100% or less, preferably 0.090% or less, more preferably 0.080% or less, still more preferably 0.070% or less, particularly preferably 0. It is 0.060% or less, most preferably 0.050% or less.
- the solder alloy according to the present invention contains at least one of In, Ga, As, Fe, Pd, Mn, Zn, Zr, and Mg in a total amount of 0.1% or less. At least one of In, Ga, As, Fe, Pd, Mn, Zn, Zr, and Mg can be contained in a total amount of 0.1% or less to the extent that the effects of the above are not deteriorated.
- the lower limit is not particularly limited, but may be 0.0001% or more.
- the remainder of the solder alloy according to the present invention is Sn, and may contain inevitable impurities in addition to the above-mentioned elements.
- the solder alloy according to the present invention may have the remainder consisting of Sn and unavoidable impurities. Even when unavoidable impurities are contained, the above-mentioned effects are not affected. Note that it is better not to include P since the solder powder will aggregate. Moreover, when a large amount of P is contained, the liquidus temperature increases.
- the liquidus temperature of the solder alloy according to the present invention is preferably 210°C or more and 251°C or less, and more preferably the upper limit is 235°C or less. In view of the driving temperature of electronic components, it is more preferable that the liquidus temperature is 218° C. or higher.
- the solidus temperature may be 210°C or higher. The solidus temperature is below the liquidus temperature.
- Equations (1) to (4) 426 ⁇ (Ag ⁇ Cu)/(Ni ⁇ Co) ⁇ 8530 (1) 0.10 ⁇ Bi/Sb ⁇ 0.28 (2) 10.8 ⁇ Sn/Sb ⁇ 18.0 (3) 0.00004 ⁇ Bi ⁇ Sb ⁇ Ni ⁇ Co ⁇ 0.00254 (4)
- Sn, Ag, Cu, Bi, Sb, Ni, and Co are each contained in mass % of the solder alloy.
- the solder alloy according to the present invention preferably satisfies formulas (1) to (4).
- formula (1) Ag and Cu are precipitation-strengthening elements, and Ni and Co are elements that contribute to the formation of fine precipitates at the bonding interface.
- it is better not to improve only the tensile strength or only the shear strength, but to balance them so that both effects can be achieved to a degree that poses no problem in practical use.
- wettability is further improved.
- formula (1) is a decimal number and the last digit is rounded off
- formula (2) is a decimal number and the third digit is rounded off
- formula (3) is a decimal number and the last digit is rounded off.
- the second digit is rounded off
- formula (4) is calculated by rounding off the last six digits in decimal.
- the lower limit of formula (1) is preferably 426 or more, more preferably 595 or more, even more preferably 661 or more, even more preferably 1063 or more, particularly preferably 1190 or more, and 2975 or more. , 3063 or more, 3188 or more, 4375 or more, 4958 or more, 5313 or more, 5950 or more, or 6563 or more.
- the upper limit of formula (1) is preferably 8,530 or less, more preferably 7,438 or less.
- Equation (2) is a relational expression that indicates the balance between the contents of Bi and Sb.
- Bi and Sb contribute to the precipitation of fine SnSb compounds, and by controlling the amount of precipitation of solid phase components of the molten solder, wettability can be further improved.
- the lower limit of formula (2) is preferably 0.10 or more, more preferably 0.11 or more, even more preferably 0.12 or more, still more preferably 0.13 or more, and particularly preferably is 0.14 or more, most preferably 0.16 or more, and may be 0.17 or more, 0.18 or more, 0.19 or more, or 0.20 or more.
- the upper limit of formula (2) is preferably 0.28 or less, more preferably 0.27 or less, even more preferably 0.26 or less, still more preferably 0.25 or less, and especially It is preferably 0.24 or less, most preferably 0.24 or less, and may be 0.23 or less, 0.22 or less, or 0.21 or less.
- Equation (3) is a relational expression that takes into account the balance between the contents of Sn and Sb.
- the tensile strength and shear strength are improved by the precipitation of fine SnSb. It is also possible to make further improvements.
- the lower limit of formula (3) is preferably 10.8 or more, more preferably 11.0 or more, even more preferably 11.1 or more, still more preferably 12.5 or more, and particularly preferably is 12.6 or more, most preferably 14.7 or more, 14.8 or more, 15.6 or more, 15.7 or more, 16.2 or more, 16.3 or more, 16.9 or more, 17. It may be 0 or more, or 17.5 or more.
- the upper limit of formula (3) is preferably 18.0 or less, more preferably 17.7 or less, and even more preferably 17.6 or less.
- Equation (4) is a relational expression that takes into account the content of element groups that contribute to the precipitation of SnSb compounds, SnNi compounds, and SnCo compounds. By blending the contents of Bi, Sb, Ni, and Co in a well-balanced manner, excessive hardening of the solder alloy can be suppressed, and joint interface fracture in HSS can be sufficiently suppressed.
- equation (4) is also a relational equation for contributing to further improvement of wettability, since excessive addition of either element will result in poor wettability.
- the lower limit of formula (4) is preferably 0.00004 or more, more preferably 0.00010 or more, even more preferably 0.00020 or more, still more preferably 0.00041 or more, and particularly preferably is 0.00098 or more, most preferably 0.00102 or more, 0.00106 or more, 0.00109 or more, 0.00115 or more, 0.00131 or more, 0.00134 or more, 0.00136 or more, 0. It may be 00141 or more, 0.00146 or more, 0.00152 or more, or 0.00154 or more.
- the upper limit of formula (4) is preferably 0.00254 or less, more preferably 0.00253 or less, even more preferably 0.00246 or less, still more preferably 0.0245 or less, and especially Preferably it is 0.00237 or less, most preferably 0.00230 or less, 0.00228 or less, 0.00224 or less, 0.00219 or less, 0.00211 or less, 0.00204 or less, 0.00196 or less, 0 It may be .00192 or less, 0.00182 or less, 0.00176 or less, 0.00170 or less, or 0.00163 or less.
- solder paste of the present invention is a mixture of solder powder and flux having the above-mentioned alloy composition.
- the flux used in the present invention is not particularly limited as long as it can be soldered by a conventional method. Therefore, an appropriate mixture of commonly used rosin, organic acid, activator, and solvent may be used.
- the mixing ratio of the metal powder component and the flux component is not particularly limited, but is preferably 70 to 90% by mass for the metal powder component and 10 to 30% by mass for the flux component.
- solder joint is suitable for use in connecting an IC chip and its substrate (interposer) in a semiconductor package, or connecting a semiconductor package and a printed wiring board.
- solder joint refers to a joint between electrodes.
- the method for manufacturing the solder alloy according to the present invention may be carried out according to a conventional method.
- the joining method using the solder alloy according to the present invention may be carried out according to a conventional method using, for example, a reflow method.
- the structure can be made even finer by considering the cooling rate during solidification. For example, the solder joint is cooled at a cooling rate of 2 to 3° C./s or more. Other bonding conditions can be adjusted as appropriate depending on the alloy composition of the solder alloy.
- the solder alloy according to the present invention can be produced by using a low ⁇ -ray material as a raw material.
- a low ⁇ -ray material As a raw material, it becomes possible to suppress soft errors.
- evaluation 1 solidus temperature and liquidus temperature
- evaluation 2 wettability
- evaluation 3 tensile strength
- evaluation 4 shear strength
- evaluation 5 HSS shear.
- Strength Evaluation 6: Drop impact resistance was evaluated.
- Test plate The wettability of the solder alloy was measured according to the meniscograph test method. Flux ("ES-1100” manufactured by Senju Metal Industry Co., Ltd.) was applied to a copper plate (width 10 mm x length 30 mm x thickness 0.3 mm). The copper plate coated with flux was heat-treated at 120° C. for 15 minutes in an air atmosphere to obtain a test plate. Five such test plates were prepared for each of the examples and comparative examples shown in Table 1.
- Shear strength A soldering pattern (1.6 x 0.8 mm) in a FR-4 glass epoxy board with a size of 110 mm x 110 mm and a thickness of 1.6 mm has a size of 3.2 x 1.6 x 0. .55 (mm) 3216 chip resistor components were soldered.
- the solder paste was printed on the board using a metal mask with a thickness of 150 ⁇ m, and then heated in a reflow oven at a peak temperature of 245° C. and a holding time of 40 seconds. Thereafter, the shear strength was measured using a joint strength tester STR-5100 at a shear speed of 6 mm/min and a test height of 100 ⁇ m from the substrate surface.
- HSS Shear Test The HSS Shear Test was conducted as follows. A solder ball with a diameter of 0.3 mm and having the alloy composition shown in Table 1 was placed on a PCB board using an FR-4 glass epoxy board with a size of 36 mm x 50.4 mm and a thickness of 1.2 mm. Then, it was heated in a reflow oven with a peak temperature of 245° C. and a holding time of 40 seconds. Thereafter, a shear test was conducted using a high speed bond tester 4000HS at a shear speed of 4000 mm/sec (240000 mm/min), and the failure mode was visually confirmed.
- Both ends of the printed circuit board to which the CSP was soldered were fixed on a dropping jig with a gap of 1 cm between the jig and the jig.
- a drop jig is dropped from a height at which an acceleration of 1500 G is applied to give a shock to the printed circuit board.
- the central portion of the printed circuit board, whose both ends are fixed to the jig vibrates, and the solder joint between the printed circuit board and the CSP receives a shock from this vibration.
- the progress of cracks in the CSP solder joints was confirmed by checking whether the electrical resistance value increased by 50% from the initial value.
- Comparative Example 1 had poor wettability due to the low Ag content.
- Comparative Example 2 since the content of Ag was high, joint interface failure occurred in the HSS shear test, and the drop impact resistance was also poor.
- Comparative Example 3 had poor wettability due to the low Cu content.
- Comparative Example 4 since the content of Cu was high, wettability, tensile strength, and shear strength were poor, and joint interface failure occurred in the HSS shear test.
- Comparative Example 5 the drop impact resistance was poor due to the low Ni content, and joint interface failure occurred in the HSS shear test. Comparative Example 6 was inferior in all evaluation items because the Ni content was too high.
- Comparative Example 7 had poor tensile strength because the Sb content was low.
- Comparative Example 8 the wettability was poor due to the high content of Sb, and bonding interface failure occurred in the HSS shear test.
- Comparative Example 9 had poor wettability due to the low Bi content.
- Comparative Example 10 bond interface failure occurred in the HSS shear test due to the high Bi content.
- Comparative Example 11 had poor shear strength due to the low Co content. Comparative Example 12 had poor wettability due to the high Co content.
- Comparative Examples 13 and 14 since the Sb content was low and the Bi content was high, joint interface failure occurred in the HSS shear test, and the drop impact resistance was also poor.
- Comparative Example 15 the content of Cu was high and the content of Sb and Bi were low, so the wettability, tensile strength, and shear strength were poor, and joint interface failure occurred in the HSS shear test.
- FIG. 1 is an optical microscope photograph of the PCB substrate surface after the HSS shear test of Example 5
- FIG. 2 is an optical microscope photograph of the PCB substrate surface after the HSS shear test of Comparative Example 8.
- the solder alloy remained in the electrode, indicating that bulk fracture occurred.
- no solder alloy remained and the intermetallic compound was exposed, indicating that the joint interface was fractured.
- Example 5 It was also confirmed that the following examples were bulk fractures or bulk fractures + joint interface fractures.
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Abstract
Description
特許文献1のNo.2には、Sn-3.54Ag-1.04Cu-0.05Ni-3.46Sb-0.29Bi-0.05Coはんだ合金(数値は質量%を表す。以下も同様である。)が開示されている。特許文献1には、このはんだ合金の液相線温度が226℃であり、適度な温度であることが開示されている。しかし、このはんだ合金は、前述のように、Biの含有量が少なく濡れ性が劣る知見が得られた。
これらの知見により得られた本発明は次の通りである。
(1)質量%で、Ag:0.1~3.9%、Cu:0.1~1.0%、Bi:0.6~1.4%、Sb:5.1~7.9%、Ni:0.01~0.30%、Co:0.001~0.100%、および残部がSnからなる合金組成を有することを特徴とするはんだ合金。
)~上記(2)のいずれか1項に記載のはんだ合金。
426≦(Ag×Cu)/(Ni×Co)≦8530 (1)
0.10≦Bi/Sb≦0.28 (2)
10.8≦Sn/Sb≦18.0 (3)
0.00004≦Bi×Sb×Ni×Co≦0.00254 (4)
上記(1)~(4)式中、Sn、Ag、Cu、Bi、Sb、Ni、およびCoは、各々はんだ合金の質量%としての含有量である。
(1) Ag:0.1~3.9%
Agは、溶融はんだの濡れ性を向上させ、融点上昇を抑制する。さらに、Agは、ハイスピードシェア試験(以下、単に「HSS」と称する。)において、接合界面破壊や耐落下衝撃性の低下を妨げる。
Cuは、溶融はんだの濡れ性を向上させる。また、Cuは、はんだ合金の析出強化により引張強度の上昇に寄与する。さらに、HSSによる接合界面破壊を抑制することができる。これに加えて、シェア強度も向上する。
Biは、濡れ性を向上させる。また、Bi量を適切な量とすることで、脆性にならないため、HSSによる接合界面破壊を抑制することができる。
Sbは、Snマトリックス中に侵入する固溶強化型の元素であるとともに、Snへの固溶限を超えた分が微細なSnSb金属間化合物を形成する析出分散強化型のはんだ合金を形成する。このため、引張強度が向上する。また、Biに比べて脆性になりにくいため、HSSによる接合界面破壊を抑制することができる。また、耐落下衝撃性の低下を妨げる。
Niは、Snと反応して生じるSnNi化合物がはんだ合金中に分散析出し、はんだ合金の組織が微細になることで引張強度を調整することができる。また、耐落下衝撃性およびシェア強度が向上し、HSSによる接合界面破壊が抑制される。さらに、Niは、電極とはんだ合金との接合界面付近に析出する金属間化合物中に均一に分散し、金属間化合物層が改質し、電極とはんだ合金との接合界面での破断を抑制するため、シェア強度が向上する。
Coは、Niと同時に添加されることによりNiの前述の効果を高め、また、Snと反応して生じるSnCo化合物がはんだ合金中に分散析出し、はんだ合金の組織が微細になる。このため、接合界面に形成される金属間化合物も微細になり、シェア強度を改善する。
本発明に係るはんだ合金は、上記必須元素に加えて、本発明の効果を劣化させない程度において、In、Ga、As、Fe、Pd、Mn、Zn、Zr、およびMgの少なくとも1種を合計で0.1%以下の量を含有することができる。下限は特に限定されないが、0.0001%以上であればよい。
本発明に係るはんだ合金の残部はSnであり、前述の元素の他に不可避的不純物を含有してもよい。本発明に係るはんだ合金は、残部がSn及び不可避不純物からなるものであってもよい。不可避的不純物を含有する場合であっても前述の効果に影響することはない。なお、Pは、はんだ粉末が凝集するために含有しない方がよい。また、Pを多量に含有する場合は液相線温度が上昇してしまう。
本発明に係るはんだ合金は、液相線温度が210℃以上251℃以下であることが好ましく、上限が235℃以下であることが更に好ましい。電子部品の駆動温度を鑑みると、液相線温度は218℃以上であることが更に好ましい。固相線温度は210℃以上であればよい。固相線温度は液相線温度以下である。
426≦(Ag×Cu)/(Ni×Co)≦8530 (1)
0.10≦Bi/Sb≦0.28 (2)
10.8≦Sn/Sb≦18.0 (3)
0.00004≦Bi×Sb×Ni×Co≦0.00254 (4)
上記(1)~(4)式中、Sn、Ag、Cu、Bi、Sb、Ni、およびCoは、各々はんだ合金の質量%としての含有量である。
本発明のソルダペーストは、上述の合金組成を有するはんだ粉末とフラックスとの混合物である。本発明において使用するフラックスは、常法によりはんだ付けが可能であれば特に制限されない。したがって、一般的に用いられるロジン、有機酸、活性剤、そして溶剤を適宜配合したものを使用すればよい。本発明において金属粉末成分とフラックス成分との配合割合は特に制限されないが、好ましくは、金属粉末成分:70~90質量%、フラックス成分:10~30質量%である。
本発明に係るはんだ継手は、半導体パッケージにおけるICチップとその基板(インターポーザ)との接続、或いは半導体パッケージとプリント配線板との接続に使用するのに適している。ここで、「はんだ継手」とは電極の接合部をいう。
本発明に係るはんだ合金の製造方法は常法に従って行えばよい。本発明に係るはんだ合金を用いた接合方法は、例えばリフロー法を用いて常法に従って行えばよい。また、本発明に係るはんだ合金を用いて接合する場合には、凝固時の冷却速度を考慮した方がさらに組織を微細にすることができる。例えば2~3℃/s以上の冷却速度ではんだ継手を冷却する。この他の接合条件は、はんだ合金の合金組成に応じて適宜調整することができる。
表1に記載した各合金組成を有するはんだ合金について、DSC曲線から各々の温度を求めた。DSC曲線は、セイコーインスツルメンツ社製のDSC(型番:Q2000)により、大気中で5℃/minで昇温して得られた。得られたDSC曲線から液相線温度を求め、溶融温度とした。また、DSC曲線から固相線温度も評価した。固相線温度が210℃以上であるとともに、液相線温度が235℃未満である場合には、「◎」と判定した。固相線温度が210℃以上であるとともに、液相線温度が235℃以上251℃以下である場合には、「〇」と判定した。固相線温度が210℃未満であるか、または液相線温度が251℃を超える場合には、「×」と判定した。
(1)試験板の作製
はんだ合金の濡れ性は、メニスコグラフ試験の方法に準拠して測定された。フラックス(千住金属工業株式会社製「ES-1100」)を、銅板(幅10mm×長さ30mm×厚さ0.3mm)に対して塗布した。フラックスを塗布した銅板を、120℃で15分間、大気雰囲気で加熱処理して、試験板を得た。このような試験板を、表1に示す各実施例及び各比較例のそれぞれについて、5枚ずつ用意した。
得られた試験板を、それぞれ、表1に示す合金組成を有する溶融はんだが導入されているはんだ槽に浸漬させ、ゼロクロスタイム(sec)を得た。ここで、試験装置としてSolder Checker SAT-5100(RHESCA社製)を用い、次のように評価した。各実施例及び各比較例の5枚の試験板のゼロクロスタイム(sec)の平均値により、はんだ濡れ性を評価した。試験条件は、以下のように設定した。
はんだ槽への浸漬深さ:4mm
はんだ槽への浸漬時間:10sec
はんだ槽温度:255℃
ゼロクロスタイム(sec)の平均値が短いほど、濡れ速度は速くなり、はんだ濡れ性が良いことを意味する。
ゼロクロスタイム(sec)の平均値が1.3秒以下である場合には「◎」と判定し、1.3秒を超え、1.5秒以下である場合には「〇」と判定し、1.5秒を超える場合には、「×」と判定した。
引張強度は、JISZ3198-2に準じて測定された。表1に記載の各はんだ合金について、金型に鋳込み、ゲージ長が30mm、直径8mmの試験片が作製された。作製された試験片は、Instron社製のType5966により、室温で、6mm/minのストロークで引っ張られ、試験片が破断したときの強度が計測された。
サイズが110mm×110mm、厚さが1.6mmのFR-4のガラスエポキシ基板内のはんだ付けパターン(1.6×0.8mm)に、大きさが3.2×1.6×0.55(mm)の3216チップ抵抗部品をはんだ付けした。はんだ付けは、150μm厚のメタルマスクを用いて、ソルダペーストを基板に印刷後、ピーク温度が245℃、保持時間を40秒としてリフロー炉で加熱した。その後、継手強度試験機STR-5100を用いて、シェア速度が6mm/min、試験高さは基板表面から100μmの条件でシェア強度を測定した。
HSSシェア試験は、下記のように行われた。サイズが36mm×50.4mm、厚さが1.2mmのFR-4のガラスエポキシ基板を用いたPCB基板に、表1の合金組成を有する直径0.3mmのはんだボールを載置した。そして、ピーク温度が245℃、保持時間を40秒としてリフロー炉で加熱した。その後、ハイスピードボンドテスター4000HSを用いて、シェア速度が4000mm/sec(240000mm/min)の速度でシェア試験を実施し、破壊モードを目視にて確認した。
外形12×12(mm)、電極196個のバンプを有するCuめっきのCSPを用意した。30×120(mm)のガラスエポキシプリント基板中央にソルダペーストを塗布し、CSPを搭載しリフロー炉で加熱してCSPをプリント基板にはんだ付けを行った。
Claims (5)
- 質量%で、Ag:0.1~3.9%、Cu:0.1~1.0%、Bi:0.6~1.4%、Sb:5.1~7.9%、Ni:0.01~0.30%、Co:0.001~0.100%以下、および残部がSnからなる合金組成を有することを特徴とするはんだ合金。
- 前記合金組成は、更に、質量%で、In、Ga、As、Fe、Pd、Mn、Zn、Zr、およびMgの少なくとも1種を合計で0.1%以下の量を含有する、請求項1に記載のはんだ合金。
- 前記合金組成は、下記(1)~(4)式の少なくとも1式を含有する、請求項1または2に記載のはんだ合金。
426≦(Ag×Cu)/(Ni×Co)≦8530 (1)
0.10≦Bi/Sb≦0.28 (2)
10.8≦Sn/Sb≦18.0 (3)
0.00004≦Bi×Sb×Ni×Co≦0.00254(4)
上記(1)~(4)式中、Sn、Ag、Cu、Bi、Sb、Ni、およびCoは、各々はんだ合金の質量%としての含有量である。 - 請求項1または2に記載のはんだ合金を有することを特徴とするはんだペースト。
- 請求項1または2に記載のはんだ合金を有することを特徴とするはんだ継手。
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| CN202380059026.0A CN119677613A (zh) | 2022-08-12 | 2023-08-11 | 软钎料合金、焊膏和钎焊接头 |
| US19/103,045 US20250276411A1 (en) | 2022-08-12 | 2023-08-11 | Solder Alloy, Solder Paste, and Solder Joint |
| EP23852651.1A EP4570420A1 (en) | 2022-08-12 | 2023-08-11 | Solder alloy, solder paste, and solder joint |
| KR1020257007693A KR20250041178A (ko) | 2022-08-12 | 2023-08-11 | 땜납 합금, 땜납 페이스트 및 땜납 조인트 |
| MYPI2025000940A MY209966A (en) | 2022-08-12 | 2023-08-11 | Solder alloy, solder paste, and solder joint |
| JP2023565129A JP7421157B1 (ja) | 2022-08-12 | 2023-08-11 | はんだ合金、はんだペースト及びはんだ継手 |
| MX2025001701A MX2025001701A (es) | 2022-08-12 | 2025-02-10 | Aleacion de soldadura, pasta de soldadura y junta de soldadura |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2014028391A (ja) * | 2012-06-29 | 2014-02-13 | Harima Chemicals Inc | はんだ合金、ソルダペーストおよび電子回路基板 |
| JP2014057974A (ja) * | 2012-09-14 | 2014-04-03 | Senju Metal Ind Co Ltd | はんだ合金 |
| WO2018181873A1 (ja) * | 2017-03-31 | 2018-10-04 | 千住金属工業株式会社 | はんだ合金、ソルダペースト及びはんだ継手 |
| JP6730999B2 (ja) | 2015-05-05 | 2020-07-29 | インディウム コーポレーション | 過酷な環境での電子機器用途のための高信頼性無鉛はんだ合金 |
| JP6836040B1 (ja) | 2020-07-31 | 2021-02-24 | 千住金属工業株式会社 | はんだ合金 |
| WO2021043437A1 (en) | 2019-09-02 | 2021-03-11 | Alpha Assembly Solutions Inc. | High temperature ultra-high reliability alloys |
| CN112475664A (zh) | 2020-11-24 | 2021-03-12 | 苏州优诺电子材料科技有限公司 | 一种焊锡合金及其制备方法 |
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| EP3838473A1 (en) * | 2015-05-05 | 2021-06-23 | Indium Corporation | High reliability lead-free solder alloys for harsh environment electronics applications |
| US11577343B2 (en) * | 2017-11-09 | 2023-02-14 | Alpha Assembly Solutions Inc. | Low-silver alternative to standard SAC alloys for high reliability applications |
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2023
- 2023-08-11 TW TW112130355A patent/TWI858864B/zh active
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Patent Citations (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2014028391A (ja) * | 2012-06-29 | 2014-02-13 | Harima Chemicals Inc | はんだ合金、ソルダペーストおよび電子回路基板 |
| JP2014057974A (ja) * | 2012-09-14 | 2014-04-03 | Senju Metal Ind Co Ltd | はんだ合金 |
| JP6730999B2 (ja) | 2015-05-05 | 2020-07-29 | インディウム コーポレーション | 過酷な環境での電子機器用途のための高信頼性無鉛はんだ合金 |
| WO2018181873A1 (ja) * | 2017-03-31 | 2018-10-04 | 千住金属工業株式会社 | はんだ合金、ソルダペースト及びはんだ継手 |
| WO2021043437A1 (en) | 2019-09-02 | 2021-03-11 | Alpha Assembly Solutions Inc. | High temperature ultra-high reliability alloys |
| JP6836040B1 (ja) | 2020-07-31 | 2021-02-24 | 千住金属工業株式会社 | はんだ合金 |
| JP2022026827A (ja) * | 2020-07-31 | 2022-02-10 | 千住金属工業株式会社 | はんだ合金 |
| CN112475664A (zh) | 2020-11-24 | 2021-03-12 | 苏州优诺电子材料科技有限公司 | 一种焊锡合金及其制备方法 |
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