Classifications

• • 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°C
  • B23K35/262—Sn as the principal constituent
• • 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
  • B23K35/02—Rods, electrodes, materials, or media, for use in soldering, welding, or cutting characterised by mechanical features, e.g. shape
  • B23K35/0222—Rods, electrodes, materials, or media, for use in soldering, welding, or cutting characterised by mechanical features, e.g. shape for use in soldering or brazing
  • B23K35/0244—Powders, particles or spheres; Preforms made therefrom
  • B23K35/025—Pastes, creams or slurries
• • 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
• • 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°C
• • 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 powders, solder pastes, solder balls, solder preforms and solder joints.
• the present application claims priority based on Japanese Patent Application No. 2020-071024 filed in Japan on April 10, 2020, the contents of which are incorporated herein by reference.
• Electronic components mounted on printed circuit boards are increasingly required to be smaller and have higher performance.
• Examples of such electronic components include semiconductor packages.
• a semiconductor package a semiconductor element having electrodes is sealed with a resin component. Solder bumps made of a solder material are formed on this electrode. Further, the solder material connects the semiconductor element and the printed circuit board.
• solder materials In solder materials, the effect of ⁇ rays on soft errors becomes a problem. In order to reduce such adverse effects on the operation of semiconductor devices, low ⁇ -dose materials including solder materials are being developed.
• the factor that becomes the ⁇ -ray source is, for example, a trace amount of radioactive elements contained in the solder alloy in the solder material, particularly the base tin (Sn) bullion.
• the solder alloy can be produced by melting and mixing the raw material metals. In such a solder alloy, it is important to remove upstream radioactive elements such as uranium (U), thorium (Th), and polonium (Po) from the alloy composition in order to design a low ⁇ -dose material. On the other hand, it is not technically difficult to remove U, Th, and Po in the refining of Sn bullion (see, for example, Patent Document 1). Generally, Sn contains lead (Pb) and bismuth (Bi) as impurities.
• Radioisotopes 210 Pb and 210 Bi in Pb and Bi are ⁇ -decayed to 210 Po, 210 Po is ⁇ -decayed, and ⁇ rays are generated when 206 Pb is generated.
• This series of decay (uranium series) is said to be the main cause of ⁇ -ray generation from solder materials.
• Cph / cm 2 is often used as the unit.
• Cph / cm 2 is an abbreviation for “counts per hours / cm 2 ” and means the number of alpha rays counted per 1 cm 2 per hour.
• the half-lives of Pb and Bi are as follows.
• the half-life of 210 Bi is about 5 days.
• the half-life of 210 Pb is about 22.3 years.
• the degree of influence (abundance ratio) can be expressed by the following equation (see Non-Patent Document 1). That is, the influence of Bi on ⁇ -ray generation is much lower than that of Pb.
• [ 210 Bi] represents the molar concentration of 210 Bi.
• [ 210 Pb] represents the molar concentration of 210 Pb.
• the ⁇ dose generated from the solder material basically increases with the passage of time. It is said that this is because radioactive Pb and radioactive Bi in the solder alloy are ⁇ -decayed, the amount of Po is increased, and Po is ⁇ -decayed to generate ⁇ rays. Although the material having an extremely low ⁇ -dose contains almost no of these radioactive elements, the ⁇ -dose may increase with time due to the segregation of 210 Po. 210 Po originally emits ⁇ rays, but when the solder alloy is solidified, it segregates at the center of the solder alloy, so that the emitted ⁇ rays are shielded by the solder alloy. Then, with the passage of time, 210 Po is uniformly dispersed in the alloy and is also present on the surface where ⁇ rays are detected, so that the ⁇ dose increases with time (see Non-Patent Document 2).
• the generated ⁇ -dose increases due to the influence of a very small amount of impurities contained in the solder alloy. For this reason, in the design of low ⁇ -dose materials, it becomes difficult to simply add various elements as in the conventional manufacturing method of solder alloys.
• a method of adding arsenic (As) to a solder alloy is known in order to suppress the increase in viscosity of the solder paste over time (see, for example, Patent Document 2).
• the present invention has been made in view of the above circumstances, suppresses an increase in the viscosity of the solder paste over time, has a small temperature difference ( ⁇ T) between the liquidus line temperature and the solidus line temperature, and has mechanical properties.
• Solder alloy that can enhance and suppress the occurrence of soft errors, solder powder made of this solder alloy, solder paste containing this solder powder and flux, solder balls made of this solder alloy, solderp It is an object of the present invention to provide a remodeling and a solder joint.
• the present inventors have studied for the purpose of designing a low ⁇ -dose solder alloy capable of suppressing thickening of solder paste over time without adding As with impurities containing radioactive elements. Through such studies, it was found that the above object can be achieved by adjusting the alloy composition to contain Sn as a main component and a predetermined amount of Bi and Sb, which are noble metals as compared with Sn in ionization tendency. , The present invention has been completed. That is, the present invention employs the following means in order to solve the above problems.
• One aspect of the present invention is U: less than 5 mass ppb, Th: less than 5 mass ppb, Pb: less than 5 mass ppm, As: less than 5 mass ppm, Bi: 0% by mass or more and 0.9% by mass or less, and Sb. : It has an alloy composition of 0% by mass or more and 0.3% by mass or less, and the balance is Sn, satisfies the following formula (1), and has an ⁇ dose of 0.02 cph / cm 2 or less. It is a solder alloy. 0.005 ⁇ Bi + Sb ⁇ 1.2 (1) In the formula (1), Bi and Sb each represent the content (mass%) in the alloy composition.
• One aspect of the present invention is U: less than 5 mass ppb, Th: less than 5 mass ppb, Pb: less than 5 mass ppm, As: less than 5 mass ppm, Bi: more than 0 mass% and 0.9 mass% or less, and Sb. : It has an alloy composition of 0% by mass or more and 0.3% by mass or less, and the balance is Sn, satisfies the following formula (1), and has an ⁇ dose of 0.02 cph / cm 2 or less. It is a solder alloy. 0.005 ⁇ Bi + Sb ⁇ 1.2 (1) In the formula (1), Bi and Sb each represent the content (mass%) in the alloy composition.
• One aspect of the present invention is U: less than 5 mass ppb, Th: less than 5 mass ppb, Pb: less than 5 mass ppm, As: less than 5 mass ppm, Bi: 0% by mass or more and 0.9% by mass or less, and Sb. : It has an alloy composition of 0% by mass or more and less than 0.1% by mass, and the balance is Sn, satisfies the following formula (1), and has an ⁇ dose of 0.02 cph / cm 2 or less. It is a solder alloy. 0.005 ⁇ Bi + Sb ⁇ 1.2 (1) In the formula (1), Bi and Sb each represent the content (mass%) in the alloy composition.
• one aspect of the present invention is a solder powder characterized by being composed of a solder alloy according to the one aspect of the present invention.
• one aspect of the present invention is a solder paste characterized by containing the solder powder and the flux according to the one aspect of the present invention.
• one aspect of the present invention is a solder ball characterized by being made of a solder alloy according to the one aspect of the present invention.
• one aspect of the present invention is a solder preform characterized by being made of a solder alloy according to the one aspect of the present invention.
• one aspect of the present invention is a solder joint characterized by being made of a solder alloy according to the one aspect of the present invention.
• the increase in the viscosity of the solder paste over time is suppressed, the temperature difference ( ⁇ T) between the liquidus line temperature and the solidus line temperature is small, the mechanical properties can be improved, and soft errors occur.
• a solder alloy capable of suppressing the above, a solder powder made of this solder alloy, a solder paste containing the solder powder and a flux, a solder ball made of this solder alloy, a solder preform and a solder joint. ..
• ppb relating to the solder alloy composition is “mass ppb” unless otherwise specified.
• Ppm is “mass ppm” unless otherwise specified.
• % Is “mass%” unless otherwise specified.
• solder alloy The solder alloy according to one aspect of the present invention has U: less than 5% by mass, Th: less than 5% by mass, Pb: less than 5% by mass, As: less than 5% by mass, Bi: 0% by mass or more and 0.9% by mass.
• Bi and Sb each represent the content (mass%) in the alloy composition.
• the solder alloy of this embodiment has U: less than 5 mass ppb, Th: less than 5 mass ppb, Pb: less than 5 mass ppm, As: less than 5 mass ppm, Bi: 0 mass% or more and 0.9 mass% or less, and Sb: It has an alloy composition of 0% by mass or more and 0.3% by mass or less, and the balance is Sn, and satisfies the above formula (1).
• U and Th are radioactive elements.
• the contents of U and Th in the solder alloy are based on the total mass (100% by mass) of the solder alloy from the viewpoint that the ⁇ dose generated from the solder alloy is 0.02 cf / cm 2 or less. , Each less than 5 ppb. From the viewpoint of suppressing the occurrence of soft errors in high-density mounting, the contents of U and Th are preferably 2 ppb or less, and the lower the better.
• ⁇ Pb: less than 5 mass ppm Sn contains Pb as an impurity.
• the radioactive isotope in this Pb undergoes ⁇ -decay to become 210 Po, and 210 Po undergoes ⁇ -decay to generate ⁇ -rays when 206 Pb is generated.
• the content of Pb, which is an impurity, in the solder alloy is as small as possible.
• the content of Pb in the solder alloy is less than 5 ppm, preferably less than 2 ppm, and more preferably less than 1 ppm with respect to the total mass (100% by mass) of the solder alloy.
• the lower limit of the Pb content in the solder alloy may be 0 ppm or more.
• ⁇ As less than 5 mass ppm ⁇ Adding As to the solder alloy is effective in suppressing the thickening of the solder paste over time, but with the addition of As, the alloy also contains radioactive elements, and the ⁇ dose generated from the solder material increases. It will increase.
• An object of the present embodiment is to suppress thickening of the solder paste over time without adding As with impurities containing radioactive elements.
• the content of As in the solder alloy is less than 5 ppm, preferably less than 2 ppm, and more preferably less than 1 ppm with respect to the total mass (100% by mass) of the solder alloy.
• the lower limit of the As content in the solder alloy may be 0 ppm or more.
• a SnAg alloy containing Ag which is noble to Sn, is less likely to be ionized than Sn. Therefore, it is presumed that the alloy containing an element nobler than Sn is difficult to ionize, and the effect of suppressing the thickening of the solder paste over time can be enhanced.
• Bi 0% by mass or more and 0.9% by mass or less Bi is an element whose ionization tendency is noble with respect to Sn, has low reactivity with flux, and exhibits an effect of suppressing thickening of solder paste over time. be.
• Bi is an element capable of suppressing deterioration of wettability because it lowers the liquidus temperature of the solder alloy and reduces the viscosity of the molten solder. However, depending on the content, the solidus temperature is remarkably lowered, and the temperature difference ( ⁇ T) between the liquidus temperature and the solidus temperature becomes wide.
• the content of Bi in the solder alloy is 0% or more and 0.9% or less, preferably 0.030% or more and 0.9, based on the total mass (100% by mass) of the solder alloy. % Or less.
• the lower limit of the Bi content in the solder alloy is 0% or more, preferably 0.0025% or more, more preferably 0.0050% or more, based on the total mass (100% by mass) of the solder alloy. , 0.010% or more is more preferable, and 0.030% or more is particularly preferable.
• the upper limit of the Bi content in the solder alloy is 0.9% or less, preferably 0.7% or less, and 0.5% or less with respect to the total mass (100% by mass) of the solder alloy.
• the content of Bi in the solder alloy is 0% or more and 0.9% or less, preferably 0.0025, with respect to the total mass (100% by mass) of the solder alloy. % Or more and 0.7% or less, more preferably 0.0050% or more and 0.5% or less, further preferably 0.010% or more and 0.3% or less, and particularly preferably 0.030% or more. It is 0.1% or less.
• Sb 0% by mass or more and 0.3% by mass or less
• Sb is an element having an ionization tendency noble to Sn, has low reactivity with flux, and suppresses thickening of solder paste over time, like Bi. It is an element that shows an effect. If the content of Sb in the solder alloy is too large, the wettability deteriorates. Therefore, when Sb is added, it is necessary to set the content to an appropriate level.
• the content of Sb in the solder alloy is 0% or more and 0.3% or less, preferably 0.0040% or more and 0.3, based on the total mass (100% by mass) of the solder alloy. % Or less, more preferably 0.010% or more and 0.3% or less.
• the lower limit of the Sb content in the solder alloy is 0% or more, preferably 0.0025% or more, more preferably 0.0040% or more, based on the total mass (100% by mass) of the solder alloy. , 0.0050% or more is more preferable, and 0.010% or more is particularly preferable.
• the upper limit of the Sb content in the solder alloy is 0.3% or less, preferably 0.1% or less, and less than 0.1% with respect to the total mass (100% by mass) of the solder alloy. More preferably, 0.090% or less is further preferable.
• the content of Sb in the solder alloy is 0% or more and 0.3% or less, preferably 0.0025, with respect to the total mass (100% by mass) of the solder alloy. % Or more and 0.1% or less, more preferably 0.0040% or more and less than 0.1%, further preferably 0.0050% or more and 0.090% or less, and particularly preferably 0.010% or more. It is 0.090% or less.
• the alloy composition of the solder alloy of the present embodiment satisfies the following equation (1). 0.005 ⁇ Bi + Sb ⁇ 1.2 (1)
• Bi and Sb each represent the content (mass%) in the alloy composition.
• Both Bi and Sb in the formula (1) are elements that show the effect of suppressing the thickening of the solder paste over time.
• both Bi and Sb also contribute to the wettability of the solder alloy.
• the total content of Bi and Sb in the solder alloy needs to be 0.005% or more and 1.2% or less with respect to the total mass (100% by mass) of the solder alloy, preferably 0.03. Must be greater than or equal to% and less than or equal to 1.2%.
• the total content of Bi and Sb in the solder alloy is 0.005% or more, preferably 0.03% or more and 1.0% or less, based on the total mass (100% by mass) of the solder alloy.
• the lower limit of the total content of Bi and Sb in the solder alloy is 0.005% or more, preferably 0.01% or more, and 0, based on the total mass (100% by mass) of the solder alloy. .02% or more is more preferable, and 0.03% or more is further preferable.
• the upper limit of the total content of Bi and Sb in the solder alloy is 1.2% or less, preferably 1.0% or less, and 0, based on the total mass (100% by mass) of the solder alloy.
• the total content of Bi and Sb in the solder alloy is preferably 0.01% or more and 1.0% or less, more preferably 0, with respect to the total mass (100% by mass) of the solder alloy. It is 0.02% or more and 0.9% or less, more preferably 0.03% or more and 0.5% or less, and particularly preferably 0.03% or more and 0.1% or less.
• the "total content of Bi and Sb" is the content of Sb when the content of Bi in the solder alloy is 0% by mass, and the content of Sb in the solder alloy is 0% by mass.
• the content of Sb in the solder alloy is 0% by mass.
• it is% it is the content of Bi, and when it has both Bi and Sb, it is the total content of these.
• the ratio of Bi and Sb in the solder alloy is preferably 0.008 or more and 10 or less as the mass ratio represented by Sb / Bi, and more. It is preferably 0.01 or more and 10 or less, more preferably 0.1 or more and 5 or less, particularly preferably 0.1 or more and 2 or less, and most preferably 0.1 or more and 1 or less. If the mass ratio of Sb / Bi is in the above-mentioned preferable range, the effect of the present invention can be more easily obtained.
• the alloy composition of the solder alloy of the present embodiment may contain elements other than the above-mentioned elements, if necessary.
• elements other than the above-mentioned elements, if necessary.
• at least one of Ag: 0% by mass or more and 4% by mass or less and Cu: 0% by mass or more and 0.9% by mass or less is further added. It may be contained.
• Ag 0% by mass or more and 4% by mass or less
• Ag is an arbitrary element capable of forming Ag 3 Sn at the crystal interface to improve the reliability of the solder alloy.
• Ag is an element whose ionization tendency is noble with respect to Sn, and when it coexists with Bi and Sb, the effect of suppressing thickening of the solder paste over time is enhanced.
• the content of Ag in the solder alloy is preferably 0% or more and 4% or less, more preferably 0.5% or more and 3.5%, based on the total mass (100% by mass) of the solder alloy. It is less than or equal to, more preferably 1.0% or more and 3.0% or less, and particularly preferably 2.0% or more and 3.0% or less.
• Cu 0% by mass or more and 0.9% by mass or less
• Cu is an optional element that is used in general solder alloys and can improve the joint strength of solder joints. Further, Cu is an element whose ionization tendency is noble with respect to Sn, and when it coexists with Bi and Sb, the effect of suppressing thickening of the solder paste over time is enhanced.
• the content of Cu in the solder alloy is preferably 0% or more and 0.9% or less, more preferably 0.1% or more and 0.1% or more, based on the total mass (100% by mass) of the solder alloy. It is 8% or less, more preferably 0.2% or more and 0.7% or less.
• the ratio of Cu and Bi in the solder alloy is preferably 0.5 or more and 280 or less as the mass ratio represented by Cu / Bi, and more preferably. It is 0.5 or more and 150 or less, more preferably 0.5 or more and 20 or less, and particularly preferably 1 or more and 15 or less. If the Cu / Bi of such a mass ratio is in the above-mentioned preferable range, the effect of the present invention can be more easily obtained.
• the ratio of Cu and Sb in the solder alloy is preferably 1 or more and 280 or less, and more preferably 1 or more as the mass ratio represented by Cu / Sb. It is 150 or less, more preferably 5 or more and 125 or less. If the Cu / Sb having such a mass ratio is in the above-mentioned preferable range, the effect of the present invention can be more easily obtained.
• the ratio of Cu, Bi and Sb in the solder alloy is preferably 0.4 or more and 150 or less as the mass ratio represented by Cu / (Bi + Sb). It is more preferably 5 or more and 100 or less. If the mass ratio of Cu / (Bi + Sb) is in the above-mentioned preferable range, the effect of the present invention can be more easily obtained.
• the alloy composition of the solder alloy of the present embodiment further contains at least one of Ni: 0 mass ppm or more and 600 mass ppm or less, and Fe: 0 mass ppm or more and 100 mass ppm or less, in addition to the above-mentioned elements. You may.
• Ni 0% by mass or more and 600% by mass or less
• soldering promotes the formation of Sn-containing intermetallic compounds (Sn-containing intermetallic compounds) in the vicinity of the bonding interface in the solder alloy, and this Sn-containing intermetallic compound is precipitated. , The mechanical strength of the solder joint deteriorates.
• Ni is an element that suppresses the formation of the Sn-containing intermetallic compound at the bonding interface. When the solder alloy contains Ni, the formation of the Sn-containing intermetallic compound is suppressed, and the mechanical strength of the solder joint is maintained.
• the content of Ni in the solder alloy exceeds 600 mass ppm, SnNi compounds may precipitate in the vicinity of the bonding interface in the solder alloy, and the mechanical strength of the solder joint may deteriorate.
• the content of Ni in the solder alloy is preferably 0 ppm or more and 600 ppm or less, more preferably 20 ppm or more and 600 ppm or less, based on the total mass (100% by mass) of the solder alloy.
• Fe 0 mass ppm or more and 100 mass ppm or less Fe is an element that suppresses the formation of Sn-containing intermetallic compounds at the bonding interface, similar to Ni. In addition, within a predetermined content range, precipitation of acicular crystals due to the SnFe compound is suppressed, and a short circuit of the circuit can be prevented.
• the term "acicular crystal” as used herein refers to a crystal derived from one SnFe compound having an aspect ratio of 2 or more, which is the ratio of the major axis to the minor axis.
• the content of Fe in the solder alloy is preferably 0 ppm or more and 100 ppm or less, more preferably 20 ppm or more and 100 ppm or less, based on the total mass (100% by mass) of the solder alloy.
• the alloy composition of the solder alloy of the present embodiment further contains at least one of Ni: 0 mass ppm or more and 600 mass ppm or less and Fe: 0 mass ppm or more and 100 mass ppm or less
• the alloy composition is as follows ( It is preferable to satisfy the formula 2). 20 ⁇ Ni + Fe ⁇ 700 (2)
• Ni and Fe each represent the content (mass ppm) in the alloy composition.
• Both Ni and Fe in the formula (2) are elements that suppress the formation of Sn-containing intermetallic compounds at the bonding interface.
• both Ni and Fe also contribute to the effect of suppressing the thickening of the solder paste over time.
• the total content of Ni and Fe in the solder alloy is preferably 20 ppm or more and 700 ppm or less, more preferably 40 ppm or more and 700 ppm or less, still more preferably 40 ppm, based on the total mass (100% by mass) of the solder alloy. More than 600 ppm or less.
• total content of Ni and Fe is the content of Fe when the content of Ni in the solder alloy is 0 mass ppm, and the content of Fe in the solder alloy is 0 mass ppm. When it is ppm, it is the content of Ni, and when it has both Ni and Fe, it is the total content of these.
• the ratio of Ni and Fe in the solder alloy is preferably 0.4 or more and 30 or less as the mass ratio represented by Ni / Fe, and more preferably. It is 0.4 or more and 10 or less, and more preferably 0.4 or more and 5 or less. If the mass ratio of Ni / Fe is in the above-mentioned preferable range, the effect of the present invention can be more easily obtained.
• the balance of the alloy composition of the solder alloy of the present embodiment is Sn.
• unavoidable impurities may be contained. Even if it contains unavoidable impurities, it does not affect the above-mentioned effects.
• the solder alloy of this embodiment has an ⁇ dose of 0.02 cf / cm 2 or less. This is an ⁇ -dose that does not cause soft errors in high-density mounting of electronic components.
• the ⁇ dose in the solder alloy of the present embodiment is preferably 0.01 cf / cm 2 or less, more preferably 0.002 cf / cm 2 or less, from the viewpoint of suppressing soft errors in further high-density mounting. , More preferably 0.001 cf / cm 2 or less.
• the ⁇ dose generated from the solder alloy can be measured as follows.
• the method for measuring the ⁇ dose is based on the international standard JEDEC STANDARD.
• a measurement sample a solder alloy sheet obtained by melting a solder alloy and forming a sheet having an area of 900 cm 2 on one surface is used.
• the solder alloy sheet is installed as a measurement sample in the ⁇ -dosimetry device, and PR gas is purged therein.
• PR gas For PR gas, use one that complies with the international standard JEDEC STANDARD. That is, it is assumed that the PR gas used for the measurement is the decay of radon (Rn) after 3 weeks or more have passed since the gas cylinder was filled with the mixed gas of 90% argon and 10% methane.
• the solder alloy of the present embodiment can be produced, for example, by using a production method having a step of melting and mixing at least one of Bi and Sb and a raw material metal containing Sn. Since the purpose is to design a low ⁇ -dose solder alloy, it is preferable to use a low- ⁇ -dose material as the raw material metal. In addition, it is preferable to use the one from which U, Th and Pb have been removed.
• a Sn produced according to the production method described in JP-A-2010-156502 (Patent Document 1) can be used.
• the Bi as the raw material metal for example, one manufactured according to Japanese Patent Application Laid-Open No. 2013-185214 can be used.
• As the raw material metal for example, one manufactured in accordance with Japanese Patent No. 5692467 can be used.
• a conventionally known method can be used for the operation of melting and mixing the raw metal.
• each constituent element constituting the solder alloy does not function independently, and various effects can be exhibited only when the contents of each constituent element are all within a predetermined range. ..
• the solder alloy of the embodiment described above when the content of each constituent element is within the above range, the increase in viscosity of the solder paste over time can be suppressed, the mechanical strength of the solder joint can be increased, and the mechanical strength of the solder joint can be increased. , The occurrence of soft errors can be suppressed. That is, the solder alloy of the present embodiment is useful as a target low ⁇ -dose material, and by applying it to the formation of solder bumps around the memory, it is possible to suppress the occurrence of soft errors.
• Another object of the present embodiment is to design a low ⁇ -dose solder alloy capable of suppressing thickening of solder paste over time without actively adding As.
• the purpose is achieved by adopting a solder alloy containing Bi and Sb, which are metals having an ionization tendency higher than Sn, in a specific ratio in addition to Sn as a main component.
• Sn for low ⁇ -dose solder alloys has a very high purity, and when the molten alloy is solidified, the crystal size of Sn becomes large. Further, the oxide film in Sn also forms a sparse oxide film corresponding to the oxide film.
• the ⁇ dose after heat treatment at 100 ° C. for 1 hour is applied to the solder alloy sheet formed into a sheet having an area of 900 cm 2 on one surface. It is preferably 0.02 cf / cm 2 or less, more preferably 0.01 cf / cm 2 or less, still more preferably 0.002 cf / cm 2 or less, and particularly preferably 0. It is 001 cph / cm 2 or less.
• a solder alloy exhibiting such an ⁇ dose is useful because segregation of 210 Po is unlikely to occur in the alloy and the influence of changes in the ⁇ dose over time is small. By applying a solder alloy exhibiting such an ⁇ dose, the occurrence of soft errors is further suppressed, and stable operation of the semiconductor element can be more easily ensured.
• solder powder The solder powder according to one aspect of the present invention is made of the above-mentioned solder alloy according to one aspect of the present invention.
• the solder powder of this embodiment is suitable for the solder paste described later.
• Solder powder is produced by known methods such as a dropping method of dropping a molten solder alloy to obtain particles, a spraying method of centrifugal spraying, an atomizing method, a submerged granulation method, and a method of crushing a bulk solder alloy. Can be adopted.
• the dropping or spraying method the dropping or spraying is preferably carried out in an inert atmosphere or a solvent in order to form particles.
• the solder powder of this embodiment is preferably a spherical powder.
• the spherical powder improves the fluidity of the solder alloy.
• the symbols 1 to 8 are satisfied, and the symbols 4 to 8 are satisfied in the powder size classification (Table 2) in JIS Z 3284-1: 2014. It is more preferable to have.
• the particle size of the solder powder satisfies this condition, the surface area of the powder is not too large, the increase in the viscosity of the solder paste over time is suppressed, and the aggregation of the fine powder is suppressed, so that the viscosity of the solder paste increases. May be suppressed. Therefore, it is possible to solder to finer parts.
• the solder powder of the present embodiment also has two or more kinds of solder alloy particle groups having different particle size distributions. As a result, the slipperiness of the solder paste is enhanced, and workability such as easy printing is improved.
• the sphericity of the spherical powder is preferably 0.8 or more, preferably 0.9 or more, more preferably 0.95 or more, still more preferably 0.99 or more.
• the "spherical degree of spherical powder" referred to here shall be measured using a CNC image measurement system (Ultra Quick Vision ULT RA QV350-PRO measuring device manufactured by Mitutoyo Co., Ltd.) that uses the minimum region center method (MZC method). Can be done.
• the sphericity represents the deviation from the sphere, and is, for example, an arithmetic mean value calculated when the diameter of each of 500 solder alloy particles is divided by the major axis, and the value is 1.00, which is the upper limit. The closer it is, the closer it is to a true sphere.
• solder paste contains the solder powder according to one aspect of the present invention and a flux.
• the flux used in the solder paste of the present embodiment is composed of, for example, any one of a resin component, an active component, a solvent, and other components, or a combination of two or more of these components.
• Examples of the resin component include rosin-based resins.
• Examples of the rosin-based resin include raw material rosins such as gum rosin, wood rosin and tall oil rosin, and derivatives obtained from the raw material rosin.
• Examples of the derivative include purified rosin, hydrogenated rosin, disproportionated rosin, polymerized rosin and ⁇ , ⁇ unsaturated carboxylic acid modified products (acrylicated rosin, maleated rosin, fumarized rosin, etc.), and the polymerized rosin.
• the resin components include terpene resin, modified terpene resin, terpenephenol resin, modified terpenephenol resin, styrene resin, modified styrene resin, xylene resin, modified xylene resin, acrylic resin, polyethylene resin, and acrylic. -Polyethylene copolymer resin, epoxy resin and the like can be mentioned.
• modified terpene resin examples include aromatic modified terpene resin, hydrogenated terpene resin, hydrogenated aromatic modified terpene resin and the like.
• modified terpene phenol resin examples include hydrogenated terpene phenol resin and the like.
• modified styrene resin examples include styrene acrylic resin and styrene maleic acid resin.
• modified xylene resin examples include a phenol-modified xylene resin, an alkylphenol-modified xylene resin, a phenol-modified resol-type xylene resin, a polyol-modified xylene resin, and a polyoxyethylene-added xylene resin.
• Examples of the active ingredient include organic acids, amines, halogen-based activators, thixotropic agents, solvents, metal inactivating agents and the like.
• organic acids include succinic acid, glutaric acid, adipic acid, pimelli acid, suberic acid, azelaic acid, sebacic acid, dimer acid, propionic acid, 2,2-bishydroxymethylpropionic acid, tartrate acid, malic acid and glycol.
• examples thereof include acids, diglycolic acid, thioglycolic acid, dithioglycolic acid, stearic acid, 12-hydroxystearic acid, palmitic acid, oleic acid and the like.
• amines include ethylamine, triethylamine, ethylenediamine, triethylenetetramine, 2-methylimidazole, 2-undecylimidazole, 2-heptadecylimidazole, 1,2-dimethylimidazole, 2-ethyl-4-methylimidazole, 2 -Phenylimidazole, 2-phenyl-4-methylimidazole, 1-benzyl-2-methylimidazole, 1-benzyl-2-phenylimidazole, 1-cyanoethyl-2-methylimidazole, 1-cyanoethyl-2-undecylimidazole, 1-Cyanoethyl-2-ethyl-4-methylimidazole, 1-cyanoethyl-2-phenylimidazole, 1-cyanoethyl-2-undecylimidazolium trimerite, 1-cyanoethyl-2-phenylimidazolium trimerite, 1-
• halogen-based activator examples include amine hydrogen halides and organic halogen compounds.
• Amine halide hydrohydrate is a compound obtained by reacting an amine with hydrogen halide.
• the amine here include ethylamine, ethylenediamine, triethylamine, diphenylguanidine, ditrilguanidine, methylimidazole, 2-ethyl-4-methylimidazole and the like
• examples of the hydrogen halide include chlorine, bromine and the like. Examples include hydrides of iodine.
• organic halogen compound examples include trans-2,3-dibromo-2-butene-1,4-diol, triallyl isocyanurate 6 bromide, 1-bromo-2-butanol, 1-bromo-2-propanol, 3 -Bromo-1-propanol, 3-bromo-1,2-propanediol, 1,4-dibromo-2-butanol, 1,3-dibromo-2-propanol, 2,3-dibromo-1-propanol, 2, Examples thereof include 3-dibromo-1,4-butanediol and 2,3-dibromo-2-butene-1,4-diol.
• Examples of the thixotropy include wax-based thixotropy, amide-based thixotropy, sorbitol-based thixotropy, and the like.
• Examples of the wax-based thixotropy include castor oil and the like.
• Examples of amido-based fatty acid agents include monoamide-based fatty acid agents, bis-amide-based fatty acid agents, and polyamide-based fatty acid agents.
• examples of the sorbitol-based thixotropy include dibenzylidene-D-sorbitol, bis (4-methylbenzylidene) -D-sorbitol and the like.
• Examples of the solvent include water, alcohol-based solvents, glycol ether-based solvents, terpineols and the like.
• Examples of the alcohol solvent include isopropyl alcohol, 1,2-butanediol, isobornylcyclohexanol, 2,4-diethyl-1,5-pentanediol, 2,2-dimethyl-1,3-propanediol, and the like.
• glycol ether-based solvent examples include diethylene glycol mono-2-ethylhexyl ether, ethylene glycol monophenyl ether, 2-methylpentane-2,4-diol, diethylene glycol monohexyl ether, diethylene glycol dibutyl ether, and triethylene glycol monobutyl ether. Can be mentioned.
• metal inactivating agent examples include hindered phenolic compounds and nitrogen compounds.
• the flux contains either a hindered phenolic compound or a nitrogen compound, the effect of suppressing the thickening of the solder paste can be easily enhanced.
• the term "metal inactivating agent" as used herein refers to a compound having the ability to prevent the metal from deteriorating due to contact with a certain compound.
• the hindered phenolic compound refers to a phenolic compound having a bulky substituent (for example, a branched or cyclic alkyl group such as a t-butyl group) at at least one of the ortho positions of the phenol.
• the hindered phenolic compound is not particularly limited, and is, for example, bis [3- (3-tert-butyl-4-hydroxy-5-methylphenyl) propionic acid] [ethylenebis (oxyethylene)], N, N.
• Z is an optionally substituted alkylene group.
• R 1 and R 2 are independently optionally substituted alkyl group, aralkyl group, aryl group, heteroaryl group, cycloalkyl. It is a group or a heterocycloalkyl group.
• R 3 and R 4 are alkyl groups that may be substituted independently of each other.
• Examples of the nitrogen compound in the metal inactivating agent include hydrazide nitrogen compounds, amide nitrogen compounds, triazole nitrogen compounds, and melamine nitrogen compounds.
• the hydrazide-based nitrogen compound may be any nitrogen compound having a hydrazide skeleton, and is bis dodecanoate [N2- (2-hydroxybenzoyl) hydrazide], N, N'-bis [3- (3,5-di-tert).
• the amide-based nitrogen compound may be any nitrogen compound having an amide skeleton, and N, N'-bis ⁇ 2- [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionyloxyl] ethyl. ⁇ Oxamide and the like can be mentioned.
• the triazole-based nitrogen compound may be any nitrogen compound having a triazole skeleton, and N- (2H-1,2,4-triazole-5-yl) salicylamide, 3-amino-1,2,4-triazole, Examples thereof include 3- (N-salicyloyl) amino-1,2,4-triazole.
• the melamine-based nitrogen compound may be any nitrogen compound having a melamine skeleton, and examples thereof include melamine and melamine derivatives. More specifically, for example, trisaminotriazine, alkylated trisaminotriazine, alkoxyalkylated trisaminotriazine, melamine, alkylated melamine, alkoxyalkylated melamine, N2-butyl melamine, N2, N2-diethyl melamine, N, Examples thereof include N, N', N', N'', N''-hexakis (methoxymethyl) melamine and the like.
• Examples of other components include surfactants, silane coupling agents, antioxidants, colorants and the like.
• the surfactant examples include nonionic surfactants and weak cationic surfactants.
• the nonionic surfactant examples include polyethylene glycol, polyethylene glycol-polypropylene glycol copolymer, aliphatic alcohol polyoxyethylene adduct, aromatic alcohol polyoxyethylene adduct, polyhydric alcohol polyoxyethylene adduct and the like.
• the weak cationic surfactant examples include terminal diamine polyethylene glycol, terminal diamine polyethylene glycol-polypropylene glycol copolymer, aliphatic amine polyoxyethylene adduct, aromatic amine polyoxyethylene adduct, and polyvalent amine polyoxy. Examples include polyethylene adducts.
• surfactants other than the above include polyoxyalkylene acetylene glycols, polyoxyalkylene glyceryl ethers, polyoxyalkylene alkyl ethers, polyoxyalkylene esters, polyoxyalkylene alkyl amines, polyoxyalkylene alkyl amides and the like. ..
• the content of the flux in the solder paste of the present embodiment is preferably 5 to 95% by mass, more preferably 5 to 50% by mass, based on the total mass (100% by mass) of the solder paste. It is more preferably 5 to 15% by mass. When the flux content is in this range, the thickening suppressing effect caused by the solder powder is sufficiently exhibited.
• the solder paste of the present embodiment can be produced by a production method common in the art.
• a solder paste can be obtained by heating and mixing the compounding components constituting the flux to prepare a flux, and stirring and mixing the solder powder in the flux. Further, in anticipation of the effect of suppressing thickening over time, zirconium oxide powder may be further blended in addition to the solder powder.
• solder ball The solder ball according to one aspect of the present invention is made of the above-mentioned solder alloy according to one aspect of the present invention.
• the solder alloy of the above-described embodiment can be used as a solder ball.
• the solder ball of the present embodiment can be manufactured by using a dropping method which is a common method in the art.
• the particle size of the solder balls is preferably 1 ⁇ m or more, more preferably 10 ⁇ m or more, further preferably 20 ⁇ m or more, and particularly preferably 30 ⁇ m or more.
• the particle size of the solder balls is preferably 3000 ⁇ m or less, more preferably 1000 ⁇ m or less, further preferably 600 ⁇ m or less, and particularly preferably 300 ⁇ m or less.
• the particle size of the solder balls is, for example, preferably 1 ⁇ m or more and 3000 ⁇ m or less, more preferably 10 ⁇ m or more and 1000 ⁇ m or less, further preferably 20 ⁇ m or more and 600 ⁇ m or less, and particularly preferably 30 ⁇ m or more and 300 ⁇ m or less.
• solder preform The solder preform according to one aspect of the present invention is made of the above-mentioned solder alloy according to one aspect of the present invention.
• the solder alloy of the above-described embodiment can be used as a preform.
• Examples of the shape of the preform of the present embodiment include washers, rings, pellets, discs, ribbons, wires, and the like.
• solder joint The solder joint according to one aspect of the present invention is made of the above-mentioned solder alloy according to one aspect of the present invention.
• the solder joint of the present embodiment is composed of an electrode and a solder joint.
• the solder joint portion refers to a portion mainly formed of a solder alloy.
• the solder joint of the present embodiment is formed by, for example, joining an electrode of a PKG (Package) such as an IC chip and an electrode of a substrate such as a PCB (printed circuit board) with the solder alloy of the above-described embodiment. be able to.
• the solder joint of the present embodiment is manufactured by processing by a method common in the art, such as mounting one solder ball of the above-described embodiment on one electrode coated with flux and joining the solder joint. can do.
• ppb for the solder alloy composition is “mass ppb”
• ppm is “mass ppm”
• % is “mass%”.
• solder alloy> (Examples 1 to 414, comparative examples 1 to 8) The raw metal was melted and stirred to prepare solder alloys of each example having the alloy compositions shown in Tables 1A to 25B.
• solder powder The solder alloys of each example are melted and composed of the solder alloys of each example having the alloy compositions shown in Tables 1A to 25B by the atomization method. A solder powder having a size (particle size distribution) satisfying the symbol 4 was prepared.
• a rosin-based resin was used as the resin component.
• a thixotropic agent, an organic acid, an amine and a halogen-based activator were used as the active ingredient.
• a glycol ether solvent was used as the solvent. 42 parts by mass of rosin, 35 parts by mass of glycol ether solvent, 8 parts by mass of thixo agent, 10 parts by mass of organic acid, 2 parts by mass of amine, and 3 parts by mass of halogen-based activator are mixed and flux ( F0) was prepared.
• solder paste ⁇ Manufacturing of solder paste>
• the flux (F0) and a solder powder made of the solder alloys of each example having the alloy compositions shown in Tables 1A to 25B were mixed to produce a solder paste.
• Verification method 1 The ⁇ -dose was measured by using an ⁇ -dose measuring device of a gas flow proportional counter and following the above-mentioned procedures (i), (ii) and (iii). As a measurement sample, a solder alloy sheet immediately after production was used. This solder alloy sheet was obtained by melting the solder alloy immediately after production and forming it into a sheet having an area of 900 cm 2 on one surface. This measurement sample was placed in an ⁇ -dose measuring device, and PR-10 gas was allowed to flow for 12 hours and allowed to stand, and then the ⁇ -dose was measured for 72 hours.
• Verification method 2 The ⁇ dose was measured in the same manner as in (1) Verification method 1 above, except that the measurement sample was changed.
• a measurement sample a solder alloy sheet formed by melting a solder alloy immediately after production and forming a sheet having an area of 900 cm 2 on one surface is heat-treated at 100 ° C. for 1 hour and allowed to cool. board.
• Verification method 3 After storing the solder alloy sheet of the measurement sample whose ⁇ -dose was measured in the above (1) verification method 1 for one year, the ⁇ -dose is again followed by the above-mentioned procedures (i), (ii) and (iii). Was measured to evaluate the change in ⁇ dose over time.

Landscapes

• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• Chemical & Material Sciences (AREA)
• Materials Engineering (AREA)
• Metallurgy (AREA)
• Organic Chemistry (AREA)
• Electric Connection Of Electric Components To Printed Circuits (AREA)

Priority Applications (3)

Applications Claiming Priority (2)

Publications (1)

Family

ID=78023297

Family Applications (1)

Country Status (5)

Families Citing this family (2)

Citations (6)

Family Cites Families (11)

• 2021
  • 2021-02-19 TW TW110105773A patent/TWI782423B/zh active
  • 2021-02-19 CN CN202180041107.9A patent/CN115768591A/zh active Pending
  • 2021-02-19 KR KR1020227034653A patent/KR102587716B1/ko active Active
  • 2021-02-19 WO PCT/JP2021/006450 patent/WO2021205760A1/ja not_active Ceased
  • 2021-02-19 JP JP2022514327A patent/JP7212300B2/ja active Active

Patent Citations (7)

Also Published As

Similar Documents

Legal Events