Photon Attenuation Characteristics of Au–Sn Solder Alloys

Öz

Lead-based solders have long been used in electronics; however, their use has declined following restrictions introduced by the Restriction of Hazardous Substances (RoHS) Directive. Au–Sn solders are attractive lead-free alternatives owing to their high service temperature, creep resistance, mechanical strength, and thermal stability, making them suitable for electronic packaging applications. Since electronic systems in radiation-exposed environments may be subjected to ionizing radiation, understanding the photon interaction characteristics of Au–Sn solders is important. The gamma-ray attenuation characteristics of four Au–Sn solder alloys with Au/Sn weight ratios of 80:20, 78:22, 75:25, and 73:27 were investigated over 1 keV–100 GeV using the XCOM database and Phy-X/PSD software. The evaluated parameters included the mass attenuation coefficient (μ/ρ), half-value layer (HVL), tenth-value layer (TVL), mean free path (λ), effective atomic number (Zeff), transmission factor (TF), exposure buildup factor (EBF), and energy absorption buildup factor (EABF). Au–20Sn exhibited the highest μ/ρ, reaching 7.646 cm²/g at 81 keV. An increase occurred near the Au K-absorption edge (~80.7 keV). At 81 keV, increasing the Au–20Sn thickness from 10 to 150 µm reduced the TF from 89.48% to 18.87%. Differences among the alloys were greatest at low energies and decreased with increasing energy.

Anahtar Kelimeler

• Au–Sn solder alloys
• Effective atomic number
• Gamma-ray attenuation
• Photon buildup factors
• XCOM

Au–Sn Lehim Alaşımlarının Foton Zayıflatma Özellikleri

Öz

Kurşun bazlı lehimler elektronik uygulamalarda uzun süredir kullanılmaktadır; ancak Tehlikeli Maddelerin Kısıtlanması (RoHS) Direktifi ile getirilen sınırlamaların ardından kullanımları azalmıştır. Au–Sn lehimler, yüksek çalışma sıcaklıkları, sürünme dirençleri, mekanik dayanımları ve termal kararlılıkları nedeniyle elektronik paketleme uygulamaları için uygun, kurşunsuz alternatiflerdir. Radyasyona maruz kalan ortamlarda çalışan elektronik sistemler iyonlaştırıcı radyasyona maruz kalabileceğinden, Au–Sn lehimlerin foton etkileşim özelliklerinin anlaşılması önemlidir. Bu çalışmada, Au/Sn ağırlık oranları 80:20, 78:22, 75:25 ve 73:27 olan dört Au–Sn lehim alaşımının gama ışını zayıflatma özellikleri, XCOM veri tabanı ve Phy-X/PSD yazılımı kullanılarak 1 keV–100 GeV enerji aralığında incelenmiştir. Değerlendirilen parametreler kütle zayıflatma katsayısı (μ/ρ), yarı değer kalınlığı (HVL), onda bir değer kalınlığı (TVL), ortalama serbest yol (MFP), etkin atom numarası (Zeff), geçirgenlik faktörü (TF), maruz kalma buildup faktörü (EBF) ve enerji soğurma buildup faktörü (EABF) kapsamaktadır. Au–20Sn, 81 keV'de 7,646 cm²/g değerine ulaşarak en yüksek μ/ρ değerini göstermiştir. Au K-soğurma kenarı (~80,7 keV) yakınında bir artış gözlenmiştir. 81 keV'de Au–20Sn kalınlığının 10 µm'den 150 µm'ye artırılması TF'yi %89,48'den %18,87'ye düşürmüştür. Alaşımlar arasındaki farklılıklar düşük enerjilerde en belirgin düzeyde olup artan enerjiyle birlikte azalmıştır.

Anahtar Kelimeler

• Au–Sn lehim alaşımları
• Etkin atom numarası
• Gama ışını zayıflatması
• Buildup faktörleri
• XCOM

Kaynakça

1. [1] G. S. Matijasevic, C. C. Lee, and C. Y. Wang, “Au Sn alloy phase diagram and properties related to its use as a bonding medium,” Thin Solid Films, vol. 223, no. 2, pp. 276–287, Feb. 1993, doi: 10.1016/0040-6090(93)90533-U.
2. [2] N. Wu, Y. Hu, and S. Sun, “Microstructure Characterization and Interfacial Reactions between Au-Sn Solder and Different Back Metallization Systems of GaAs MMICs,” Materials, vol. 13, no. 6, p. 1266, Mar. 2020, doi: 10.3390/ma13061266.
3. [3] V. Chidambaram, J. Hattel, and J. Hald, “Design of lead-free candidate alloys for high-temperature soldering based on the Au–Sn system,” Mater. Des., vol. 31, no. 10, pp. 4638–4645, Dec. 2010, doi: 10.1016/j.matdes.2010.05.035.
4. [4] S. Tabatabaei, A. Kumar, H. Ardebili, P. J. Loos, and P. M. Ajayan, “Synthesis of Au–Sn alloy nanoparticles for leadfree electronics with unique combination of low and high melting temperatures,” Microelectronics Reliability, vol. 52, no. 11, pp. 2685–2689, Nov. 2012, doi: 10.1016/j.microrel.2012.04.008.
5. [5] Z. X. Zhu, C. C. Li, L. L. Liao, C. K. Liu, and C. R. Kao, “Au–Sn bonding material for the assembly of power integrated circuit module,” J. Alloys Compd., vol. 671, pp. 340–345, Jun. 2016, doi: 10.1016/j.jallcom.2016.02.065.
6. [6] Z. Fang, X. Mao, J. Yang, and F. Yang, “A wafer-level Sn-rich Au–Sn intermediate bonding technique with high strength,” Journal of Micromechanics and Microengineering, vol. 23, no. 9, p. 095008, Sep. 2013, doi: 10.1088/09601317/23/9/095008.
7. [7] J. W. Elmer and R. P. Mulay, “Superplastic creep of AuSn eutectic solder alloy,” Scr. Mater., vol. 120, pp. 14–18, Jul. 2016, doi: 10.1016/j.scriptamat.2016.03.031.
8. [8] P. T. Vianco, A. C. Kilgo, and B. M. McKenzie, “Gold-Tin Solder Wetting Behavior for Package Lid Seals,” J. Electron. Packag., vol. 140, no. 2, Jun. 2018, doi: 10.1115/1.4039749.

9. [9] J. He et al., “Microstructure evolution and deformation behavior of Au–20Sn eutectic alloy during hot rolling process,” J. Alloys Compd., vol. 831, p. 154824, Aug. 2020, doi: 10.1016/j.jallcom.2020.154824.
10. [10] J.-W. Yoon, H.-S. Chun, and S.-B. Jung, “Reliability evaluation of Au–20Sn flip chip solder bump fabricated by sequential electroplating method with Sn and Au,” Materials Science and Engineering: A, vol. 473, no. 1–2, pp. 119125, Jan. 2008, doi: 10.1016/j.msea.2007.03.050.
11. [11] J.-W. Yoon, H.-S. Chun, J.-M. Koo, and S.-B. Jung, “Au–Sn flip-chip solder bump for microelectronic and optoelectronic applications,” Microsystem Technologies, vol. 13, no. 11–12, pp. 1463–1469, Jul. 2007, doi: 10.1007/s00542-006-0330-9.
12. [12] R. R. Chromik, D.-N. Wang, A. Shugar, L. Limata, M. R. Notis, and R. P. Vinci, “Mechanical Properties of Intermetallic Compounds in the Au–Sn System,” J. Mater. Res., vol. 20, no. 8, pp. 2161–2172, Aug. 2005, doi: 10.1557/JMR.2005.0269.
13. [13] G. Ghosh, “Phase stability and cohesive properties of Au–Sn intermetallics: A first-principles study,” J. Mater. Res., vol. 23, no. 5, pp. 1398–1416, May 2008, doi: 10.1557/JMR.2008.0175.
14. [14] W. Wang et al., “A Method for Fast Au-Sn Bonding at Low Temperature Using Thermal Gradient,” Micromachines (Basel)., vol. 14, no. 12, p. 2242, Dec. 2023, doi: 10.3390/mi14122242.
15. [15] X. Wang, L. Zhang, and M. Li, “Structure and Properties of Au–Sn Lead-Free Solders in Electronic Packaging,” Mater. Trans., vol. 63, no. 2, p. MT-M2021200, Feb. 2022, doi: 10.2320/matertrans.MT-M2021200.
16. [16] Indium Corporation, “Off-Eutectic AuSn Alloys for Die-Attach Applications,” 2020.
17. [17] L. Gerward, N. Guilbert, K. B. Jensen, and H. Levring, “WinXCom—a program for calculating X-ray attenuation coefficients,” Radiation Physics and Chemistry, vol. 71, no. 3–4, pp. 653–654, Oct. 2004, doi: 10.1016/j.radphyschem.2004.04.040.
18. [18] M. J. Berger and J. H. Hubbell, “XCOM: Photon Cross Sections on a Personal Computer,” Gaithersburg, MD, Jul. 1987.
19. [19] E. Şakar, Ö. F. Özpolat, B. Alım, M. I. Sayyed, and M. Kurudirek, “Phy-X / PSD: Development of a user friendly online software for calculation of parameters relevant to radiation shielding and dosimetry,” Radiation Physics and Chemistry, vol. 166, p. 108496, Jan. 2020, doi: 10.1016/j.radphyschem.2019.108496.
20. [20] S. Erdönmez, “The effect of cerium oxide nanoparticles on gamma-ray shielding capacity of vinyl ester resin: experimental, MCNP6 and WinXCOM results,” Radiation Effects and Defects in Solids, pp. 1–26, Nov. 2025, doi: 10.1080/10420150.2025.2581580.
21. [21] M. Çağlar, H. Kayacık, Y. Karabul, M. Kılıç, Z. Güven Özdemir, and O. İçelli, “Na2Si3O7/BaO composites for the gamma-ray shielding in medical applications: Experimental, MCNP5, and WinXCom studies,” Progress in Nuclear Energy, vol. 117, p. 103119, Nov. 2019, doi: 10.1016/j.pnucene.2019.103119.
22. [22] F. Akman, O. Kilicoglu, H. Ogul, H. Ozdogan, M. R. Kacal, and H. Polat, “Assessment of neutron and gamma-ray shielding characteristics in ternary composites: Experimental analysis and Monte Carlo simulations,” Radiation Physics and Chemistry, vol. 219, p. 111682, Jun. 2024, doi: 10.1016/j.radphyschem.2024.111682.
23. [23] H. Ozdogan, M. R. Kacal, O. Kilicoglu, H. Polat, H. Ogul, and F. Akman, “Experimental, simulation, and theoretical investigations of gamma and neutron shielding characteristics for reinforced with boron carbide and titanium oxide composites,” Radiation Physics 10.1016/j.radphyschem.2024.112167. and Chemistry, vol. 226, p. 112167, Jan. 2025, doi:
24. [24] M. Mokhtari Dorostkar and A. Abdi Saray, “Comparative analysis of Monte Carlo simulations and experimental evaluation of PMMA reinforced with hgo for gamma radiation shielding,” Sci. Rep., vol. 15, no. 1, p. 28286, Aug. 2025, doi: 10.1038/s41598-025-14223-5.
25. [25] S. Erdönmez, “The Role of Rare Earth Oxides in Enhancing Radiation Shielding of Thermoplastic Polyurethane Composites: A Combined WinXCom and MCNP6 Study,” Journal of Advanced Research in Natural and Applied Sciences, vol. 11, no. 1, pp. 36–52, Mar. 2025, doi: 10.28979/jarnas.1615044.
26. [26] C. AKSOY, “The Shielding Parameters of the Superconducting Tin Based Solders,” El-Cezeri Fen ve Mühendislik Dergisi, Aug. 2021, doi: 10.31202/ecjse.963643.
27. [27] A. A. Rotkovich et al., “The structural and gamma radiation shielding characteristics of plastic-tungsten composites,” Radiation Physics and Chemistry, vol. 247, p. 114041, Oct. 2026, doi: 10.1016/j.radphyschem.2026.114041.
28. [28] B. TÜYSÜZ and S. DİZMAN, “Bazı Seramiklerin Radyasyon Soğurma Kapasitelerinin Belirlenmesi,” El-Cezeri Fen ve Mühendislik Dergisi, Feb. 2022, doi: 10.31202/ecjse.972672.
29. [29] Z. K. Heiba, S. A. Mouhammad, A. Badawi, and M. B. Mohamed, “Dielectric, and Radiation Shielding Investigations of Poly (Vinyl Alcohol)/Poly (Ethylene Glycol)/Zn 0.75-x Mn x Cd 0.25 S Nanocomposites Polymeric Blend,” Journal of Macromolecular Science, Part B, vol. 65, no. 7, pp. 1113–1130, Jul. 2026, doi: 10.1080/00222348.2025.2488175.
30. [30] T. A. Çelebi, G. Hoşgör, and E. Tabar, “Gamma-ray shielding properties of the P2O5–ZnO–SrO glass system: A Geant4 Monte Carlo simulation study,” Radiation Physics and Chemistry, vol. 250, p. 114309, Jan. 2027, doi: 10.1016/j.radphyschem.2026.114309.
31. [31] Z. IŞIK KARADOĞAN, Y. ÖZDEMİR, and E. KAVAZ, “Ni Tabanlı Bazı Süperalaşımların Foton Etkileşim Özelliklerinin İncelenmesi,” El-Cezeri Fen ve Mühendislik Dergisi, Jan. 2021, doi: 10.31202/ecjse.831869.
32. [32] L. G. Rosa, C. A. Anjinho, P. M. Amaral, and J. C. Fernandes, “Mechanical Properties of Some Metallic Powder Alloys and Their Contribution to the Performance of Diamond Tools Used for Cutting Granite,” Metals (Basel)., vol. 9, no. 11, p. 1219, Nov. 2019, doi: 10.3390/met9111219.
33. [33] B. Alshahrani et al., “Amorphous alloys with high Fe content for radiation shielding applications,” Radiation Physics and Chemistry, vol. 183, p. 109386, Jun. 2021, doi: 10.1016/j.radphyschem.2021.109386.
34. [34] M. Kurudirek, M. Büyükyıldız, and Y. Özdemir, “Effective atomic number study of various alloys for total photon interaction in the energy region of 1 keV–100 GeV,” Nucl. Instrum. Methods Phys. Res. A, vol. 613, no. 2, pp. 251–256, Feb. 2010, doi: 10.1016/j.nima.2009.11.061.
35. [35] M. J. R. Aldhuhaibat, M. S. Amana, N. J. Jubier, and A. A. Salim, “Improved gamma radiation shielding traits of epoxy composites: Evaluation of mass attenuation coefficient, effective atomic and electron number,” Radiation Physics and Chemistry, vol. 179, p. 109183, Feb. 2021, doi: 10.1016/j.radphyschem.2020.109183.
36. [36] A. Acikgoz, G. Demircan, D. Yılmaz, B. Aktas, S. Yalcin, and N. Yorulmaz, “Structural, mechanical, radiation shielding properties and albedo parameters of alumina borate glasses: Role of CeO2 and Er2O3,” Materials Science and Engineering: B, vol. 276, p. 115519, Feb. 2022, doi: 10.1016/j.mseb.2021.115519.
37. [37] M. S. Al-Buriahi, Z. A. Alrowaili, C. Eke, J. S. Alzahrani, I. O. Olarinoye, and C. Sriwunkum, “Optical and radiation shielding studies on tellurite glass system containing ZnO and Na2O,” Optik (Stuttg)., vol. 257, p. 168821, May 2022, doi: 10.1016/j.ijleo.2022.168821.
38. [38] B. Jr. Leavitt, “The Impact of AuSn Preforms Thickness on Solder Joint Reliability,” in IMAPS High Temperature Electronics Network (HiTEN 2019), Oxford, UK: IMAPS High Temperature Electronics Network (HiTEN 2019), Jun. 2019, pp. 56–60.
39. [39] J. Liang, L. Zhang, L. Wang, Y. Dong, and T. Ueda, “Flip Chip Bonding of a Quartz MEMS-Based Vibrating Beam Accelerometer,” Sensors, vol. 15, no. 9, pp. 22049–22059, Sep. 2015, doi: 10.3390/s150922049.