Photon Attenuation Characteristics of Au–Sn Solder Alloys

Abstract

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.

Keywords

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

Au–Sn Lehim Alaşımlarının Foton Zayıflatma Özellikleri

Abstract

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.

Keywords

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

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