• 한국전기전자재료학회논문지
• /
• 제37권1호
• /
• pp.74-78
• /
• 2024

We have studied the effects of Ag on the characteristics of Sn₄₈In₅₂Ag_x (wt%) low-melting solders for photovoltaic ribbons. The Sn₄₈In₅₂ (wt%) solder coexisted in the InSn₄ and In₃Sn alloys. Ag atoms added in the solder formed an AgIn₂ alloy by reacting with some part of In atoms, while they did not react with Sn atoms. The addition of Ag atoms in the Sn₄₈In₅₂Ag_x (wt%) solders showed useful results; an increase in peel strength and a decrease in melting temperature. The peel strength of the ribbon plated with the Sn₄₈In₅₂ (wt%) solder was 53.6 N/mm², and that of the Sn₄₈In₅₂Ag₁ (wt%) solder largely increased to 125.1 N/mm². In the meanwhile, the melting temperature of the Sn₄₈In₅₂ (wt%) solder was 119.2℃, and that of the Sn₄₈In₅₂Ag₁ (wt%) solder decreased to 114.0℃.

• 대한기계학회논문집A
• /
• 제28권12호
• /
• pp.1856-1863
• /
• 2004

In the last 50 years, lead-contained solder materials have been the most popular interconnect materials used in the electronics industry. Recently, lead-free solders are about to replace lead-contained solders for preventing environmental pollutions. However, the reliability of lead-free solders is not yet satisfactory. Several researchers reported that lead-contained solders have a good fatigue property. The others published that the lead-free solders have a longer thermal fatigue life. In this paper, the reason for the contradictory results published on the estimation of fatigue life of lead-free solder is investigated. In the present study, fatigue behavior of 63Sn37Pb, and two types of lead-free solder joints were compared using pseudo-power cycling testing method, which provides more realistic load cycling than chamber cycling method does. Pseudo-power cycling test was performed in various temperature ranges to evaluating the shear strain effect. A nonlinear finite element model was used to simulate the thermally induced visco-plastic deformation of solder ball joint in BGA packages. It was found that lead-free solder joints have a good fatigue property in the small temperature range condition. That condition induce small strain amplitude. However in the large temperature range condition, lead-contained solder joints have a longer fatigue life.

• 한국주조공학회지
• /
• 제20권2호
• /
• pp.116-121
• /
• 2000

Interfacial reaction and mechanical properties between Sn-Zn-X ternary alloys(X : 3wt.%In, 4wt.%Bi) and Cu-substrate were studied. Cu/solder joints were subjected to aging treatments for up to 50days to see interfacial reaction at $100^{\circ}C$ and then were examined changes of microstructure and interfacial compound by optical microscopy, SEM and EDS. Cu/solder joints were aged to 30days and then loaded to failure at cross head speed of 0.3 mm $min^{-1}$ to measure tensile strength. According to the results of the solderability test, additions of In and Bi in the Sn-9wt.%Zn solder improve the wetting characteristics of the alloy and lower the melting temperature. Through the EDS and XRD analysis of Cu/Sn-9wt.%Zn solder joint, it was concluded that the intermetallic compound was the ${\gamma}-Cu_5Zn_8$ phase. Cu-Zn intermetallics at Cu/solder interfaces played an important role in both the microstructure evolution and failure of solder joints. Cu/solder joint strength was decreased by aging treatment, and those phenomenon was closely related to the thickening of intermetallic layer at Cu/solder joints.

• Journal of Mechanical Science and Technology
• /
• 제16권7호
• /
• pp.919-926
• /
• 2002

In this study, the numerical prediction of the thermal fatigue lie? of a $\mu$BGA (Micro Ball Grid Array) solder joint was focused. Numerical method was performed using the three-dimensional finite element analysis for various solder alloys such as Sn-37%Pb, Sn-3.5%Ag, Sn-3.5%Ag-0.7%Cu and Sn-3.5%Ag-3%In-0.5%Bi during a given thermal cycling. Strain values obtained by the result of mechanical fatigue tests for solder alloys, were used to predict the solder joint fatigue life using the Coffin-Manson equation. The numerical results showed that Sn-3.5%Ag with the 50-degree ball shape geometry had the longest thermal fatigue life in low cycle fatigue. A practical correlation for the prediction of the thermal fatigue life was also suggested by using the dimensionless variable γ. Additionally Sn-3.5Ag-0.75Cu and Sn-2.0Ag-0.5Cu-2.0Bi were applied to 6$\times$8$\mu$BGA obtained from the 63Sn-37Pb Solder. This 6$\times$8$\mu$BGA were tested at different aging conditions at 130$\^{C}$, 150$\^{C}$, 170$\^{C}$ for 300, 600 and 900 hours. Thickness of the intermetallic compound layer was measured thor each condition and the activation energy thor their growth was computed. The fracture surfaces were analyzed using SEM (Scanning Electron Microscope) with EDS ( Energy Dispersive Spectroscopy).

• 마이크로전자및패키징학회지
• /
• 제12권1호
• /
• pp.87-93
• /
• 2005

Au 층의 두께를 $0.1{\~}0.7{\mu}m$로 변화시킨 $0.1{\mu}m$ Ti/3 ${\mu}m$ Cu/Au UBM 상에서 48Sn-52In 솔더를 $150-250^{\circ}C$의 온도 범위에서 리플로우시 UBM/솔더 반응에 의한 금속간화합물의 형성거동을 분석하였다. 또한 Ti/Cu/Au UBM의 Au 두께 및 리플로우 온도에 따른 볼 전단강도와 전단에너지를 분석하였다. $150^{\circ}C$와 $200^{\circ}C$에서 리플로우 시에는 UBM/솔더 계면에 $Cu_6(Sn,In)_5$와 $AuIn_2$ 금속간 화합물이 형성되어 있으나, $250^{\circ}C$에서 리플로우 시에는 솔더 반응이 크게 증가하여 UBM이 대부분 소모되었다. 볼 전단강도는 UBM/솔더 반응과 일치하지 않는 결과를 나타내었으나, 전단 에너지는 UBM/솔더 반응과 잘 일치하는 변화 거동을 나타내었다.

• 마이크로전자및패키징학회지
• /
• 제5권1호
• /
• pp.7-18
• /
• 1998

In the flip chip interconnection on organic substrates using eutectic Pb/Sn solder bumps highly reliable Under Bump Metallurgy (UBM) is required to maintain adhesion and solder wettability. Various UBM systems such as 1$\mu$m Al/0.2$\mu$m Pd/1$\mu$m Cu, laid under eutectic Pb/Sn solder were investigated with regard to their interfacial reactions and adhesion proper-ties. The effects of numbers of solder reflow and aging time on the growth of intermetallic compounds (IMCs) and on the solder ball shear strength were investigated. Good ball shear strength was obtained with 1$\mu$m Al/0.2$\mu$m Ti/5$\mu$m Cu and 1$\mu$m Al/0.2$\mu$m ni/1$\mu$m Cu even after 4 solder reflows or 7 day aging at 15$0^{\circ}C$. In contrast 1$\mu$m Al/0.2$\mu$m Ti/1$\mu$m Cu and 1$\mu$mAl/0.2$\mu$m Pd/1$\mu$m 쳐 show poor ball shear strength. The decrease of the shear strength was mainly due to the direct contact between solder and nonwettable metal such as Ti and Al resulting in a delamination. In this case thin 1$\mu$m Cu and 0.2$\mu$m Pd diffusion barrier layer were completely consumed by Cu-Sn and pd-Sn reaction.

• Journal of Welding and Joining
• /
• 제20권5호
• /
• pp.72-77
• /
• 2002

Flip-chip interconnection that uses solder bump is an essential technology to improve the performance of microelectronics which require higher working speed, higher density, and smaller size. In this paper, the shear strength of Cr/Cr-Cu/Cu UBM structure of the high-melting solder b01p and that of low-melting solder bump after aging is evaluated. Observe intermetallic compound and bump joint condition at the interface between solder and UBM by SEM and TEM. And analyze the shear load concentrated to bump applying finite element analysis. As a result of experiment, the maximum shear strength of Sn-97wt%Pb which was treated 900 hrs aging has been decreased as 25% and Sn-37wt%Pb sample has been decreased as 20%. By the aging process, the growth of $Cu_6Sn_5$ and $Cu_3Sn$ is ascertained. And the tendency of crack path movement that is interior of a solder to intermetallic compound interface is found.

• 마이크로전자및패키징학회지
• /
• 제10권4호
• /
• pp.73-79
• /
• 2003

Sn-Ag 전해도금시 도금욕의 Ag 이온의 농도, 전류밀도, 펄스 주기, 첨가제등의 인자들이 솔더의 조성과 표면형상에 미치는 영향에 관하여 연구하였다. Ag 이온의 농도와 시편에 가해지는 전류밀도를 변화시킴으로써 Sn-Ag 솔더내의 Ag 조성을 조절하는 것이 가능하였고 또한 전류밀도를 증가시키면 솔더의 미세조직의 크기가 감소되는것을 관찰하였다. 펄스 인가 주기와 첨가제의 양등을 변화시키면 솔더내 Ag의 조성이 달라지고 솔더의 표면 거칠기가 감소하면서 표면 형상이 변화됨을 확인하였다. 이러한 과정을 통하여 30 $\mu\textrm{m}$의 미세피치와 15$\mu\textrm{m}$의 범프 높이를 가지는 공정 Sn-Ag 솔더 범프를 형성하였다. 도금된 솔더의 조성은 EDS와 WDS 분석을 통하여 확인하였고 표면형상은 SEM과 3D surface analyzer를 사용하여 분석하였다.

• 마이크로전자및패키징학회지
• /
• 제11권2호
• /
• pp.53-58
• /
• 2004

63Sn-37Pb 공정솔더의 electromigration 현상을 용이하게 관찰하기 위해 63Sn-37Pb 공정솔 더를 증착하여 스트립 형태의 시편을 제작 후 electromigration 테스트를 실시하였다. $80{\sim}150^{\circ}C$의 온도 및 $1{\times}10^4{\sim}1{\times}10^5\;A/cm^2$의 전류밀도에서 electromigration 테스트시 스트립 형상의 63Sn-37Pb 솔더 합금에서 hillock과 void의 발생이 관찰되었으며, 온도와 전류밀도가 높아질수록 void의 형성이 빨라져서 평균파괴시간이 단축되었다. 평균파괴시간을 이용하여 Black의 식으로부터 구한 63Sn-37Pb 솔더 스트립의 electromigration에 대한 활성화 에너지는 $0.16{\sim}0.5\;eV$이었다.

• 마이크로전자및패키징학회지
• /
• 제12권4호통권37호
• /
• pp.301-306
• /
• 2005

새로 개발된 Sn-1.8Bi-0.7Cu-0.6In 솔더의 리플로우 후 고온시효 특성을 전당강도 및 미세구조 분석을 통하여 평가하였다. 범프 형성을 위하여 스텐실 프린트법을 사용하였다. Sn-1.8Bi-0.7Cu-0.6In 솔더의 전단강도가 초기 및 고온시효 후에도 가장 높았고, 생성된 계면 금속간화합물은 리플로우 초기뿐만 아니라 시효 후 동일 하게 $(Cu,\;Ni)_6Sn_5$가 형성되었다. 또한, 500시간 시효 이전에 솔더의 분리 현상이 관찰되었다.