• Title/Summary/Keyword: Solder joint

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Optimal Shape of $\mu$BGA Solder Joints and Thermal Fatigue Life ($\mu$BGA 솔더접합부의 형상과 수명평가)

  • 신영의;황성진;김종민
    • Proceedings of the International Microelectronics And Packaging Society Conference
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    • 2002.05a
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    • pp.117-120
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    • 2002
  • In this paper, several methods to predict the solder joint shape are studied. Although there are various methods to predict the solder joint shape, such as truncated sphere method, force-bal tranced analytical solution, and energy-based methods like surface evolver developed by Ken Brakke, we calculate solder joint shape of $\mu$BGA by two solder joint shape prediction methods(truncated sphere method and surface evolver) and then compare results of each method. The results in dicate that two methods can accurately predict the solder joint shape in an accurate range. After that, we calculate reliability solder joint shape under thermal cycle test by FEA program ANSYS. As a result, it could be found that optimal solder joint shape calculated by solder joint prediction method has best reliability in thermal cycle test.

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A Study on Characteristics of Sn-37Pb and Sn-4.0Ag-0.5Cu Solder Joints as Various A:V Ratio (A:V Ratio 변화에 따른 Sn-37Pb, Sn-4.0Ag-0.5Cu Solder 접합부의 특성 연구)

  • Han, Hyun-Joo;Lim, Seok-Jun;Moon, Jung-Tak;Lee, Jin
    • Proceedings of the International Microelectronics And Packaging Society Conference
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    • 2001.11a
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    • pp.67-73
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    • 2001
  • To investigate the relationships of solder joint characteristics with solder composition and A:V ratio (solder volume per pad area), Sn-37Pb and Sn-4.0Ag-0.5Cu solder balls with 330, 400, 450 and $457{\mu}{\textrm}{m}$ size were reflowed on same substrate. Sn-37Pb and Sn-4.0Ag-0.5Cu was reflowed at $220^{\circ}C$ and $240^{\circ}C$ respectively by IR-type soldering machine. As a result of reflowed solder- ball diameter(D) and height(H) measurement, D/H was decreased with solder ball size increment in range of 330~450 ${\mu}{\textrm}{m}$. But, D/H was increased in the solder joint for 457 ${\mu}{\textrm}{m}$ size, it was caused possibly by decrement of solder ball height increment compared with solder volume increment. As a result of shear and pull test, joint strength with A:V ratio was high. Joint strength of Sn-4.0Ag-0.5Cu was higher than Sn-37Pb. However, Sn-37Pb had more stable solder joint of small standard deviation. A thick and clean scallop type Ni-Cu-Sn intermetallic compound layer was formed in high A:V ratio and Sn-4.0Ag-0.5Cu solder joint interface.

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Prediction of Thermal Fatigue Life on $\mu$BGA Solder Joint Using Sn-3.5Ag, Sn-3.5Ag-0.7Cu, and Sn-3.5Ag-3.0In-0.5Bi Solder Alloys (Sn-3.5Ag, Sn-3.5Ag-0.7Cu, Sn-3.5Ag-3.0In-0.5Bi Solder를 이용한 $\mu$BGA Solder접합부의 열피로 수명예측)

  • 김연성;김형일;김종민;신영의
    • Journal of Welding and Joining
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    • v.21 no.3
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    • pp.92-98
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    • 2003
  • This paper describes the numerical prediction of the thermal fatigue life of a $\mu$BGA(Micro Ball Grid Array) solder joint. Finite element analysis(FEA) was employed to simulate thermal cycling loading for solder joint reliability. Strain values, along with the result of mechanical fatigue tests for solder alloys were then used to predict the solder joint fatigue life using the Coffin-Manson equation. The results show that Sn-3.5mass%Ag solder had the longest thermal fatigue life in low cycle fatigue. Also a practical correlation for the prediction of the thermal fatigue life was suggested by using the dimensionless variable ${\gamma}$, which was possible to use several lead free solder alloys for prediction of thermal fatigue life. Furthermore, when the contact angle of the ball and chip has 50 degrees, solder joint has longest fatigue life.

Reliability Estimation of Solder Joint by Using Failure Probability Model (파손확률 모델을 이용한 솔더 조인트의 건전성 평가)

  • Myoung, No-Hoon;Lee, Ouk-Sub;Kim, Dong-Hyeok
    • Proceedings of the KSME Conference
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    • 2004.04a
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    • pp.365-370
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    • 2004
  • Generally, component and FR-4 board are connected by solder joint. Because material properties of components and FR-4 board are different, component and FR-4 board show different coefficients of thermal expansion (CTE) and thus strains in component and board are different when they are heated. That is, the differences in CTE of component and FR-4 board cause the dissimilarity in shear strain and solder joint' failure. The first order Taylor series expansion of the limit state function incorporating with Tresca failure criterion is used in order to estimate the failure probability of solder joints under heated condition. Using shear stresses and shear strains appeared on the solder joint, we estimate the failure probability of solder joints with the Tresca failure criterion. The effects of random variables such as CTE, distance of the solder joint from the neutral point(DNP), temperature variation and height of solder on the failure probability of the solder joint are systematically studied by using the failure probability model with first order reliability method(FORM).

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Study on Joining Strength Improvement of Solder Joint with Pb Free Solder (Pb Free 솔더를 사용한 솔더 접합부의 접합 강도 향상에 관한 연구)

  • 신영의;김영탁
    • Journal of Welding and Joining
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    • v.15 no.2
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    • pp.36-42
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    • 1997
  • In this paper, stability of initial strength at solder joint with lead free solders, such as Sn-In (52-48%) and Sn-Ag (96.5-3.5wt%) was studied. To obtain at solder joint with high quality, it is very important to control the temperature at the interface of solder joints. It is found that the thermal EMF (electro motive force) occurs betwee lead frame and copper pad on a substrate during reflow soldering process using heated tip. As a result of control the temperature at interface of solder joints, variation of initial strength at solder joint decreases from about $\pm40%$ to $\pm20%$, and it is realized Pb free soldering process using Sn/In and Sn-Ag solder paste.

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Prediction of Three-Dimensional Solder Joint Profile in Gullwing Lead using Finite Element Modeling (유한요소 모델링을 이용한 Gullwing 리드의 3차원 솔더 접합부 형상 예측)

  • 최동필;유증돈;이태수
    • Journal of Welding and Joining
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    • v.16 no.4
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    • pp.109-116
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    • 1998
  • The three-dimensional profile of a solder fillet is predicted by minimizing the surface tension and gravity energies of the solder joint using finite element modeling. Geometric complexity stemming from the inclined plane of the gullwing lead is resolved by employing three element types. These element types are used to describe the joint profile formed on the vertical, inclined and interfacial planes. The predicted solder joint profiles show good agreements with the experimental data provided that the solder volume is adjusted considering the wicking effects. Effects of the pad length, inclined lead angle and solder volume on joint profiles are also investigated.

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A study on the implementation of wave soldering process and the solder joint reliability of it using Sn-Cu-Ni lead-free solder (Sn-Cu-Ni계를 이용한 Pb-free wave Soldering의 공정 적용 및 신뢰성에 관한 연구)

  • 유충식;정종만;김진수;김미진
    • Proceedings of the International Microelectronics And Packaging Society Conference
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    • 2001.11a
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    • pp.89-98
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    • 2001
  • Pb-free wave soldering process of AC Adapter was implemented by six sigma method using Sn-Cu-Ni type solder. The solder joint appearance, microstructural change, a lift-off phenomenon and reliability were evaluated through thermal shock teal. $(Cu,Ni)_6Sn_5$-type intermetallic compound of which thickness is about 5 micron was found at solder joint between Sn-Cu-Ni solder and copper land. After applying the thermal shock test of as-soldered product up to 750 cycles, no crack was found at the solder joint and the newly developed product was superior to conventions; one in terms of productivity and reliability.

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Solder Joint Reliability of Bottom-leaded Plastic Package (BLP 패키지의 솔더 조인트의 신뢰성 연구)

  • 박주혁
    • Proceedings of the International Microelectronics And Packaging Society Conference
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    • 2002.05a
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    • pp.79-84
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    • 2002
  • The bottom-leaded plastic(BLP) packages have attracted substantial attention since its appearance in the electronic industry. Since the solder materials have relatively low creep resistance and are susceptible to low cycle fatigue, the life of the solder joints under the thermal loading is a critical issue for the reliability The represent study established a finite element model for the analysis of the solder joint reliability under thermal cyclic loading. An elasto-plastic constitutive relation was adopted for solder materials in the modeling and analysis. A 28-pin BLP assembly is modeled to investigate the effects of various epoxy molding compound, leadframe materials on solder joint reliability. The fatigue life of solder joint is estimated by the modified Coffin-Hanson equation. The two coefficients in the equation are also determined. A new design for lead is also evaluated by using finite element analysis. Parametric studies have been conducted to investigate the dependence of solder joint fatigue life on various package materials.

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Reliability of Fine Pitch Solder Joint with Sn-3.5wt%Ag Lead-Free Solder (Sn-3.5wt%Ag 비납솔더를 이용한 미세피치 솔더접합부의 신뢰성에 관한 연구)

  • 하범용;이준환;신영의;정재필;한현주
    • Journal of Welding and Joining
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    • v.18 no.3
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    • pp.89-96
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    • 2000
  • As solder becomes small and fine, the reliability and solderability of solder joint are the critical issue in present electronic packaging industry. Besides the use of lead(Pb) containing solders for the interconnections of microelectronic subsystem assembly and packaging has enviromental problem. In this study, using Sn/Pb and Sn/Ag eutectic solder paste, in order to obtain decrease of solder joint strength with increasing aging time, initial solder joint strength and aging strength after 1000 hour aging at $100^{\circ}C$ were measured by peel test. And in order to obtain the growth of intermetallic compound(IMC) layer thickness, IMC layer thickness was measured by scanning electron microscope(SEM). As a result, solder joint strength was decreased with increasing aging time. The mean IMC layer thickness was increased linearly with the square root of aging time. The diffusion coefficient(D) of IMC layer was found to $1.29{\times}10^{-13}{\;}cm^2/s$ at using Sn/Pb solder paste, 7.56{\times}10^{-14}{\textrm}{cm}^2/s$ at using Sn/Ag solder paste.

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Thermal Fatigue Life Prediction of ${\mu}BGA$ Solder Joint Using Sn-37mass%Pb Solder and Sn-3.5mass%Ag Lead-free Solder (Sn-37mass%Pb 솔더 및 Sn-3.5mass%Ag 무연솔더를 이용한 ${\mu}BGA$ 솔더접합부의 열피로수명 예측)

  • 신영의;이준환;하범용;정승부;정재필
    • Journal of Welding and Joining
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    • v.19 no.4
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    • pp.406-412
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    • 2001
  • This study is focussed on the numerical prediction of the thermal fatigue life of a ${\mu}BGA$(Micro Ball Grid Array) solder joint. Numerical method is used to perform three-dimensional finite element analysis for Sn-37mass%Pb. Sn-3.5mass%Ag solder alloys during the given thermal cycling. Strain values, along with the result of mechanical fatigue tests for solder alloys were then used to predict the solder joint fatigue life using the Coffin-Manson equation. In this study, a practical correlation for the prediction of the thermal fatigue life is suggested by using the dimensionless variable $\gamma$. As a result. it could be found that Sn-3.5mass%Ag has longer fatigue life than Sn-37mass%Pb in low cycle fatigue. In addition. the result with ${\gamm}ashow$a good agreement with the FEA results.

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