• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2000.07a
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• pp.640-644
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• 2000

The microstructure, wettability, shear strength and aging effect of Sn-3.5Ag/Cu and Alloy42 lead-frame solder joints were measured for comparison. In the case of Sn-3.5Ag/Cu, Ag$_3$Sn and Cu$\sub$6/Sn$\sub$5/ phases in the matrix Sn and 1∼2$\mu\textrm{m}$ thick Cu$\sub$6/Sn$\sub$5/ Phase at the interface of solder/lead-frame were formed. In the case of Sn-3.5AAg/A11oy42, only Ag$_3$Sn Phase of low density in the matrix Sn and 0.5∼1.5$\mu\textrm{m}$ thick FeSn$_2$phase at the interface of solder/lead-frame were formed. Comparing to Cu, Alloy42 shear strength of Alloy 42 solder joints was smaller than that of Cu and all declined after aging. After aging at 180$^{\circ}C$ for 1 week, η-Cu$\sub$6/Sn$\sub$5/ layer was formed on Cu lead-frame, while AgSn$_3$ phase in the matrix and thickened FeSn$_2$at the interface were formed on Alloy42 lead-frame.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.27 no.2
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• pp.94-98
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• 2017

In the past few years, Sn-3.0Ag-0.5Cu (weight%) solder composition has been a representative material to electronic industries as a replacement of Pb-base solder alloy. Therefore, extensive studies on process and/or reliability related with the composition have been reported. However, recent rapid rise in Ag price has demanded solder compositions of low Ag content. In this study, Sn-3.0Ag-0.5Cu solder bar sample was fabricated by melting of Sn, Ag and Cu metal powders. Crystal structure and element concentration were analyzed by XRD, optical microscope, FE-SEM and EDS. The Sn-3.0Ag-0.5Cu solder sample was composed of ${\beta}$-Sn, ${\varepsilon}-Ag_3Sn$ and ${\eta}-Cu_6Sn_5$ phases.

• Journal of Welding and Joining
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• v.25 no.2
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• pp.82-88
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• 2007

Sn-3.0Ag-0.5Cu lead fee solder was generally utilized in electronics assemblies. But it is insufficient to research about activation energy(Q) that is applying to evaluate the solder joint reliability of environmental friendly electronics assemblies. Therefore this study investigated Q values which are needed to IMC formation and growth of Sn-3.0Ag-0.5Cu/Cu and Sn-40pb/Cu solder joints during aging treatment. We bonded Sn-3.0Ag-0.5Cu and Sn-40Pb solders on FR-4 PCB with Cu pad$(t=80{\mu}m)$. After reflow soldering, to observe the IMC formation and growth of the solder joints, test specimens were aged at 70, 150 and $170^{\circ}C$ for 1, 2, 5, 20, 60, 240, 960, 15840, 28800 and 43200 min, respectively. SEM and EDS were utilized to analysis the IMCS. From these results, we measured the total IMC$(Cu_6Sn_5+Cu_3Sn)$ thickness of Sn-3.0Ag-0.5Cu/Cu and Sn-40Pb/Cu interface, and then obtained Q values for the IMC$(Cu_6Sn_5,\;Cu_3Sn)$ growth of the solder joints.

• Journal of the Microelectronics and Packaging Society
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• v.8 no.3
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• pp.43-47
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• 2001

Sn-3Ag-8Bi-5In was developed for the intermediate melting point solder. Although In-contained solder is expensive, its melting point is lower than these of Sn-Ag-Cu alloys. Sn-3Ag-8Bi-5In solder used for this research has a melting range of 188~$204^{\circ}C$. On this study wetting characteristics of Sn-3Ag-8Bi-5In were evaluated in order to investigate its availability as a Pb-free solder. Wettabilities of Sn-37Pb and Sn-3.5Ag solders were also studied to compare these of the Sn-3Ag-8Bi-5In. Experimental results showed that the zero-cross-time and wetting time at $240^{\circ}C$ for the Sn-3Ag-8Bi-5In were 1.1 and 2.2 second respectively. These values are a little better than these of Sn-37Pb and Sn-3.5Ag solders. The equilibrium wetting farce of the Sn-3Ag-8Bi-5In was 5.8 mN at $240^{\circ}C$, and it was tuned out to be a little higher than that of Sn-3.5Ag and lower than that of Sn-37Pb.

• Journal of the Korean Vacuum Society
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• v.13 no.3
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• pp.127-131
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• 2004

Package reliability test was conducted to investigate the effect of solder composition on the ball fatigue strength for BGA (Ball Grid Array) packaging. The test pieces are assembled using eutectic composition 63Sn/37Pb, 62Sn/36Pb/2Ag, and 63Sn/34.4Pb/2Ag/0.5Sb solder after pre-conditioning at MRT Lv 3 (Moisture Resistance Test Level) and then conducted under T/C (Temperature Cycle test). For each case, the ball shear strength was obtained and micro structure photos were taken. SEM (scanning electron microscope) and EDX (Energy Dispersive X-ray) were used to the analyze failure mechanism. The growth rate of Au-Sn intermetallic compound in Sn63Pb34.5Ag2Sb0.5 solder was slow when compared to 63Sn/37Pb solder and 62Sn/36Pb/2Ag solder. The degradation of shear strength of solder balls caused by solder composition was discussed.

• Journal of Korea Foundry Society
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• v.22 no.2
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• pp.89-96
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• 2002

This study examined the effects of adding Zn to Sn-3.5Ag solder on the microstructure changes and behavior of interface reaction of the solder joint with Cu substrate. The solder/Cu joints were examined with microscope to observe the characteristics of microstructure changes and interfacial reaction layer with aging treatment for up to 120 days at $150^{\circ}C$. Results of the microstructure changes showed that the microstructures were coarsened with aging treatment, while adding 1%Zn suppresses coarsening microstructures. The Sn-3.5Ag/Cu had a fast growth rate of the reaction layer in comparison with the Sn-3.5Ag-1Zn at the aging temperature of $150^{\circ}C$. Through the SEM/EDS analysis of solder joint, it was proved that intermetallic layer was $Cu_6Sn_5$ phase and aged specimens showed that intermetallic layer grew in proportion to $t^{1/2}$, and the precipitate of $Ag_3Sn$ occur to both inner layer and interface of layer and solder. In case of Zn-containing composite solder, $Cu_6Sn_5$ phase formed at the side of substrate and Cu-Zn-Sn phase formed at the other side in double layer. It seems that Cu-Zn-Sn phase formed at solder side did a roll of banrier to suppress the growth of the $Cu_6Sn_5$ layer during the aging treatment.

• Journal of Welding and Joining
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• v.18 no.6
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• pp.42-47
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• 2000

The object of this study is to estimate Sn-Ag-Bi-Ga solder alloy as a substitute for Sn-37Pb alloy. For Sn-Ag-Bi-Ga alloys, Ag, Bi and Ga contents are varied. (Ag : 1~5%, Ga : 3%, Bi : 3~6%) Comparing to Sn-37Pb alloy Sn-Ag-Bi-Ga alloys have wider melting temperature range up to max. $18.7^{\circ}C$. With increasing Ag, Bi contents, the wettability of the alloys increased up to max. 6.6 mN. The vickers hardness of the alloys was max. 46.4 Hv. The ultimate tensile stress of the alloys was max. 60.3 MPa and the elongation was max. 1.2%. The joint strength between circuit board and solder was max. 55.5 N and the joint strength between connector and solder was max. 176.1 N. There were no cracks in this alloys after thermal shock test.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.16 no.5
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• pp.151-156
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• 2007

In this paper, the creep characteristics of lead and lead-free solder joint were investigated using the QFP(Quad Flat Package) creep test. Two kind of solder pastes(Sn-3Ag-0.5Cu, Sn-0.2Sb-0.4Ag-37.4Pb) were applied to the QFP solder joints and each specimen was checked the external and internal failures(i.e., wetting failure, void, pin hole, poor-heel fillet) by digital microscope and X-ray inspection. The creep test was conducted at the temperatures of $100^{\circ}C$ and $130^{\circ}C$ under the load of 15$\sim$20% of average pull strength in solder joints. The creep characteristics of each solder joints were compared using the creep strain-time curve and creep strain rate-stress curves. Through the comparison, the Sn-3Ag-0.5Cu solder joints have higher creep resistance than that of Sn-0.3Sb-0.4Ag-37.4Pb. Also, the grain boundary sliding in the fracture surface and the necking of solder joint were observed by FE-SEM.

• Journal of the Microelectronics and Packaging Society
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• v.11 no.4 s.33
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• pp.43-48
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• 2004

Electromigration of Sn-3.5Ag-0.5Cu solder bumps was investigated with current densities of $3{\~}4{\times}10^4 A/cm^2$ at temperatures of $130{\~}160^{\circ}C$ using flip chip specimens which consisted of upper Si chip and lower Si substrate. Electromigration failure of the Sn-3.5Ag-0.5Cu solder bump occurred with complete consumption of Cu UBM and void formation at cathode side of the solder bump. The activation energies for electromigration of the Sn-3.5Ag-0.5Cu solder bump were measured as 0.61 eV at current density of $3{\times}10^4 A/cm^2$, 0.63 eV at $3.5{\times}10^4 A/cm^2$, and 0.77 eV at $4{\times}10^4 A/cm^2$, respectively.

• Journal of the Microelectronics and Packaging Society
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• v.20 no.3
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• pp.45-51
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• 2013

Thermal annealing tests were performed in an in-situ scanning electron microscope chamber at $130^{\circ}C$, $150^{\circ}C$, and $170^{\circ}C$ in order to investigate the effects of solder structure on the growth kinetics of intermetallic compound (IMC) in Cu/Sn-3.5Ag microbump. Cu/Sn-3.5Ag($6{\mu}m$) microbump with spreading solder structure showed $Cu_6Sn_5$ and $Cu_3Sn$ phase growths and then IMC phase transition stages with increasing annealing time. By the way, Cu/Sn-3.5Ag($4{\mu}m$) microbump without solder spreading, remaining solder was transformed to $Cu_6Sn_5$ right after bonding and had only a phase transition of $Cu_6Sn_5$ to $Cu_3Sn$ during annealing. Measured activation energies for the growth of the $Cu_3Sn$ phase during the annealing were 0.80 and 0.71eV for Cu/Sn-3.5Ag($6{\mu}m$) and Cu/Sn-3.5Ag($4{\mu}m$), respectively.