| 1. |
- Andersson, Cristina, 1969, et al.
(författare)
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Tensile properties and microstructural characterization of Sn-0.7Cu-0.4Co bulk solder alloy for electronics applications
- 2008
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Ingår i: Journal of Alloys and Compounds. - : Elsevier BV. - 0925-8388. ; 457:1/2, s. 97-105
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Tidskriftsartikel (refereegranskat)abstract
- The ternary Sn–Cu–Co system eutectic composition was obtained by means of CALPHAD (CALculation of PHAse Diagram) methodology and it was found to be 0.4% Co and 0.7% Cu (wt%) with a melting point of 224 ◦C. The tensile behavior of this alloy was investigated at different strain rates (10−5, 10−4 and 10−3 s−1) and compared to both Sn–37Pb and Sn–4.0Ag–0.5Cu. The Sn–4.0Ag–0.5Cu alloy depicts the highest ultimate tensile strength (UTS) followed by the Sn–37P and finally the Sn–0.7Cu–0.4Co system. The elastic modulus was also higher for the Sn–4.0Ag–0.5Cu followed by the Sn–0.7Cu–0.4Co and last the Sn–37Pb. The microstructure of the Sn–0.7Cu–0.4Co alloy is composed of two types of intermetallic phases, (Cu,Co)6Sn5 and (Co,Cu)Sn2 dispersed in a Sn-rich matrix. The microstructure of this alloy proved to be very stable, after aging at 150 °C for 24 h. The eutectic Sn–0.7Cu–0.4Co solder alloy can therefore be a very good alternative for theSACalloys for surface mount technology applications.
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| 2. |
- Andersson, Cristina, 1969, et al.
(författare)
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Thermal cycling of lead-free Sn-3.8Ag-0.7Cu 388PBGA packages
- 2009
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Ingår i: Soldering and Surface Mount Technology. - : Emerald. - 1758-6836 .- 0954-0911. ; 21:2, s. 28-38
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Tidskriftsartikel (refereegranskat)abstract
- Purpose - The purpose of this paper is to assess the effect of different temperature cycling profiles on the reliability of lead-free 388 plastic ball grid array (PBGA) packages and to deeply understand crack initiation and propagation.Design/methodology/approach - Temperature cycling of Sn-3.8Ag-0.7Cu PBGA packages was carried out at two temperature profiles, the first ranging between - 55 degrees C and 100 degrees C (TC1) and the second between 0 degrees C and 100 degrees C (TC2). Crack initiation and propagation was analyzed periodically and totally 7,000 cycles were run for TO and 14,500 for TC2. Finite element modeling (FEM), for the analysis of strain and stress, was used to corroborate the experimental results.Findings - The paper finds that TC1 had a characteristic life of 5,415 cycles and TC2 of 14,094 cycles, resulting in an acceleration factor of 2.6 between both profiles. Cracks were first visible for TC1, after 2,500 cycles, and only after 4,000 cycles for TC2. The crack propagation rate was faster for TC1 compared to TC2, and faster at the package side compared to the substrate side. The difference in crack propagation rate between the package side and substrate side was much larger for TC1 compared to TC2. Cracks developed first at the package side, and were also larger compared to the substrate side. The Cu tracks on the substrate side affected the crack propagation sites and behaved as SMD. All cracks propagated through the solder and crack propagation was mainly intergranular. Crack propagation was very random and did not follow the distance to neutral point (DNP) theory. FEM corroborated the experimental results, showing both the same critical location of highest creep strain and the independence of DNP.Originality/value - Such extensive work on the reliability assessment of Pb-free 388 PBGA packages has never been performed. This work also corroborates the results from other studies showing the difference in behavior between Pb-free and Pb-containing alloys.
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| 3. |
- Bailey, C., et al.
(författare)
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Coffin-Manson constant determination for a Sn-8Zn-3Bi Lead-Free Solder Joint
- 2006
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Ingår i: Soldering and Surface Mount Technology. - : Emerald. - 1758-6836 .- 0954-0911. ; 18:2, s. 4-11
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Tidskriftsartikel (refereegranskat)abstract
- Purpose To determine the Coffin-Manson (CM) equation constants for fatigue life estimation of Sn-8Zn-3Bi solder joints, since Sn-8Zn-3Bi solder has a melting temperature of around 199°C which is close to that of the conventional Sn-Pb solder which has previously been used in the electronics assembly industry. Design/methodology/approach Three dimensional finite element (FE) simulation analysis was used for comparison with the experimentally measured data and to determine the CM constants. Low cycle fatigue tests and FE simulations were carried out for these lead-free solder joints, and eutectic Sn-37Pb solder was used as a reference. Findings The CM equation for Sn-8Zn-3Bi solder joints was fitted to the lifetimes measured and the shear strains simulated. The constants were determined to be 0.0294 for C, the proportional constant, and for the fatigue exponent, β, −2.833. Originality/value The CM equation can now be used to predict the reliability of Sn-8Zn-3Bi solder joints in electronics assembly and the knowledge base for the properties of the Sn-Zn solder system has been increased.
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| 4. |
- Chen, S., et al.
(författare)
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Coffin-Mansson equation of Sn-4.0Ag-0.5Cu solder joint
- 2009
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Ingår i: Soldering and Surface Mount Technology. - : Emerald. - 1758-6836 .- 0954-0911. ; 21:2, s. 48-54
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Tidskriftsartikel (refereegranskat)abstract
- Purpose: The purpose of this paper is to fit Coffin-Manson equation of Sn-4.0Ag-0.5Cu lead free solder joint by using results of solders joint reliability test and finite element analysis. Also to present a novel device for solder joint reliability test. Design/methodology/approach: Two-points bending test of Sn-4.0Ag-0.5Cu lead free solder joint was carried out at three deflection levels by using a special bending tester that can control displacement exactly by a cam system. The failure criterion was defined as resistance of solder joint getting 10 percent increase. The X-section was done for all failure samples to observe crack initiation and propagation in solder joint. Finite element analysis was presented with ANSYS for obtaining shear strain range, analyzing distribution of stress and strain and supporting experimental results. Findings: The experimental results indicate that the fatigue life decreased obviously with the displacement increased. By using optical microscope and SEM photographs, two kinds of failure mode were found in solder joint. The majority failure mode took place at the bottom corner of solder joint under the termination of resistor initially, and propagated into the solder matrix. Another failure mode was delamination. It appeared at the interface between the termination of resistor and its ceramic body. The distribution status of stress and strain in solder joint and the calculation results of shear strain range at different deflection levels were obtained from simulation result. The Coffin-Manson equation of Sn-4.0Ag-0.5Cu lead free solder joint was fitted by combining experimental data with result of finite element analysis. Originality/value: This paper presents Coffin-Manson equation of Sn-4.0Ag-0.5Cu solder joint with two-points bending test. An effective and economical device was designed and applied.
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| 7. |
- Peng, Sun, 1979
(författare)
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Low Cycle Fatigue Reliability and Interfacial Reaction of Lead-free Solder Joints for Electronic Packaging
- 2005
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Two key technologies in electronics industry are chip technology and packaging technology. Solder plays a crucial role in the assembly and interconnection in the electronic packaging industry. As a joint material, solder provides electronic, thermal and mechanical continuity. The eutectic Sn-Pb alloy has been widely used in surface mount technology (SMT) for the interconnection and mechanical support between electronic components and printed circuit boards (PCB). During the last decades, there have been strong worldwide environmental movements towards "green" non-toxic electronic products. Initiatives and legislation forced the electronics industry to replace lead containing products with more environmental friendly, lead free products. Sn-Zn solder system is therefore a promising candidate, recommended for its low melting temperature, around 200°C, which is close to the melting temperature of the traditional binary tin lead solder. But the low cycle fatigue data of Sn-Zn solder system has not been reported yet and the lack of reliability data is one of the barriers to the application of the Sn-Zn system solder alloy. The aim of the present work is to investigate the low cycle fatigue behaviour of the lead-free Sn-8Zn-3Bi solder joint using lap shear test samples. Finite element simulation is presented and the Coffin-Mason equation for Sn-8Zn-3Bi solder joint is given based on the experimental and simulation results:Nf = 0.0294 ()-2.833Where the Nf is the number of cycles to failure and is the plastic shear strain.Another important issue, related to reliability of solder joints that has been investigated in this work, is the intermetallic compounds (IMCs). Generally, the interconnection by the solder joint is completed by the formation of IMCs at the interface and the reliability of the whole package is affected by IMCs due to their inherent brittle nature and tendency to generate structural defects. The interfacial reaction of Sn-3.5Ag and Sn-4.0Ag-0.5Cu solders on Au/electroless Ni metallization after high temperature storage (HTS) testing at 150°C is investigated for the reliability of electronic production from the metallurgical viewpoint in this work. It is noticed that Ni3Sn4 intermetallic compounds (IMCs) are found in the Sn-Ag system, while two kind of interfacial productions that are (Ni,Cu)3Sn4 IMC layer and (Cu,Ni)6Sn5 spalling compound gains exists in the Sn-Ag-Cu system. Kirkendall voids are found in both lead free solder joints and clear gap exists at the interface for the case of Sn-Ag solder joint after 1000 hour aging.
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| 11. |
- Sun, Peng, 1979, et al.
(författare)
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High temperature aging study of intermetallic compound formation of Sn-3,5Ag and Sn-4.0Ag-0,5Cu solders on electroless Ni(P) metallization
- 2006
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Ingår i: Journal of Alloys and Compounds. - : Elsevier BV. - 0925-8388. ; 425:1-2, s. 191-199
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Tidskriftsartikel (refereegranskat)abstract
- The Sn-3.5Ag and Sn-4.0Ag-0.5Cu solders on Au/electroless Ni(P) metallization exhibited different interfacial morphologies after high temperature storage (HTS) at 150 °C. Ni 3 Sn 4 intermetallic compounds (IMCs) were found in the Sn-Ag system, while for the Sn-Ag-Cu system the IMCs consisted of two kinds of interfacial reactions. For the Sn-3.5Ag solder, the Ni 3 Sn 4 IMC particles lost adhesion/contact to the electroless Ni(P) layer and clear gap was observed in the samples after high temperature storage (HTS) aging for 1000 h. In the Sn-4.0Ag-0.5Cu solder joint, both (Cu,Ni) 6 Sn 5 and (Ni,Cu) 3 Sn 4 compounds were observed after HTS aging. Since the difference in nucleation site and growth rate for kinds of IMCs, (Cu,Ni) 6 Sn 5 was observed at top and (Ni,Cu) 3 Sn 4 at bottom when the interfacial compound layer became thicker as a function of thermal aging. Some voids were found between the electroless Ni(P) interface and the Sn-Ag solder after 168 and 500 h of thermal aging, while the clear gap between the solder and the Ni layer existed after 1000 h aging. The formation mechanism for this gap could be the interconnection and growth of the voids. In the Sn-Ag-Cu system, voids were found inside the Sn-Ni-Cu ternary interfacial compounds after 500 and 1000 h. The formation mechanism for these voids was thought to be Kirkendall effect or etching process. The interfacial layer of Sn-Ag-Cu solder on electroless Ni(P) coating showed the better thermal stable than eutectic Sn-Ag solder. © 2006 Elsevier B.V. All rights reserved.
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| 12. |
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| 13. |
- Sun, Peng, 1979
(författare)
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Interfacial Reactions and Low Cycle Fatigue of Lead-Free Solders for Electronic Packaging
- 2007
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Two key technologies used by the electronics industry are chip technology and packaging technology. Solder plays a crucial role in both of them. During the last decade, there has been a strong worldwide environmental movement towards lead-free electronic products.The Sn-Zn solder system has been presented as a promising lead-free candidate, recommended mainly for its low melting temperature, around 200°C, which is close to the melting temperature of the traditional binary Sn-Pb alloy, 183°C. The alloy composition chosen to be studied in this work was the ternary Sn-8Zn-3Bi. The low cycle fatigue behavior of this alloy was investigated using single lap shear samples. Finite element modeling was performed and the Coffin-Manson equation was given based on results from experiment and simulation both:Nf = 0.0294 (Δγ)-2.833Another important issue relating to the reliability of solder joints also investigated in this work, is the intermetallic compounds (IMCs). During soldering and the build-up of solder joints, IMCs are formed at the interface between the solder and the pad metallization. The reliability of the whole package is typically affected by the integrity of the solder joints, and the integrity of the solder joints is greatly affected by the IMCs mainly due to their inherent brittle nature and tendency to generate structural defects.The interfacial reactions between the eutectic Sn-0.4Co-0.7Cu alloy and electroless nickel, immersion gold (ENIG) metallization was investigated after reflow soldering. Common Sn-4.0Ag-0.5Cu and eutectic Sn-0.7Cu solders were used as reference. Two types of IMCs were found in the solder matrix of the Sn-0.4Co-0.7Cu alloy, namely coarser CoSn2 and finer Cu6Sn5 particles, while only one ternary (Cu,Ni)6Sn5 interfacial compound was detected between the solder alloy and the ENIG coated substrate. It was noted that the thickness of the interfacial IMC layers in the Sn-Co-Cu solder joint were thinner than both Sn-Ag-Cu and Sn-Cu IMC layers.The interfacial reaction of Sn-3.5Ag and Sn-4.0Ag-0.5Cu solders on ENIG metallization after high temperature storage (HTS) testing was investigated from a metallurgical point of view. It was noticed that only Ni3Sn4 IMCs were found in the Sn-Ag system, while two kinds of interfacial products, (Ni,Cu)3Sn4 and (Cu,Ni)6Sn5 existed in the Sn-Ag-Cu system. The interfacial layer between the Sn-Ag-Cu solder and electroless Ni(P) coating showed better thermal stability than eutectic Sn-Ag solder since no spalling was observed.Furthermore, the coupling effect in both Sn-3.5Ag-3.0Bi and Sn-8.0Zn-3.0Bi solder joints in sandwiched structure was studied as a function of reflow time. The coupling effect between the ENIG metallization and the Cu substrate was confirmed since the type of IMCs on Ni(P) layer changed from being a Ni-Sn phase to a Cu-Sn phase, apparently as a result of the diffusion of Cu atoms from the opposite Cu substrate. Furthermore, the ternary (Cu,Ni)6Sn5 compounds were formed at the interface between Sn-Ag-Bi solder and Ni(P) substrate. One complex alloy Sn-Ni-Cu-Zn was formed at the Sn-Zn-Bi/Ni(P) interface; however the growth of this complex alloy on the ENIG coated substrate was suppressed.
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| 14. |
- Sun, Peng, 1979, et al.
(författare)
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Intermetallic Compound Formation in Sn-Co-Cu, Sn-Ag-Cu and Eutectic Sn-Cu Solder Joints on Electroless Ni(P) Immersion Au Surface Finish After Reflow Soldering
- 2006
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Ingår i: Materials Science & Engineering B: Solid-State Materials for Advanced Technology. - : Elsevier BV. - 0921-5107. ; 135:2, s. 134-140
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Tidskriftsartikel (refereegranskat)abstract
- The interfacial reactions between Sn-0.4Co-0.7Cu eutectic alloy and immersion Au/electroless Ni(P)/Cu substrate were investigated after reflow soldering at 260 °C for 2 min. Common Sn-4.0Ag-0.5Cu and eutectic Sn-0.7Cu solders were used as reference. Two types of intermetallic compounds (IMC) were found in the solder matrix of the Sn-0.4Co-0.7Cu alloy, namely coarser CoSn 2 and finer Cu 6 Sn 5 particles, while only one ternary (Cu, Ni) 6 Sn 5 interfacial compound was detected between the solder alloy and the electroless nickel and immersion gold (ENIG) coated substrate. The same trend was also observed for the Sn-Ag-Cu and Sn-Cu solder joints. Compared with the CoSn 2 particles found in the Sn-Co-Cu solder and the Ag 3 Sn particles found in the Sn-Ag-Cu solder, the Cu 6 Sn 5 particles found in both solder systems exhibited finer structure and more uniform distribution. It was noted that the thickness of the interfacial IMCs for the Sn-Co-Cu, Sn-Ag-Cu and Sn-Cu alloys was 3.5 μm, 4.3 μm and 4.1 μm, respectively, as a result of longer reflow time above the alloy's melting temperature since the Sn-Ag-Cu solder alloy has the lowest melting point. © 2006 Elsevier B.V. All rights reserved.
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