| 51. |
- Andersson, Cristina, 1969, et al.
(författare)
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Low Cycle Fatigue Behavior of Sn-4.0Ag-0.5Cu Lead-free in Corrosive Environmental Conditions
- 2006
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Ingår i: ESTC 2006 - 1st Electronics Systemintegration Technology Conference; Dresden, Saxony; Germany; 5 September 2006 through 7 September 2006. - 9781424405527 ; , s. 457-467
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Konferensbidrag (refereegranskat)abstract
- Isothermal low cycle fatigue experiments of lead free Sn-Ag-Cu solder joints were executed in different corrosive environmental conditions. The environments/factors varied were temperature, humidity and salt application on to the solder joints. The experiments were executed according to a full factorial design of experiments where the three different factors and two levels for each factor were varied according to literature. The outcome of the design of experiments was the number of cycles to failure defined as 50% load drop. The main goal with this work was to analyze the fatigue behavior of this solder material as a function of the different corrosive environments, and simultaneously to analyze its corrosion behavior/resistance. The factor with the highest effect on the fatigue life was salt application followed by temperature. The factor humidity was not significant for the tests performed.
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| 52. |
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| 53. |
- Andersson, Cristina, 1969, et al.
(författare)
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Low Cycle fatigue of lead-free solders
- 2001
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Ingår i: The Fourth International Symposium on Electronic Packaging Technology. ; , s. 462-470
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Konferensbidrag (refereegranskat)
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| 54. |
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| 55. |
- 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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| 56. |
- Andersson, Cristina, 1969, et al.
(författare)
-
Thermal cycling aging effect on the shear strength, microstructure, IMC and initiation and propagation of surface mounted Sn-3.8Ag-0.7Cu and wave soldered Sn-3.5Ag ceramic chip components
- 2008
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Ingår i: IEEE Transactions on Components and Packaging Technologies. - 1521-3331. ; 31:2, s. 331-344
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Tidskriftsartikel (refereegranskat)abstract
- Temperature cycling of electronic components was carried out at two different temperature profiles, the first ranging between -55°C and 100°C (TC1) and the second between 0°C and 100°C (TC2). Totally, 7000 cycles were run at TC1 and 14500 cycles at TC2. The test board’s top-side components were surface mounted using Sn-3.8Ag-0.7Cu solder alloy, and bottom side SMD components were wave soldered with Sn-3.5Ag alloy. The solder joint degradation was investigated as a function of cycle number by means of shear strength measurements and cross-sectioning. The shear strength drop was correlated to both crack initiation time and propagation rate, and Microstructural changes. The effect of manufacturing process (reflow versus wave soldering) and component size (0805 versus 0603 components) on the shear strength were also investigated.For both reflow and wave soldered components, the harsher the test environment the faster and largest the decrease in shear strength. The shear force is higher for the 0805 components compared to the 0603. The effect of component size on the residual shear strength is higher for the testing condition TC1. TC1 also seems to have a higher effect on the residual shear strength compared to TC2. The main difference between wave soldered and reflow soldered components is that the shear strength is in average higher for the wave soldered components compared to the reflow soldered. For the reflow soldered components using SAC, the microstructure coarsens, especially the Ag3Sn intermetallic particles. Furthermore, this alloy shows an increase of the IMC layer (Cu-Ni-Sn) thickness, and the IMC layer growth is controlled by a diffusion mechanism. The IMC growth coefficient is for the SAC system tested at TC1 0.0231 μm/hr1/2 (0.00053μm/hr) and for TC2 0.0054 μm/hr1/2 (2.9*10-5μm/hr). The microstructural changes during thermal cycling are a result of both static and strain-enhanced aging. For the wave soldered components the microstructure also became coarser, however, the IMC layer (Ni3Sn4) thickness did not change.The IMC layer growth does not affect the shear strength for the test conditions applied in this work. The shear strength decrease observed in the present work as a result of thermal cycling is a result of both microstructural coarsening and crack propagation inside the solder joint.
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| 57. |
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| 58. |
- 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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| 59. |
- Andrae, Anders, 1973, et al.
(författare)
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Application of Simplified Methods for Partial Environmental Assessment of Microelectronics Soldering Materials and Processes in Small and Medium Sized Enterprises
- 2005
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Ingår i: International Journal of Life Cycle Assessment. ; 10:5
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Tidskriftsartikel (refereegranskat)abstract
- As a consequence of the environmental regulations becoming stricter for companies within the microelectronics business area, alternative materials and processes with lower environmental performance will have to come in use. These new materials and processes should be process validated, and environmentally assessed. The Swedish microelectronics manufacturers do not use environmental assessment tools to determine if one alternative is "greener" than the other, as they have neither time nor legislative pressure. Instead, they refer to ´lists´ regarding limitations in the use of forbidden chemicals, and compare the ´lists´ with material safety data sheets. IVF in Sweden had the task of co-ordinating a governmentally financed project of which one of the goals was to advise producers, of microelectronics, on how to compare different material/process alternatives when introducing Pb-free soldering manufacturing technology. The scope of this paper is the evaluation of simplified and partial environmental assessment methods for microelectronics soldering. The problem addressed was the identified scarce understanding and under-use of environmental assessment methodologies in the small and medium sized enterprises in the Swedish electronics industry. A subtask was to analyse if it would be possible to perform a useful evaluation in one working day.A literature study revealed that several methods exist for environmental assessment, but most of them were assessed to be too complicated for the purpose of the present study. Two methods were introduced in the project; a qualitative Checklist Method (CM), and the quantitative Toxic Potential Indicator (TPI) that was used as a screening approach. The methods were tested at a microelectronics manufacturer to find out the applicability and the easiness of use. The checklist was applied to two wave soldering concepts and the TPI was applied to two Sn-Pb solder pastes and two Pb-free solder pastes. The CM generates information that can be used in the identification of qualitative environmental aspects, and the TPI provides fast but coarse results. It was possible for the company to perform this limited environmental assessment in one working day, as the amount of available input information is fairly limited. The participating microelectronics manufacturers in this study have confirmed this. The companies will use fast, understandable and rapidly introducible methods. The TPI was easy to use practically, but the input data available was regarded as too rough to distinguish among similar solder pastes. Anyway, by using the methods described in this paper, it would be possible to perform the assessment in one working day. It was perceived as worthwhile for the CM, and also to some degree for the TPI, despite data gaps for flux constituents. It is recommended that the flux constituents of solder pastes are risk evaluated to provide data for indicator tools like the TPI. The CM and the TPI should also be evaluated in industry sectors other than the microelectronics sector. This is needed to generally answer whether there are useful and systematic methods of environmental risk evaluation in product development. In a broader view, it should be researched what barriers are hindering small and medium sized enterprises to invest more in design for environment.
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| 60. |
- Andrae, Anders, 1973, et al.
(författare)
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Development of a generic data collection model for upstream processes in life cycle inventory of electronic products
- 2002
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Ingår i: Proceedings of First International Conference on Design And Manufacturing for Sustainable Development. - 1860583962 ; , s. 241-253
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Considerations of cost, high speed, high reliability, high manufacturability and environmental compatibility have to be taken into account in future product development of electronic products. To simulate the environmental compatibility, for example a Life Cycle Assessment (LCA) can be performed. An electronic product usually consists of hundreds to thousands of electronic and mechanical components. To perform an LCA is very time consuming if a Life Cycle Inventory (LCI) is done for every single component. This is not needed because the unit processes in the upstream product system in some cases are the same for the ingoing components. In this paper a generic model for LCI is developed and applied to one product system (a business telephone). In this model, the components are divided into main groups and then into sub-groups that result in process modules for unit processes that are similar for the ingoing components. There already exist some models that describe the LCI of electronic products in other ways. This model takes the LCI strategy for the manufacturing phase one step further by identifying which processes constitute part of the common denominator of the upstream product system and proposes which ones should be inventoried first. The developed model makes it possible to obtain a higher resolution and level of understanding compared to earlier models with respect to both components and processes.
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