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In this paper, thick film chip resistors with two different types of solder alloys namely SnPb and SnAgCu have been evaluated for the effects of the solder alloy elemental composition on the solder joint failures under cyclic temperature loading conditions. The creep properties of both solders have been modelled using the Garofalo equation and the creep strain energy density has been extracted and...
The transition from through-hole technology to surface mount technology has increased the requirement for the reliability of the solder joint shear strength. The transition from lead to lead-free technology had issued new materials, but the most used alloy (SAC) offers an weaker shear strength to the solder joints than SnPb. The solder joints cannot fulfill the electrical and thermal functions if...
Cracking along the intermetallic compound (IMC) interface in solder joints is the most important failure mechanism in electronics packages. In order to understand the failure mechanism well, a 2D solder/IMC interface model is used to examine the stress around the interface. Three solder materials, Sn37Pb, Sn3.5Ag and Sn3.0Ag0.5Cu, and various IMC thicknesses, which represent different growth stages...
The article states first results of reliability measurement of committing of electronic modules with printed circuit board by lead-free solder balls (SAC 305). In order to obtain experimental data, the test boards are periodically exposed to thermal load from -20°C to +100°C with 20 minutes dwell time on the maximum and minimum temperatures. Test samples are produced on alumina ceramics and/or four-layer...
The increasing demand for portable electronics has led to the shrinking in size of electronic components and solder joint dimensions. The industry also made a transition towards the adoption of lead-free solder alloys, commonly based around the Sn-Ag-Cu alloys. As knowledge of the processes and operational reliability of these lead-free solder joints (used especially in advanced packages) is limited,...
To satisfy the requirements of the newest mobile product, smaller solder ball is needed for electronic packages such as chip scale package (CSP). The purpose of this study was to investigate the effect of solder ball size on the interfacial reaction. In this study, 400, 300, and, 200 ??m diameter solder balls of 98.5 wt.% Sn, 1 wt.% Ag, and 0.5 wt.% Cu(SAC105) were formed on the Cu/OSP and electroplated...
In this study, the reliabilities of low Ag SAC alloys doped with Mn or Ce (SACM or SACC) were evaluated under JEDEC drop, dynamic bending, thermal cycling, and cyclic bending test conditions against eutectic SnPb, SAC105, and SAC305 alloys. The Mn or Ce doped low cost SAC105 alloys achieved a higher drop test and dynamic bending test reliability than SAC105 and SAC305, and exceeded SnPb for some test...
In this work, the SAC solder joints with minor Mn or RE (rare earth) additions were bonded on the substrate of OSP Cu surface finishes for evaluating the influence of minor alloying on BIT (ball impact test) behavior. The Mn-doped samples had a better resistance to the degradation in BIT performance suffering long time aging at 150??C. The greater impact force and toughness compared to the other samples...
In this study, lead free (Sn-4Ag-0.5Cu (SAC)) and lead (62Sn-36Pb-2Ag (SP)) solder joint on various surface finished of ball grid array (BGA) pad, such as Immersion Tin (ImSn), Organic solderability preservatives (OSPs), Ni-P/Pd/Au (ENEPIG), and Ni-P/Au (ENIG) was investigated by its interface morphology and its physical properties. To evaluate the mechanical and physical properties of BGA pad with...
A complete halogen-free test vehicle was achieved by assembling five ball grid array (BGA) components with daisy-chain on an 8-layer high density interconnection (HDI) printed circuit board with a low-halide Sn1.0Ag0.5Cu (SAC105) Pb-free solder pastes for reducing the formation of Ag3Sn. Afterward a board-level cyclic bending test was enforced on the as-reflowed assemblies according to the JESD22-B113...
In this paper, a new application of 4-point cyclic bending test for the solder joint reliability evaluation is discussed. In light of the long cycle time of thermal cycle testing, the industry has been searching for a more cost-effective and time-effective way to achieve the evaluation task. The 4-point cyclic bending test is considered a good candidate in this study. The thermal cycle test and 4-point...
This paper deals with presentation of some new aspects of solder ternary alloy 96.5Sn3Ag0.5Cu (wt.%) - SAC305, in order to determine variations in mechanical properties and microstructure caused by treatment in vapour phase soldering (VPS) as well as by accelerated isothermal aging. These specimens have been melted and solidified on HASL (hot air solder levelling) and Ni/Au (ENIG) PCB (printed circuit...
Most accelerated temperature cycling (ATC) tests reported the observations that SnAgCu (SAC) solders have better thermal fatigue reliability than SnPb solders due to their lower creep strain rate. But material studies revealed that this is true only when stress level is below a certain level. When the stress level in the solder increases, eventually the creep strain rate of SAC solder may outgrow...
Electronic assembly technology is in the transition from traditional tin-lead to lead-free, which leading to challenge in many aspects. It is accepted that nitrogen can improve the wettability and reliability of lead-free solders; however, few systemic researches have been reported. In this work, the spreading ratio of Sn-Ag-Cu solder was measured through spreading tests under different atmosphere...
This study concerns the failure mechanism of a lead-free SAC305 solder joint under the isothermal bending fatigue condition. For this, series of bending fatigue tests are carried out with the variations of bending displacement and frequency, and FEM analysis is conducted to examine the relationship between mechanical behavior of a solder joint and fatigue life cycle. The results of this investigation...
In this study, the reliabilities of low Ag SAC alloys doped with Mn or Ce (SACM or SACC) were evaluated under JEDEC drop, dynamic bending, thermal cycling, and cyclic bending test conditions against eutectic SnPb, SAC105, and SAC305 alloys. The Mn or Ce doped low cost SAC105 alloys achieved a higher drop test and dynamic bending test reliability than SAC105 and SAC305, and exceeded SnPb for some test...
Flip chip solder joints made with Cu and Ni underbump metallurgy (UBM) on the chip under current stressing were studied. The effects of material and various thicknesses (5, 10, 15, and 20 mum) of UBM on reliability were investigated. The solder material used was lead-free (Sn4.0Ag0.5Cu). Time to failure of both cases (Cu and Ni UBMs) was forecasted through the physical damage occurring at the bump...
The electronics industry has successfully transitioned to lead free soldering for computer and consumer products while in the automotive industry due to the very high reliability requirements this step is still in an ongoing process. In order to ensure or even to enhance the reliability of electronics the improvement of lead free solder joints based on Sn-Ag-Cu (SAC) solder has been the focus of many...
Electronic assemblies deployed in harsh environments may be subjected to multiple thermal environments during the use-life of the equipment. Often the equipment may not have any macro-indicators of damage such as cracks or delamination. Quantification of thermal environments during use-life is often not feasible because of the data-capture and storage requirements, and the overhead on core-system...
Reliability of SnAgCu solder joints under mechanical stress is not proven, in particular for Aeronautic and High Performance (AHP) products. They are subjected to high temperatures, severe mechanical stresses and long-term mission profiles. This work is comprehended within a larger study, which has as objective the characterization of the SnAgCu alloys mechanical behaviour at the solder joint scale...
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