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Due to growing environmental concerns, lead-free solder materials are being widely used in electronic assemblies. The Anand viscoplastic constitutive model is frequently used to represent mechanical behavior of lead-free solder materials in finite element simulations. However, prior experimental results have demonstrated that properties of lead-free solder materials degrade over time when exposed...
Solder joints in electronic packages are frequently exposed to thermal cycling. Such exposures can occur in real life applications as well as in accelerated thermal cycling tests used for the fatigue behavior characterization. Due to the CTE mismatches of the assembly materials, cyclic temperature leads the solder joints to be subjected to cyclic (tensile/compressive) mechanical loading. On the other...
Electronic systems may be subjected to prolonged and intermittent periods of storage prior to deployment or usage. Prior studies have shown that the lead-free solder interconnects show measurable degradation in the mechanical properties even after the brief exposures to high temperature. In this paper, a method has been developed for determining the equivalent storage time to produce identical damage...
Solder joints in electronic assemblies are often subjected to cyclic (positive/negative) mechanical strains and stresses. Such exposures can occur in variable temperature application environments or during accelerated life thermal cycling tests used for qualification. Cyclic loading leads to damage accumulation, crack initiation, crack propagation, and eventually to fatigue failure. In this investigation,...
Electronics in automotive underhood applications may be subjected to temperatures in the neighborhood of 150°C to 175°C. Several electronic functions such as lane departure warning systems, collision avoidance systems are critical to vehicle operation. Prior studies have shown that low silver leadfree SnAgCu alloys exhibit pronounced deterioration in mechanical properties even after short exposure...
Electronics in automotive underhood applications may be subjected to temperatures in the neighborhood of 150°C to 175°C. Several of the electronics functions such as lane departure warning systems, collision avoidance systems are critical to vehicle operation. Prior studies have shown that low silver leadfree SnAgCu alloys exhibit pronounced deterioration in mechanical properties even after short...
Industry migration to leadfree solders has resulted in a proliferation of a wide variety of solder alloy compositions. The most popular amongst these are the Sn-Ag-Cu family of alloys like SAC105 and SAC305. Electronics subjected to shock and vibration may experience strain rates of 1–100 per sec. Electronic product may often be exposed to high temperature during storage, operation and handling in...
Leadfree solders have been used as interconnects in electronic packaging, due to its environmental friendly chemical property. However, those materials may experience high strain rates when subjected to shock and vibration. Consequently, failure will occur to electronics in those situations. Therefore, knowing the material properties of lead-free solders are extremely important, but research on mechanical...
Electronic systems may be subjected to prolonged and intermittent periods of storage prior to deployment or usage. Prior studies have shown that leadfree solder interconnects show measurable degradation in the mechanical properties even after brief exposures to high temperature. In this paper, a method has been developed for the determining equivalent storage time to produce identical damage at a...
Electronics subjected to shock and vibration may experience strain rates of 1–100 sec−1. High strain rate data is scarce for leadfree solders at strain rates in the range of 1–100 sec−1, typical of drop-impact, shock and vibration. A new experimental method has been developed to achieve constant strain rate in the neighborhood of 1 to 100 sec−1 during the entire deformation history. SAC105 and SAC305,...
Field deployed electronics may accrue damage due to environmental exposure and usage after finite period of service but may not often have any macro-indicators of failure such as cracks or delamination. A method to interrogate the damage state of field deployed electronics in the pre-failure space may allow insight into the damage initiation, progression, and remaining useful life of the deployed...
Electronics may experience high strain rates when subjected to high g-loads of shock and vibration. Material and damage behavior of electronic materials at high strain rates typical of shock and vibration is scarce. Previously studies have shown that second-level interconnects have a high propensity for failure under shock and vibration loads in fine pitch electronics. Exposure to shock and vibration...
The microstructure, mechanical response, and failure behavior of lead free solder joints in electronic assemblies are constantly evolving when exposed to isothermal aging and/or thermal cycling environments. In our prior work on aging effects, we have demonstrated that the observed material behavior variations of Sn-Ag-Cu (SAC) lead free solders during room temperature aging (25°C) and elevated temperature...
In this paper, thermo-mechanical reliability of four different low-silver SnAgCu (SAC) lead free alloys is investigated in a harsh thermal environment of -55 to 125°C. Four configuration of test boards were assembled all having identical 100 I/O, 0.8mm pitch chip array ball grid array (CABGA) packages. Previous researchers have demonstrated the superior performance of low-silver leadfree alloys in...
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