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Analytical models of stress and deformxation of through-silicon vias (TSV), relative to numerical ones, have the advantage of being inexpensive to evaluate and in providing insight. They have the additional advantage of allowing one to embed them in ECAD tools for real time design decisions. Motivated by this reasoning, in this paper, an analytical model for the three-dimensional state of stress in...
The mechanical properties of polymer materials are often a key concern of the microelectronic packaging industry. The theoretical analysis of stress, strain, and deformation induced in electronic assemblies due to environmental exposures such as moisture adsorption, isothermal aging, and thermal cycling require the complete characterization of mechanical properties and constitutive behavior of the...
Presence of a thermal enabling load applied to Ball Grid Array (BGA) components creates a distinctive set of evaluations to be completed for reliability of solder joints (SJ) that connect the BGA to the board. This becomes especially relevant for newer technologies that drive to smaller component form factors. In this comprehensive study, a computational mechanics based Design of Experiments approach...
In the electronic packaging industry, it is important to be able to make accurate predictions of board level solder joint reliability during thermal cycling exposures. The Anand viscoelastic constitutive model is often used to represent the material behavior of the solder in finite element simulations. This model is defined using nine material parameters, and the reliability prediction results are...
One of the most critical failure modes in a BGA package is the solder interconnect failure (2nd level). Conventionally, the solder damage is due to the mismatch of coefficient of thermal expansion (CTE) between the various package components and the PCB. It is absolutely critical to identify and minimize the BGA damage under thermal cycling to improve the package reliability. In the past, the critical...
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...
The macroscopic stress dependence of bipolar junction transistors (BJTs) can be modeled by three transport model parameters as a function of stress: saturation current IS, forward current gain βF, and Early voltage VA. Recent research has shown that Early voltage VA is independent of stress, so it is not discussed in detail in this paper. Unfortunately, accurate extraction of model parameters IS and...
Ensuring adequate thermal performance is essential for the reliable operation of flip-chip electronic packages. Thermal interface materials (TIMs), applied between the die and a heat spreader form a crucial thermal junction between the first level package and external cooling mechanisms such as heat-sinks and cooling fans. Selection of a good TIM is dependent not only on its thermal properties but...
The following study is motivated by the need to capture the elasto-viscoplastic behavior of a “real” industrial power module lead-free solder joint. In this work, we carried out a numerical design of experiments in order to forecast the ability of an experimental bending system to identify the specimen material properties. As a proof of principle, the micro-mechanical elastic behavior of power module...
Solder materials in electronic packages are often subjected to thermal cycling, either during their application in products or during accelerated life qualification testing. Cyclic temperatures cause the solder joints to be subjected to cyclic mechanical stresses and strains due to the mismatches in the thermal expansion coefficients of the assembly materials. Such loads lead to thermomechanical fatigue...
Experimental testing and microstructural characterization have revealed that lead-free solders exhibit evolving properties that change significantly with environmental exposures such as isothermal aging and thermal cycling. These changes are especially large in harsh environments, where the effects of aging on solder joint behavior must be accounted for and included in constitutive models when predicting...
Lead free solder materials are widely used in electronic packaging industry due to environmental concerns. However, experimental testing and microstructural characterization have revealed that Pb-free solders exhibit evolving properties that change significantly with environmental exposures such as isothermal aging and thermal cycling. These changes are especially large in harsh environments, where...
Transient liquid phase (TLP) soldering is one option for high temperature interconnects with the advantage of processing conditions being close to those for conventional soldering. In the Cu-Sn system addressed in the paper, a high post-processed melting point of the solder interconnects is achieved due to the formation of Cu6Sn5 and Cu3Sn intermetallic compounds (IMC). A specific low melting solder...
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