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Electronic Assemblies
Published in Michael Pecht, Handbook of Electronic Package Design, 2018
The dice are mounted to the tabs using solder or eutectic mounting methods. Figure 4.4 shows a typical phase diagram for a solder. The x axis of the diagram gives the composition of the alloy. The y axis is temperature. The liquidus lines indicate the temperature at which a given composition will completely melt, or be in a liquid phase. The solidus lines indicate the temperature at which a given composition will crystallize, or become completely solid. The areas between the liquidus and solidus lines represent the plastic zones of a given composition. The plastic zone is one in which both liquid and solid phases are present. In other words, as the temperature is increased for a given composition, that composition starts to melt when the temperature matches that of the solidus and has completely melted when the temperature matches that of the liquidus. The eutectic is the point in which the solidus and liquidus intersect. A eutectic alloy is one whose composition yields the eutectic point; it is the composition with the lowest melting point, going from solid to liquid at one temperature (i.e., a eutectic alloy has no plastic zone). Eutectic die mounting is the method for mounting die which uses a eutectic alloy as the means of attachment.
Phase Equilibria
Published in Franco Battaglia, Thomas F. George, Understanding Molecules, 2018
Franco Battaglia, Thomas F. George
Examples of a eutectic mixture are those of ice-sodium chloride and ice-sucrose (Figure 10.18 represents a simplified version of the phase diagrams). The ice-sodium chloride eutectic has an interesting application: it allows us to prepare the freezing mixture, which is useful to maintain for a reasonably long time the eutectic temperature. If sodium chloride is added to ice, once some of this melts, the salt dissolves into the liquid water. However, the melting process absorbs heat from the local environment, whereby the mixture’s temperature decreases. If this has been prepared in suitable proportion of the components, at the eutectic temperature—which for the water-sodium chloride mixture is −21°C—the three phases ice+salt+solution are in equilibrium at their eutectic point: the eutectic temperature stays constant as long as the ice is not completely melted or the salt completely dissolved.
Solidification and Melting
Published in Greg F. Naterer, Advanced Heat Transfer, 2018
The phase diagram for solid–liquid mixtures illustrates the effects of species concentration on the phase change processes. Figure 7.1 illustrates a typical phase diagram for a binary alloy. When a liquid alloy is cooled, it first solidifies at the liquidus temperature corresponding to the concentration of constituent A in the mixture of A and B. The solid has a composition determined by the solidus line at the same temperature. A two-phase mixture of solid and liquid coexist in equilibrium in the region between the liquidus and solidus lines (also called a mushy region). The mixture is cooled further until it reaches the eutectic temperature. This temperature refers to the minimum temperature of the two-phase region between the solidus and liquidus lines that contains unfrozen liquid. The eutectic point refers to the composition of the minimum freezing point, or the temperature at which a liquid of eutectic composition freezes. The eutectic temperature is the temperature at which a liquid of eutectic composition freezes to form two solids simultaneously under equilibrium conditions.
Numerical Analysis of Phase Change Material Characteristics Used in a Thermal Energy Storage Device
Published in Heat Transfer Engineering, 2018
Nima Bonyadi, Süleyman Kazım Sömek, Cemil Cihan Özalevli, Derek Baker, İlker Tarı
Using PCMs in TES devices to store sensible and latent heat became an important part of energy management following the 1973–1974 energy crisis [5]. Since then, different PCMs were developed and tested by researchers. PCMs are generally divided into gas–liquid, solid–gas, solid—liquid, and solid–solid classifications. Among solid–liquid PCMs, organic and inorganic materials are widely used as a latent heat energy storage medium [6]. The most common storage material used for cold storage is water due to its availability, low cost, and good thermal characteristics. Paraffin, alcohols, and fatty acids are classified as organic materials. On the other hand, inorganic materials are compounds and eutectics like salt hydrates. Eutectics are formed by combining two or more components and freeze and melt at constant temperature. Eutectics include organic–organic, organic–inorganic, and inorganic–inorganic compounds [7]. Water-based eutectic solutions have sharp melting points like a pure substance and their volumetric storage density is slightly greater than organic compounds. Different eutectic solutions have been developed, which are commercially available. While the thermal properties of these materials do not differ significantly, their phase change temperature varies based on their compositions [8].
Development of novel phase change materials based on methyl laurate and fatty acids for low-temperature applications
Published in Energy Sources, Part A: Recovery, Utilization, and Environmental Effects, 2023
Zifeng Ma, Kai Yue, Zhihan Yao, Xinxin Zhang
The melting point and latent heat of the pure materials are presented in Table 1 and are used to calculate the specific compositions and eutectic points of the binary eutectic mixtures (Eq.. (1)) and plot the binary phase diagrams in MATLAB. Figure 3(a) shows that the liquidus temperature of the ML decreases, while that of LA increases with increasing molar ratio of LA. The two liquidus lines intersect at the point where the molar ratios of LA and ML are 14.05% and 85.95%, respectively. At this point (i.e., the ML-LA eutectic point), the two components simultaneously melt at the same temperature of 4.25°C. Moreover, the binary eutectic phase diagram demonstrates that the eutectic point has the lowest melting temperature in the mixture.