Thermal properties delamination temperature

Various thermal material properties (as opposed to thermal stability. Chapter 9) are discussed in Chapter 16. These include coefficient of expansion, melting temperature, Vicat softening point, heat deflection/distortion temperature by thermomechanical analysis, also brittleness temperature, minimum filming temperature, delamination temperature, meltflow index, heat of volatilisation, thermal conductivity, specific heat and ageing in air. 

In addition to providing circuit interconnection, a multilayer printed wiring board (ML-PWB) provides the electrical and mechanical platform for the system. This means that the electrical and thermal properties of the ML-PWB material are very important for the proper functioning of the system. Among the properties of importance are dielectric constant, Du (also known as Er) dielectric loss, Df (or tan 8) glass transition temperature, Tg time to delamination,Txxx thermal decomposition temperature.Ta coefficient of thermal expansion, CTE and moisture absorption. The following sections discuss the importance of these properties to an ML-PWB snbstrate. 

Thermal Properties. The important thermal properties of a laminate are the glass transition temperature, the coefficient of thermal expansion, the time to delamination, and the decomposition temperature. - These properties quantify the material s reactions to extreme temperatures and so are indicator s of the materials suitability for a particular reflow profile and residual capacity for withstanding heat input (such as rework or hot use environments). Tgalone is insufficient to predict a materials response to LFA tenperatures. In fact, since each test measures a different response to temperature, all the tests together provide a broad determination of suitability to a particular use. 

Newer high velocity thermal spray coating processes produce coatings in compression rather than tension because of the shot peening effect of the supersonic particles on impact. This has permitted coating as thick as 12,500 p.m without delamination as compared to older processes limited to 1,250 p.m. The reduced residence time of particles at temperature minimises decomposition of carbides present in conventional d-c plasma. This improves wear and hardness (qv) properties. 

At a specified temperature, the thermal conductivity of FRP composite materials depends on the properties of the constituents at this temperature, as well as the content of each constituent As a result, if the temperature-dependent thermal conductivity is known for both fibers and resin, the property of the composite material can be estimated. During decomposition, however, decomposed gases and delaminating fiber layers will influence significantly the thermal conductivity (trae against effective thermal conductivity). An alternative method to determine the effective thermal conductivity is to suppose that the materials are only composed of two phases the undecomposed material and the decomposed material. The content of each phase can thereby be determined from the mass transfer model introduced above. As a result, the effects owing to decomposition can be described [12]. 

Due to their tailorable combinations of properties, MMCs may play a key role in advanced electronic packaging, e.g., in power semiconductor diodes. In this application, the silicon wafer cannot be directly soldered to the copper electrode, due to a DIE mismatch (a (Si) = 4.1 X 10 a (Cu) = 17 x 10 C ). Under service conditions, interface delamination would occur as the result of thermal stresses arising from temperature changes. In conventional power diodes, the problem is partly solved by using an intermediate molybdenum or tungsten layer with a CTE between those of silicon and copper (a (Mo) = 5.0 x 10 ° and a (W) = 4.6 x 10 °C ). Another concept is the use a carbon fiber reinforced copper electrode. Carbon fibers have negative CTEs with a CTE matching that of Si [50]. 

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