Thermoset moldable compounds

Thermoset moldable compounds can be mixed with a very wide variety of fillers to modify their properties to meet the requirements for a given application. Adding suitable fillers can produce coefficients of thermal expansion and elongation behavior virtually identical to those of copper. Once thermoset materials have cured, moreover, their three-dimensional molecular network structure gives them a very high level of dimensional stability. Consequently, in terms of temperature resistance to soldering many of the materials in this class are potentially suitable as MID substrates. Table 2.5 summarizes some of the important thermal properties of commercially available thermoset moldable compounds. Thermoset moldable compounds, moreover, have economic potential because in some cases the cost of the material Is low. Phenolic resin moldable compounds in particular are available at a price of less than about 7 (EUR 5) per kg and could therefore be considered an economical alternative to LDS high-temperature thermoplastics. 

However, the reiativeiy high price of TCP remains a motivator for the development and production of new high-performance materials so that MID suitable for lead-free soldering can still be produced economically. The thermoset, moldable compounds that are not yet the accepted state of the art in MID technology have properties profiles that appear to offer more than enough points of departure for use as substrate materials for molded Interconnect devices. 

TABLE 2.5 Important Thermal Properties of Selected Thermoset Moldable Compounds [136,167]... 

Phenol-formaldehyde was reported as the first commercially synthetic polymer (1899) which was introduced as BakeliteT by Baekeland in 1909. This was the period which marked the dawn for the production of commercial synthetic thermosetting polymers. Other advances in the field included the discovery of urea-formaldehyde resins in 1884 and the beginning of their commercialization as Beetle moldable resin in 1928, followed by thiourea-formaldehyde (1920), aniline-formaldehyde (Cibatine by Ciba, 1935) and melamine-formaldehyde (1937) moulding powders. The year 1909 marked the discovery of epoxy compounds by Prileschaiev, which were not used until World War 2. The first thermoset polyesters, invented by Ellis, date back to 1934 and in 1938 was reported their first use in the forms of glass-reinforced materials [1]. 

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