Transfer molding compositions

Youssef K. Hamidi, Levent Aktas, M. Cengiz Altan, Three-dimensional features of void morphology in resin transfer molded composites. Composites Science and Technology 65 (2005), pp. 1306-1320. 

Typical transfer molding compositions for encapsulation of electronic devices are mixtures of an epoxy novolac resin, a phenolic resin hardener, a catalyst, large amounts of inorganic filler (e.g., Si02) flame-retardant ingredients, internal lubricants, carbon black, and sometimes other additives such as getters to trap ionic impurities (34,35), corrosion-protection materials, and stress-relief ingredients. 

Both CMOS and bipolar devices encapsulated with the new transfer molding compositions performed well under thermal cycling between -65°C and + 150°C and also under accelerated life testing at 145°C, 85% RH and 18V bias. Further optimization of this type of molding composition is expected to improve its performance as a protective material for integrated circuitry. 

J.L. O Dell, Natural Fibers in Resin Transfer Molded Composites, in Proceedings of Fourth International Conference on Woodfiber-Plastic Composites, pp. 280-285, Madison, Wisconsin (1997). 

Bhat, R, Merotte, J., Simacek, P. and Advani, S. G., Process analysis of compression resin transfer molding , Composites Part A Applied Science and Manufacturing, 40(4), 431 41, 2009. 

Ruiz, E., Achim, V., Soukane, S., Trochu, F. and Breard, J., 2006. Optimisation of injection flow rate to minimise miero/macio-voids formation in resin transfer molded composites . Composites Science and Techrwlogy, 66,475-486. 

Yenilmez B, Sozer EM. A grid of dielectric sensors to monitor mold filling and resin cure in resin transfer molding. Composites Part A Applied Science and Manufacturing, 2009 40(4) 476-M89. DOl 10.1016/j.compositesa.2009.01.014. 

Bickerton S, Stadtfeld HC, Steiner KV, Advani SG. Design and application of actively controlled injection schemes for resin-transfer molding. Composites Science and Technology, 2001-61 Uy. 1625-1637. DOl 10.1016/s0266-3538(01)00064-l. 

Nalla A R, Fuqua M, Glancey J, Lelievre B (2007) A multi-segment injection line and real-time adaptive, model-based controller for vacuum assisted resin transfer molding. Composites Part A 38 1058-1069. 

Sreekumar P. A., Selvin P. Thomas, Jean marc Saiter, Kuruvilla Joseph, Unni Krishnan G., and Sabu Thomas. (2009). Effect of fiber surface modification on the mechanical and water absorption characteristics of sisal/polyester composites fabricated by resin transfer molding. Composites Part A Applied Science and Manufacturing 4Q n), 1777-1784. 

Lundstrom, T.S. Bubble transport through constricted capillary tubes with application to resin transfer molding. Polym. Compos. 1996, 17, 770-779. Lundstrom, T.S. Void collapse in resin transfer molding. Composites A 1997, 28A, 201-214. 

Lee, D.G., Chin, W.S., Kwon, J.W., Yoo, A.K., 2002. Repair of underground buried pipes with resin transfer molding. Composite Structures 57, 67—77. 

SCRIMP process This Seeman Composites Resin Infusion Process (SCRIMP) is described as a gas-assist resin transfer molding process. As an example glass fiber fabrics/ thermoset vinyl ester polyester plastic and polyurethane foam panels (for insulation) are placed in a segmented tool. A vacuum is pulled with a bag so that a huge amount of plastic can be drawn into the mold (Marco process approach). Its curved roof is made separately and bonded to the box with mechanical and adhesive fastening. It is similar to various reinforced plastics molding processes. 

Conversion of cyclic oligomers to composite structures via Resin Transfer Molding (RTM) and Reaction Injection Molding (RIM) techniques has been demonstrated, and will be the subject of subsequent publications. Glass loadings... 

Differentiate between pultrusion, resin transfer molding, and filament winding methods for fiber-reinforced composite production. 

Resin transfer molding (RTM) is a hybrid of two polymer processing techniques we have already described transfer molding and reaction injection molding (RIM). The key difference is that a reinforcement is incorporated during molding to create a composite. 

Figure 7.90 Schematic diagram of a typical resin transfer molding (RTM) process. Reprinted, by permission, M. Schwartz, Composite Materials Handbook, 2nd ed., p. 4.56. Copyright 1992 by McGraw-HiU.

The stability, growth, and transport of voids during composite processing is reviewed. As a framework for this model, the autoclave process was selected, but the concepts and equations may be applied equally effectively in a variety of processes, including resin transfer molding, compression molding, and filament winding. In addition, the problem of resin transport and its intimate connection with void suppression are analyzed. 

Rigid caul plates are typically constructed of thick metal or composite materials. Thick caul plates are used on very complex part applications or cocured parts where dimensional control is critical. Many rigid caul plates result in a matched die configuration similar to compression or resin transfer molding. Parts processed in this manner are extremely challenging because resin pressure is much more dependant on tool accuracy and the difference in thermal expansion between the tool and the part. Tool accuracy is critical to ensure no pinch points are encountered that would inhibit a tool from forming to the net shape of the part. 

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