Study On Preparation And Properties Of Epoxy Encapsulating Material

Epoxy resins is a kind of thermosets. They have been used in electronic encapsulating fields as their high performance, such as excellent adhesive properties, good thermal and electrical properties. The reaction of epoxy resin to form thermosets is carried out using hardeners. Acid anhydrides are mostly used in electronic encapsulating fields, whereas high temperatures are needed for acid anhydride curing. So accelerators are employed together with acid anhyrides. They could improve curing speed and also lower curing temperature. The choice of the accelerators again has a large influence on heat sensitive parts and saving energy.In this paper, the epoxy encapsulating material was manufactured by E-51 as matrix resin, methyl natrium dick anhydride (MNA) as accelerator, carboxylic butyl rubber (CTBN) as toughness agents. The conformation of each resin was characterized by Fourier Transform Infrared Spectrum (FTIR). Then the fracture surface morphology of encapsulating material were analyzed by Scanning Electron Microscope (SEM). The mechanical properties, thermal stability, and dielectric properties were tested. The effect of compose to them was analysed.The result of mechanical properties showed the stretch modulus decreased and elongation to break increased when dosage of latex enhanced, so toughness of the system higher.The SEM image of fracture showed particles of CTBN dispersion in system. The system of Cr(MM)3 and 2E4MZ as accelerator was brittleness rupture, however other system was toughness rupture. The IR spectrum showed epoxy group disappear in the system and absolute cure.The final decomposition temperature of system including Cr(MM)3 is 480℃. The final decomposition temperature of system unincluding Cr(MM)3 is 550℃. The result of thermal stability showed the final decomposition temperature lower with Cr(MM)3 as accelerator.DMA showed glass transition temperature(Tg) changed with different dosage of hardener. The highest glass transition temperature is 167℃, when the epoxy resin is 100% and acid anhydrides is 85%. The thermal stability is improved because of different accelerator.The analysis of glass transition temperature and the dielectric loss showed that the thermal stability of encapsulating material is best with BPO and DMP-30 as accelerator.The dielectric loss test of encapsulating material showed that species of accelerator and dosage of CTBN had great effect on the dielectric loss. The dielectric loss of encapsulating material is lowest when dosage of epoxy resin is 100%, dosage of acid anhydrides is 85%, CTBN is 15%, DMP-30 is 0.1%, and BPO is 0.3%. It is 0.0029.The best formula of encapsulating material is E-51:MNA:CTBN:DMP-30: BPO 0.3%=100:85:15:0.1:0.3.The curing temperature is 100℃/2h+150℃/5h.