Modification Of Thermal Conductivity And Halogen-Free Flame Retardancy For Pouring Sealant

Silicone and epoxy, as two common electronic pouring sealants, have been widely usedin electronics, electrical, aerospace and other fields, for their good electrical insulationproperties, chemical stability and simple preparation. However, these two kinds of pouringsealants both had shortcomings, such as their thermal conductivity were low( thermalconductivity about 0.2W/(m·K)) and they were very easy to burn, these disadvantages limitedtheir applications in the field of electronic packaging. In this paper, in order to improve thethermal conductivity and flame retardant properties, halogen-free flame retardant and thermalpowder were used to be added into the polymer matrix respectively to prepare high thermalconductivity and good halogen-free flame retardant silicone and epoxy pouring sealants. Themain research contents and results are as follows:In chapter 2, silicone pouring sealant with good flowability, halogen-free flame retardant,thermal conductive, high thermal conductivity, thermal stability, mechanical properties andinsulating properties was prepared through using vinyl silicone oil and hydrosilicone oil asbasic glue, a long carbon chain silane coupling agent modified alumina as thermal conductivefiller and aluminum diethyl phosphinate(ADP) as flame retardant.the modified aluminareduced oil absorption value and slowed its sedimentation speed. When loading ADP 50 phr,modified alumina 600 phr, the generated silicone sealant gave the viscosity of 8500 m Pa·s,the thermal conductivity of the cured sealant was 2.12 W/(m·K), the vertical flame test ratingFV-0,the limiting oxygen index 46%, the tensile strength 1.72 MPa, and the elongation atbreak 62%, volume resistivity 3.9×1012Ω·cm..In chapter 3, epoxy pouring sealant with good construction fluidity, excellent flameretardant, high thermal conductivity, good thermal stability, insulating and mechanicalproperties was prepared through using modified nitrogen and phosphorus flame retardant asflame retardant, alumina and boron nitride as thermally conductive filler. When loadingmodified retardant 30 phr, modified alumina 115 phr, modified boron nitride 25 phr, thegenerated epoxy sealant gave the viscosity of 8300 m Pa·s, the thermal conductivity of thecured sealant was 1.31 W/(m·K), the vertical flame test rating FV-0,the limiting oxygen index34%, the tensile strength 29.8 MPa, impact strength 5.6 k J/m2, bending strength 55 MPa,volume resistivity 1.5×1013Ω·cm.