Magnetic Alignment of Hexagonal Boron Nitride Platelets in Polymer Matrix: Toward High Performance Anisotropic Polymer Composites for Electronic Encapsulation

Abstract

We report magnetic alignment of hexagonal boron nitride (hBN) platelets and the outstanding material properties of its polymer composite. The magnetically responsive hBN is produced by surface modification of iron oxide, and their orientations can be controlled by applying an external magnetic field during polymer curing. Owing to the anisotropic properties of hBN, the epoxy composite with aligned hBN platelets shows interesting properties along the alignment direction, including significantly reduced coefficient of thermal expansion, reaching ∼28.7 ppm/°C, and enhanced thermal conductivity, 104% higher than that of unaligned counterpart, both of which are observed at a low filler loading of 20 wt %. Our modeling suggests the filler alignment is the major reason for these intriguing material properties. Finite element analysis reveals promising applications for the magnetically aligned hBN-based composites in modern microelectronic packaging.

Hot pressing-induced alignment of hexagonal boron nitride in SEBS elastomer for superior thermally conductive composites

“…As shown in Fig. 7 ), 51,52 the alignment of hBN is more effective to limit the motion of the molecular chain of SEBS, especially along the alignment direction. The negative in-plane CTE of hBN also contributed to the CTE reduction of the composites.…”

“…[1][2][3][4]10,13,18,19 In recent years, much effort has been directed to the rational design and controlled preparation of hBN-lled polymer composites. 1,[3][4][5]13,[20][21][22][23][24] As reported previously, the thermal property of hBN-lled composites is mainly inuenced by the interface and dispersion state of hBN in polymer composites. 1,4,5,[20][21][22][23]25,26 The interface is mainly inuenced by the compatibility between the llers and matrix.…”

“…1,[3][4][5]13,[20][21][22][23][24] As reported previously, the thermal property of hBN-lled composites is mainly inuenced by the interface and dispersion state of hBN in polymer composites. 1,4,5,[20][21][22][23]25,26 The interface is mainly inuenced by the compatibility between the llers and matrix. Modication by hBN can enhance the affinity of the hBN/polymer interface.…”

Polymer composites based on hexagonal boron nitride and their application in thermally conductive composites

“…Thus, iron oxide-coated h-BN lled epoxy composites exhibited excellent thermal properties. 12,13,97 The highest thermal conductivity obtained was 4.7 W m À1 K À1 at 20 vol% iron oxide-coated h-BN for an epoxy resin system. 13 Luo et al 98 used a similar method to fabricate iron oxide-coated h-BN/SiR composites.…”

“…Owing to its distinct features, h-BN exhibits various properties, such as anisotropy parallel and perpendicular to a basal plane, [12][13][14] constant wide band gap ($5.97 eV), 15 superior antioxidative and structural stabilities (high thermal stability of up to 1000 C in air and 1400 C in vacuum), 16 …”