Spherical Boron Nitride (BN) Powder is a polycrystalline sphere made up of micron-sized single boron nitride crystals. It is an excellent option for high thermal conductivity and heat dissipation in electronic products. It possesses isotropic thermal conductivity attributed to its distinctive particle structure, addressing the limitations associated with the anisotropic thermal conductivity of flake boron nitride. It attains commendable planar thermal conductivity at a reduced filling ratio and exhibits the favorable characteristics of low density and a low dielectric constant akin to conventional boron nitride. Comparatively, at an equivalent filling amount, the thermal conductivity of spherical boron nitride surpasses that of standard platelet boron nitride powder by more than threefold.

 

When platelet BN is added as a filler to a polymer, a blended material is formed having poor rheological properties. At loaded concentrations above 30 wt.% BN, the blended material is so viscous that it is difficult to dispense from a mechanical dispenser such as a syringe.

 

U.S. Pat. No. 6,731,088 discloses a dry powder of spherically shaped agglomerates of irregular non-spherical BN particles bound together by a binder and subsequently spray dried. Binder Material for the Slurry: The binder for use in the present invention is any binder which bonds the BN particles during spray drying and/or modifies its viscosity characteristic. In one embodiment, the binder comprises at least a material which reacts/decomposes in the process of the invention, forming a residue or coating on the spherical BN agglomerates, for the agglomerates to have a function alized surface. Examples include aluminum acetate; nickel acetate; polyacrylates (acrylics), polyvinyls (such as poly vinyl butyral, polyvinyl alcohol, and polyvinyl butyral which typically decompose or further react forming residues at the temperature of the spray drying process. [US 2006/O127422 A1]

 

The spherically shaped BN agglomerates can be compounded into polymer compositions at levels of 35-50 wt.% for compositions with viscosity below about 300 cp.

 

Ref.) US Patent 8,933,157, "Mixed Boron Nitride Composition and Method for Making Thereof" (2015)

 

Commercially Available Spherical Boron Nitride Fillers:

 

(1) 3M™ Boron Nitride Cooling Filler Agglomerates

(2) Spherical Boron Nitride (BN) Powder

(3) BN5027 Spherical Boron Nitride Powder

(4) Denka

(5) Others