1. Schematic diagrams of (a) the anti-hydrolysis mechanism of phosphoric acid on AlN and (b) the preparation process of CCL

2. (a-d) Particle size distribution curves and (e-h) SEM images of AlN with different particle sizes

3. XRD patterns of samples before and after hydrolysis

4. SEM images of (a-d) cross-sections and (e-h) surfaces of CCLs filled with pAlN of same filling ratio but different sizes

5. SEM images of the cross-section of CCLs with different filling ratios of pAlN((a) no filler; (b) pAlN-50 μm-20%; (c) pAlN-50 μm-60%; (d) pAlN-50 μm60%-5 μm5%); (e) EDS scan selection area with the inset showing the element distribution; (f) the full element scan image; (g-j) corresponding element distributions of Al, N, Si, C

6. Heat conduction mechanism diagram of CCLs under different filling schemes

7. (a) Effects of pAlN with different sizes, different filling amounts and (b) gradation filling (pAlN-50 μm x%-5 μm y%, x=0-60, y=0-15, same below) on the thermal conductivity of CCLs

8. (a) Effects of pAlN with different sizes, different filling amounts and (b) gradation filling on the peel strength of CCLs

9. (a) Effects of pAlN with different sizes, different filling amounts and (b) gradation filling on the bending strength of CCLs

10. Effect of pAlN with different size and filling amount on the dielectric constant (a) and dielectric loss (b) of the CCLs; Influence of gradation filling on the dielectric constant (c) and dielectric loss (d) of corresponding CCLs

11. (a) Effect of pAlN with different size and different filling amount and (b) gradation filling on the water absorption of CCLs

Table 1. Effect of phosphoric acid treatment of AlN on the performance of CCLs