Features of Green SiC powder for polishing AlN ceramic surface
AlN(Aluminum Nitride) ceramic PCB substrate is a high-performance electronic substrate material that uses aluminum nitride ceramic as the core insulating and heat-dissipating base, combined with metal conductive layers (usually copper) to form a printed circuit board (PCB) for high-power, high-frequency electronic devices. Green SiC powder for polishing AlN ceramic surface can acheive a excellent surface toughness. It is chosen because it simultaneously satisfies four advantages that no other commercial abrasive can match as well:
1. Hard-enough / soft-enough window
Knoop 2 600–2 800 kg mm-2 (≈ 30 % harder than AlN, 12 000 MPa) , it can grind the nitride rapidly. Yet is still less than hardness of diamond, so it does not generate the deep sub-surface cracks that would kill AlN’s 170–200 W m-1 K thermal conductivity.
2. Sharp, α-SiC platelets
Blocky, sharp particles give a micro-chipping action instead of ploughing; stock removal rate is several times of that of white Al2O3 at equal pressure with efficient grinding.
3. Self-limiting chemical edge
The thin native SiO2 layer (≈ 3 nm) that forms in aqueous slurry is slightly acidic (pH 4–5). It complexes with the Al2O3 tribo-film on AlN, producing a soft Al-O-Si gel that lubricates the contact, preventing the “pull-out” of AlN grains that normally causes porosity-looking pits.
- Typical specification actually purchased for AlN CMP pre-polish step
Grit: GC F360(D50 26-30 µm) → GC F500(D50 15-17 µm)→ F800 (D50 7-8 µm) → F1000 (D50 4-5 µm)
Bulk density: 1.42 g cm-3 (loose)
Specific surface: 0.9 m2 g-1 (BET)
Zeta potential: –45 mV at pH 9 (stable 30 wt % slurry)
Crystal type: 6H α-SiC ≥ 98 %
