700 W/(m·K) thermal conductivity × 8.1 ppm/K low CTE — a new-generation choice for high-power module cooling
Ag Diamond is a silver-diamond composite heat spreader (heatsink) material developed for high-power modules by an international manufacturer represented by Altra. Its thermal conductivity reaches 700 W/(m·K) — roughly 1.8× that of pure copper (394 W/(m·K)) and 4× that of CuW (174 W/(m·K)) — while its coefficient of thermal expansion is only 8.1 ppm/K (RT–800°C), close to CuW (7.9 ppm/K) and far below pure copper (19.4 ppm/K). It therefore raises cooling capability substantially while lowering thermal stress on the chip and the ceramic package. Flatness of 14 μm matches the CuW class, and it runs through the same process flow and brazing integration as CuW, making it well suited to next-generation RF and power semiconductor packaging.
Chip generates heat
High-power chips such as GaN and SiC are concentrated heat sources; the heat passes downward through the chip bonding layer.
Rapid conduction + lateral spreading
At 700 W/(m·K) — about 4× CuW — Ag Diamond pulls heat away from the chip and spreads it across the whole base.
Low-stress bonding
A CTE of 8.1 ppm/K matches brazed joints to ceramic packages (AlN 4.9 / Al₂O₃ 6.7), so the joint resists degradation under thermal cycling.
Out to the system
Heat passes into the system baseplate or heatsink and is released to the ambient, completing the thermal path.
Specifications
| Item | Specification |
|---|---|
| Material structure | Silver (Ag) matrix + diamond particle composite |
| Thermal conductivity | 700 W/(m·K) |
| Coefficient of thermal expansion (CTE) | 8.1 ppm/K（RT–800°C） |
| Flatness | 14 μm (measured over 10.4×5.6 mm) |
| Package size range | Approx. 10×10 to 100×100 mm |
| Process compatibility | Same process flow as CuW; integrated by brazing |
| Compatible ceramic packages | AlN, Al₂O₃ and similar ceramic package materials |
| Product stage | Development stage (sample evaluation and design-in enquiries welcome) |
Heat Spreader Material Comparison
The heat spreader dilemma: the best conductor (Cu) expands too much, while the low-expansion options (CuW / CuMo) do not conduct enough. Ag Diamond delivers both and lands in the ideal zone.
| Item | Ag Diamond | Pure Cu | CuW | CuMo |
|---|---|---|---|---|
| Thermal conductivity W/(m·K) | 700 | 394 | 174 | 195 |
| CTE ppm/K (RT–800°C) | 8.1 | 19.4 | 7.9 | 7.5 |
| Flatness | 14 μm | – | 14 μm | – |
| Thermal stress on the chip | Low | High | Low | Low |
- High-power module cooling
- RF and telecom base stations
- Satellite communications
- Laser processing equipment
- Next-generation RF and power semiconductor packaging
- 700 W/(m·K) thermal conductivity — about 4× CuW and 1.8× pure copper
- CTE of 8.1 ppm/K (RT–800°C) — close to CuW and less than half that of copper, markedly reducing thermal stress
- Flatness of 14 μm, the same class as CuW
- Same process flow and brazing integration as CuW — low barrier to adoption on existing lines
- Can be brazed to AlN and Al₂O₃ ceramic packages
FAQ
How does Ag Diamond compare with a CuW heat spreader?
Ag Diamond offers 700 W/(m·K) thermal conductivity — about 4× that of CuW (174 W/(m·K)). Its CTE of 8.1 ppm/K is close to CuW (7.9 ppm/K) and flatness is the same 14 μm class. It also runs through the same process flow as CuW, so adopting it on an existing line takes little effort.
How does Ag Diamond compare with a pure copper heat spreader?
Ag Diamond conducts heat about 1.8× better than pure copper (700 vs. 394 W/(m·K)), while its CTE (8.1 ppm/K) is less than half that of copper (19.4 ppm/K). That sharply reduces thermal stress on the chip and the ceramic package, improving reliability.
Which ceramic packages can Ag Diamond be used with?
It can be brazed to ceramic package materials such as AlN (aluminium nitride) and Al2O3 (alumina) to serve as the heat spreader in a high-power module.
What applications is Ag Diamond suited to?
Thermal management for high-power modules — RF and telecom base stations, satellite communications, laser processing equipment, and next-generation RF and power semiconductor packaging.
Is Ag Diamond available to order? How do I get a sample?
Ag Diamond is currently at the development stage; we accept sample evaluation and design-in enquiries. Contact Altra Tech. Incorporated through our contact form or your usual representative and we will help assess your application.
