Aluminum Nitride (ALN) Submounts
High-purity ALN ceramic submounts for laser diodes, telecom modules, datacom transceivers, and industrial laser systems. Direct from ISO9001-certified manufacturers — 2–4 week lead time, samples from $25.
Thermal conductivity
170–210 W/m·K
6–8× better than alumina
CTE
4.3–4.6 ppm/°C
Best match for InP and GaAs devices
Lead time
2–4 weeks
Samples from $25/piece
Why aluminum nitride for laser diode submounts
Aluminum nitride (ALN) is the dominant submount material for single-mode and multimode laser diodes in telecom, datacom, and industrial applications. Its combination of high thermal conductivity, well-matched coefficient of thermal expansion (CTE), and high electrical insulation makes it uniquely suited for direct die attachment under a laser diode junction.
At 170–210 W/m·K, ALN removes heat from the laser junction 6–8 times faster than standard alumina. For a 200–500 mA CW single-mode DFB laser, this keeps junction temperature within operating limits and extends device lifetime significantly. For higher-power devices, ALN's thermal performance is often the difference between a module that meets spec and one that fails thermal qualification.
The CTE of ALN at 4.3–4.6 ppm/°C closely matches InP (4.5 ppm/°C) and GaAs (5.7 ppm/°C) — the two most common laser diode semiconductor materials. This close match minimizes mechanical stress during thermal cycling, preventing delamination and preserving optical alignment over thousands of power cycles.
ALN vs. other submount materials
| Material | Thermal conductivity | CTE (ppm/°C) | Electrical insulation | Best application |
|---|---|---|---|---|
| ALN (FerraLink) | 170–210 W/m·K | 4.3–4.6 | Excellent (>10¹² Ω·cm) | InP/GaAs laser diodes, telecom, datacom |
| SiC (FerraLink) | 350–400 W/m·K | 3.7–4.3 | Good (semi-insulating) | GaN/Si power devices, high-power laser bars |
| Alumina (Al₂O₃) | 26–30 W/m·K | 6.5–7.5 | Excellent | Low-power, cost-sensitive applications |
| Silicon (Si) | 150 W/m·K | 2.6 | Poor (semiconductor) | VCSEL arrays, low-power photonics |
ALN submount specifications
| Parameter | Standard grade | High-conductivity grade | Unit |
|---|---|---|---|
| Thermal conductivity | 170–185 | 190–210 | W/m·K |
| CTE (RT–400°C) | 4.3–4.5 | 4.5–4.6 | ppm/°C |
| Flexural strength | ≥400 | ≥350 | MPa |
| Dielectric constant (1 MHz) | 8.5–8.6 | 8.5–8.6 | — |
| Volume resistivity | >10¹⁴ | >10¹⁴ | Ω·cm |
| Surface finish (Ra) | ≤0.1 (polished) | ≤0.05 (precision polished) | µm |
| Substrate thickness | 0.10–1.00 | 0.10–1.00 | mm |
| Standard sizes | Custom + stock | Custom + stock | — |
| Bow / warp | ≤10 µm | ≤5 µm | — |
Metallization options
Ti / Pt / AuMost commonUniversal — wire bonding, flip-chip, die attach. Pt barrier prevents Ti diffusion to Au surface.
Ti / Ni / AuHigher Au thickness for solder die attach. Ni barrier, robust against reflow profiles up to 300°C.
Au/Sn 80/20 (3–5 µm)RecommendedPredeposited on bonding pad. Eliminates solder preform handling. Improves yield in edge-emitting LD assembly.
Edge gap down to 5 µm available for precision edge-emitting laser diode assembly. Side metallization and custom pad geometry on request.
Applications
Telecom & Datacom
DFB and EML laser diodes in SFP+, QSFP28, coherent DWDM transceivers. 2.5G, 10G, 25G, 100G modules.
Industrial Lasers
Pump laser modules, fiber laser seed sources, material processing. Multi-watt CW single-mode and multimode.
LiDAR & Sensing
FMCW lidar at 1550 nm, single-mode emitters for ToF sensing, structured light, spectroscopy.
Medical & Scientific
Surgical laser modules, fluorescence excitation, flow cytometry, confocal microscopy sources.
Standard part numbers
| Part number | Size (mm) | Thickness (mm) | Metallization | Sample price |
|---|---|---|---|---|
| FL-ALN-005 | 0.5 × 0.5 | 0.10–0.30 | Ti/Pt/Au | $25 |
| FL-ALN-010 | 1.0 × 1.0 | 0.15–0.50 | Ti/Pt/Au or Au/Sn | $25 |
| FL-ALN-015 | 1.5 × 1.5 | 0.20–0.50 | Ti/Pt/Au or Ti/Ni/Au | $25 |
| FL-ALN-020 | 2.0 × 2.0 | 0.25–1.00 | Ti/Pt/Au or Au/Sn | $25 |
| FL-ALN-035455-001 | 3.5 × 4.55 | 0.30 | Ti/Pt/Au + Au/Sn | $25 |
Custom sizes, thicknesses, and metallization stacks available. Send design files in DXF, DWG, or Gerber to info@ferralink.com.
Related technical guides
ALN vs SiC Submounts: Which Should You Choose?
Thermal conductivity, CTE matching, metallization, and cost comparison.
AuSn Pre-deposited Submounts: Why They Improve Assembly Yield
How predeposited Au/Sn eliminates solder preform handling and improves yield.
How to Qualify a Ceramic Substrate Supplier
Step-by-step checklist for incoming inspection and supplier qualification.
How to Reduce Laser Packaging Costs
Where packaging cost comes from and how to reduce it without compromising quality.
Ready to evaluate ALN submounts?
10-piece sample box — $250. Individual samples — $25/piece. Ships in 2–4 weeks with material certs and lot documentation.