Three pain points, three clean fixes
1. CTE mismatch — your bond cracks the moment it cools.
Ceramic substrates and metal electrodes often have a CTE gap of 30–80×10⁻⁷/°C. Hard-braze it hot, and as soon as the part cools down, the interface is fighting itself. Microcracks are almost guaranteed.
Low-melt glass powder can be tuned anywhere from 50 to 136×10⁻⁷/°C. Pick a grade that sits between your two materials, and you basically eliminate the residual stress. Real example: one of our alumina-substrate customers was running a standard 90×10⁻⁷ recipe. We swapped it for a custom 85×10⁻⁷. Their thermal-cycle test (-55°C to 150°C) went from batch-cracking at 30 cycles to a steady 10⁻⁹ Pa·m³/s leak rate at 100 cycles. Same line, same equipment — just better glass.
2. Sealing temperature is too high — your substrate can't take it.
Most traditional sealing glasses need 700–850°C. That kills LTCC, coated glass, anything temperature-sensitive, and any pre-mounted components.
Low-melt glass powder gets you down to a 330°C onset (our FD46 grade, for instance) with a process temperature around 500°C. Sensitive substrates stay happy.
3. Hermeticity — organic adhesives just can't hold it.
Automotive sensors, MEMS, vacuum devices — they all need long-term hermetic seals. Epoxy starts softening around 200°C. Moisture gets in. The seal fails.
A glass-powder seal is fully inorganic. It survives 800°C+, holds 10⁻⁹ Pa·m³/s hermeticity, and shrugs off acid, alkali, and salt spray.
How it stacks up
What you need | Low-melt glass powder | Leaded sealing glass | Epoxy adhesive |
Sealing temp | 330–1100°C, you pick | 600–900°C | Room temp |
RoHS / lead-free | Yes, fully | No, leaded | Depends |
Long-term service | 800°C+ | Brittle over time | Usually<300° |
CTE matching | Yes, 50–136×10⁻⁷ | No |
Data: Anywherepowder's lab reports + customer trials, updated Sept 2026.
How to pick the right grade (it's simpler than you think)
Two numbers tell you almost everything: your substrate CTE and your process temperature ceiling. Match those, and you're 80% there. Particle size comes down to your process — 1500 mesh for screen-printable pastes, 2000 mesh and up for precision tape casting or spot coating.
Best way to validate: grab a 200 g sample, run a real sealing trial on your actual substrate, and test three things — leak rate, thermal cycling, and cross-section metallography. Once those pass, scale up.
We can customize the CTE and the sintering window to your substrate. Our tech team can also help you match operating conditions. Free sample at www.anywherepowder.com.
