Low-temperature Sealing Glass

What is a Preform?

Preforms are pressed from a proprietary glass powder into a wide variety of shapes and sizes and then sintered. The sintering process provides green strength for the assembly operation and removes all organic residue. There is no measurable outgassing during or after the sealing process.
They are designed for assembling and hermetically sealing small optical and electronic components. The preforms adhere well to a wide variety of metals, glasses, ceramics, and semiconductor materials. Applications include sealing glass optical fibers in a metal package without fiber metallization and they replace AuSn solder seals.
They are used in high reliability products that meet Telcordia GR-468.


  • Optical fibers in ferrules or tubes
  • Fiber coupler/splitters
  • Fiber V-groove assemblies
  • Ribbon fibers
  • Lenses in lens holders or package walls
  • Lids and windows

Typical properties

Characteristics DM2700PF DM2760PF DM2995PF
Sealing Temperature ℃ 350 400 500
Tg(℃) 215 260 362
C.T.E. (25 to 150℃) ppm/℃ 7.5 7.5 6.4
Density of Sealed Glass g/cc 7.6 7.0 5.4
Helium leak rate ATM-cc/sec <10-8 <10-8 <10-9

Size and Shape

Wide variety of shapes and sizes (round, sliver, oblong, etc.) are available.
List of preforms


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