MACOR® Feedthroughs

Providing excellent electrical properties and easily machined, our MACOR® Machinable Glass Ceramic (MGC) is frequently used to create hermetic seals and electrically insulating feedthroughs.

MACOR® machinable glass ceramic offers exceptional electrical properties and as such it has become the natural choice within electrical insulation applications. We often utilise conductive materials through our MACOR® machinable glass ceramic requiring our MACOR® MCG feedthroughs to be sealed without sacrificing strength, hermeticity and high use temperature.

Whilst there are many sealing materials, we employ a range of sealing glasses to ensure that desirable properties are achieved without compromising effectiveness.

Sealing Glasses

Ferro Code1 Firing Cycle2 Continuous use temperature (°C) Coefficient of Thermal Expansion
7555* 450°C-20 min. 300 88.5 x 10-7/°C
7570* 470°C-30 min. 330 84 x 10-7/°C
7572 450°C-60 min. 425 95 x 10-7/°C
7575 450°C-60 min. 425 89 x 10-7/°C

1  Ferro Corporation, PO Box 6550, 4150 E. 56th Street, Cleveland OH, 44101. Tel. (216) 641-8585, ext. 7426, Fax (412) 641-8857.

2  These are idealised conditions. Heating and cooling rates and soak times are dependent on the size and geometry of the parts. The time is the hold at the corresponding temperature.

*  Vitreous solder glass.

MACOR® machinable glass ceramic (corning code 9658) can be used to hermetically seal glass, ceramic or metal due to its high glass content.

This glass content combined with a high coefficient of thermal expansion makes it possible to seal MACOR® to a wide range of different metals and glasses.

Using solder glass frit it is possible to achieve vacuum tight seals which can be used at high temperatures. MACOR® machinable glass ceramic and solder glass frit can be sealed to the following:


  • Platinum
  • Titanium
  • Sealmet
  • Dumet
  • Chrome-iron stainless
  • 52% nickel alloys
  • Sylvania #4


  • Fosterite

To find out more about our MACOR® product range, or to place an order, please contact us.

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