Lid Systems for Capacitors

Product Description

Aging Effects on Polymer Sealing

Electrolyte leakage impacts capacity

Aluminum electrolyte capacitors are susceptible to electrolyte dry-out over the lifetime of their application. Even small amounts of moisture infiltration through an imperfect terminal seal can lead to the formation of harmful gases inside the capacitor over time.

A common cause of electrolyte loss is evaporation through rubber seals of the capacitor terminals. Rubber, an organic material, ages naturally and can become brittle and lose gas-tightness over time.
Glass-To-Aluminum Sealing

SCHOTT GTAS® Gas-tight Capacitor Lids

Gas-tight capacitor lids are a newly developed technology that eliminates electrolyte dry-out in aluminum electrolyte capacitors by using a high-performance glass seal for the capacitor terminals instead of organic sealing materials.

As a result, the capacitor terminals are hermetically sealed into the aluminum lid (GTAS: glass-to aluminum seals) and protect the capacitor from moisture intrusion through the pin seals. Glass-to-aluminum sealing is a proprietary technology developed utilizing SCHOTT's expertise in specialty glass and glass-to-metal sealing (GTMS), dating back over 75 years to 1939.


SCHOTT’s lid systems for capacitors offer numerous performance improvements*:
  • Up to 20% reduction in capacitor package volume
  • 60% reduction in capacitance loss
  • 50% improvement of internal resistance
  • High temperature resistance ranging from -40 degrees Celsius to +150 degrees Celsius
  • 10-15 year increase in product longevity
Design capabilities enabled for capacitor manufacturers:
  • Smaller capacitors with increased capacitance
  • New capacitor types with increased capacitance and greater longevity
  • New capacitors able to withstand much higher temperatures
  • High-performance ultracapacitors and electric double layer capacitors that fulfill the harsh requirements of new applications, including EVs, E-Bus, Renewable Energy, Heavy Industry, and Defense & Aerospace

From prototype to mass production, SCHOTT is a reliable partner with full in-house development and production capabilities.

* (Values may vary, depending on final capacitor design)


New designs of aluminum electrolyte capacitors, such as electric double layer capacitor and ultracapacitors, are currently in development for modern and emerging applications, including electric vehicles, high-power applications, renewable energy, and many more.

These applications pose new technical requirements on the capacitor, demanding long-lasting high performance. GTAS leak-tight, lid systems for capacitors can enable both small and large capacitor designs to fulfill such requirements.
Applications for GTAS

Technical Details


Since the 1930s, SCHOTT has been manufacturing hermetic housings using glass-to-metal sealing (GTMS) technology. This technology is proven in many high volume applications, such as automotive sensor housings and battery covers of lithium thionyl chloride (Li-SOCl2) batteries.

Drawing on more than 20 years of sealing experience for primary batteries, innovative glass-to-aluminum sealing technology was specifically designed for long-lasting lithium-ion batteries and capacitors.

Sintered glass preforms are melted around the conductors to provide electrical insulation, enhance mechanical strength and center the conductors in the openings for the feedthroughs. The special glass is matched to the metal – in this case aluminum – with considerations for its coefficient of thermal expansion, creating natural compression during cooling. In its application, the conductors remain firmly fixed by the solidified glass, even if mechanical pressure is applied or the temperature changes dramatically.
Electrical isolation Small designs: 108 Ω to 109
Large designs: 107 Ω to 108 Ω 
Chemical resistance   High against range of standard
(from +40°C to + 150°C)
Pressure tightness High, > 10 bar for the glass-to-
aluminium seal
Mechanical strength High, depending on dimension
even very high
Sealing material SCHOTT glass
Pins/Lid Aluminium
Lifetime 15 years


All our production facilities are ISO 9001 certified. For more information, please refer to our quality assurance processes.

Trade Fairs & Events
Trade fair CIOE - China International Optoelectronic Exposition, Shenzhen, China, 01.09 - 03.09.2021
Trade fair Gastech, Singapore, Singapore, 13.09 - 16.09.2021
Trade fair Battery Experts Forum, Frankfurt, Germany, 05.10 - 07.10.2021
Christoph-Dorner-Strasse 29
84028 Landshut
E-Mail to SCHOTT+49 (0)871/826-0