Laser process for bonding glass to metal

A force- and vibration-free joining process for metal and thin glass was developed at the Laser Zentrum Hannover e.V.. In this process, the thin glass is pressed onto the metal substrate with as little contact as possible and the two joining partners are heated by means of laser radiation, resulting locally in a partly seamless, partly form-fit connection.

Challenge

In many areas, connections between the materials glass and metal are required. In the field of architecture, connections by adhesive bonding have been sufficient up to now. In many other areas, however, the connections must have higher strengths and better chemical resistance, so processes such as welding and soldering are used. A crucial prerequisite for welding glass or glass ceramics and metal is a similar thermal expansion coefficient. Joining the material by soldering is possible only by using special bonding agents.

Our solution

At the Laser Zentrum Hannover e.V., a force- and vibration-free joining process of metal and thin glass was developed. In this process, the thin glass is pressed onto the metal substrate, preferably contactless (e.g. with air pressure), and the two joining partners are heated by means of laser radiation so that a partly seamless bonding and partly form-fitting connection is created locally. The laser technology used enables significantly short process times with simultaneous precise and accurate joints. By applying laser radiation to thin glass (up to < 50 µm thickness), joints on non-planar structures are also achievable. An adjustment of the two coefficients of thermal expansion is not necessary, since thermal length expansions of the different materials are tolerated by these glasses. One promising application, for example, is in the encapsulation of OLEDs, which are currently still bonded. This way, the OLEDs could become significantly more durable. The process can be implemented with a CO2 laser so that glass is heated from the top side and the underlying metal is heated via thermal conduction. The process time is about 10 s for a diameter of 25 mm. Alternatively, a solid-state laser can be used so that the interface between the glass and the metal is heated briefly to form a material bond. Additional roughening of the interface carried out in advance leads to additional interlocking of the joining partners.

CPA-2097-LZH-imageJoint between thin glass of 100 µm thickness and chrome-nickel steel. (Left) frontside and (right) backside of the steel sheet. (source: Laser Zentrum Hannover e.V.)

Advantages

  • Enables easy and flexible joint between glass and metal
  • Laser based created joints with higher firmness
  • Joining partners can have independent thermal expansion coefficients
  • High process speed
  • Joints on non-planar structures due to laser processing is achievable

Applications

  • Sensor technology (insulator layer)
  • Extensometers (thin glass insulator layer on steel shafts)
  • OLEDs, LEDs (encapsulation)
  • Optics
  • Medical technology

Development Status

Process successfully tested with different lasers and joining partners (glasses and metals)

Patent Status

Laser Zentrum Hannover e.V.
DE102017129877B4 (granted)

References

 

Contact

Dr. Markus Muchow
Patent Manager Physics & Technology
E-Mail: This email address is being protected from spambots. You need JavaScript enabled to view it.
Tel.: +49 551 30724 159
Reference: CPA-2097-LZH

Tags: Laser physics and optics, Physics and Technology & Software

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