Ultrasonic Welding

Ultrasonic welding is a well-established and rapid method for welding polymers. It uses high-frequency ultrasonic vibrations to melt energy directors, joining the parts together. 

This technique is especially effective for bonding larger structures or assembling components like blisters or reservoirs. The efficiency and speed of ultrasonic welding make it ideal for high-volume production. 

Ultrasonic welding involves the application of ultrasonic vibrations to generate heat by friction. An ultrasonic tool is pushed on the part and the energy is applied onto the stacked parts. Our equipment is specifically designed to provide an automated and accurate process cycle for precision parts. This includes a good uniformity of the applied energy and good process control. 

The friction is focussed on so-called 'energy directors', which are ridges on your parts. The ridges are designed along the fluidic structures to create a line weld around the functional parts. During welding the ridges are compressed. Compression and polymer flow must be carefully controlled. 

Technology benefits include;

  1. Suitable for a broad range of polymer materials and combinations
  2. Robust and strong bond
  3. Soft on biological reagents due to room temperature process

Most importantly, the technology is proven to be usable for high production volumes.

This technology is mainly recommended for the integrations of larger parts, such as blisters or reservoirs, or with larger fluidic circuits. This is due to the related compression and polymer melt flow. Energy directors need to be manufactured along the fluidic structures. 

For acceptable polymer flow the energy directors need to be significantly smaller than the fluidic structures. This can result in thin weld lines and thus a weak bond for small energy directors. Polymer melt is typically not accurately up to the channel edge. This can impact microfluidic functionality (specifically capillary valves or pumps) and polymer melt in the channels can even damage cells passing the microchannel. 

For microfluidic applications we recommend Bondus' direct bonding or UV adhesive bonding. 

Ultrasonic welding

Rapid melting and compression of energy directors

Functional and robust

Strong bond with good thermal- and chemical resistance

Biocompatible

Room temperature process and no chemical introduced

High volume capability

Cycle times within seconds possible, allowing high-volume production

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