Photopolymer improves IC, display assembly, says Terecircuits

Technology News | May 5, 2023

By Peter Clarke

Displays & Interfaces microLED Electromechanical Packaging Materials & processes Wearables

Terecircuits Corp. (Mountain View, Calif.) is a 2015 startup with a photopolymer mass transfer technology that it claims can improve on traditional pick-and-place technology in IC and display packaging.

The company is focused on microLED display panel assembly and system-in-packaging (SiP) components for IoT devices, where its claims the advantages of its technology will be required.

Wayne Rickard, CEO of Terecircuits said that in IC packaging, picking and placing of individual die for the assembly process has been successful for 50 years. But the packaging environment is becoming increasingly diverse, with SiP, MEMS, multi-die components and chiplet style assembly of components. Increasingly die are being thinned by back grinding and becoming fragile. Whether a vacuum nozzle, or die-attach film (DAF) is used to move bare die there usually has to be an ejector pin to release the die and this causes yield problems, Rickard said.

In extreme cases, such as microLED, individual devices can be 2 to 40 microns across and at this size Van der Waals and electrostatic forces are more powerful than gravity making die release difficult.

UV light

Terecircuits approach is to use a thin layer – one micron or less – of photopolymer on a transparent plate to hold the die. To release the die deep UV light is to decompose the polymer. Rickard that the decomposition turns the liquid polymer into a gas which uniformly presses the die into place.

Conventional pick-and-place tools, are inherently serial and need to slow down the smaller the geometry of the items to accommodate the mechanical settling time needed for placement accuracy.

In contrast Terecircuits claims that with its technology a suitable tool could place thousands of components at once, achieving greater than 400,000 Units Per Hour (UPH) with sub-micron placement accuracy.

The release process produces CO2 and water vapor as by products but Rickard said the quantities are miniscule. “It’s less than a printer and no cleaning is required,” he said. The extreme low energy of the release process – 5 to 15mJ per square centimeter, support its sustainability credentials, Rickard said.

Partners in place

Rickared said Terecircuits has joint development agreements with semiconductor manufacturers that he would not name at this time. It is also working with seven tool manufacturers, who he also declined to name. “We are building pilot tools with partners,” said Rickard. He added: “That’s good because we thought we would have to develop and sell the tools. We no longer need to build a tool.” Rickard said Terecircuits planned to announce its partners towards the end of the year.

As a result the company expects to come to market with a business model that includes photopolymer material sales and process licensing where appropriate. This will probably start with semiconductor market die attach in 2025 and microLED display fabrication in 2027, Rickard said.

Terecircuits was founded in 2015 by Jayna Sheats, who now serves the company as CTO but has licensed technology from a predecessor company Terapac Corp. Sheats founded Terepac in 2008 and developed a roll-to-roll process for manufacturing multi-chip integrated RFID-type inlays for Internet of Things (IoT) and smartcard products.

Since its foundation Terecircuits has been funded by business angels, raised about US$5.3 million in equity funding and received US$1.25 million in the form of a National Science Foundation grant. “We will be raising an additional round of funding,” Rickard said.