Oliver Haupt | Coherent Corp.: How can structural polymer degradation turn a self-regulating PTC heater into a runaway thermal hazard?
00:06:20 - 00:08:16
Other snippets from this talk
Summary of the clip:
How can advanced laser systems resolve the dual challenges of mechanical delamination in foldable displays and high-throughput microLED mass transfer?
In flexible and foldable OLED manufacturing, maintaining structural integrity during final shape cutting is a critical bottleneck. While picosecond ultraviolet (UV) lasers operating at up to 50 watts remain the industry standard for conventional display cutting, the mechanical stresses of folding demand a transition to ultra-short pulse regimes. Utilizing femtosecond laser systems minimizes the heat-affected zone (HAZ), effectively preventing micro-delamination along the cut edges of sensitive multilayered flexible substrates.
For next-generation microLED displays, laser processing is indispensable across the entire manufacturing chain, replacing traditional chemical etching of the epitaxial wafer. Laser lift-off (LLO) utilizes short UV wavelengths to decouple the gallium nitride or other compound semiconductor dies from their sapphire growth substrates. Following lift-off, laser-enabled mass transfer and selective repair protocols position the functional dies, which are then permanently secured to the receiver substrate's bonding pads using targeted diode laser bonding.
Optimizing the throughput of the LLO step requires matching the laser beam profile to the production volume requirements. Laser architectures can be scaled from single-spot systems, which operate in the hour-per-wafer range, to step-and-repeat square field configurations that reduce processing to minutes. For high-volume manufacturing, fully optimized high-throughput line-beam systems compress the entire lift-off process down to a matter of seconds.
In this short video, you can learn:
* Why femtosecond lasers are replacing picosecond UV systems to prevent delamination in foldable OLED displays.
* The critical role of lasers in the microLED process chain, from sapphire wafer lift-off to selective die repair and final diode bonding.
* How scaling laser beam delivery from single-spot to high-throughput configurations reduces processing times from hours to seconds.
📋 **Clip Abstract**
The speaker outlines the transition from picosecond to femtosecond lasers for cutting foldable OLED displays to prevent delamination, alongside a detailed breakdown of laser applications in microLED manufacturing. He explains how laser lift-off, mass transfer, repair, and diode bonding processes can be scaled from single-spot systems taking hours to high-throughput solutions completed in seconds.
🎤 Speaker: Oliver Haupt
🏢 Company: Coherent Corp.
📅 Event: Printed Electronics Innovation Day 2024
📍 Location: TechBlick | Online Platform
🌐 Learn more at the next TechBlick event: https://www.techblick.com
#PTCCarbonHeaters, #NTCInversion, #ThermalRunaway, #PolymerDegradation, #PrintedElectronics, #ThermalManagement
This is a highlight of the presentation:
More Highlights from the same talk.
00:02:54 - 00:04:57
Why are standard linear heaters losing ground to self-regulating exponential PTC carbon materials?
How can next-generation microLED and automotive display fabs reconcile the demand for Gen 8 scaling with the stringent cost-of-ownership targets of automated production lines?
Low-Temperature Polycrystalline Silicon (LTPS) remains the definitive process of record for high-performance backplanes, driving both established OLED displays and emerging microLED architectures for large-format and automotive applications. To unlock true economies of scale, the industry is actively transitioning from Gen 6 to Gen 8 glass substrates. Because global display manufacturers already possess deep institutional expertise in LTPS processing, they are uniquely positioned to adapt their existing backplane circuitry to meet the rigorous drive requirements of microLED arrays.
To optimize the Cost of Ownership (COO) in these highly automated Gen 8 facilities, equipment architectures must evolve beyond legacy excimer laser annealing systems. While traditional 308 nm excimer lasers represent a mature, industry-proven standard with hundreds of active installations, Diode-Pumped Solid-State (DPSS) lasers operating at 355 nm have emerged as a highly viable alternative. These DPSS systems match the critical energy density, power output, and repetition rates of excimer sources while significantly reducing maintenance overhead and aligning with modern fab automation.
Following the critical LTPS crystallization phase, the manufacturing workflow shifts from material modification to high-throughput singulation. Integrating carbon dioxide (CO2) laser systems into the post-annealing processing line enables precise, stress-free cutting of these advanced display substrates. This hybrid approach—combining optimized solid-state annealing with reliable gas-laser cutting—provides a robust, scalable manufacturing route for next-generation display architectures.
In this short video, you can learn:
* How display manufacturers leverage existing LTPS backplane infrastructure to transition into microLED and large-format automotive display production.
* The operational and maintenance advantages of adopting 355 nm DPSS lasers over traditional 308 nm excimer lasers for LTPS annealing.
* The role of CO2 lasers in the post-annealing cutting and singulation stages of display substrate fabrication.
📋 **Clip Abstract**
The speaker discusses the scaling of LTPS backplanes to Gen 8 formats for OLED and microLED displays, comparing traditional excimer laser annealing with newer, lower-maintenance DPSS laser systems. He also introduces the role of CO2 lasers in the subsequent substrate cutting process.
🎤 Speaker: Oliver Haupt
🏢 Company: Coherent Corp.
📅 Event: Printed Electronics Innovation Day 2024
📍 Location: TechBlick | Online Platform
🌐 Learn more at the next TechBlick event: https://www.techblick.com
#PTCCarbonHeaters, #SelfRegulatingHeating, #CarbonPolymerComposites, #PositiveTemperatureCoefficient, #PrintedElectronics, #FlexibleElectronics
00:08:18 - 00:09:50
How does the spatial design of silver finger electrodes directly program the equilibrium temperature of a PTC carbon heater?
How can display manufacturers overcome the yield and throughput bottlenecks of sub-10-micron microLED mass transfer?
As microLED architectures demand rapid, high-volume assembly, traditional mechanical pick-and-place methods hit physical limits. Laser-enabled mass transfer has emerged as the enabling technology for high-yield pitch conversion, offering processing times measured in seconds. This optical approach bypasses mechanical contact, allowing manufacturers to manipulate ultra-small dies at speeds that make commercial display production viable.
The versatility of laser and optical transfer systems allows them to integrate seamlessly into diverse fabrication workflows. Whether transferring directly from the epitaxial growth wafer to the backplane, utilizing a single temporary carrier, or executing complex multi-step red-green-blue (RGB) co-location on intermediate substrates before final backplane bonding, advanced laser optics adapt to the specific integration path chosen by the manufacturer.
To achieve the cost reduction necessary for widespread market adoption, microLED dies must continue to shrink. As die dimensions scale down to 5x5 microns, laser mass transfer exhibits increasingly pronounced advantages over alternative methods. Recent advancements demonstrate that laser-based systems can successfully transfer these microscopic dies while maintaining exceptional placement accuracy and high yield.
In this short video, you can learn:
* How laser mass transfer processes achieve high-throughput pitch conversion in seconds.
* The adaptability of laser and optical systems across different transfer workflows, including direct epi-to-backplane and multi-carrier RGB integration.
* The scaling advantages of laser mass transfer as microLED dimensions shrink to 5x5 microns with high placement accuracy.
📋 **Clip Abstract**
The speaker discusses various process workflows for microLED pitch conversion and mass transfer, emphasizing that laser and optical systems can support direct, temporary, or multi-carrier RGB bonding methods. He explains that shrinking die sizes to 5x5 microns is essential for cost reduction, and demonstrates that laser mass transfer provides the necessary yield and placement accuracy at these smaller scales.
🎤 Speaker: Oliver Haupt
🏢 Company: Coherent Corp.
📅 Event: Printed Electronics Innovation Day 2024
📍 Location: TechBlick | Online Platform
🌐 Learn more at the next TechBlick event: https://www.techblick.com
#PTCCarbonHeaters, #InterdigitatedElectrodes, #TaperedBusBars, #ElectrodePitch, #PrintedElectronics, #ThermalManagement