Chisato Oyama | Komori Corp: Is Multi-Layer Printed Silver the Ultimate Solution for Sub-30-Micron MicroLED Bonding?
00:11:15.600 - 00:12:48.400
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Is Multi-Layer Printed Silver the Ultimate Solution for Sub-30-Micron MicroLED Bonding?
High-precision silver bump printing provides a high-conductivity alternative to solder for fine-pitch micro-device mounting. By printing 7 to 10 layers of silver paste in exactly the same position, developers can build up high-aspect-ratio vertical interconnects. This requires a printing system with sub-5-micron registration accuracy to prevent lateral misalignment between successive layers.
Applying this technique to high-density integration has demonstrated successful die mounting on printed traces down to a 28-micron pitch. This enables direct bonding of micro-ICs and microLEDs directly onto thin film traces. Every single bump must achieve simultaneous coplanar contact across the array to ensure high-yield connectivity.
Cross-sectional and electrical evaluations confirm that these printed silver bumps provide robust electrical paths without shorting adjacent lines. The resulting joints demonstrate reliable mechanical adhesion and stable contact resistance. This proves that printed metallization can replace vacuum-evaporated bumps for fine-pitch displays and advanced packaging.
In this short video, you can learn:
* How to print 7 to 10 layers of silver paste exactly in register to form tall, high-conductivity bumps
* Achieving high-density IC and MicroLED mounting on traces down to a 28-micron pitch
* Verification of contact reliability and electrical connectivity using printed silver interconnects
š **Clip Abstract** This clip covers the formulation and execution of multi-layer silver bump printing for fine-pitch micro-IC and microLED packaging. It showcases how a 28-micron pitch interconnect array can be printed and verified for electrical conductivity.
#PrintedSilverBumps, #MicroLEDBonding, #FinePitchInterconnect, #HighAspectRatioPrinting, #AdvancedPackaging, #MicroLEDDisplays
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00:03:31.500 - 00:05:16.000
Can Gravure Offset Printing Overcome the Limits of Screen Printing for Sub-10-Micron Electronics?
Can Gravure Offset Printing Overcome the Limits of Screen Printing for Sub-10-Micron Electronics?
The gravure offset printing process relies on a precise three-step transfer mechanism to surpass the physical limits of conventional screen printing. First, a doctor blade fills a micro-grooved gravure plate with high-viscosity functional paste. A silicone blanket then rolls over the plate to pick up the pattern, subsequently transferring it onto the target substrate with minimal physical deformation.
Unlike screen printing, where mesh deflection introduces spatial distortion and registration errors, the gravure offset method maintains continuous contact between the silicone blanket, the plate, and the substrate. This direct-contact rolling mechanism virtually eliminates alignment drift and positional gaps during transfer. This allows the system to achieve highly repeatable deposition within a tight registration budget.
To achieve ultra-high definition at sub-10-micron scales, developers must optimize a complex multi-variable material system. This requires precise chemical and mechanical matching between the functional paste rheology, the surface energy of the silicone blanket, the gravure plate depth, and the printing speed. When these parameters are properly balanced, the system can reliably print fine features down to 5 microns.
In this short video, you can learn:
* The mechanics of three-step gravure offset transfer using a doctor blade and silicone blanket
* Why continuous blanket contact eliminates registration drift compared to screen printing
* How to optimize paste, plate, and blanket characteristics for stable high-resolution printing
š **Clip Abstract** This clip explains the core mechanical steps of gravure offset printing and how it achieves superior positional precision over conventional screen printing. It outlines the transfer process from plate to blanket to substrate and highlights the path to optimizing sub-10-micron printed features.
#GravureOffsetPrinting, #SubTenMicron, #SiliconeBlanketTransfer, #PasteRheology, #PrintedElectronics, #AdditiveElectronics
00:08:14.500 - 00:09:41.900
How Do We Print Sub-10 Micron Solder Bumps for Next-Generation MicroLED Integration?
How Do We Print Sub-10 Micron Solder Bumps for Next-Generation MicroLED Integration?
Integrating microLEDs requires printing solder bumps at pitches and dimensions far below conventional surface-mount technology (SMT) capabilities. Using Type 9 fine-particle solder pastes, gravure offset printing has successfully achieved dot arrays with diameters as small as 6 microns. This allows display manufacturers to deposit uniform interconnect sites across a full 300mm wafer footprint.
To prevent bridging while ensuring sufficient vertical volume for reliable joints, aspect ratio engineering is critical. By taking advantage of high-precision registration, developers can overprint the same site multiple times to stack the solder paste. This increases bump height to 4 microns for micro-scale dots, and up to 30 microns for larger features, significantly improving the mechanical and electrical robustness of the contact.
The scaling of solder paste to sub-10-micron sizes requires meticulous control over metal load and solvent evaporation rates. As the feature size shrinks, the surface area-to-volume ratio increases, meaning any instability in the paste can cause transfer failures or incomplete wetting during reflow. Layer-by-layer stacked printing offers a robust path to overcome these rheological limitations and achieve stable micro-junctions.
In this short video, you can learn:
* Realizing 6-micron to 20-micron solder dot patterns using Type 9 solder paste
* Stacked multi-pass printing to control bump aspect ratio and vertical height
* The challenges of managing fine-particle solder rheology for 300mm wafer-scale microLED packaging
š **Clip Abstract** This clip details the successful printing of Type 9 solder paste dots down to 6 microns for microLED and semiconductor packaging. It explains how multi-pass overprinting is used to increase the aspect ratio and height of micro-solder bumps.
#GravureOffsetPrinting, #Type9SolderPaste, #StackedMultiPassPrinting, #MicroSolderBumps, #MicroLEDPackaging, #AdvancedPackaging