Ryota Shimizu | Satosen Co.,Ltd: How does repeated stretching lead to electrical failure in conventional stretchable PCBs?
00:04:44 - 00:05:01
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Summary of the clip:
How does repeated stretching lead to electrical failure in conventional stretchable PCBs?
Conventional stretchable PCBs, whether utilizing meandering copper traces or printed silver paste, face durability challenges under repeated stretching. While silver paste allows for straight patterns and higher design density compared to the complex shapes required for copper, both materials exhibit a common failure mode. This failure manifests as an increase in resistance after repeated stretching cycles, ultimately leading to electrical discontinuity.
The root cause of this resistance increase lies in the formation and propagation of cracks within the conductive material. As the PCB undergoes repeated stretching, micro-cracks initiate and grow, disrupting the conductive pathways. This crack formation is exacerbated by the inherent limitations of copper and silver paste in withstanding tensile stress, leading to a gradual degradation of electrical performance.
The presenter highlights that while the resistance fluctuates with each stretch and release cycle, the critical issue is the continuous upward trend in resistance over time. This trend signifies irreversible damage accumulation, eventually resulting in an open circuit and rendering the PCB unusable. This limitation restricts the lifespan and warranty potential of current stretchable PCB technologies.
In this short video, you can learn:
* The limitations of copper and silver paste in stretchable PCBs.
* How repeated stretching leads to crack formation and increased resistance.
* Why current stretchable PCBs have limited durability and short lifespans.
š **Clip Abstract:** This segment explains the failure mechanisms in conventional stretchable PCBs due to repeated stretching, focusing on crack formation and resistance increase in conductive materials. It highlights the limitations of current technologies and sets the stage for introducing liquid metal as a solution.
š Link in comments š
#StretchablePCBs, #CopperTraces, #SilverPaste, #ElectricalFailureMode, #FlexibleElectronics, #WearableTech
This is a highlight of the presentation:
Next Generation of Stretchable PCB with Liquid Metal
More Highlights from the same talk.
00:06:39 - 00:07:33
What is the significance of the encapsulation layer in the liquid metal-based stretchable PCB design?
What is the significance of the encapsulation layer in the liquid metal-based stretchable PCB design?
The presenter introduces a hybrid structure employing gallium-indium liquid metal to address the durability issues of conventional stretchable PCBs. This design involves printing a silver stretchable paste, followed by spraying the gallium-indium alloy, and finally encapsulating the structure. This three-layer stack-up is crucial for maintaining the liquid metal's functionality as a conductor at critical points within the PCB.
A key aspect of this hybrid structure is the metallic bond formed between the silver paste and the gallium-indium alloy. This bond ensures good electrical contact and facilitates the self-healing properties of the liquid metal. However, the encapsulation layer plays an equally vital role in preventing the gallium-indium alloy from leaking or flowing out of the designated conductive pathways.
The presenter emphasizes that the encapsulation layer is essential for the widespread adoption of this technology. By preventing leakage, the encapsulation layer contributes to both the engineering performance and the economic viability of the stretchable PCB. It allows for minimizing the amount of expensive liquid metal required while maintaining high electrical performance.
In this short video, you can learn:
* The three-layer structure of the liquid metal-based stretchable PCB.
* The role of the metallic bond between silver paste and gallium-indium.
* The importance of the encapsulation layer in preventing liquid metal leakage.
š **Clip Abstract:** This segment details the structure of the liquid metal-based stretchable PCB, emphasizing the crucial role of the encapsulation layer in preventing leakage and ensuring the economic viability of the technology. It highlights the importance of balancing engineering and economic considerations for widespread adoption.
š Link in comments š
#LiquidMetalPCB, #EncapsulationLayer, #GalliumIndium, #StretchableElectronics, #WearableElectronics, #FlexibleHybridElectronics
00:11:41 - 00:12:48
How can the resistance change in the liquid metal-based PCB be used for strain sensing?
How can the resistance change in the liquid metal-based PCB be used for strain sensing?
The presenter highlights the results of extensive durability testing, including bending, twisting, and stretching, demonstrating the robustness of the liquid metal-based stretchable PCB. Notably, after 250,000 stretching cycles, the PCB maintains its functionality. This durability stems from the self-healing properties of the liquid metal, which flows into cracks that form in the silver paste, maintaining electrical conductivity.
The presenter then focuses on the correlation between resistance change and strain level in the liquid metal-based PCB. Data from the 250,000-cycle stretching test reveals a strong coupling between the applied strain and the measured resistance. As the PCB stretches, the resistance increases, and as it returns to its original position, the resistance decreases, creating a synchronized wave pattern.
This close correlation suggests that the stretchable PCB can function not only as a mechanical and electrical support but also as a strain sensor. By monitoring the resistance changes, it is possible to detect and quantify the strain experienced by the PCB. This opens up possibilities for applications requiring real-time strain monitoring, such as wearable sensors and structural health monitoring.
In this short video, you can learn:
* The durability of the liquid metal-based PCB under various deformation modes.
* The correlation between resistance change and strain level.
* The potential of the PCB to function as a strain sensor.
š **Clip Abstract:** This segment presents data demonstrating the durability and strain-sensing capabilities of the liquid metal-based stretchable PCB. It highlights the strong correlation between resistance change and strain, suggesting potential applications in real-time strain monitoring.
š Link in comments š
#LiquidMetalPCB, #StretchableElectronics, #StrainSensing, #SelfHealingMaterials, #WearableSensors, #FlexibleElectronics