ESD Protective Device with Internal Conductor for Heat Dissipation
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Solution Overview
Problem
ESD protective devices experience degradation in discharge characteristics due to repeated discharges, leading to increased discharge starting voltage and gap between discharge electrodes, caused by melting, peeling, and over-sintering of facing portions, especially when glass components diffuse and form large metal grains.
Innovation Solution
Incorporating a conductor portion within the ceramic multilayer substrate to cover the facing ends of discharge electrodes, dissipate heat, and prevent glass component diffusion, thereby maintaining the discharge characteristics and preventing over-sintering, along with a discharge auxiliary portion containing dispersed metal and semiconductor materials to stabilize discharge.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If discharge is repeatedly performed in the ESD protective device, then the discharge function is activated to protect circuits, but the facing portions of the discharge electrodes are melted or peeled away, causing the gap between facing portions to increase and discharge characteristics to degrade
Solution Approach 1:
The patent applies beforehand cushioning by forming a conductor portion (heat dissipation conductor) in advance within the ceramic multilayer substrate, positioned to face the facing portions of the discharge electrodes. This conductor portion acts as a pre-positioned heat sink that absorbs and dissipates heat generated during discharge operations before the heat can cause melting or peeling of the discharge electrode facing portions, thereby preventing the increase in gap between facing portions and maintaining stable discharge characteristics over repeated operations.
2Reliability
If discharge is repeatedly performed, then excessive voltage is guided to ground to protect circuits, but heat generated in discharge causes the facing portions to be melted or peeled away, increasing the discharge starting voltage
Solution Approach 1:
The patent introduces an intermediary element - the conductor portion (heat dissipation conductor) - that is positioned between the discharge electrodes and the surrounding environment. This intermediary conductor portion serves as a heat transfer medium that receives heat from the discharge electrodes during discharge operations and conducts it away to the ground or surrounding structures, thereby mediating the heat transfer process and preventing excessive temperature rise in the facing portions while maintaining the circuit protection function.
3Length of moving object
If the facing portions are formed thin to reduce gap, then discharge characteristics improve, but the facing portions are more susceptible to melting and peeling during repeated discharge
Solution Approach 1:
The patent applies local quality by creating a non-uniform structure where the conductor portion is positioned specifically at the location facing the thin facing portions of the discharge electrodes. This localized placement of the heat dissipation conductor provides targeted thermal protection precisely where the thin facing portions are most vulnerable to heat damage, allowing the facing portions to maintain their thin geometry for reduced gap while gaining localized strength and heat resistance through the adjacent conductor portion.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution effectively suppresses the degradation of discharge characteristics by maintaining the gap and preventing over-sintering, ensuring consistent and reliable discharge performance even after repeated discharges.
Implementation Method 1
at least one conductor portion formed inside the ceramic multilayer substrate so as to cover at least one of facing front ends of the facing portions of the discharge electrodes... dissipate heat
Implementation Method 2
conductor portion formed inside the ceramic multilayer substrate so as to cover at least one of facing front ends of the facing portions of the discharge electrodes... prevent glass component diffusion, thereby maintaining the discharge characteristics and preventing over-sintering
Implementation Method 3
when an excessive voltage is applied, such as the case in which a static charge is applied from an antenna of a mobile phone or the like, discharge is generated between the discharge electrodes of the ESD protective device, and as a result, the static charge can be guided to the ground side
Data Source
AI summary
Inside an insulating multilayer substrate 12 in which a plurality of insulating layers are laminated, a cavity portion 13, at least one pair of discharge electrodes 14 and 15, and conductor portions 34 and 35 are formed. The discharge electrodes 14 and 15 are connected to external electrodes 18 and 19 and have facing portions 14a and 15a which are formed along an inner surface of the cavity portion 13 and which face each other with a space provided therebetween. The conductor portions 34 and 35 are formed to cover at least one of facing front ends 14s and 15s of the facing portions 14a and 15a of the discharge electrodes 14 and 15 when viewed in a lamination direction of the insulating layers, a facing direction of the facing portions 14a and 15a, or a direction perpendicular both to the lamination direction and the facing direction.