Liquid Discharge Head Substrate ESD Protection via Segmented Conductive Layer
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Solution Overview
Problem
The existing liquid discharge head substrates face challenges with dielectric breakdown due to Electro Static Discharge (ESD) when the film thickness and arrangement range of the conductive protection layer are reduced, leading to potential warpage and loss of electric charge release sites.
Innovation Solution
A liquid discharge head substrate configuration that includes a substrate with an intermediate layer, an insulating layer, and a conductive layer, where the wiring layer and energy-generating element overlap, featuring an electric connecting portion, a non-insulated portion, and an opening portion to connect the conductive layer, which helps in charge release and reduces dielectric breakdown risk.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Shape
If the film thickness of the conductive layer is decreased to prevent substrate warpage, then substrate warpage is reduced, but the ability to release electric charges is lost and dielectric breakdown may occur
Solution Approach 1:
The conductive layer is segmented into multiple regions with different functions: a first conductive region for charge release connected to the non-insulated portion, and a second conductive region for protecting the element. This segmentation allows the conductive layer to simultaneously provide charge release pathways and element protection without requiring increased film thickness throughout.
Solution Approach 2:
Different regions of the conductive layer are designed with different properties: the first conductive region has higher conductivity and is positioned to receive ESD, while the second conductive region provides protective coverage. The insulating layer also has local quality variations with non-insulated portions strategically placed to facilitate charge release while maintaining insulation where needed.
2Reliability
If the arrangement range of the protection layer is decreased to reduce dielectric breakdown probability, then dielectric breakdown risk is reduced, but the ability to release electric charges is compromised
Solution Approach 1:
A non-insulated portion of the intermediate layer serves as an intermediary between the liquid chamber and the first conductive region. This intermediary structure provides a dedicated pathway for electric charge release while maintaining the protective coverage of the conductive layer over the element, thus resolving the contradiction between reduced protection range and charge release capability.
3Reliability
If the film thickness of the conductive layer is increased to improve element protection, then element protection is enhanced, but substrate warpage occurs
Solution Approach 1:
The conductive layer is divided into functional segments that provide adequate protection where needed while minimizing overall material usage. The second conductive region provides element protection, while the first conductive region handles charge release, allowing thinner overall construction that prevents warpage.
Solution Approach 2:
The conductivity parameter is optimized by using different conductive materials or structures in different regions. The first conductive region has higher conductivity for charge release, while the second provides protective coverage, allowing the overall film thickness to be reduced without compromising element protection.
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
This configuration effectively reduces the risk of dielectric breakdown from ESD by providing a path for electric charge release, maintaining substrate integrity and preventing warpage while ensuring efficient ink discharge.
Implementation Method 1
the heat energy generated by the heat generating resistive element induces a foaming phenomenon of a liquid
Implementation Method 2
dielectric breakdown of the insulating layer due to ESD (Electro Static Discharge)
Data Source
AI summary
A substrate includes a layer including a base material and an intermediate layer including a wiring layer, an element formed on a side of the intermediate layer, and configured to generate energy for discharging a liquid, an insulating layer covering the element and the layer against a liquid chamber, and a conductive layer formed on the insulating layer so as to cover the element against the liquid chamber. The substrate further includes an electric connecting portion configured to electrically connect the wiring layer and the element, a non-insulated portion formed on a side of the intermediate layer and configured to be covered by the insulating layer against the liquid chamber, and an opening portion formed in the insulating layer at a position. The non-insulated portion is connected to the conductive layer via the opening portion.