Inkjet Printhead Wiring Structure for Through-Hole Break Containment
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Solution Overview
Problem
Inkjet print heads experience issues with voltage drop and heater element malfunctions due to wire breaks, leading to reduced ejection stability and image quality, particularly as through hole aspect ratios increase with miniaturization, compromising the effectiveness of barrier metal layers in preventing wiring dissolution.
Innovation Solution
A liquid ejection head print element board design featuring a heater layer, common wiring, and an anti-cavitation layer with a conductive plug that extends in the opposite direction from the heater layer, using the same material for the anti-cavitation layer to form a buffer that prevents the propagation of wire breaks and maintains heater functionality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the wiring layer thickness is increased to reduce voltage drop, then the electrical resistance decreases, but the through hole aspect ratio increases and barrier metal coverability deteriorates
Solution Approach 1:
The invention introduces a new dimensional approach by forming the barrier metal layer not only on the lateral walls but also on the bottom surface of the through hole. This bottom coating structure adds a new dimension to the barrier metal coverage, ensuring complete protection even when the aspect ratio is high and lateral coverage is insufficient.
Solution Approach 2:
The barrier metal layer is segmented into two functional parts: lateral wall coverage and bottom surface coverage. This segmentation allows each part to perform its specific function optimally, with the bottom coating providing the critical protection against ink penetration that lateral coverage alone cannot achieve in high aspect ratio holes.
2Productivity
If the through hole diameter is miniaturized to increase heater density, then the number of heaters increases, but the barrier metal layer cannot sufficiently cover the plug bottom section
Solution Approach 1:
By adding bottom surface coating to the barrier metal layer, the invention compensates for the reduced lateral coverage that occurs with miniaturized through holes. This dimensional addition ensures that even as hole diameter decreases, the plug remains fully protected from ink penetration.
3Reliability
If a wire break occurs at the heater element, then the heater malfunctions, but the dissolution propagates to adjacent heaters through common wiring
Solution Approach 1:
The barrier metal layer acts as an intermediary between the conductive plug and the ink environment. It prevents direct contact between ink and the conductive material, thereby stopping the dissolution propagation that would otherwise spread through the common wiring to affect adjacent heaters.
Solution Approach 2:
The invention converts the potential harm of wire breaks and dissolution into a controlled situation by using the barrier metal layer to contain the issue. Even when a wire break occurs, the barrier metal prevents the dissolution from spreading, turning a potentially catastrophic failure into a localized, manageable problem.
4Object-affected harmful factors
If the wiring is exposed to ink due to wire break, then the wiring dissolves, but adjacent heaters remain functional with proper barrier coverage
Solution Approach 1:
The barrier metal layer serves as a protective intermediary that isolates the conductive wiring from the ink environment. This intermediary layer prevents ink from dissolving the wiring, thereby maintaining the functionality of adjacent heaters even when one heater experiences a wire break.
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 prevents the progression of wire break-induced dissolution, maintaining the stability and functionality of adjacent heaters, thereby ensuring consistent ink ejection and high image quality even with high aspect ratios.
Implementation Method 1
a first plug that extends in an opposite direction of the first direction from the heater layer, fills an inside of a through hole directly connected to the heater with a conductive material, and supplies voltage to the heater
Implementation Method 2
a print head that uses a system of using heat from heaters to eject ink
Data Source
AI summary
A liquid ejection head print element board, includes: a heater layer where a plurality of heaters are formed; a wiring layer where common wirings electrically connected to the plurality of heaters are formed; and an anticavitation layer laminated in a first direction on the heater layer, the liquid ejection head print element board further including: a first common wiring that is one of the common wirings and is for supplying voltage from an outside; and a first plug that extends in an opposite direction of the first direction from the heater layer, fills an inside of a through hole directly connected to the heater with a conductive material, and supplies voltage to the heater, in which the first common wiring and the first plug are electrically connected to each other via wiring formed of a material identical to that of the anticavitation layer.