Inkjet Head Unit Flexible Substrate Layout for Solder Inspection
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Solution Overview
Problem
Existing inkjet printers face challenges in visually inspecting the integrity of solder joints between substrates, making it difficult to ensure proper electrical connectivity.
Innovation Solution
A head unit configuration with a flexible substrate design that includes a first and second flexible substrate, where the second substrate has a specific stack arrangement with a cover member, conductive member, and base member, allowing for improved visibility of solder joints by omitting solid GND and cover layers over the terminals, enabling clear visual inspection of solder quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If substrates are mounted with terminals soldered together, then electrical connection is achieved, but visual inspection of solder joint quality becomes difficult
Solution Approach 1:
The patent removes the solid GND layer and cover layers from specific regions above the terminals on the flexible substrate. This extraction of unnecessary layers enables direct visual inspection of the solder joints between terminals while maintaining the electrical connection function through the remaining substrate structure.
Solution Approach 2:
The patent applies different structural characteristics to different regions of the flexible substrate. The regions above terminals are designed without solid GND and cover layers to enable visual inspection, while other regions maintain complete layer stacks for electrical shielding and grounding functions.
2Object-affected harmful factors
If cover layers and solid GND are present over terminals, then electrical shielding is improved, but visibility of solder joints is reduced
Solution Approach 1:
The patent divides the flexible substrate into different regions: regions above terminals where cover layers and solid GND are removed for visibility, and other regions where complete layer stacks are maintained for electrical shielding. This segmentation allows simultaneous achievement of both visibility and shielding functions in appropriate locations.
Solution Approach 2:
The patent extracts (removes) the cover layers and solid GND from specific regions above terminals. This extraction eliminates the obstruction to visual inspection while the remaining substrate structure and other region layers continue to provide necessary electrical shielding functions.
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
Facilitates easy visual verification of solder joints, ensuring proper electrical coupling and reducing the risk of short circuits, particularly in high-density nozzle arrangements and reactive ink applications.
Implementation Method 1
a piezoelectric element that varies a capacity of the pressure chamber in response to an electrical signal
Implementation Method 2
the terminal being joined to the first flexible substrate with solder
Data Source
AI summary
A head unit to be mounted in a liquid ejecting apparatus includes: a liquid ejecting section; a first flexible substrate that transmits the electrical signal to a joining terminal of the piezoelectric element; and a second flexible substrate that transmits the electrical signal to the first flexible substrate. The second flexible substrate includes: a first region having a stack of the cover member, the conductive member, and the base member; and a second region having a stack of the conductive member and the base member. The second flexible substrate has a surface on which a terminal is disposed within the second region, the terminal being joined to the first flexible substrate with solder.