Electronic Device Wiring Substrate Pitch Conversion
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Solution Overview
Problem
The miniaturization of liquid ejecting devices is hindered by the misalignment of terminal pitches between the drive IC and the piezoelectric element, making it difficult to secure sufficient wiring intervals and widths without increasing the size of the sealing plate and drive IC.
Innovation Solution
The electronic device features a wiring substrate with distinct regions on each surface, allowing for pitch conversion through relay wiring portions on both surfaces, reducing the interval between terminals while maintaining sufficient wiring intervals and widths, and incorporating a conductive layer with elasticity for reliable conduction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If pitch conversion is performed on one surface of the sealing plate with steep inclination wirings, then terminal pitch misalignment is compensated, but wiring interval and wiring width cannot be secured sufficiently
Solution Approach 1:
The patent transitions from two-dimensional pitch conversion on a single surface to three-dimensional pitch conversion utilizing both upper and lower surfaces of the sealing plate. By forming wirings on the lower surface in addition to the upper surface, the patent creates vertical separation between wiring layers, allowing pitch conversion to occur in the thickness direction of the sealing plate. This dimensional transition enables sufficient wiring intervals and widths to be maintained while achieving the required pitch conversion to compensate for terminal pitch misalignment between the drive IC and piezoelectric element.
2Reliability
If the interval between terminals on drive IC side and piezoelectric element side is increased to secure wiring interval and width, then wiring integrity is improved, but the sizes of sealing plate and drive IC are increased
Solution Approach 1:
The patent utilizes the thickness direction of the sealing plate as an additional dimension for wiring routing. By forming wirings on both the upper and lower surfaces of the sealing plate, the patent effectively uses the vertical space within the sealing plate thickness to achieve pitch conversion and maintain wiring intervals. This approach allows wiring integrity to be preserved without increasing the planar area of the sealing plate, thereby maintaining device miniaturization while ensuring reliable electrical connections.
3Productivity
If the number of nozzles is increased for high density arrangement, then productivity is improved, but terminal pitch narrowing makes pitch conversion more difficult
Solution Approach 1:
The patent enables effective pitch conversion by utilizing the third dimension (thickness direction) through wiring formation on both upper and lower surfaces of the sealing plate. This approach provides additional spatial freedom for routing wirings during pitch conversion, making it feasible to accommodate the increased number of terminals required for high-density nozzle arrangements. The vertical separation between upper and lower surface wirings allows for more flexible wiring paths, enabling pitch conversion even when terminal pitches are narrowly spaced due to high nozzle density requirements.
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 enables the miniaturization of the electronic device by allowing pitch conversion on both surfaces of the wiring substrate, reducing terminal intervals, and ensuring reliable conduction through the use of an elastic conductive layer, thereby facilitating the miniaturization of the device without compromising wiring integrity.
Implementation Method 1
a piezoelectric element (a type of a drive element) causing a pressure fluctuation in liquid inside the pressure chamber
Implementation Method 2
incorporating a conductive layer with elasticity for reliable conduction
Data Source
AI summary
An electronic device includes a sealing plate including a first surface connected to a pressure chamber formation substrate, and a second surface having a drive IC provided thereon. The sealing plate includes a first region in which a plurality of individual connection terminals are arranged, and a second region in a position different from the first region. A plurality of bump electrodes are arranged at a pitch different from a pitch of an individual connection terminals, in a region overlapping a second region, and a wiring group connecting the individual connection terminal and a bump electrode includes a first wiring of which a position of a pass-through wiring relaying the first surface and the second surface is within the first region. A second wiring of which a position of a pass-through wiring connecting the first surface and the second surface is within the second region.