Liquid Discharging Head Wafer Recess Layout for Crack-Free Dicing
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Solution Overview
Problem
Conventional methods for manufacturing liquid discharging heads, such as ink jet heads, result in poor dimensional accuracy and frequent chipping of wafers due to difficulty in controlling bending and pull forces during cutting, leading to issues like cracks and scratches when connecting electric input terminals to electric wiring boards.
Innovation Solution
A method involving the formation of a recessed portion on the rear surface of the wafer corresponding to cutting lines, with the recessed area minimized under the terminal region to prevent fragments and cracks during dicing and joining, using a dicing tape and precise control of the dicing blade to minimize wafer scattering.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a recessed portion is formed in the wafer at the cutting line to suppress burr formation, then cutting quality is improved, but a slope is created at the outer periphery that causes cracks during terminal joining
Solution Approach 1:
The patent applies local quality by creating a recessed portion only at specific locations (cutting lines) on the wafer rear surface, while keeping other areas flat. This localized modification suppresses burr formation at cutting lines without creating slopes at terminal positions, thus resolving the contradiction between cutting quality and crack resistance.
Solution Approach 2:
The recessed portion is formed in advance on the wafer rear surface before the dicing process. This preliminary action prepares the wafer structure to prevent burr formation during cutting, while the careful design of the recessed portion's location and dimensions ensures it does not interfere with terminal joining operations.
2Productivity
If conventional dicing methods are used to cut the wafer, then productivity is maintained, but dimensional accuracy is poor and chipping occurs frequently
Solution Approach 1:
The recessed portions are formed on the wafer rear surface before the dicing process. This preliminary preparation allows conventional dicing methods to be used without modification, maintaining productivity, while the recessed portions guide the dicing blade to cut precisely along the intended lines, improving dimensional accuracy and reducing chipping.
Solution Approach 2:
The recessed portions act as intermediaries between the dicing blade and the wafer material. They provide a physical guide that directs the blade along the cutting line, improving cut precision without requiring changes to the dicing equipment or process parameters, thus maintaining productivity.
3Manufacturing precision
If the recessed portion is positioned to suppress burrs, then cutting precision is improved, but the slope created prevents proper load reception during ultrasonic joining
Solution Approach 1:
The patent applies local quality by strategically positioning recessed portions only at cutting lines on the wafer rear surface, while ensuring that terminal regions remain flat. This selective localization allows the recessed portions to improve cutting precision without creating slopes that would interfere with load reception during ultrasonic joining of terminals.
Solution Approach 2:
The wafer rear surface is segmented into different functional zones: areas with recessed portions for cutting lines and flat areas for terminal regions. This segmentation allows each zone to serve its specific function optimally, with recessed portions improving cutting precision and flat areas ensuring proper load reception during joining.
Data Source
AI summary
A method of manufacturing a liquid discharging head includes preparing a wafer provided with an element and a discharge port formation member on a front surface of the wafer, forming a recessed portion in a rear surface of the wafer, attaching the rear surface of the wafer and a dicing tape, cutting the wafer along cutting lines to form an element board, and connecting an electric wiring board and a terminal of the element board. The element board includes a discharge port formation member having a discharge port for discharging liquid and includes the element to supply energy to the discharge port for liquid discharge. The recessed portion is formed at a location corresponding to the cutting lines, and an area of a region where the terminal overlaps the recessed portion is smaller than an area of a region where the terminal does not overlap the recessed portion.