Overmolded Printhead Dies with Non-Rectangular Shapes
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Solution Overview
Problem
The challenge in inkjet printhead manufacturing is to reduce costs while maintaining print quality and reliability, as smaller die sizes lead to tighter slot pitches and increased fragility, complicating assembly and increasing failure rates due to the removal of material for ink delivery slots.
Innovation Solution
The use of an overmolded epoxy mold compound to support multiple printhead dies, eliminating the need for fluid distribution manifolds and simplifying assembly by extending electrical interconnects to printed circuit boards, and employing non-rectangular shaped dies in a stitching configuration to optimize fluid delivery and nozzle alignment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If smaller die sizes are used to reduce costs, then manufacturing cost is reduced, but die strength decreases and fragility increases
Solution Approach 1:
The printhead die is constructed as a composite structure combining a substrate (silicon or glass) with an overmolded epoxy mold compound. This composite approach allows the substrate to provide mechanical strength while the epoxy overmold provides structural support and protection, enabling smaller die sizes without compromising strength. The epoxy overmold acts as a reinforcing layer that distributes mechanical stresses across the entire die structure.
Solution Approach 2:
The epoxy overmold is applied selectively to specific regions of the printhead die where additional support is needed, such as around the ink delivery slots and at the edges. This localized application provides targeted reinforcement without adding unnecessary material throughout the entire die, optimizing the strength-to-cost ratio for smaller die designs.
2Adaptability or versatility
If material is removed for ink delivery slots, then fluid delivery capability is improved, but die strength decreases and failure rate increases
Solution Approach 1:
The epoxy overmold compensates for the structural weakness created by ink delivery slots by providing a continuous supporting matrix throughout the die. This composite structure allows material to be removed for fluid delivery while the epoxy reinforcement maintains overall die integrity and prevents crack propagation, thereby reducing failure rates.
Solution Approach 2:
The epoxy overmold is applied before the die undergoes subsequent processing and assembly steps, providing preemptive structural reinforcement. This beforehand cushioning protects the die from mechanical damage during handling and assembly, reducing the likelihood of failure before the die is fully assembled into the printhead.
3Adaptability or versatility
If fluid distribution manifolds are used, then fluid delivery is improved, but device complexity increases and assembly becomes more difficult
Solution Approach 1:
The fluid distribution function is merged directly into the printhead die structure through integrated fluid delivery channels formed within the substrate and epoxy overmold. This eliminates the need for separate fluid distribution manifolds by combining the fluid delivery pathway with the die itself, thereby reducing device complexity and simplifying assembly.
Solution Approach 2:
The separate fluid distribution manifold component is extracted and eliminated from the design. Instead, fluid delivery is achieved through channels directly formed in the die structure and epoxy overmold, removing unnecessary components and simplifying the overall assembly process while maintaining effective fluid delivery.
4Productivity
If non-rectangular shaped dies are used, then fluid delivery optimization is improved, but manufacturing precision requirements increase
Solution Approach 1:
The printhead die employs non-rectangular shapes with optimized geometries that improve fluid delivery efficiency and nozzle alignment. The asymmetric design allows for better fluid distribution patterns and more effective stitching configuration, while the epoxy overmold provides the precision required to maintain accurate nozzle alignment despite the complex shape.
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 approach significantly reduces fabrication costs, enhances die strength, and simplifies the assembly process, while maintaining print quality and reliability by using a moldable substrate with fluid slots that can be narrower or wider than the printhead dies, and allowing for efficient fluid delivery through a variety of ink slot arrangements.
Implementation Method 1
Fluid may be ejected from the ejection chamber by, for example, heating a resistive element
Implementation Method 2
overmolded epoxy mold compound to support multiple printhead dies
Implementation Method 3
a fluid slot defined in the print head to an ejection chamber beneath a nozzle
Data Source
Figure 1
Figure 2A~2F
Figure 3A~3E
AI summary
A printhead includes a moldable substrate, and a number of printhead dies molded into the moldable substrate. The printhead dies include a number of printhead dies molded into the moldable substrate. The dies comprise a non-rectangular shape. A number of fluid slots are defined in the moldable substrate to fluidically coupled to the printhead dies to feed fluid to the printhead dies. The number of fluid slots is not equal to the number of printhead dies.