Coplanar Modular Printbar CTE Matching
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Solution Overview
Problem
Existing printbar manufacturing methods often result in seams or gaps between individual printheads, which can lead to issues such as ink leakage and water vapor loss, especially when subjected to temperature changes, due to mismatched thermal expansion coefficients between the printheads and filling materials.
Innovation Solution
A manufacturing mold and molding system that aligns modular fluid ejection subassemblies with a mold material having a matching coefficient of thermal expansion (CTE) to form a seamless coplanar multi-module printbar, using techniques like transfer or injection molding to fill seams with epoxy mold compound (EMC) or thermoplastics, ensuring a continuous, planar surface without gaps.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If multiple printheads are stitched together to form a printbar using adhesive or molding material, then the printbar can be formed with multiple printing elements, but seams or gaps between printheads cause ink leakage and water vapor loss due to mismatched thermal expansion coefficients
Solution Approach 1:
The patent changes the thermal expansion parameter by selecting a molding material (epoxy mold compound) whose coefficient of thermal expansion matches that of the printhead substrates. This parameter matching eliminates the thermal expansion mismatch that causes seam separation during temperature changes, thereby preventing ink leakage and maintaining seam integrity while allowing multiple printheads to be stitched together
Solution Approach 2:
The patent uses a composite structure where the molding material forms an integrated bond between printhead substrates. The molding material is specifically selected to have compatible thermal properties with the substrates, creating a composite assembly that behaves as a unified structure during thermal cycling, preventing separation at the seams between individual printheads
2Strength
If adhesive or molding material is used to fill seams between printheads, then the printheads can be joined, but thermal expansion mismatch causes gaps and potential ink leakage
Solution Approach 1:
The patent modifies the thermal expansion parameter of the bonding material by selecting an epoxy mold compound with a coefficient of thermal expansion that matches the printhead substrates. This ensures that during temperature changes, the bonding material and substrates expand and contract together, maintaining precise seam closure and preventing gap formation that would compromise bonding integrity
3Strength
If a monolithic molding is used to surround printhead dies, then the printheads can be enclosed and protected, but the molding material may not match the thermal expansion of the printheads causing separation
Solution Approach 1:
The patent changes the thermal expansion parameter of the enclosure material by selecting an epoxy mold compound whose coefficient of thermal expansion matches that of the printhead substrates. This ensures that the monolithic molding and printhead dies maintain a stable relationship during temperature changes, preventing separation and maintaining both enclosure integrity and thermal stability
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 creates a seamless printbar that maintains a consistent thermal expansion behavior with the printheads, reducing ink leakage and water vapor loss, and ensuring a strong, continuous bond across the printbar surface.
Implementation Method 1
A manufacturing mold and molding system that aligns modular fluid ejection subassemblies with a mold material having a matching coefficient of thermal expansion (CTE) to form a seamless coplanar multi-module printbar
Data Source
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AI summary
In various examples, a printbar is formed from multiple modular fluid ejection subassemblies joined together through a molding process that provides for a continuous planar substrate surface. A mold may secure the modular fluid ejection subassemblies during a molding process in which a runner conveys a molding material to seams between the joined modular fluid ejection subassemblies.