Fluid Ejection Die Slot Molding to Prevent EMC Flash
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Solution Overview
Problem
The formation of epoxy molding compound (EMC) flash on contact pads of fluid ejection devices during the molding process, which can lead to mechanical issues and reduce the accuracy of the slot molding process.
Innovation Solution
The use of an upper mold chase with a slot forming feature that covers ink feed holes and defines a slot in the resulting EMC panel, reducing the cantilever length between the slot end and the fluid ejection die end to less than 1.5mm, thereby minimizing EMC flash on contact pads.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the slot molding process is used to provide fluid to the fluid ejection die, then the fluid supply function is improved, but EMC flash forms on the contact pads during molding
Solution Approach 1:
The slot is formed in the carrier before the molding process, and the slot is positioned such that it does not extend to the ends of the carrier. This preliminary configuration prevents EMC material from reaching the contact pads during subsequent molding, thereby eliminating EMC flash while maintaining fluid supply capability.
Solution Approach 2:
The slot is designed with varying properties along its length - it provides open fluid pathways in regions where fluid supply is needed, while being positioned away from contact pad regions to prevent EMC contamination. This local differentiation allows the slot to serve fluid supply functions without causing EMC flash on contact pads.
2Productivity
If the slot extends to the end of the carrier, then fluid supply coverage is improved, but the cantilever length increases causing mechanical instability
Solution Approach 1:
The slot extends partially along the carrier length rather than to the very ends, providing sufficient fluid supply coverage for the fluid ejection die without creating excessive cantilever length. This partial extension achieves the necessary fluid distribution while maintaining mechanical stability by keeping the slot within a reasonable distance from the carrier ends.
3Device complexity
If the molding process is performed without a slot forming feature, then the manufacturing process is simpler, but slot sidewall quality deteriorates
Solution Approach 1:
A slot forming feature is introduced as an intermediary component in the molding process. This feature serves as a mold insert or template that defines the slot geometry, ensuring high slot sidewall quality and precision. The slot forming feature acts as a mediator between the molding process and the final slot structure, enabling precise slot formation without requiring complex direct molding techniques.
Data Source
Figure 1
Figure 2
Figure 3A~3C
AI summary
A fluid ejection device includes a fluid ejection die including a first end portion positioned adjacent a first end of the fluid ejection die, and a fluid ejection portion positioned adjacent the first end portion. The fluid ejection die includes a contact pad positioned in the first end portion, and a fluid actuation device positioned in the fluid ejection portion. A carrier is attached to the fluid ejection die. The carrier includes a slot to provide fluid to the fluid actuation device. The slot extends longitudinally along the fluid ejection portion to a first slot end. A length from the first slot end to the first end of the fluid ejection die is less than 1.5mm.