High Aspect Ratio Power Bond Pads for Fluidic Die
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Solution Overview
Problem
Fluidic dies in printing and additive manufacturing face challenges with non-uniform power delivery to fluid actuators due to parasitic resistances, leading to variations in drop characteristics and decreased print quality, and the complexity of bond pad connections results in failed wire bonds and potential scrapping of the die.
Innovation Solution
The implementation of high aspect ratio power bond pads with multiple bonding sites on fluidic dies to enhance power uniformity, reduce substrate space usage, and allow for re-work of failed wire bonds, ensuring continued operation even if some bonds fail.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If traditional bond pad connections are used, then the die can be manufactured with standard processes, but parasitic resistances cause non-uniform power delivery and variations in drop characteristics
Solution Approach 1:
Multiple bonding sites are merged into a single bond pad structure, allowing multiple wire bonds to connect to one integrated pad rather than requiring separate pads for each connection. This merging reduces the overall complexity of bond pad connections while improving power delivery uniformity through distributed bonding across the pad surface.
Solution Approach 2:
The bond pad design transitions from a two-dimensional planar connection to a three-dimensional structure with multiple bonding sites distributed across the pad surface. This dimensional approach allows power delivery to be uniform across different spatial locations, compensating for parasitic resistances by providing multiple parallel current paths.
2Manufacturing precision
If multiple bond pads are used to reduce parasitic resistance, then power uniformity improves, but substrate space is consumed and device complexity increases
Solution Approach 1:
Multiple bonding sites are consolidated into a single bond pad structure, eliminating the need for multiple separate bond pads. This merging achieves power uniformity through distributed bonding while conserving substrate space that would otherwise be occupied by multiple discrete pad structures and their associated spacing.
3Ease of manufacture
If standard bond pads are used, then manufacturing is simpler, but wire bond failures result in scrapped dies with no re-work capability
Solution Approach 1:
The bond pad is designed with multiple bonding sites as a preventive measure against wire bond failures. If one bond fails, the additional sites provide redundant connection paths, cushioning against complete failure and allowing re-work without scrapping the die. This beforehand cushioning maintains manufacturing simplicity while significantly improving reliability.
4Productivity
If bond pad area is minimized to increase fluid actuator density, then device integration improves, but power delivery uniformity deteriorates due to increased parasitic resistance
Solution Approach 1:
The bond pad utilizes a high aspect ratio geometry with multiple bonding sites distributed across its surface, transitioning from a simple planar connection to a multi-dimensional bonding structure. This allows the pad to maintain a compact footprint that accommodates high fluid actuator density while achieving power delivery uniformity through the distributed multi-site bonding approach.
Data Source
AI summary
In one example in accordance with the present disclosure, a fluidic die is described. The fluidic die includes a substrate and fluid actuators, the fluid actuators being disposed on the substrate. The fluidic die also includes a bond pad region defined on the substrate. The bond pad region includes a high aspect ratio power delivery bond pad with multiple bonding sites and a high aspect ratio power return bond pad with multiple bonding sites.