Microfluidics Sensor Package Standoff Pattern for Cavity Gap Control
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Solution Overview
Problem
Microfluidics sensor chips, such as PCR chips, face challenges in precisely controlling fluid flow, which is crucial for accurate laboratory functions like DNA amplification, due to limitations in creating a controlled microfluidics cavity.
Innovation Solution
A microfluidics sensor package is designed with a standoff pattern on the sensor die that precisely spaces a lid above the active surface, creating a microfluidics cavity with a controlled gap height, allowing for precise fluid control through the use of a non-collapsible and inflexible material like copper, and a lid adhesive to secure the lid at a specific height.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a microfluidics cavity is created without precise spacing structure, then the device complexity is reduced, but the manufacturing precision of the cavity gap height deteriorates
Solution Approach 1:
The standoff pattern is formed on the sensor die before the lid is attached, establishing the precise cavity gap height in advance. This preliminary action ensures that when the lid is subsequently attached, the cavity is automatically formed with the correct dimensions without requiring additional precision machining steps.
Solution Approach 2:
The standoff pattern acts as an intermediary element between the sensor die and the lid. It mediates the spacing relationship, providing a mechanical reference that defines the cavity gap height. This intermediary structure transfers the precision requirement from the final assembly to a discrete component that can be manufactured and measured separately.
2Ease of operation
If bond pads and wires are exposed to fluid, then the ease of operation is improved, but the reliability of the sensor package deteriorates
Solution Approach 1:
The sensor die is segmented into distinct functional regions: the active sensing area that interfaces with fluid, and the bond pad area that remains protected. The standoff pattern is positioned to define a cavity over the active area while leaving bond pads outside the fluid exposure zone, creating spatial separation between fluid interaction and electrical connection functions.
Solution Approach 2:
Different regions of the sensor die are assigned different properties: the region under the cavity is designed for fluid interaction, while the region with bond pads is designed for electrical connection and protection. The standoff pattern creates a local fluid containment zone that preserves the protective environment for bond pads while enabling fluid access to the sensing area.
Data Source
AI summary
A microfluidics sensor package includes a microfluidics sensor die having an active surface, bond pads on the active surface, and an active area on the active surface. A standoff pattern is formed on the active surface to extend to a precise height above the active surface. A lid is mounted to the standoff pattern by a lid adhesive. By using the standoff pattern to precisely space the lid above the active surface, a microfluidics cavity between the lid and the active surface is precisely created allowing for precise control of fluid flowing through the microfluidics cavity. By precisely controlling the flow of fluid through the microfluidics cavity, accurate results, e.g., of the laboratory functions performed on the fluid, are provided.