Oval Cam Latch for Wafer Container Friction Reduction
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Solution Overview
Problem
Conventional front opening unified pods (FOUPs) for semiconductor wafers suffer from high failure rates and excessive mechanical friction during operation, leading to wafer pollution and inadequate air tightness, due to complex mechanical latch components and inefficient wafer restraint mechanisms.
Innovation Solution
The design incorporates an oval cam and moving bars with rollers and a locating spring, allowing the latch component to move in a single plane, reducing friction and pollution, and features a recess for full wafer engagement, enhancing stability and air tightness by using an externally wide and internally narrow groove structure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional complex mechanical latch components are used, then the door can be securely fastened, but the failure rate increases and mechanical friction becomes excessive
Solution Approach 1:
The latch component is divided into functionally independent elements: the oval cam structure for driving motion, the moving bar for linear displacement, and the roller for friction reduction. This segmentation allows each element to perform its specific function efficiently, reducing overall system complexity while maintaining reliability.
Solution Approach 2:
The patent replaces complex mechanical latch mechanisms with a simplified oval cam-driven moving bar system. The oval cam geometry inherently provides the necessary motion conversion from rotational to linear, eliminating the need for additional mechanical components and reducing both complexity and failure points.
2Reliability
If conventional latch components with complex mechanical structures are used, then the door can be secured, but excessive mechanical friction occurs leading to wafer pollution
Solution Approach 1:
A roller is introduced as an intermediary element between the moving bar and the door surface. This roller mediates the contact interaction, converting sliding friction into rolling friction, which significantly reduces mechanical friction and prevents wafer pollution while maintaining effective door securing.
Solution Approach 2:
The oval cam structure utilizes curved geometry to convert rotational motion into linear motion of the moving bar. The curved surface of the oval cam reduces contact friction compared to flat mechanical interfaces, and the inherent geometry provides smooth motion transfer without excessive mechanical friction.
3Reliability
If wafer restraint module is disposed in recess of door inner surface, then wafer displacement can be prevented, but the length between front and back side of FOUP is not effectively shortened
Solution Approach 1:
The wafer restraint function is achieved by utilizing the door inner surface area in a different spatial arrangement. The recess is positioned to optimize wafer contact while minimizing the projection depth, effectively using surface area rather than volume to achieve restraint, thereby reducing the overall FOUP length.
4Object-affected harmful factors
If wafer restraint module is frequently separated and assembled for cleaning, then accumulated dust particles can be removed, but the wafer restraint module becomes easily slackened
Solution Approach 1:
The wafer restraint function is integrated into the door structure itself through the recess, rather than being a separate removable module. This extraction of the restraint function from a detachable module and its integration into the permanent door structure eliminates the need for frequent assembly and disassembly, preventing slackening while still allowing dust removal through accessible cleaning methods.
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 design simplifies the latch mechanism, reduces mechanical friction, improves wafer containment, and maintains air tightness, resulting in a more stable and reliable wafer container with reduced production costs and pollution risks.
Implementation Method 1
each latch component includes an oval cam and a pair of moving bars, a first end of each moving bar connecting to one of the two opposite sides of the oval cam
Implementation Method 2
a locating spring being formed as an integral part of the moving bars for controlling the turning of oval cam to drive each moving bar to move to and fro
Implementation Method 3
at least a pair of rollers being disposed in the platform and each roller being embedded in each moving groove of moving bar
Data Source
AI summary
A wafer container includes a container body and a door joined with opening of the container body for protecting wafers therein. At least one latch component is disposed in the door, and each latch component includes an oval cam and a pair of moving bars, a first end of each moving bar connecting to one of the two opposite sides of the oval cam and a second end of each moving bar having a guiding structure, a pair of moving grooves being disposed between the first end and the second end of each moving bar, at least a pair of rollers being disposed on the door and each roller being embedded in each moving groove of moving bar, and a locating spring being formed as an integral part of the moving bars.