Flexural Pick Arm for High-Speed Electronic Device Bonding
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Solution Overview
Problem
Conventional pick arms for electronic device bonding systems, which rely on bearing devices for vertical motion, suffer from increased load, moment of inertia, axial clearance-induced side play, end-point vibration, and maintenance requirements, leading to reduced positional accuracy and increased operational costs.
Innovation Solution
The use of flexures instead of conventional bearing devices in the pick arm design, with a compliant four-bar mechanism comprising a pair of resilient support members, such as leaf springs, to enable vertical motion and reduce the need for complex bearing systems.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If bearing devices are used for vertical motion guidance in pick arm, then motion guidance is provided, but load and moment of inertia increase
Solution Approach 1:
The patent replaces conventional bearing devices with a flexure-based compliant mechanism. The flexures provide vertical motion guidance through elastic deformation rather than mechanical contact, eliminating the need for traditional bearings while reducing load and moment of inertia. This substitution of mechanical contact-based guidance with flexibility-based guidance resolves the contradiction between reliable motion guidance and reduced weight.
2Reliability
If bearing devices are used for vertical motion guidance in pick arm, then motion guidance is provided, but moment of inertia increases
Solution Approach 1:
The flexure-based compliant mechanism replaces heavy bearing devices, significantly reducing the moment of inertia of the pick arm assembly. The flexures provide necessary motion constraints through their geometric design and material properties rather than through heavy mechanical components, thus resolving the contradiction between reliable motion guidance and reduced moment of inertia for high-speed operation.
3Reliability
If bearing devices are used in pick arm, then vertical motion is supported, but axial clearance causes side play and end-point vibration
Solution Approach 1:
The compliant mechanism eliminates axial clearance by using continuous flexural deformation instead of discrete mechanical contact elements. The flexures maintain constant contact through their elastic nature, preventing side play and end-point vibration that plague bearing-based systems. This substitution resolves the contradiction between vertical motion support and positional accuracy.
4Reliability
If bearing devices are used in pick arm, then vertical motion guidance is provided, but device complexity and part number increase
Solution Approach 1:
The patent merges multiple functions into the flexure components: motion guidance, compliance, and vibration reduction are all achieved through the flexural elements themselves rather than requiring separate bearing devices, compliance mechanisms, and dampers. This consolidation reduces device complexity and part count while maintaining vertical motion guidance functionality.
5Reliability
If bearing devices are used in pick arm, then vertical motion is supported, but maintenance requirements increase
Solution Approach 1:
The flexure-based system replaces bearing devices that require periodic lubrication, adjustment, and replacement. Flexures are inherently maintenance-free as they rely on elastic deformation rather than sliding or rolling contact that generates wear. This substitution resolves the contradiction between vertical motion support and reduced maintenance requirements, extending bond head lifetime.
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 enhances the pick arm's performance by reducing load, moment of inertia, and vibrations, improving positional accuracy, and lowering operational costs through reduced part complexity and maintenance needs, while maintaining high precision and rigidity.
Implementation Method 1
first and second flexures connecting the first rigid body to the second rigid body... an actuator operative to apply a biasing force onto the second rigid body so as to bend the first and second flexures relative to the first rigid body
Data Source
AI summary
A pick arm for a pick and place apparatus for electronic devices has a main body having a proximal end whereat the pick arm is mountable onto a pick arm support, and a distal end at which a collet is mounted for holding an electronic device. A first rigid body is located adjacent to the proximal end of the pick arm and a second rigid body is located adjacent to the distal end of the pick arm. The first and second flexures connect the first rigid body to the second rigid body. Moreover, the first flexure is spaced from the second flexure, and the first and second flexures have opposing faces that are arranged substantially parallel to each other. An actuator is operative to apply a biasing force onto the second rigid body so as to bend the first and second flexures relative to the first rigid body for biasing the collet of the pick arm to move.