Wire Bonding Rotary Stage Reducing Motor Load
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Solution Overview
Problem
Current wire bonders face issues with high force and power requirements due to increased speed, leading to motor reliability and accuracy problems, as well as vibrations affecting bond placement, and existing solutions like air bearings are costly and inefficient.
Innovation Solution
A wire bonding apparatus with a bondhead that uses a compact vertical axis rotary stage driven by a theta motor, reducing the load on the X-stage and allowing high acceleration over small distances, and employing flexure-pivots instead of air bearings for reduced complexity and cost.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the wire bonder speed is increased to improve productivity, then productivity increases, but the force and power requirements from direct drive motors increase, leading to motor reliability reduction and heat generation
Solution Approach 1:
The patent replaces the conventional direct drive motor system with a cam mechanism that converts rotary motion into the required linear and rotational motion of the bonding tool. The cam profile is specifically designed to provide the necessary motion characteristics (vertical Z-axis movement and horizontal X-axis movement) while reducing the force and power requirements on the driving motor, thereby improving motor reliability during high-speed operations
Solution Approach 2:
Instead of using a motor to directly drive the bonding tool along linear paths, the patent inverts the approach by using a cam that rotates to generate the linear motion. The motor only needs to rotate the cam, which then mechanically generates the complex motion paths required for wire bonding, significantly reducing the force requirements on the motor
2Productivity
If the wire bonder speed is increased to improve productivity, then productivity increases, but vibrations are generated that affect bond placement accuracy
Solution Approach 1:
The cam mechanism provides smooth, predetermined motion paths that reduce vibrations compared to direct motor-driven linear stages. The cam profile can be precisely engineered to minimize acceleration and deceleration shocks, thereby maintaining bond placement accuracy even at higher speeds
Solution Approach 2:
The cam profile is designed with smooth transitions and predetermined acceleration/deceleration characteristics that cushion the motion changes, preventing sudden vibrations that would compromise bond placement accuracy during high-speed operations
3Productivity
If the X-stage is designed to move the largest mass at high accelerations to improve productivity, then productivity increases, but the X-motor becomes the bulkiest component and generates large amounts of heat
Solution Approach 1:
The cam mechanism replaces the bulky X-motor that would be required to move the largest mass at high accelerations. The cam converts rotary motion into linear motion with mechanical advantage, allowing a smaller motor to drive the cam rotation while the cam itself generates the force needed to move the bonding tool assembly
Solution Approach 2:
The cam mechanism uses periodic rotary motion to generate the required linear and rotational movements of the bonding tool. This periodic action allows the use of a smaller motor that only needs to provide rotational torque, while the cam's geometry provides the force multiplication needed to move the large mass
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 achieves efficient high-speed wire bonding with reduced heat generation and vibrations, enabling more accurate and reliable bonding while maintaining compactness and lowering operational costs.
Implementation Method 1
The bondhead body 10 and ultrasonic transducer 12 are drivable to rotate about the X-axis by a direct drive actuator such as a voice coil motor 18
Implementation Method 2
The X and Y stages of the XY table are separately driven by direct drive motors called linear motors
Implementation Method 3
a bonding tool such as an ultrasonic transducer 12 is mounted for generating ultrasonic bonding energy
Data Source
AI summary
A wire bonding apparatus, comprising a bonding tool mounted on a bondhead body which is in turn mounted on a positioning table, is provided for bonding electronic devices. The positioning table has first and second motors coupled to it that are operative to drive the bondhead body to positions along respective first and second orthogonal axes. The bondhead body is connected to the positioning table through a pivot such that the bondhead body is rotatable relative to the positioning table about a third axis which is substantially orthogonal to the first and second axes. Further, a third motor drives the bondhead body to rotate about the third axis.