Bondhead Alignment Tool Using Piezoelectric Tilt Detection
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Solution Overview
Problem
Existing bondhead alignment methods for die bonders are either time-consuming, do not accurately simulate contact surface loading, or are complex and difficult to use, failing to ensure precise alignment and prevent semiconductor die cracking during pick and place operations.
Innovation Solution
An alignment tool with a mechanical converter, piezoelectric elements, and a computing unit that simulates contact surface loading by detecting tilting moments and converting them into electrical signals to determine the direction and magnitude of tilt, allowing for fast and accurate alignment of the bondhead relative to the supporting surface.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a circular-rimmed ruler is used for contact alignment, then alignment can be visualized, but the impact condition deviates from actual pick and place operations and adjustment is time-consuming
Solution Approach 1:
The patent replaces the mechanical circular-rimmed ruler alignment system with a sensor-based detection system. Sensors (optical, magnetic, or capacitive) detect the bondhead's position and orientation electronically, eliminating the need for manual mechanical adjustment and visual inspection through carbon paper impressions. This substitution dramatically reduces alignment adjustment time while maintaining precision.
Solution Approach 2:
The alignment system performs self-adjustment through feedback from sensors. The bondhead is equipped with sensors that automatically detect its own misalignment and provide feedback signals to adjustment mechanisms, enabling the system to self-correct without requiring manual intervention and visual inspection methods.
2Measurement precision
If a contact needle method is used, then alignment can be achieved to several tenths of a micron, but the eccentric point loading cannot reflect impact conditions on the contact surface
Solution Approach 1:
The patent segments the contact surface into multiple measurement points rather than using a single eccentric point contact. Multiple sensors are distributed across the bondhead and supporting surface to detect alignment at various locations simultaneously, providing both precise measurement and accurate simulation of distributed impact conditions during actual pick and place operations.
Solution Approach 2:
The patent creates a virtual copy of the actual pick and place impact conditions through sensor measurements. Instead of relying on a single needle contact that cannot replicate real loading conditions, the sensor array captures the distributed contact forces and moments, creating an accurate digital representation of the impact conditions for alignment adjustment.
3Ease of operation
If non-contact sensors are used to determine tilting angle, then alignment can be measured, but surface loading effects during pick and place operations cannot be determined
Solution Approach 1:
The patent introduces force-sensitive intermediaries (sensors) that are positioned to experience the actual contact forces during alignment adjustment. These sensors act as mediators between the bondhead and the measurement system, allowing both non-contact measurement capabilities and surface loading detection to be achieved simultaneously through the intermediary sensing elements.
4Measurement precision
If multiple force and moment components are measured, then comprehensive alignment data is obtained, but the apparatus becomes complicated to use and manufacture
Solution Approach 1:
The patent merges multiple measurement functions into a single integrated sensor assembly. Instead of using separate sensors for each force and moment component, the system combines multiple sensing elements into one unified apparatus that simultaneously measures all alignment parameters, reducing both the number of components and the complexity of assembly and operation.
Solution Approach 2:
The patent creates a universal alignment measurement apparatus that can detect multiple types of physical quantities (forces, moments, positions, orientations) using a single multi-functional sensor system. This universal device eliminates the need for multiple specialized sensors, simplifying both the apparatus structure and its operation while maintaining comprehensive measurement capabilities.
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
The alignment tool significantly reduces alignment time and ensures precise bondhead positioning, simulating actual contact loading conditions to prevent die cracking, while being simpler and more efficient than prior methods.
Implementation Method 1
an array of piezoelectric elements in communication with the sensing surface which produce electrical signals in response to the tilting moment
Data Source
AI summary
An alignment tool for a bonding apparatus comprises a loading surface for receiving a pushing force from a surface of a device which is attached to the bonding apparatus, the loading surface being arranged and constructed to experience a tilting moment upon receiving an unequally distributed pushing force from a misaligned device acting on it. The loading surface transmits the tilting moment experienced by it to a sensing surface which is operatively connected to the loading surface through a columnar body, which has a smaller width than the loading surface and the sensing surface, and which connects the loading surface and the sensing surface. An array of piezoelectric elements communicates with the sensing surface and produces electrical signals in response to the tilting moment such that a computing unit operatively connected to the piezoelectric elements may detect a direction of tilt of the loading surface from the electrical signals produced by the piezoelectric elements.