Bondhead Alignment via Non-Contact Capacitive Sensing
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Solution Overview
Problem
Conventional methods for determining the alignment of a bondhead relative to a workchuck in die bonding are inaccurate and require human intervention, especially at high temperatures, leading to potential side forces and placement errors that compromise the quality and reliability of the die bonding process.
Innovation Solution
An apparatus comprising non-contact capacitive sensors and a positioning device that measures distances between multiple locations on the bondhead and workchuck, allowing for precise alignment determination even at high temperatures (200° C. to 400° C.) with minimal human intervention, using a sensor mount made of low thermal expansion materials for stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If carbon paper method is used to determine alignment, then the method is simple to operate, but the measurement precision is poor and requires human intervention
Solution Approach 1:
The patent replaces the mechanical carbon paper contact method with a non-contact optical measurement system. Optical sensors (autocollimators or lasers) are used to measure the alignment between bondhead and workchuck surfaces without physical contact, eliminating the need for carbon paper and manual inspection while providing automated, precise measurement data.
Solution Approach 2:
The patent introduces optical sensors as an intermediary between the bondhead and workchuck for alignment measurement. The sensors act as mediators that capture optical reflections or laser patterns to determine parallelism, replacing the direct mechanical contact method and enabling automated feedback for alignment adjustment.
2Measurement precision
If optical sensors such as autocollimators or lasers are used to determine parallelism, then the measurement precision is improved, but the device cannot operate at high temperatures due to air density disturbance
Solution Approach 1:
The patent introduces a reference plane as an intermediary element that can be positioned between the optical sensor and the hot bonding zone. This reference plane allows optical measurements to be performed from a cooler, stable position while still measuring the alignment of hot components, effectively decoupling the sensor operating temperature from the bonding process temperature.
Solution Approach 2:
The measurement system is segmented into separate functional zones: the optical sensor operates in a cool measurement zone while the bondhead and workchuck are in a hot bonding zone. The reference plane acts as an interface between these zones, allowing the system to maintain precise optical measurements without exposing the sensor to high temperatures that cause air density disturbances.
3Device complexity
If manual determination of tilt angle is performed, then the device complexity is low, but the reliability of alignment is compromised due to human intervention
Solution Approach 1:
The patent implements an automated feedback system where optical sensors continuously measure the alignment between bondhead and workchuck, and the measurement data is automatically processed to determine tilt angles and generate correction signals. This closed-loop feedback eliminates manual intervention, ensuring consistent and reliable alignment adjustments while maintaining relatively simple device architecture.
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 solution provides higher measurement accuracy and ensures the parallelism of the bondhead and workchuck, enhancing the quality and reliability of the die bonding process by automatically adjusting the bondhead position based on precise alignment data.
Implementation Method 1
a sensor configured to measure a distance between the bondhead and the sensor
Data Source
AI summary
Disclosed is an apparatus for determining an alignment of a bondhead of a die bonder relative to a workchuck. Specifically, the apparatus comprises: i) a sensor configured to measure a distance between the bondhead and the sensor; and ii) a positioning device coupled to the sensor, the positioning device being configured to position the sensor relative to a plurality of locations on the bondhead facing the sensor. In particular, the sensor is operative to measure a set of distances between each of the plurality of locations on the bondhead and the sensor, the set of distances being for determining the alignment of the bondhead. A method of determining an alignment of a bondhead of a die bonder relative to a workchuck is also disclosed.