Dual-Encoder Die Positioning for Thermal-Stable Bonding Accuracy
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional die bonding systems suffer from placement accuracy issues due to thermal expansion of encoder scales and carriages, as well as scale engraving defects, which are critical for hybrid bonding applications requiring ±50nm precision.
Innovation Solution
A die bonding apparatus and method utilizing a linear motor-driven carriage with dual encoder heads and a controller to align the bond-head with a target location, compensating for thermal expansion and scale defects by measuring and correcting alignment errors using multiple encoder heads and cameras.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a single encoder head is used to measure carriage position, then the device complexity is low, but the placement accuracy deteriorates due to thermal expansion and scale defects
Solution Approach 1:
The single encoder head is segmented into two separate encoder heads (first and second encoder heads) positioned at different locations on the carriage. Each encoder head independently measures the position of the carriage relative to the encoder scale, allowing for differential measurement that compensates for thermal expansion and scale defects, thereby improving die placement accuracy to ±50nm
Solution Approach 2:
The controller acts as an intermediary that receives position measurements from both encoder heads, calculates the differential position, and determines the corrected carriage position. This intermediary processing enables compensation for thermal expansion and scale defects without requiring physical modification of the encoder scale itself
2Ease of operation
If the carriage moves over long distances to accommodate camera and bond-head separation, then the operational flexibility is improved, but thermal expansion effects increase causing measurement errors
Solution Approach 1:
The system implements feedback by continuously monitoring the relative positions of the first and second encoder heads on the moving carriage. The controller uses this feedback to calculate thermal expansion effects in real-time and compensates for them, maintaining placement accuracy regardless of the carriage movement distance or camera-bond-head separation
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
Achieves highly accurate die placement with ±50nm precision, insensitivity to thermal expansion and scale defects, ensuring reliable electrical connections in semiconductor devices.
Implementation Method 1
a linear encoder comprising an encoder scale extending along the travel direction of the carriage, at least a first and a second encoder heads mounted on the carriage
Implementation Method 2
a camera configured to detect the target location for positioning the die and for measuring an alignment error between the optical axis of the camera and said target location
Implementation Method 3
A die bonding apparatus and method utilizing a linear motor-driven carriage
Data Source
Figure 1~1b
Figure 1c~2a
Figure 2b~2c
AI summary
The invention relates to a die positioning method using die bonding apparatus (10) comprising a carriage (12), a linear encoder comprising an encoder scale (20) and a first and a second encoder heads (22a, 22b) mounted on the carriage. The carriage comprises a bond-head (14) and a camera (16). The central axis of the bond-head (14) and the optical axis of the camera (16) are distant from each other along the traveling direction by a first distance (D1). The first and second encoder heads (22a, 22b) are distant from each other along said traveling direction by a second distance corresponding to said first distance and an offset corresponding to an alignment error between said first and second encoder heads and the central axis of the bond-head and the optical axis of the camera respectively. The method comprises the steps of: a) finding with the camera (16) of the carriage (12) a target location (30) for positioning a die (50), b) measuring or recording an alignment error (ΔX) between the camera optical axis and said target location (30), c) recording a difference (δ) between said first distance (D1) and said second distances (D2), d) recording a position (P1) of the carriage (12) with the first encoder head (22a; 122a), e) aligning the bond-head (14) with said target location (30) by moving the carriage (12) as a function of: i) the outputs of the first and second encoder heads (22a, 22b; 122a, 124a), ii) said recorded difference (δ), and iii) optionally said alignment error (ΔX), and f) actuating the bond-head (14) in the Z-direction to place the die at said target location (30).