Package Wafer Laser Processing Using Exposed Key Patterns
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Solution Overview
Problem
Existing methods for aligning and processing package wafers with a resin-sealed front surface suffer from low accuracy and long processing times due to individual differences in solder ball shape and size, and unclear intersection lines, making precise alignment challenging.
Innovation Solution
A package wafer processing method using a rotatable holding table, pulse laser irradiation, and imaging to detect and correct key pattern positions, allowing for high-accuracy alignment and processing along planned dividing lines, with a control unit managing the processing steps and feed mechanisms to maintain precision.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If solder balls or intersection points are used as alignment targets, then alignment time is reduced, but alignment accuracy deteriorates due to individual differences in shape and size
Solution Approach 1:
The patent uses key patterns that are precisely copied from the original device design and remain visible after resin sealing. These key patterns serve as accurate alignment targets by reproducing the original alignment references, eliminating the need to use imprecise features like solder balls while maintaining alignment accuracy throughout the manufacturing process
Solution Approach 2:
The key patterns are pre-established in the device design before resin sealing, and their positions are pre-calculated and stored in the control unit. This preliminary preparation allows the system to directly use these pre-positioned patterns for alignment without needing to search or select targets during processing, thereby reducing alignment time while maintaining high accuracy
2Measurement precision
If multiple key patterns are searched and selected by operator, then alignment accuracy can be maintained, but processing time increases
Solution Approach 1:
The system performs automatic alignment using the imaging unit to detect key patterns and the control unit to calculate positions based on pre-stored information. This self-service automation eliminates the need for operator intervention in pattern selection, maintaining alignment accuracy through systematic detection and calculation while significantly improving processing speed
Solution Approach 2:
The control unit pre-stores the positions of all key patterns and their relationships to dividing lines before processing begins. This preliminary preparation enables the system to quickly locate and use the appropriate key patterns during alignment without requiring operators to search or select them manually, thereby maintaining accuracy while enhancing productivity
3Manufacturing precision
If alignment is performed using exposed key patterns, then processing accuracy is maintained, but the method requires figuring out positions from multiple data types
Solution Approach 1:
The control unit merges multiple data sources (key pattern positions, distances to dividing lines, interval information, and resin-sealed region positions) into a unified coordinate system. This integration allows the system to automatically calculate and identify the appropriate exposed key patterns for alignment, maintaining processing accuracy while managing data complexity through systematic combination of information
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 method enables high-accuracy alignment and processing of package wafers in a shorter time by utilizing exposed key patterns outside the resin-sealed region, ensuring precise formation of processing grooves and maintaining processing accuracy without operator intervention.
Implementation Method 1
a laser beam irradiation unit that carries out irradiation with a pulse laser beam having such a wavelength as to be absorbed by the package wafer held by the holding table
Data Source
AI summary
A package wafer processing method includes a processing step of processing a package wafer along planned dividing lines by a laser beam irradiation unit and forming processing grooves in the package wafer. The processing step includes detecting a processing groove and an exposed key pattern closest to the planned dividing line corresponding to the processing groove at a predetermined timing and measuring, as a deviation amount, the difference between the distance from the processing groove to the exposed key pattern and the distance that is registered in a registration step and is from the planned dividing line corresponding to the processing groove to the closest key pattern. An indexing feed mechanism is corrected according to the deviation amount.