Package Substrate Division via Groove Formation and Burr Removal
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Solution Overview
Problem
Existing methods for dividing package substrates, such as QFN and CSP, often result in burr formation leading to short circuits and defective mounting due to burr drag during full cutting, and difficulties in maintaining precise cutting positions on sealed surfaces, which can cause odd-form chips.
Innovation Solution
A method involving groove formation along division lines on the mount surface, followed by burr removal using high-pressure water, and subsequent grinding of the sealing layer to achieve the finished thickness, ensuring precise cutting and reducing the likelihood of short circuits and odd-form chips.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If full cutting is performed from the front side after half-cutting, then the package substrate can be divided into device packages, but the cutting blade side surface contacts the electrode side surface causing burr drag and additional burr production
Solution Approach 1:
The cutting process is segmented into two independent stages: half-cutting to create grooves with electrode burrs, followed by separate burr removal treatment, and then full cutting. This segmentation prevents the cutting blade from contacting electrode side surfaces, eliminating burr drag while maintaining division efficiency.
Solution Approach 2:
The half-cutting step is performed as a preliminary action before full cutting. This creates grooves and exposes electrode burrs that are then removed in advance, so that when full cutting occurs, no burr drag happens. The preliminary burr removal prepares the workpiece for clean final cutting.
2Object-generated harmful factors
If full cutting is performed from the back side after half-cutting, then cutting can proceed without electrode contact, but position misalignment occurs due to sealed surface lack of patterns, producing odd-form chips
Solution Approach 1:
Instead of cutting from the back side where alignment is difficult, the method inverts the approach by performing half-cutting from the front side where patterns provide precise alignment reference. The grooves created serve as alignment guides for subsequent full cutting operations from the same side.
Solution Approach 2:
The half-cut grooves created in the first step serve as a template or copy guide for the full cutting operation. The groove positions are replicated exactly in the full cutting step, ensuring precise alignment without relying on back side pattern matching.
3Device complexity
If cutting depth is insufficient in half-cutting, then the process can be simpler, but projections remain on chip side surfaces creating odd-form chips
Solution Approach 1:
The half-cutting step performs a preliminary partial cut to a specific depth that exposes electrodes but stops before complete separation. This preliminary action creates grooves that guide subsequent full cutting, ensuring proper depth control and preventing projections while maintaining process structure.
4Productivity
If burrs are not removed after half-cutting, then the process can be shorter, but short circuits and defective mounting occur
Solution Approach 1:
Burr removal is performed as a preliminary action between half-cutting and full cutting. This intermediate step eliminates electrode burrs that would cause short circuits or mounting defects, ensuring reliability before the final cutting operation completes the division.
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 effectively reduces the occurrence of short circuits, defective mounting, and odd-form chips by ensuring accurate cutting and burr removal, maintaining the integrity of the package substrate during division.
Implementation Method 1
spraying high-pressure water to the front side of the package substrate along the half-cut groove, thereby removing the burrs
Implementation Method 2
a grinding step of grinding the sealing layer of the package substrate so that a thickness of the package substrate is reduced to the finished thickness
Data Source
AI summary
A method for dividing a package substrate into a plurality of device packages. The package substrate has a mount surface on the front side where a plurality of division lines are formed and a sealing layer formed on the back side, in which devices are sealed. The method includes a groove forming step of forming a groove along each division line on the mount surface of the package substrate so that the groove has a depth corresponding to a finished thickness of each device package, a burr removing step of removing burrs produced from electrodes in the groove forming step, and a grinding step of grinding the sealing layer of the package substrate so that a thickness of the package substrate is reduced to the finished thickness, after performing the burr removing step, thereby dividing the package substrate into the plural device packages.