QFN Package Singulation via Segmented Cutting and De-flashing
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Solution Overview
Problem
High-speed dicing of QFN packages results in metal burrs, leading to short-circuits and poor planarization, while reducing cutting velocity to prevent burrs decreases singulation throughput.
Innovation Solution
A method involving two cutting steps: initial high-speed cutting of leads and resin, followed by de-flashing using chemical treatment and high-pressure water to remove burrs, allowing for increased cutting speed and throughput.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If high-speed dicing is used to increase singulation throughput, then productivity is improved, but metal burrs are generated on the cutting plane causing short-circuits and poor planarization
Solution Approach 1:
The cutting process is divided into two separate steps: first cutting the leads and then cutting the resin. This segmentation allows each cutting operation to be optimized independently - the lead cutting can be performed at high speed for productivity, while the resin cutting follows to complete the separation, thereby avoiding burr-related short-circuits while maintaining high throughput
Solution Approach 2:
The leads are cut first before the resin is cut. This preliminary action of separating the metal leads from the resin body beforehand prevents the generation of metal burrs on the final cutting plane, as the leads are already separated when the resin cutting occurs at high speed
2Manufacturing precision
If cutting velocity is reduced to prevent metal burr generation, then manufacturing precision is improved, but singulation throughput decreases
Solution Approach 1:
By segmenting the cutting process into lead cutting and resin cutting steps, the velocity constraint is eliminated. The resin can be cut at high velocity since it is softer and does not generate harmful metal burrs, while the lead cutting is performed separately at optimized speed, thus achieving both high precision and high productivity
Solution Approach 2:
The cutting velocity parameter is optimized differently for different materials: lower velocity for lead cutting to prevent burr generation, and higher velocity for resin cutting to maximize throughput. This parameter change based on material type resolves the contradiction between precision and productivity
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 approach effectively removes burrs, enhancing dimensional precision and flatness of QFN packages while maintaining high singulation throughput.
Implementation Method 1
a dicing blade is driven to move along the cutting line, so that at least the leads are fully cut
Implementation Method 2
the cut portion is de-flashed, and then the blade cuts the remaining portion of the resin
Data Source
AI summary
The objective of the invention is to provide a semiconductor device manufacturing method with which the generation of burrs can be suppressed while increasing the singulation speed of the package. In a manufacturing method of a QFN package of the present invention, a molding prepared by sealing a lead frame with plural semiconductor chips carried on it en bloc with a resin; the operation comprises the following processing steps: a first singulation processing step S101 in which the molding is half-cut along the cutting plane; a de-flashing processing step S102 in which the burrs on the cut portion of the half-cut molding are removed; and a second singulation processing step S103 in which the de-flashed molding is completely cut along the cutting plane.