Copper Alloy Sheet for QFN Lead Frame Dicing
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Solution Overview
Problem
Conventional lead frames for QFN packages suffer from significant lead burrs and rapid dicing blade abrasion during the dicing process, leading to reduced productivity and package reliability due to inadequate dicing workability.
Innovation Solution
A copper alloy sheet with specific compositions and processing methods, including 0.01-0.50% Fe, 0.01-0.20% P, and controlled micro Vickers hardness and elongation, is developed to minimize lead burrs and reduce dicing blade abrasion, enhancing dicing workability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If conventional copper alloys (e.g., CDA194) are used for lead frames, then the lead frame can be manufactured with standard materials, but significant lead burrs form and dicing blade abrasion occurs rapidly during the dicing process
Solution Approach 1:
The patent applies parameter changes by precisely controlling the chemical composition parameters of the copper alloy (Fe: 0.01-0.50%, P: 0.01-0.20%, and other elements within specified ranges) and physical parameters (micro Vickers hardness: 150 or above, uniform elongation: 5% or below, local elongation: 10% or below). These parameter optimizations resolve the contradiction by enabling standard manufacturability while minimizing lead burrs and blade abrasion through the specific alloy composition and mechanical properties
Solution Approach 2:
The patent uses composite materials by creating a multi-element copper alloy system that combines Cu with Fe, P, and other elements in specific proportions. This composite alloy structure provides both the manufacturability of conventional copper alloys and improved dicing workability by reducing burr formation and blade wear through the synergistic effects of the alloying elements
2Productivity
If the dicing process is used to cut QFN packages from the lead frame, then productivity is improved through simultaneous molding of multiple packages, but the rapid abrasion of the dicing blade increases dressing frequency and reduces yield
Solution Approach 1:
The patent resolves this contradiction by changing the physical parameters of the lead frame material, specifically optimizing the micro Vickers hardness to 150 or above and controlling the elongation properties. These parameter changes reduce the abrasion of the dicing blade during the high-productivity simultaneous molding and dicing process, thereby reducing dressing frequency and maintaining high yield without sacrificing throughput
3Object-generated harmful factors
If the lead frame material has high strength to reduce burrs, then dicing workability improves, but the material becomes more difficult to process and manufacture
Solution Approach 1:
The patent resolves this contradiction by precisely controlling multiple parameters simultaneously: chemical composition (Fe: 0.01-0.50%, P: 0.01-0.20%, and other elements) and mechanical properties (micro Vickers hardness: 150 or above, uniform elongation: 5% or below, local elongation: 10% or below). This balanced parameter optimization achieves high strength to reduce burrs while maintaining ease of manufacture through the specific alloy composition that facilitates processing
Data Source
AI summary
A QFN package is provided with a lead frame formed by processing a copper alloy sheet containing 0.01 to 0.50% by mass Fe, 0.01 to 0.20% by mass P, and Cu and inevitable impurities as other components, having a micro Vickers hardness of 150 or above, a uniform elongation of 5% or below and a local elongation of 10% or below, or a copper alloy sheet containing 0.05 to 2% by mass Ni, 0.001 to 0.3% by mass P, 0.005 to 5% by mass Zn, and Cu and inevitable impurities as other components, having a micro Vickers hardness of 150 or above, a uniform elongation of 5% or below and a local elongation of 10% or below. Lead burrs formed during the dicing of the QFN package are short, and a dicing blade used for dicing the QFN package is abraded at a low wear-out rate.