Cemented Carbide Composition for PCB Drill Edge Wear Resistance
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Solution Overview
Problem
The increased hardness of printed circuit boards due to improved heat resistance leads to wear of drill cutting edges, resulting in deteriorated precision during hole formation in fine processing.
Innovation Solution
A cemented carbide composition with specific grain size distribution and cobalt content, optimized to maintain cutting tool sharpness and hardness, comprising more than 78 volume % tungsten carbide grains with average diameters between 0.5 μm and 1.2 μm, and up to 22 volume % cobalt, ensuring excellent processing precision and tool life.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If fine-grain cemented carbide with tungsten carbide grains of less than or equal to 1 μm is used, then manufacturing precision for small-diameter holes is improved, but tool life deteriorates due to cutting edge wear
Solution Approach 1:
The patent changes the grain size distribution parameters of tungsten carbide, specifically setting the average grain size to 0.3 μm or more and controlling the proportion of fine grains (≤0.2 μm) to 20% or less, while adjusting cobalt content to 6-12 mass%. These parameter changes optimize the balance between cutting edge sharpness for precision and grain durability for tool life.
Solution Approach 2:
The patent creates a composite microstructure combining tungsten carbide grains of specific size ranges with cobalt binder in controlled proportions. This composite approach, with 78-92 volume% tungsten carbide phase and 8-22 volume% cobalt phase, achieves both precision cutting capability and enhanced wear resistance.
2Strength
If cobalt content is increased to improve toughness and reduce bending, then hardness and wear resistance deteriorate
Solution Approach 1:
The patent optimizes cobalt content within the narrow range of 6-12 mass%, which provides sufficient toughness to prevent bending while maintaining cutting edge hardness. This precise parameter control resolves the contradiction between strength and reliability.
3Manufacturing precision
If tungsten carbide grain size is reduced to improve precision, then cutting edge strength and wear resistance worsen
Solution Approach 1:
The patent sets the average tungsten carbide grain size to 0.3 μm or more, preventing excessive fineness that would compromise strength. This parameter optimization maintains sufficient cutting edge strength while achieving the required precision for small-diameter hole formation.
Solution Approach 2:
The patent creates a composite structure with controlled grain size distribution, where the majority of grains fall in the 0.3-1.0 μm range providing strength, while maintaining overall fine grain characteristics for precision. The cobalt binder phase fills interstices to strengthen the cutting edge.
Data Source
AI summary
A cemented carbide consists of: a first phase consisting of a plurality of tungsten carbide grains; and a second phase including cobalt, an average value of equivalent circle diameters of the tungsten carbide grains is 0.5 μm to 1.2 μm, on number basis, the tungsten carbide grains include less than or equal to 13% of first tungsten carbide grains each having an equivalent circle diameter of less than or equal to 0.3 μm, on number basis, the tungsten carbide grains include less than or equal to 12% of second tungsten carbide grains each having an equivalent circle diameter of more than 1.3 μm, in a histogram indicating a distribution of the equivalent circle diameters of the tungsten carbide grains. Fmax/Fmin is less than or equal to 7.0, Fmax/Fmin being a ratio of a maximum frequency Fmax to a minimum frequency Fmin.