Fixed Abrasive 3D Lapping Plate for Advanced Material Finishing
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Solution Overview
Problem
Existing lapping and polishing methods for advanced materials like AlTiC, SiC, and GaN suffer from high surface roughness and inefficient material removal rates due to the limitations of free and fixed abrasive combinations, which result in suboptimal surface finish and frequent diamond slurry recharging, and abrasive pads that lose flatness over time.
Innovation Solution
A fixed abrasive three-dimensional plate incorporating micron-sized diamond spheres or a mixture of abrasive particles and metal oxide beads, bonded with polymeric binders and fillers, is developed. This plate is mounted on a steel or aluminum substrate, featuring controlled porosity to enhance lapping and polishing efficiency, with the binder matrix wearing faster than the diamond particles, ensuring continuous exposure and reducing scratching.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If free and fixed abrasive diamond lapping method is used, then material removal rate is improved, but surface roughness increases
Solution Approach 1:
The lapping process is segmented into two distinct stages: rough lapping using free/fixed abrasive method for high material removal rate, and fine lapping using fixed abrasive method with lubricant vehicle for improved surface finish. This segmentation allows each stage to optimize for its specific function without compromising the other.
Solution Approach 2:
The invention changes the parameters of the lapping system by introducing a lubricant vehicle without aggressive abrasives in the fine lapping stage, and by controlling the embedding depth and distribution of diamond particles in the fixed abrasive plate. This parameter control enables reduced surface roughness while maintaining adequate material removal rate.
2Productivity
If diamond slurry is dripped continuously to maintain abrasive coverage, then material removal rate is maintained, but diamond charging efficiency decreases and waste increases
Solution Approach 1:
Diamond particles are pre-embedded into the metal turning plate before the lapping process begins. This preliminary action ensures that abrasive particles are already in position and do not require continuous replenishment during operation, thereby eliminating diamond waste from continuous slurry dripping while maintaining material removal rate.
Solution Approach 2:
The fixed abrasive plate serves itself by having diamond particles permanently embedded in the metal matrix. The plate automatically maintains its abrasive coverage throughout the lapping process without requiring external intervention for slurry replenishment, thus eliminating diamond waste while sustaining productivity.
3Duration of action of stationary object
If diamond particles are embedded deeply into the plate for fixed abrasive lapping, then abrasive life is extended, but diamond particles may dislodge and scratch the workpiece
Solution Approach 1:
The invention creates local quality variation in the metal matrix by controlling the embedding depth and distribution of diamond particles. Different regions of the plate have optimized particle depths suitable for their specific function, ensuring particles are embedded sufficiently to remain secure but not so deeply that they become unstable and cause scratching.
Solution Approach 2:
The invention uses a composite material system consisting of diamond particles embedded in a metal matrix (such as zinc, tin, or tin-alloy). This composite structure provides both the hardness of diamond for effective lapping and the ductility of metal for secure particle retention, preventing particle dislodge ment and workpiece scratching while extending plate life.
4Ease of operation
If abrasive pads are used for lapping, then portability and ease of operation are improved, but flatness is lost over time causing edge rounding
Solution Approach 1:
The invention uses a rigid plate with a spherical or curved surface geometry that maintains its shape stability during lapping operations. The spherical configuration distributes contact pressure evenly across the workpiece, preventing edge rounding and maintaining flatness over extended use, while the rigid construction ensures long-term dimensional stability.
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
The solution achieves significant material removal rates and improved surface roughness, reducing the AlTiC surface roughness from 30 nm to 3 nm in less than 15 minutes and SiC surface roughness to 0.4 nm or less in 60 minutes, while maintaining the integrity of the workpiece and extending the life of the lapping plate.
Implementation Method 1
the binder matrix wearing faster than the diamond particles, ensuring continuous exposure and reducing scratching
Implementation Method 2
The fixed abrasive three-dimensional plate, which incorporates diamond beads or a mixture of abrasive particles and metal oxide beads, and fillers, bonded together with the aid of one or more binders and additives
Data Source
AI summary
A fixed abrasive three-dimensional plate includes micron size diamond beads or a mixture of abrasive particles and metal oxide beads, ranging in size from a few microns to a few tens of microns, incorporated into a matrix of one or more inorganic binders and fillers. The composition is formed into a rigid plate blank, and the abrasive plate is mounted on a substrate forming a lapping/polishing plate. The abrasive plate is capable of delivering high material removal rates coupled with reduced surface roughness when lapping/polishing advanced materials, including sapphire, titanium carbide reinforced alumina, silicon carbide, gallium nitride, aluminum nitride, zinc selenide, and other compound semiconductor materials, as well as, glass, ceramic, metallic, and composite workpieces. The diamond beads incorporated in the fixed abrasive three-dimensional plate include diamond particles ranging in size from a few nanometers to a few tens of microns, bonded with one or more inorganic binders and additives.