Abstract
Sapphire lapping is of key importance for the successful planarization of wafers that are widely present in electronic devices. However, the high hardness of sapphire makes it extremely challenging to improve its material removal rate during the lapping process without compromising surface quality and dimensional accuracy. In this work, a novel composite lapping plate consisting of a rigid resin frame and flexible sol–gel balls was fabricated with consciously designed patterns. Through lapping experiment, it was revealed that the diamond grits imbedded in the sol–gel balls can effectively lap the sapphire at a promising material removal rate (MRR), without the formation of undesirable scratches and loss of surface integrity. Moreover, by designing the arrangement patterns of sol–gel balls, the total thickness variation (TTV) can also be ensured for lapped sapphire substrates. The implications of experimental results were also discussed based on the trajectory analysis and contact mechanics of lapping grits in order to demonstrate the potential of the newly developed composite abrasive tools for sapphire-lapping applications.
Highlights
Monocrystalline α-alumina, known as sapphire, is one of the most important engineering ceramics
Considerable research effort has been dedicated to improving the material removal rate (MRR) during sapphire lapping, little progress has been achieved as the improvement of MRR is often linked with a loss of surface/subsurface integrity and dimensional accuracy
Crystals 2020, 10, 293 with an uncontrollable trajectory of free diamond abrasives, which reduces the MRR and makes it difficult to guarantee the dimensional accuracy of the lapped sapphire substrate; the latter often suffer from the formation of surface scratching or subsurface damage due to the nonuniform height of fixed diamond abrasives
Summary
Monocrystalline α-alumina, known as sapphire, is one of the most important engineering ceramics. Considerable research effort has been dedicated to improving the material removal rate (MRR) during sapphire lapping, little progress has been achieved as the improvement of MRR is often linked with a loss of surface/subsurface integrity and dimensional accuracy This dilemma may be attributed to the fact that sapphire lapping is carried out using plates with either free or fixed diamond abrasives. Crystals 2020, 10, 293 with an uncontrollable trajectory of free diamond abrasives, which reduces the MRR and makes it difficult to guarantee the dimensional accuracy of the lapped sapphire substrate; the latter often suffer from the formation of surface scratching or subsurface damage due to the nonuniform height of fixed diamond abrasives. Novel composite lapping plates that consist of a rigid resin frame and flexible sol–gel balls were fabricated based on the trajectory analysis of variable patterns of diamond abrasive blocks. Our experimental results demonstrated the feasibility for improving the lapping efficiency and quality by consciously designing the pattern of abrasive blocks on the composite lapping plates
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