Light-emitting diodes (LEDs) are widely used in display and lighting applications due to their low cost, long lifespan, and low power consumption [1], [2]. Among them, Mini/Micro-LED devices have become core components in emerging applications such as 4K/8K ultra-clear displays [3], vehicle displays [4], and wearable displays [5], [6] due to their advantages such as wide color gamut, high brightness, good reliability, miniaturization, and high power efficiency. In the manufacturing process of micro-LED display devices, packaging manufacturing is an important step to isolate the LED chip from the external environment, protect the chip from water, oxygen erosion, and mechanical damage, and improve the stability and lifespan of the LED device [7]. In recent years, improving the light output efficiency and high dynamic display performance of devices by introducing functional structures during the LED packaging manufacturing process has become a research hotspot [8]. However, common LED packaging materials such as silicone resin have the drawbacks of high elasticity, low hardness, and poor workability at room temperature, which are important reasons for the difficulty in manufacturing microstructures on the LED packaging surface [9], [10]. In traditional processing, soft elastic materials have increasingly serious problems, such as low processing accuracy and poor surface processing quality as the processing size decreases, a significant factor hindering the development of micro-LED devices. Using cryogenic-assisted processing methods is expected to solve the problem of insufficient machining accuracy of soft elastic packaging materials, achieving high-precision microstructures in the process of LED packaging preparation [11].
Cryogenic processing technology introduces cryogenic media into material processing [12]. It can effectively reduce the processing temperature, improve the surface quality of the processed material [13], and improve processing defects [14], achieving high-quality processing of difficult-to-machine materials. Cryogenic processing technology was initially applied to the processing of difficult-to-machine metals, and it has gradually been applied to other processing fields [15]. Wu et al. [16] applied cryogenic processing technology to process Ti-based alloy thin-walled parts and conducted comparative experimental analysis on different cutting conditions such as water cooling, micro-lubrication, and cryogenic micro-lubrication. The results showed that compared to water cooling and micro-lubrication, the maximum deformation was reduced by 41.4% and 44.7%, respectively, when the spindle speed was 4500 r/min, and the surface roughness of the workpiece was reduced by 34.5% and 45.8%, respectively. Altas et al. [17] studied the effect of cryogenic tool pre-treatment on the milling performance of NiTi shape memory alloy. They found that cryogenic treatment significantly improved the surface roughness of the processed material, averaging a reduction of about 7%. Jia et al. [18] first proposed the concept of an appropriate processing temperature range for CFRP. The results showed that the hardened matrix could better support the fibers and achieve higher surface quality at lower temperatures. When the cutting area temperature dropped below − 25°C, the surface roughness Ra reached 1.6 \(\mu m\), showing good surface integrity. Friedrich [19] concluded that silicone and acrylic polymers are soft and difficult to process at room temperature. Their softness and adhesive properties are the main constraints for tool processing. Cryogenic processing technology can be applied to polymer processing, freezing the workpiece material and effectively enhancing its workability. This process helps to transform soft and elastic polymers into hard and brittle materials, thus significantly improving their mechanical properties and workability [20]. Song et al. [21] proposed a tool compensation method that considers the low-temperature shrinkage of PDMS to improve the geometric accuracy of processing. They also used the relationship between cutting temperature, other processing parameters, and surface roughness to generate surface microchannels with different roughnesses. Mechanical micro-machining technology has the advantages of geometric solid control and high surface smoothness, providing an effective manufacturing method for micro-machining soft polymer materials [22]. However, in the micro-machining of soft elastic materials, most studies have not discussed the deformation phenomenon during processing.
A significant research challenge involves addressing the low processing accuracy frequently encountered during machining soft elastic materials. This work utilizes a three-dimensional (3D) finite element analysis to investigate the occurrence of deformation overcutting during the dicing process of soft elastic materials at varying temperatures and the influence of spindle speed on the dicing accuracy of these materials. The experimental results show that the tilt and torsion deformation of the workpiece are the reasons for the low machining accuracy in the traditional machining process, and cryogenic dicing significantly improves the machining accuracy of the soft elastic material.