Papers by Author: Yue Xian Song

Abstract: Due to the weak rigidity of micro-drills and impulse effects, the micro-drill breakage is a common problem in printed circuit board micro-drilling. Traditional micro-drill breakage detection methods and principles, including vacuum-type, laser-type, and contact-type detection, were reviewed in this paper. The comparison of three detection methods showed that the contact-type detection can more satisfy the performance of CNC drilling machine. Three effective contact-detection circuits, including no transformer and rectifier circuit pulse-type, active-type, and trigger-type detection circuit, were introduced. And as a conclusion, differences of these detection methods were compared. Based on the characteristic of three effective micro-drill breakage contact detection circuits, the development trends and designs of innovative detection circuit were proposed to meet the challenges in micro-drill breakage measurement during PCB drilling.

Abstract: There are four kinds of ultra-precision lapping machine bed were developed: with/without reinforcing rib, with/without a pair of closed sides. The finite element analysis was used to find the optimal design of the machine bed. The 3D model of the ultra-precision lapping machine bed was built by SolidWorks, and ANSYS software was used for static analysis and modal analysis. The results suggest that when reinforcing rib and a pair of closed sides were owned, the machine bed had some better static and dynamic characteristics. The mix-deformation of this machine bed was 1.911μm, and the first-order inherent frequency was 101.74Hz.

Abstract: Micro-abrasive water jet technology for deburring is a new type of removing burrs technics with advantages of high productivity, high flexibility, no cutter damage and less residual damage etc, which is applied more and more extensively. This paper introduces the difference of premixed micro-abrasive water jet and post-mixed micro-abrasive water jet on jet formation, the difference of system principles and applications. This paper also provides the formula that how to quantitatively calculate the impact force of water jet. The principles and factors which influence on deburring and some application examples are also described in this paper.

Abstract: An ultra-precision lapping machine is developed, with precision turning technology to condition lapping plate in situ, pressurizating by cylinder pressure, and cooling frictional heat with inner cooling system, the lapping machine is used for ultra-precision lapping of brittle materials. The design concept and the structure of the key components of the utra-precision sngle-plane lpping mchine are discussed. After precision turning, the flatness of lapping plate is down to 0.002 mm/400 mm, and experimental results show that the flatness of circular grating glass has been greatly improved after ultra-precison lapping.

Abstract: Abrasive jet technology is widely used with the advantages of environmental protection, with better energy concentration and processing quality, free from any tool passivation, heat affected zone, spark, or any changing in physical or chemical properties of workpiece. Due to the fact that jet characteristics are the main reasons which influence processing quality, numerical analysis is used as the major method of researching currently. The existing research of jet characteristics of abrasive jet by numerical simulation methods is discussed in the paper, including jet fluidizing and mixing process simulation, jet formation process simulation and jet erosion workpiece simulation. Finally the key problems of the simulation on the jet characteristic are given.

Abstract: Some technologies of ultra-precision single-plane polishing and lapping devices, including spindle section, polishing pad, cooling system, dressing system and pressurization system are discussed. The development trends of ultra-precision single-plane polishing and lapping devices are also analyszed as more controllable, integrated and high-precision in the future.

Abstract: Cutting force is one of the most important parameters in the drilling process of FPC (Flexible printed circuit board). It has a directly affect on the micro-drills’ life and the micro-holes quality. It causes the FPC delamination, pulling of the plastic, the burr of exit hole and other processing defects. In this paper, some experimental investigations of cutting force of high speed micro-drilling are carried out to improve the drilling quality of FPC. The results indicate that the drilling parameters(spindle speed, feed speed and drill-bit diameter) have significant influence on micro-drilling thrust force. The thrust force of drill copper foil is larger than the thrust force of drill adhesiver layer and the thrust force of drill PI layer is the smallest. The larger the thrust force is, the bigger the exit burr is.

Abstract: 7CrSiMnMoV (HRC65) hardened steel mold was cutted to investigate the effects of cutting parameters (cutting speed, feed speed, radial cutting depth, axial cutting depth) on cutting force and cutting temperature. Cutting was done with the ball-mill tool coating with TiAlN and without coolant with a high-speed. The aim of this study is putting forward the principle of reasonable choice of cutting parameters and optimizing cutting parameters.

Abstract: In the PCB micro drilling, because the force signal is tiny, and when the micro-drill drill to a certain degree of multilayer PCB, alternate force signals will not appear obvious, through to the drilling force signal analysis, we can know the drill bit position and the materials to the influence of the drill failure, so the drilling force signals denoise seems extremely important. In the processing of the non-stationary signal, traditional signal processing method has a certain extent of insufficient, using the wavelet packet decomposition signal, the white noise variance and amplitude decrease with the increase of wavelet scales, but the signal variance and amplitude has nothing to do with the wavelet transform. According to the view of the signal energy, first of all, we make the multiscale decomposition of the signal, then, by using some of the wavelet packet that has efficient energy to reconstruct the original signal. Comparing with the traditional threshold denoising ,using this method in the test signal to deal with the noise can effectively eliminate the white noise interference, and has good denoising effects besides the simple calculation.

Abstract: This work is focused on the investigation of the influence of the materials of PCB, feed rate, spindle speed and tool wear on thrust force when drilling PCB using 0.3 mm diameter cemented tungsten carbide drills. The results indicate that thrust force increases with feed rate and drill wear, but decreases with spindle speed firstly and then increases with it within the cutting range tested. Thrust force caused by the copper foil is much larger than that caused by the epoxy glass fiber cloth when feed rate is low. However, the difference between them decreases as feed rate increases. The thickness of nail head increases with thrust force. The accuracy of hole location increases with thrust force firstly but decreases afterward. The influence of thrust force on hole wall roughness is not obvious.