Papers by Keyword: Flexible Printed Circuit Board

Abstract: An optical Transceiver is a device that is used for transmitting and receiving digital data which is modulated into the light source, and also consisted of two main parts as lens (one for transmitter (Tx) and another one for receiver (Rx)) and flexible printed circuit board (FPCB). The surfaces of the FPCB was manually cleaned by Isopropyl alcohol (IPA) using cotton buds, and then were joined to the lens using the glues of the adhesive Urethane Acrylate (UAA) which cured using UV light, and followed by the adhesive Black Epoxy (BEA), respectively. The joined specimen then was cured in a thermal oven. The work-piece, especially the joined between lens and FPCB was inspected by optical appearances and shear force test. The nonconformance (NC) of work-piece that is the lower specification of shear force and turbidity of the cured UAA was found about 35% of the production. The aim of this research was to reduce the joining defect of the lens and FPCB in the optical Transceiver assembly process. The applied condition and obtained output of each workstation started from backward of the process was characterized applying the Scanning Electron Microscope (SEM), the quality tools and statistical analysis in order to find root causes of the problem and to improve the process. The study found that (1) the lower shear force was related to the higher turbidity of cured UAA which normally was transparences after thermal curing; (2) the turbidity of cured UAA was resulted by repeated rubbing of using one cotton bud of worker during cleaning the FPCB surface that causes the surface contaminated and then lower adhesive force of the joint; (3) a single trip of rubbing per cotton-bud was applied and could remarkably decrease the adhesive joining defect (NC) of work-piece to 7% of the production.

Abstract: Industrial areas using FPCB are broadening from simple conection for bending of rigid PCB to main component of elecronic equipment. Fume is generated by melting of adhesion material during the hot press process for manufacturing of FPCB. Release film sheet is used for elemination of gas and absorption of shock in the hot press process. In this paper, release film automatic adhesion machine for hot press process is developed, and ultrasonic welding condition is proposed for optimization of adhesion strength between release films. The performance test of developed machine is conducted.

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: The electrochemical migration (ECM) with flexible printed circuit board (PCB) was affected by factors such as distance between the electrodes and bias voltage using water drop (WD) test. The rate of migration was increased by decreasing the distance between electrodes of the opposite polarity and increasing the bias voltage.

Abstract: Flexible printed circuit board (PCB), which is used for folder and slide type cellular phones, consists of flexible copper clad laminate (FCCL) and cover layer. Through it an electric current is applied to liquid crystal display (LCD) from the main board of cellular phone. In thin Cu foils of flexible PCB fatigue cracks due to repeated bending motion generate and propagate, and they cause a short circuit. Fatigue behavior of thin Cu foils being used for flexible PCB must be evaluated and confirmed to resolve this problem. It is based on findings by several researches that the mechanical properties of thin film materials differ from those of their bulk counterparts. Thin film properties have been investigated over the last years; however fatigue behavior of thin films has not yet been studied as thoroughly as monotonic behavior. In this study fatigue properties of thin Cu foils for the application in flexible PCB are obtained. Fatigue testing was performed for two kinds of Cu foils that were made by rolling and electrochemical procedures respectively. Differences of fabrications in fatigue behavior of thin foils were distinguished. Especially for rolled Cu foils, effects of rolling directions in fatigue properties were evaluated.