Xuemei He

Preparation of PMMA/PGMA Blend to Apply for Metallographic Cross Section of Printed Circuit Board

Poly (methyl methacrylate)/poly (glycidyl methacrylate) (PMMA/PGMA) blend was prepared with the reaction of PMMA, glycidyl methacrylate (GMA) and methyl methacrylate (MMA) at room temperature. Effects of the proportions of MMA and GMA were investigated to analyze the performance of PMMA/PGMA blend. When the weight fraction of GMA in GMA/MMA was 0.25, PMMA/PGMA blend exhibited good performance as curing time of 29 min, volume shrinkage of 9.83%, bending strength of 50 MPa, tensile strength of 31 MPa and bonding strength of 1.52 MPa. PMMA/PGMA blend could well cover the cross section of printed circuit board. Introduction Printed circuit board (PCB) is an indispensable module for signal transmission of electronic products .PCB quality at each process should be monitored to finally obtain reliable PCB structure due to the limitation of its complex manufacture processes [1]. Metallographic cross section of PCB is a useful method to directly observe the inside structure of PCB to find out the defects of delamination, skip plating, undercut, conductive anodic filament and copper migration etc [2].However, the fixation of PCB section is hard to be completed to avoid the structure damage after cutting a local segment from the whole PCB. Cold mounting is generally used for the fixation of PCB section since PCB section can be stable without the influence of outside pressure, heat and deformation during its grinding process. Epoxy resin for cold mounting is not suitable for quick observation of PCB section since the reaction of epoxy monomer needs long curing time (more than 12 h) under the presence of organic amine catalyst. Thus, other polymer system should be found to meet the requirement of quick evaluation of PCB section. Methacrylate monomer could exhibit short copolymerization time at room temperature so. In this paper, poly (methyl methacrylate)/poly (glycidyl methacrylate) (PMMA/PGMA) blend was prepared for the application of the fixation of PCB section. The performance of PMMA/PGMA blend was investigated to examine its compatibility of cold mounting for PCB-section observation. 3rd Annual International Conference on Advanced Material Engineering (AME 2017) Copyright

Copper coin-embedded printed circuit board for heat dissipation: manufacture, thermal simulation and reliability

Purpose – The purpose of this paper is to form copper coin-embedded printed circuit board (PCB) for high heat dissipation. Design/methodology/approach – Manufacturing optimization of copper coin-embedded PCB involved in the design and treatment of copper coin, resin flush removal and flatness control. Thermal simulation was used to investigate the effect of copper coin on heat dissipation of PCB products. Lead-free reflow soldering and thrust tests were used to characterize the reliable performance of copper coin-embedded PCB. Findings – The copper coin-embedded PCB had good agreement with resin flush removal and flatness control. Thermal simulation results indicated that copper coin could significantly enhance the heat-dissipation rate by means of a direct contact with the high-power integrated circuit chip. The copper coin-embedded PCB exhibited a reliable structure capable of withstanding high-temperature reflow soldering and high thrust testing. Originality/value – The use of a copper coin-embedded PCB could lead to higher heat dissipation for the stable performance of high-power electronic components. The copper coin-embedded method could have important potential for improving the design for heat dissipation in the PCB industry.

Research on the effect of inorganic components on brightener in horizontal pulse plating solution by Cyclic Voltammetric Stripping method

The effect of Fe³⁺, Cu²⁺ and Cl^- with different concentration on the electro-deposition process of Cu in the medium of CuSO₄-H₂SO₄ with platinum as work electrode has been studied by CVS (Cyclic Voltammetric Stripping) method and the assay value of brightener is also studied. The research results show that different concentration of Fe³⁺, Cu²⁺ and CL^- affects the assay value of brightener to some extent, the brighteners extreme concentration value change are R_Fe3+=10.33ml/l, R_CL-=1.22ml/l, R_Cu2+=3.1ml/l respectively, the concentration of Fe³⁺ has the greatest influence on brightener concentration measurement. So, the effect of Fe³⁺ should be taken into consideration with CVS analyzer to monitor the concentration of brightener in electroplating solution. The study result is of some reference and guiding significance for the electroplating liquid composition control and production process.

Study on manufacturing process of semi-flex Printed Circuit Board using buried material

In this paper, the semi-flex Printed Circuit Board (PCB) was manufactured by using buried material to prevent resin of high-flow prepreg from flowing into the flexible area in lamination process. Windows in which the buried materials were imbedded were shaped in advance in prepreg and cores. The circuit in flexible area was protected by polyimide (PI) cove layer. The preventing capability of resin for the three different buried materials including epoxy resin base material, silicon sheet and Teflon (PTFE) were studied by microsection manufacture and Optical Critical Dimension, and the results showed that the silicon sheet was the most appropriate one. Manufacturing processes such as the heating rate in lamination process, sizes of silicon sheet and windows of prepreg were studied by the orthogonal tests and the optimal manufacturing parameters were analyzed and achieved by Minitab Software. Several demonstration tests were conducted under optimal manufacturing condition and the results including resin length and flexural ability were acceptable. The reliability of semi-flex PCB was evaluated by solder float test, thermal shock test and salt spray test. The results showed that the flexible area had substantially no defects such as bubbles, separation and flaws occurred and delamination had not occurred in the rigid-flex joint of the products, and the resistance value change was 5.37% in thermal shock test. The reliability of semi-flex PCB was acceptable.

Compaction uniformity and environmental adaptability of printed RFID antenna

The manufacture of RFID antenna tags (RFIDs) using silk-screen printing technology with conductive silver paste is one of economic methods to reduce the cost of RFIDs. The distance between conductive particles is minified via hot compaction to conductive silver paste, resulting in lower resistance and higher Q value. The compaction conditions, including temperature, pressure and time, were systematically studied based on the analysis method of uniform design, with regression equation by nonlinear regression analysis fitted by Minitab Statistical Analysis Software. The effect of environmental factors to resistance of RFID antenna was also studied through the high and low temperature impact test and the constant temperature and humidity test. The results indicate that resistance of RFID antenna printed with conductive silver paste can be reduced more than 50%, the resistance variation of RFID antenna can be predicted by regression equation with correlation coefficient 99.8% in certain range and antenna printed with conductive silver paste have good environmental adaptability.