| Driven by the development of electronic product form and high-speed communication technology,buried optical fiber rigid-flexible optoelectronic printed circuit board as a new generation of high-end printed circuit board,with its small size,light weight,and with bendable,high-speed communication and low loss characteristics,by domestic and foreign enterprises and researchers are highly concerned.However,because the optical fiber is made of brittle materials,in the process of embedding,its surrounding materials will be squeezed by thermal expansion,which will easily lead to damage or even breakage of the optical fiber;at the same time,the optical fiber will produce a certain offset after embedding,and if the offset is too large,it will reduce the coupling efficiency of the optical fiber and other optical components,which will lead to the overall board can not work properly.The production cost of rigid-flexible optoelectronic printed board is high,whether the fiber is damaged in the burial process or buried fiber offset phenomenon is serious,will directly reduce the product yield and increase the production cost.In order to improve the reliability of buried optical fiber rigid deflection photoelectric printed board products and reduce the production cost.In this paper,based on the previous research,combined with the actual needs of photoelectric printed board research projects,the buried optical fiber rigid flexible photoelectric printed board as the research object,through finite element analysis method to study the impact of thermal-solid coupling load,optical fiber buried slot structure on the internal fiber stress and offset,and the optimization of the preferred slot structure parameters,the results of the study of similar products at home and abroad development and design The results of the study are of great practical significance for the development and design of similar products at home and abroad.The main research contents and results are as follows.(1)Research on the effects of three factors on fiber stress and fiber offset: buried fiber groove structure,buried fiber type and buried fiber location.The finite element analysis model of a rigid-flexible photovoltaic printed board with different slot shapes was established using COMSOL simulation software,and the effects of the three factors on the fiber stress and deflection were simulated and analyzed for the buried fiber slot structure,fiber coating layer and fiber buried position under the lamination process.The simulation results show that the maximum stress and offset of the fiber buried in the three groove shapes occur in the lamination stage of the lamination process;the fiber coating layer can effectively reduce the internal fiber stress in the lamination process;the closer the fiber buried position is to the ends of the flexible substrate,the higher the stress value and the smaller the offset of the fiber in the lamination process.In the lamination process,the maximum stress value of the fiber with coating layer is 25.671 MPa and the maximum offset of the fiber is 5.368 ?m,which is 14.167 MPa less than that of the fiber without coating layer and 0.05 ?m greater than that of the fiber without coating layer.The optical fiber with coating layer is buried in the trapezoidal slot structure to produce rigid flexing photoelectric printed circuit board.(2)Based on the single target analysis method,four factors,namely,slot depth,slot width,slot angle and fiber embedment spacing,were selected to analyze the influence of the trapezoidal slot on the fiber stress and offset.The analysis shows that the fiber stress decreases with the increase of groove depth and then increases slowly,and the fiber offset increases with the increase of groove depth;the fiber stress increases with the increase of groove width and the fiber offset decreases with the increase of groove width;the fiber stress decreases with the increase of groove angle and the fiber offset increases with the increase of groove angle;the fiber stress and offset both increase with the increase of fiber embedding distance.(3)Based on the response surface method,three design variables were selected as the slot depth,slot width and slotting angle of the trapezoidal slot,and the fiber stress and fiber offset were used as the optimization targets.The analysis results show that the fitting effect of the quadratic term fitting is better for the two optimization objectives of fiber stress and fiber offset;the significance of the fitted model is good.The response surface analysis of the fitted model shows that when the three design variables of slot depth,slot width and groove angle are crossed,the fiber stress increases with the increase of slot width and groove angle,decreases with the increase of slot depth,and then increases;the fiber offset increases with the increase of slot depth and groove angle,and decreases with the increase of slot width.(4)Based on the fitted model obtained by response surface method,the non-dominated ranking genetic algorithm(NSGA-II)is applied to the bi-objective optimal design of the parameters of the fiber buried groove structure,and the prediction accuracy and application value of the related optimization model are verified.According to the optimized Pareto front,the fiber stress and fiber offset caused by the slot structure parameters show a negative correlation,therefore,there is no slot structure parameter that minimizes both fiber stress and fiber offset;the optimized structure parameter based on the minimum fiber stress is 188.24 ?m,the slot width is 155 ?m,and the inscribed slot angle is65°,corresponding to the actual stress of the fiber under this structure parameter is 18.589 MPa.The optimized structure based on the minimum fiber stress is 188.24 ?m,the slot width is 155 ?m,the groove angle is 65°,and the actual offset of the fiber is 5.2387 ?m with the optimized rate of 2.4%.The deviation between the predicted and actual values of fiber stress and fiber offset in the Pareto front solution is within 5%,which indicates that the optimization model has high prediction accuracy and application value. |
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