Research On The Influence Of The Reliability Of Metallized Holes On Printed Boards

In recent years,the technology of printed circuit board has developed rapidly,and the basic research of technology has lagged behind,which cannot solve the risks and problems brought by new technologies.Plated through holes are important carriers for electrical connection between layers of printed boards.Defects in plated through hole are one of the main causes of failure of printed circuit board.In this paper,the thermal stress finite element simulation of the plated through hole of the printed circuit board is carried out.The effects of the copper plating layer and the degree of lamination curing on the plated-through-hole are studied in combination with the simulation results,and the plated through hole are tested by the interconnect stress test.Finite element simulation mainly analyzes the stress-strain distribution of holes in wave soldering,reflow soldering and temperature shock testing.The results of the theoretical analysis and the reliability test are compared with the results obtained by the simulation to measure the degree of agreement between the two.A set of definition and test methods for the average thickness and minimum thickness of holes based on statistical methods are established.According to the statistical results,the integral formula is used to improve the calculation formula between the hole resistance and the thickness.The results of the resistance test show that the new formula has a significant improvement in accuracy over the conventional formula.The relationship between the micro-morphology under scanning electron microscope and the mesoscopic modulus of elasticity under continuous stiffness test was established.The reasons for the decrease of the modulus and the uniformity of the micro-morphology caused by the decrease of the pore size were explained,and the allowable boundary of the elastic modulus was given.The influence of incomplete lamination and curing on the properties of the substrate was investigated by thermomechanical analysis.Combined with the finite element simulation analysis,it was shown that incomplete lamination and curing would lead to the increase of plastic strain and decrease of reliability of copper plating on metallized holes.A method of reliability test for metallized holes by means of interconnection stress test is proposed.Compared with traditional temperature impact test,the corresponding relationship between interconnection stress test and temperature impact test is established based on the test results.