双层印制电路板交/直流下的电损伤与放电特性OA

The trend of miniaturization and high power density of power electronic equipment has led to increasingly high requirements for the performance of insulation materials used in equipment.There are a large number of interfaces between packaging materials,devices,bonding wires,and other structures.These interfaces,as weak insulation parts,need to withstand complex electric field changes for a long time,which may cause electrical damage problems such as partial discharge and electrical trees.Currently,there are few insulation problems in printed circuit board(PCB)packaging under complex electric fields.This article compares and analyzes the electrical tree characteristics of double-layer PCB samples under AC and DC voltages,as well as the partial discharge characteristics of double-layer PCB samples under AC and DC voltages.Combined with energy dispersive spectrometer(EDS)characterization of interlayer insulation damage components,it explores the differences in the mechanism of interlayer insulation degradation of PCB under AC and DC electric fields. Firstly,the initial voltage of double-layer V-shaped PCB samples under AC and DC voltages was measured.The difference in initial voltage under AC and DC voltages was compared using a two parameter Weibull distribution.The results showed that the shape parameter of the starting voltage under DC voltage was 35.19,and the scale parameter was 30.41;The shape parameter of the peak voltage of the tree under communication is 6.51,and the scale parameter is 17.74.Comparison of the morphology of electrical tree under AC and DC,the electrical tree of double-layer PCB sample are mainly branch-like under AC voltage,while the morphology of the electrical tree under DC voltage is different between lower and higher voltages.At 30 kV positive voltage,the double-layer PCB sample shows similar branch-like tree as under AC voltage,but with relatively fewer branches.When the applied voltage is 28 kV,there are multiple branching points around the V-shaped electrode. Afterwards,the discharge characteristics during the growth process of AC/DC electrical trees were measured,and the variation of discharge magnitude with the length of electrical trees during the growth process was compared and analyzed.It was found that the maximum discharge magnitude gradually increased with the increase of electrical tree length.Based on phase-resolved partial discharge(PRPD)pattern and discharge sequence voltage difference method,the characteristics of electrical tree discharge under AC were analyzed.The voltage difference plot of the discharge sequence of electrical trees under AC changes from a linear shape to a double-hook hexagonal as the length of the electrical tree increase.The analysis of electrical tree discharge under DC voltage was conducted by comparing the time difference between adjacent discharges.The time difference of the discharge sequence under DC is positively correlated with the magnitude of the previous discharge during the early stage of electrical tree growth. Finally,based on EDS of electrical damage under AC and DC voltages,the differences in damage of double-layer PCB samples under AC and DC voltages were revealed.It was found that the damage of double-layer PCB samples under lower DC voltage amplitudes was a multi start point branched damage.The results of EDS confirmed that it was a copper salt containing Cu and Cl elements,and distributed on both sides of the PCB and epoxy resin.Due to the relatively weak interface strength of the double-layer sample,Cu ions migrate and form dendritic damage at the interface under the action of a strong electric field.