环境温湿度对高速PCB信号插入损耗的影响

The Influence of Ambient Temperature and Humidity on Insertion Loss of High Speed PCB

基于三种不同高速材料制备而成具有相同介质厚度及图形设计的PCB,借助恒温恒湿箱及SPDR夹具对上述三种PCB基材在不同温度及湿度下的介电常数Dk及介电损耗Df进行了测量。同时借助矢量网络分析仪在同一湿度但不同温度下对上述三种PCB上85Ω的差分线上的高速信号的插入损耗进行了测试与对比研究。结果表明,随着环境温度升高及湿度增加,三种高速材料的Dk及Df也随之变大;受材料在不同温湿度下Dk及Df变化的影响,当环境湿度恒定时,差分线上高速信号的插入损耗的绝对值随着环境温度升高而增大,且Dk对插入损耗的影响较之Df的要大。

Three different types of high speed materials were respectively processed into PCBs which characterized with the same dielectric layer thicknesses and pattern designs.The dielectric constant Dk and dielectric loss Df of the aforementioned materials under the condition of different temperature humidity were investigated employing temperature humidity chamber and SPDR fixture.Additionally,a comparative study of the insertion loss of 85Ωdifferential impedance lines corresponding to PCBs based on the aforementioned materials was performed using Vector Network Analyzer.It was found that the Dk and Df of the three different high speed materials increased as the ambient temperature and humidity increased.When the ambient humidity was constant,the insertion loss modulus of 85Ωdifferential impedance lines increased as ambient temperature became higher,which could be attributed to variations of Dk and Df of high speed materials under different temperatures.And the insertion loss was affected more by Dk than Df.