The Research On The Influence Of Temperature On The Integrity Of High-speed Signal Transmission On PCB Board

In recent years,the communication rate of high-speed digital circuit systems has become higher,the size of large-scale integrated circuits has shrunk,and the integration density on the PCB has increased.It has caused the PCB temperature to become increasingly high,resulting in degraded signal integrity performance of the high-speed transmission channels on the PCB,which makes the performance of the entire electronic product unstable and even leads to product failure in severe cases.Therefore,engineers must analyze the impact of temperature on each area on the PCB and each independent transmission network according to the specific situation.Then,take corresponding measures to leave a signal integrity design margin to prevent "overprotection" from increasing the design cost,or "insufficient protection" leads to system performance degradation.This paper proposes a thermal-electro co-analysis method that uses the dielectric properties of PCB materials as intermediate variables to study the effect of temperature on the integrity of high-speed signals transmitted by PCB.The parameters used in traditional electro-thermal coupling analysis are electrical conductivity and thermal conductivity.In essence,it still only analyzes thermal effects and power integrity.The method proposed in this article can analyze the signal integrity together.It first obtains the temperature distribution on the PCB and the temperature curve on the high-speed transmission channel on the PCB through the traditional Power DC thermoelectric simulation.Then,use the relative dielectric constant and dissipation factor of the PCB material at the corresponding temperature to model the S-parameters of the high-speed transmission channel and substitute the S-parameter model of the channel into the highspeed link system to analyze its signal integrity.The main research content and work of this paper are as follows:(1)A thermal-electro co-analysis process with the dielectric properties of PCB materials as intermediate variables is proposed,and the structural process and temperature characteristics of PCBs,as well as the signal integrity theory related to material properties,are studied.(2)The influence of temperature on the dielectric properties of the PCB material was measured.The relative permittivity and dissipation factor of the PCB material at different temperatures were extracted by testing the S-parameters of the strip line on the PCB.The extracted results are verified by electromagnetic analysis using HFSS.(3)Analyze the temperature distribution on the PCB of the specific case,mainly including hardware design and electro-thermal coupling simulation design,so as to obtain the temperature value on the high-speed signal transmission path on the PCB to be tested.(4)Perform thermal-electro co-analysis on the PCIe transmission link on the PCB to obtain the effect of temperature on the integrity of the high-speed transmission signal on the PCB,and take corresponding PCB Layout optimization measures based on these effects.This paper found that the severe heating area on the PCB is mainly concentrated in the power module,CPU main chip,and other regions through the above research work.The high-speed digital signal passing through these areas increases with the increase in temperature,the insertion loss becomes larger,and the width of the eye pattern becomes narrower.The height is reduced,and the signal integrity performance of the link is degraded.The study also found that temperature has different effects on high-speed signal integrity on different PCB materials.When the dielectric properties of PCB materials are less affected by temperature,the high-speed signal integrity on the PCB is also less affected by temperature.