4 Replies Latest reply on Jun 28, 2014 4:14 AM by Mark Keown

    Thermal analysis : Consideration

    Prashant Bendre

      Hi
      I am using the solid work flow simulation for the thermal anallysis
      We had done the simulation for ambient temprature i.e 40 deg centigrade.

      The inside temparature of the enclouser was at 69.3deg centigrade.

      also the temprature on pcb was 110 degree centirgrade

       

      based on the above result we want to calculate the components ( Electronics ) life.

      for calculation the the life of component in the formula mentioned that ambient temprature,but a little confusion,

       

      Which temprature we should considered ?' eighter 40 degree or 69.3 degree or 110 degree?

      since component is placed on PCB.

       

      Pelase guide..

       

      Prashant

        • Re: Thermal analysis : Consideration
          Jared Conway

          ambient temp is 69.3, so not sure why you wouldn't use that

          but also if you want to be conservative, use 110

           

          but the important part is what the definition is in your your equation/reference.

            • Re: Thermal analysis : Consideration
              Prashant Bendre

              HI Jared ,

               

              Thank you for the reply.

              I am calculating the life of electrolytic capacitor, using the Arrhenius' Law of Chemical Activity.

              the formual is as follows,

              L2= L1 ( Vr/Vo) * 2^( (Tm-( Ta- dT)/10))

                           Ta= Ambient temprature

                            Tm= Maximum temp rating of capacitor

                            dT= Temprature reise from ripple current

                             Vr= Maximum Voltage rating of capaciotr

                             Vo= operating Voltage of application

                             L1= load life rating

                             L2 = Projected life of operating conditions

               

              My operating range of equipement is 10 to 40 degere centigrade.

              While we performed the Thermal analysis using the solid works we have follwing results for tempratue

              Thermal analysis was performed for ambient temprature ( considering worst case )40 degree

                 => Internal temprature ( enclouser) was 69.3 deg'

                 => The approx temprature on the PCB was 110 deg

               

              So for calcuating life of the capacitor which temp. should we considered?

              so if we taking the capacitor having load life rating of 2000 hr , and teh ambient of 63.2 degree then the maximum life will be 5 yeras .

              if we  considerred teh 110 degree then predicted life will be approx 2 yerars.

               

              We have requiremtn for 6 years of life for teh equipment .

               

              What should be the correct temprature ( ambient) should be cosidered?

               

              Prashant

              pleas guide