3 Replies Latest reply on Mar 29, 2013 10:11 PM by sabitha.jamal

    Solderability issue related to Thermal value

    sabitha.jamal

      Hello,

       

       

           This is related to the Solderability issue of Through hole joints with respect to Thermal value . We have seen, the matching of valor issue points in through hole solder joints  with the actual issue in shop floor by doing thermal checks with some specific set of values in sq mils.We set the thermal values after running the trials with different boards.Valor will consider the no of spokes and spoke width and copper oz for getting thermal value .But our customer is asking that why valor is not considering the length of the spokes because thermal resistence always dependent on length of the conductor. In my point of view this spoke length will affect the air gap area too around the drill,Is there any reason not considering this parameter in drill checks. Can you please clarify this so that we can close this point on running  DFM board.

       

       

      Thanks and Regards

      sabitha

        • 1. Re: Solderability issue related to Thermal value
          jishenbiao

          Hi,sabitha

           

          Your customer is making a high requirement as i think.And max may answer the question.

          • 2. Re: Solderability issue related to Thermal value
            max_clark

            Sabitha,

             

            I believe in the Drill Analysis you are referring to the categories "Thermal Connection (Small Pin) (Thermal Connection)" and "Thermal Connection (Large Pin) (Thermal Connection)".

             

            For these categories the calculation used is determine by the cumulative area of thermals connecting the through pin to layers. The measurement is a result of <number of thermal spokes> * <width of spokes> * <layer thickness>. Layer thickness is the value of layer attribute Copper Weight (oz) * 1.41 (the thickness of 1 ounce of copper). If you work in metric units, multiply the number obtained for layer thickness by the translation factor 25.4.

             

            You are questioning why we are using only the width and not the width times the length of the thermal spoke.

             

            width.jpglength.jpg

             

            If I have this correct and based on your explanation below, I believe you have factory based results that indicated the length does impact solderability.  I can see how that could be evaluated with good emperical results gathered from real world application.

             

            I suggest that you file an enhancement request at the Mentor's IDEAs sites and I will consider this for a future release based on acknowlegement from other Valor NPI users. ( https://mentorideas.brightidea.com/valor )

             

            Thanks,

            Max

            • 3. Re: Solderability issue related to Thermal value
              sabitha.jamal

              Hello Max

               

               

               

                       Thanks for the positive response . We were in detail Analysis stage with respect to thermal value and its solderability and found many other board facotors are affecting the solderability in addition to the thermal value .And some time thermal value will be the less factor when considering the other  board parameters ,So if we works better ,we need to add the other parameter and variable from the current setting in valor  ,please see below for our findings the solderability  w.r.t board parameters

                

               

                        1. Thermal value much not make any impact if all connected planes are in very bottom layers

                        2. If the connected planes are very less area with spokes ,this will not be any factor in solderability (mostly less than board thickness)

                        3. Spoke length also the factor of better solderability.

                        4. The solderabilty will affect if we are using with " more no of layers"

                  

               

               

              Current thermal value and solderabillity is matching if the board parameters as below mentioned

               

                        1. If the spokes and planes are connected in different layers (6 layers)

                        2. Thermal with 2 spokes not taken care in valor,and we found good result if we are having only two spokes in different layers.

                        3. Different pin sizes are available to set the value

               

              So we need to customize the ERF Setting  ,based on the board thickness ,no of layers ,spoke length ,connected layer pattern,Plane search radius .(spoke width ,small pin- large pin category and copper oz factor already there in ERF)

                      

               

              If you require our detailed analysis data ,I will share it separately .If you need any further clarifications please feel free to contact

               

               

              Thanks and Regards

              sabitha Jamal

              9495736649