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Vias in Symbol

Yoda5939

All,

Thsi poat is re-visited because I couldn't make it work the last time and had to kluge my way through my design. My situation is that I have a FET with a large pin. I need to add an array of 30(6x5) vias in the symbopl on that large pin to use as a thermal array. There was several suggestions but I couldn't get these to work and had to move on. I'm back asking for advise. Any hints will be helpful as I am am coming up on schedule.I'll attach a screen shot that will show the problem.

Thanks,.

Ron Scott CID+

ron.scott@halla.com 

Parents
  • ScottCad

     I took a look at that app note, in the app note they talk about tenting the drill holes as a means to stop wicking of the solder paste, but if you are using 13Mil holes then tenting will be a challenge as the hole is so small. A better solution is to have the holes plated shut for small holes.

    There is a dis advantage to haveing mask "Tented holes" under the bonding pad of a power part. Having mask there "Tented holes" means when the solderpaste is applied it will also cover the mask, this can lead to problems when the part goes through a reflow oven in that the solder paste will dam under the part in certain areas. The biggest issue with doing this is you are reducing heat transfer from the part.

    With the multi drill pad option you can either have a solder mask built into the pad or not. If not you will have to use a shape on the soldermask layer to achieve your desired results. In other words place a Shape of the desired size to represent the mask for the pad then if you need mask over the holes add a circular shape "Void" over each hole on the mask layer.

    Believe that should work. 

    Scott 

     

      

Reply
  • ScottCad

     I took a look at that app note, in the app note they talk about tenting the drill holes as a means to stop wicking of the solder paste, but if you are using 13Mil holes then tenting will be a challenge as the hole is so small. A better solution is to have the holes plated shut for small holes.

    There is a dis advantage to haveing mask "Tented holes" under the bonding pad of a power part. Having mask there "Tented holes" means when the solderpaste is applied it will also cover the mask, this can lead to problems when the part goes through a reflow oven in that the solder paste will dam under the part in certain areas. The biggest issue with doing this is you are reducing heat transfer from the part.

    With the multi drill pad option you can either have a solder mask built into the pad or not. If not you will have to use a shape on the soldermask layer to achieve your desired results. In other words place a Shape of the desired size to represent the mask for the pad then if you need mask over the holes add a circular shape "Void" over each hole on the mask layer.

    Believe that should work. 

    Scott 

     

      

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