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  • TI Thinks Resolved

THS3062: with power pad exhibiting overheating and shortened lifespan

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Replies: 14

Views: 807

Part Number: THS3062

The third question is in addition to the first two I already posted regarding the same subject.

1, Could solder voids (on the power pad) cause overheating and shortened lifespan? Is there a specification for the maximum void on the power pad where overheating could lead to shortened lifespan?

2. If the power pad design did not include the recommended five, 10 mil diameter vias, (I.E. If only one or two via's went through the power pad to ground plane or other), could this cause overheating and shortened lifespan? 

3. Additional question: We have been measuring the external package temperature. The nominal value for the package temperature that we have deemed acceptable is 65C. Is this acceptable?

  • Hi Tom,

    To answer your first two questions, yes it is possible that either of those conditions could cause the device to be damaged if the internal junction temperature reaches above the maximum.

    To answer your third question, I need to know which package you are using since the values are different per package.

    Regards,

    Jacob Freet 
    High Speed Amplifiers

  • In reply to Jacob%20Freet:

    Hi Jacob,
    1 The package we are using is the THS3062DGN.

    2. Regarding the question about solder voids, The vendor states that a 30% void is within the tolerance of his mfg process. We believe the solder void in some cases may be as high as 50%. We have sent PCBs out for xray analysis. Is there a percentage of solder void that would be considered acceptable?


    Thank you.
    Tom
  • Hi Tom,

    I'm not really able to give an acceptable number. It really all depends on how much power you are putting through the device and also the ambient temperature.

    When you are measuring the part with a package temperature of 65C, is that the ambient temperature or the actual device package temperature?

    Regards,

    Jacob Freet 
    High Speed Amplifiers

  • In reply to Jacob%20Freet:

    Hi Jacob.

    65C is the package temp. The ambient temp is 24C (75F).

    Thank you. Tom

  • Hi Tom, 

    I just wanted to update you that I have submitted a request to our thermal modelling team for the DGN package. The datasheet is older and only has the Theta JA and JC values which aren't great estimates to get junction temperature compared to newer standards. It could take up to two weeks to get the new numbers, but then I will be able give you a much more accurate calculation for the device temperature. 

    Regards, 

    Jacob Freet 
    High Speed Amplifiers

  • Hi Tom,

    not to have enough vias in the power pad is a real big problem!!! Keep in mind, that only by the vias the heat can be removed from the power pad. So, it's really really essential that you follow the power pad soldering recommendations given in datasheet. Excatly adopt the layout given in figure 51 and follow all the instructions given there!!!!

    Kai
  • In reply to Jacob%20Freet:

    That could prove very beneficial to our analysis. Thank you very much.

    The product is in our old and current designs and is being designed into future products as well.

    Appreciated,

    Tom

  • In reply to kai klaas69:

    That's what I like to hear and reflects my sentiments exactly. I'll pass off this info at the next design meeting.
  • Hi Tom,

    Just wanted to give you an update that I am still waiting to get the newest thermal information, but will let you know as soon as it is ready.

    Regards,

    Jacob Freet 
    High Speed Amplifiers

  • In reply to Jacob%20Freet:

    Thank you for the update.

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