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TPS50601A-SP: Thermal pad plating and gold removal recommendation

Carlton Faller
Prodigy 20 points
Part Number: TPS50601A-SP
Other Parts Discussed in Thread: TPS7A4501-SP,

We are using 5962R1022102VSC (TPS50601A-SP) converter and also 5962R1222403VXC (TPS7A4501-SP) LDO.  We intend to solder the heat spreader to the PCBs and would like to know both the plating specification for the gold on the heat spreader and also whether TI recommends gold removal.  I tried searching on the TI site and was unable to find this info.  Also the SMD and 38535 don't appear to specify the plating.

  • 0
    TI__Genius 11950 points

    Hello,

    I'm researching your question and will get back to you as soon as possible.

  • 0 in reply to Sarah Koch
    Prodigy 20 points

    Hi Sarah.  Can you give me a status on this request?

  • 0 in reply to Carlton Faller
    TI__Genius 11950 points

    Hi Carlton,

     

    The thermal pad is a 90% tungsten/10% copper alloy plated with nickel (specified as 80µm to 350 µm thick) and then gold (specified as 70 to µm 225um thick). With thickly plated gold leads on hermetic packages it is recommended to perform a solder-dip in a flowing solder pot to remove the gold.  Assuming lead tinning is done it wouldn’t hurt to do the same thing with the pad. It will make reflow easier as well. 

    In order to mitigate gold embrittlement, make sure the weight of the gold does not exceed 3% of the total weight of the solder alloy. Calculate the mass of the solder and assume all the gold on the package would go into solution with the solder and see if it is above 3%.

     

    Hope this helps,

    Sarah