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    Corrosion issues in stud mounted parts

    Is galvanic corrosion an issue for uninsulated stud mounted parts such as DO-4, DO-5 TO-94 studs?

    Heatsinks are typically copper or aluminum, not sure what those packages are made of.
    Last edited by Zak28; 8th May 2019 at 12:44.

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    Re: Corrosion issues in stud mounted parts

    I Never had any Problems
    dotcom, Than I Guess I am Not wanted here either.


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    Re: Corrosion issues in stud mounted parts

    Quote Originally Posted by chemelec View Post
    I Never had any Problems
    You probably weren't passing much current. Or it wasn't an aluminum heatsink.



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    Re: Corrosion issues in stud mounted parts

    I have used up to 40 Amps.
    But I Do use "SILICONE BASED HEAT SINK GREASE".

    - - - Updated - - -
    dotcom, Than I Guess I am Not wanted here either.


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    Re: Corrosion issues in stud mounted parts

    Quote Originally Posted by chemelec View Post
    I have used up to 40 Amps.
    But I Do use "SILICONE BASED HEAT SINK GREASE".

    - - - Updated - - -
    Whats the heatsink material?



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    Re: Corrosion issues in stud mounted parts

    Quote Originally Posted by Zak28 View Post
    Whats the heatsink material?
    almost always Aluminum.

    And Silicone Grease is Recommended by Manufactures of these type of parts.
    It Increases Heat Transfer from the part to the Heat Sink.
    dotcom, Than I Guess I am Not wanted here either.


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    Re: Corrosion issues in stud mounted parts

    I use lower thermal resistance thermal grease made for PC CPUs - silicone is far less expensive and a worse performer.

    Quote Originally Posted by chemelec View Post
    almost always Aluminum.

    And Silicone Grease is Recommended by Manufactures of these type of parts.
    It Increases Heat Transfer from the part to the Heat Sink.
    Was it anodized?



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    Re: Corrosion issues in stud mounted parts

    I presume the thread is based on pure speculation rather than observed actual problems. Stud mount parts on aluminium heatsinks have been used in older days power electronics for at least 50 years.


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    Re: Corrosion issues in stud mounted parts

    Quote Originally Posted by FvM View Post
    I presume the thread is based on pure speculation rather than observed actual problems. Stud mount parts on aluminium heatsinks have been used in older days power electronics for at least 50 years.
    I wasn't sure if corrosion would be a problem.

    Is it fine to simply screw the package into a drilled and tapped heatsink without using a nut?

    The hole would be deeper than device package stud to permit all the threads on the package to make contact with the heatsink. Not sure if this is fine since aluminum threads might not have enough strength to permit adequate mounting torque for the device package.



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    Re: Corrosion issues in stud mounted parts

    If you have the Correct Tap for the Threads, It should work Perfectly OK.
    dotcom, Than I Guess I am Not wanted here either.



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    Re: Corrosion issues in stud mounted parts

    "Is it fine to simply screw the package into a drilled and tapped heat-sink without using a nut?"

    Not my field so 'IMHO', but I'd worry about getting adequate thermal contact between the package and the heat-sink.

    Also, IIRC, setting bolts into a block thus requires some extra machining. In addition to 'base clearance' or a through-hole, I'd expect a shallow counter-sink or counter-bore to allow for incomplete threading of the bolt. That may not leave much thickness for a thread, meaning you'd need a back-nut for security...

    Unless you are using a seriously massive block as your heat-sink, which is inefficient unless doubles as structural, IMHO, you'd do better with a 'clearance' hole, heat transfer gel & washers and a correctly torqued back-nut in the usual way...

    YMMV.



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    Re: Corrosion issues in stud mounted parts

    Yes, No Nut Required.
    dotcom, Than I Guess I am Not wanted here either.



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    Re: Corrosion issues in stud mounted parts

    Was considering drilling this Intel PC CPU heatsink

    https://i.ebayimg.com/images/g/VDcAA...YV/s-l1600.jpg

    with the thermal pads removed it has a nice flat surface and even a fan.



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