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drv8825 - copper paste????

Sandra Lindner
Prodigy 20 points

Other Parts Discussed in Thread: DRV8825

dear all,

during development with the drv8825 we've faced how hard it is to solder an HTSSOP without reflow or hot air. so, one of my students had an idea to connect the heatsink to the PCB with regular copper paste. based on Parameters the copper paste have better parameters at heat transport. and it is possible to add it after soldering due the vias.

so it sounds good, but is there any problem with it?

thanks for your responses.

Regards from (Munich) Germany

Matthias J Lindner

  • 0
    TI__Mastermind 21320 points

    Hi Matthias,

    Can you provide the properties of the paste you are looking to use? What are you comparing it to?

    I don't understand how you would force the paste through the vias after soldering. <=3mm is a fairly small hole size. Can you elaborate furthur?

  • 0 in reply to Nicholas Oborny
    Prodigy 20 points

    dear sir,

    thanks for your reply. here's a link to the datasheet of the paste http://www.tme.eu/de/Document/8a9ebb4892a5f83ecd6e11a96675a855/TCA3%20COPPERP.DTE.PDF

    to force the paste through the vias is definitly plan B. with a small needle we were able to  insert a couple points to the heatsink. we are not able to put copperpaste to the whole heatsink.

    so we have to put the paste on the PCB before we solder the chip. 

    compared to regular solder tin (sn60pb40) the thermal conductivity is more than 3 times higher. 63 vs 300 W/(m*K)

    thank you

  • 0 in reply to Sandra Lindner
    TI__Mastermind 21320 points

    I do not see a spec for thermal conductivity (only temperature resistance) in this datasheet, can you clarify. I have a hard time understanding how a paste would be 5 times more conductive than solder.

    I also worry that you would not get proper contact to the thermal pad. These motor drivers need proper heat dissapation to perform to spec.