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INA240: SOLDER MASK preference

Kelly Bai
Intellectual 1330 points
Part Number: INA240

hi team,

our datasheet for INA240 have below two kind of solder mask definition,  can you help explain the different between the two definition? the solder mask can be either larger or smaller than the Metal Pin?

which one do we preferred?

thanks very much!

  • 0
    Guru 284810 points

    Both are allowed. To know which one is preferred, ask the board manufacturer.

  • 0
    Guru 140200 points

    Hi Kelly,

    packages with very small distances between the solder pads can suffer from unwanted solder connections. To avoid this, there are two methods. With the NSMD method the pads must be rather narrow to allow enough solder mask between the pads. With the SMD method, on the other hand, the solder pads can be wider. But to have enough solder mask between the solder pads the solder mask must partially overlapp the copper.

    The SMD method has the additional advantage of allowing more copper at the solder connections and by this to improve the heat flow from the package to the printed circuit board which results in a better chip cooling. Because of this, the smaller the package and the narrower the solder pads, the more the SMD technique is recommended.

    The disadvantage of the SMD method is that the board manufacturer normally generates the solder mask by using the NSMD method. So, you have to talk with the board manufacturer to allow him to use the SMD method.

    Kai

  • 0 in reply to kai klaas69
    TI__Mastermind 30910 points

    Hi Kelly,

    As mentioned by Clemens and Kai, either option is fine. I think NSMD is more common for larger geometries like this one.

    Regards, Guang