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LM137: (LM137H) - Plating Request

Gabriel Garza45
Intellectual 2275 points
Part Number: LM137

Hello,

We have a customer who is looking for plating information on this device.

There is a note in the datasheet which states Call TI, here in the Support Center, we are not finding the answer the customer is looking for.

From customer:

"We are concerned about gold embrittlement of parts that solder to a circuit board. The datasheet for LM137H says terminal pins are Au plated.
Will you please answer the following questions?

1. How thick is gold plating on terminals that solder to circuit board? Please provide a range of gold thickness or maximum plating thickness.
2. Is gold plating electroless nickel immersion gold (ENIG), nickel-palladium-gold (NiPdAu), or electroless nickel electroless palladium immersion gold (ENEPIG) finish?"

Can someone please help us out with this?
Thanks,

  • 0
    TI__Expert 5570 points

    Gabriel, what is the full part number in question?

    In general, when using packages with gold-plated leads or mounting pads with MIL-SPEC plating thickness (60 µ-in to 225 µ-in), it is strongly recommended that the units be pre-tinned (solder-dipped) before board mounting to scavenge the gold from the leads or pads.  If this is not done there is a chance of gold-embrittlement of the board-level solder-joints.  A flowing solder-pot or two passes in a static solder-part is recommended.

    Metal lid ceramic body packages use a 80%Au20%Sn gold-tin solder preform to attach the lid.  Gold-tin solder will begin to soften at 270°C and has a eutectic point of 280°C.   The package body temperature must not be allowed to exceed 265°C at any time or permanent damage will occur due to compromising the package’s hermetic seal.    Note that though-hole hermetic device specify a maximum temperature for soldering as a lead-temperature of 300°C for 10 seconds. This is not a reflow temperature.

    -Richard

  • 0 in reply to Richard Biddle
    TI__Intellectual 2275 points
    Hi Richard,

    This is the LM137H.

    Page 19 of the datasheet is what is causing the confusion. The plating options in the chart just say "Call TI".

    Customer needs to know the gold plating thickness on the leads, and a range or maximum plating thickness.

    Also wants to know if this plating is considered ENIG, NiPdAu, or Enepig.

    Thanks,
    Gabe Garza
    TI Support
  • 0 in reply to Gabriel Garza45
    TI__Intellectual 2275 points
    Hi Richard,

    Just following up to see if you could point us in the right direction here.

    Thanks,
  • 0 in reply to Gabriel Garza45
    TI__Expert 5570 points

    The leads are gold plate over nickel over KOVAR so the plating thickness is 60 µ-in to 225 µ-in which means the units should be pre-tinned (solder-dipped) before board mounting to scavenge the gold from the leads or pads.