LM2596: Color change on leads after reflow

Sunny Zeng

Part Number: LM2596

Tool/software:

Hello Dear Engineer!

During the assembly of our product, we noticed that the LM2596SX-ADJ/NOPB component exhibited a dark coloration after the reflow process.

Please see the details in the attached images. Is it normal?

Could you help analyze the cause? Also, could you provide the correct usage instructions for this product regarding soldering and reflow soldering?

Thank you very much!

Best Regards

Sunny

7 months ago

0 Pramanik Patel 7 months ago

TI__Expert 8320 points

Hi,

I will check with the concerned team and let you know soon.

Thanks,

Pramanik Patel

0 Pramanik Patel 7 months ago in reply to Pramanik Patel

TI__Expert 8320 points

Hi,

This is a MSL3 device (sensitivity to moisture)with Matte Sn leadframe. Probably the storage conditions and correct reflow profile may not have been followed.

The discoloration is possibly Tin oxide. I hope this note will help you .

Thanks,

Pramanik Patel

0 Sunny Zeng 7 months ago in reply to Pramanik Patel

Prodigy 10 points

Hi Pramanik,

Thank you very much for reply.

The parts are in OFS packing and no oxide when removed from the packing, and even no problem when soldering. color changes after reflow.

do you have the correct reflow profiles ? If yes, we'll ask our engineer to follow it and try again. thanks a lot!

0 Pramanik Patel 7 months ago in reply to Sunny Zeng

TI__Expert 8320 points

Hi,

Please give me some time I will get back to you soon.

Thanks

Pramanik

0 Pramanik Patel 7 months ago in reply to Pramanik Patel

TI__Expert 8320 points

Hi,

Figure 3 in the following app note has the profile.

MSL Ratings and Reflow Profiles (Rev. A)

Thanks,

Pramanik Patel

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LM2596: Color change on leads after reflow