TPSM846C23: TPSM846C23MOLR: Solder Reflow issue

Abhishek Manoj

Part Number: TPSM846C23

Tool/software:

Dear Team,

We had used the power module IC TPSM846C23MOLR in my board. We had followed the stencil design as provided in IC datasheet as mentioned

During the assembly process, after assembling the components, small solder balls are coming near the corners of the IC. In almost all of our boards, we are facing the same solder balls near the IC.

Can you please provide the suggestions on how to mitigate this issue. Please provide any updated stencil layout recommendations to avoid this issue.

Regards,

Abhishek

24 days ago

0 Eileen Hernandez Hernandez 24 days ago

TI__Expert 5468 points

Hi Abhishek,

We haven't had issues with the DS published stencil, typically that is what we use on our EVMs with no issue.

However you can request you CM to reduce the aperture to ~90-95% on their side, you can also request corner pads only since that is where you are seeing issues.

There's a variety of reasons for solder balls like:

-Mounting pressure been to high

-Soldering temp

-moisture

-contamination, etc

0 Abhishek Manoj 23 days ago in reply to Eileen Hernandez Hernandez

Intellectual 265 points

Hi Eileen,

I couldn't get your point correctly. Can you please provide which side aperture side to be reduced?

Regards,

Abhishek

0 Eileen Hernandez Hernandez 23 days ago in reply to Abhishek Manoj

TI__Expert 5468 points

Hi Abhishek,

Yes I can help clarify. The solder balls you are seeing can be caused by a many reasons. You can have the contract manufacture reduce the stencil aperture/opening for the corners you're seeing an issue on which based on your previous message, it looks like the pins in the corners so pin 1, 15, 27, 41. The current stencil is at 100% since that is the original, you can check and see if they can maybe reduce the stencil size for those pins to maybe 90% so make them a bit smaller. You could also have them put less pressure on the IC, or use less paste volume, that could all help too.

I would suggest also making sure that reflow is following MSL rating/Peak reflow at the end of the datasheet "Level-3-260C-168 HR", this essentially means that the device has moisture sensitivity of level 3 so part can absorb moisture from air once package is opened, part must be reflowed within 168 hours since package is opened and exposed to air else you have to bake it, and max temp of 260C that device is rated for reflow soldering process, per JEDEC standards.