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Posted by Manncorp

Ask: How to solder SAC105 BGA with SAC305 Paste?

  • Usually those kinds of issues are related with the difference between both SAC, SAC305 is liquids at 426°F and SAC105 is at 437°F, when this difference occurs you have to set the liquid point at the worst condition 437°C.  Now you will see that's is only 11°F but that difference will reduce our process windows. So when you define your new process window your liquids will be at 437°C.
  • Try a longer TAL (time above liquidus) for additional 30 sec.

Ask: How can we improve the BGA soldering process?

Few care can help you hit is right the first time.
  • Baking the BGA (Hands down. no exceptions, even if it is in vacuum sealed. it will just help your process)
  • Baking the boards.
  • Having proper stencil apertures. Use IPC-7525-L to begin with.
  • Having properly handled solder paste, thaw it to room temperature before use.
  • Using proper reflow profile. Don't have first few zones high and have proper TAL.
  • Using x-ray online inspection to make sure all solder joints are up to required or spec or to follow IPC-610D

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