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Assembly of through hole and SMD on same PCB

mrinalmani

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Hi
We need to assemble 65W laptop chargers for small to mid volume production (around 1000 units per month). The PCB has both SMD and through hole components. SMD on the bottom layer and through hole on the top layer. I was wondering what is the standard method for assembling through hole and SMD on the same PCB. We can do pick and place for the SMD and then later manually solder the through holes, but is there a better way than manual.
I saw another 230W adapter that had both SMD and through hole. It had red-adhesive on all the SMD components. What could have possibly been the assembly process for this board?
Any one with experience, please share your views.
Thank you
 

FvM

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SMD components glued to the bottom (solder) side can be wave soldered, but the technique is only compatible with larger SMD components and involves restrictions for the component orientation. State of the art is selective wave soldering of THT compenents. A certain clearance around bottom side SMD components must be observed.

1610726872869.png
1610726950526.png
 

mrinalmani

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Thanks for the reply.
Can we have 0603 size components and typical TQFP packages on the bottom side and have it wave soldered? Will it not cause bridging in the TQFP packages?
 

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TQFP is too small for SMD wave solder. Go for state of the art technology.

In mixed SMT/THT boards, top side is the first choice for placing SMD.
 

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