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If I understood correctly, current BGA components contain solder balls under the package. Do I still need additional solder paste to put on the board, or the amount of solder on the component contacts is sufficient?

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  • \$\begingroup\$ I dont actually know either, but I always thought there was just enough there already to work, because any more would fill in holes and spread around and create short circuits etc.. just pop it in place and heat her up with a hot air rework station and i guess it will seat itself and work as intended.. I need to try this eventually but I have avoided BGA packages so far with my hand soldering designs \$\endgroup\$ – KyranF Oct 24 '14 at 13:42
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    \$\begingroup\$ Flux is what you want, not solder. \$\endgroup\$ – Majenko Oct 24 '14 at 13:49
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    \$\begingroup\$ Check out this question and answer, may be interesting: electronics.stackexchange.com/questions/14265/… \$\endgroup\$ – KyranF Oct 24 '14 at 13:55
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    \$\begingroup\$ Yes, you do use solder paste on the BGA pads on your PCB. The amount of solder that comes already attached to the chip is about half of what is needed for the final joint. You use a paste mask to apply a precise additional amount to each pad. But there's a whole lot more to it than that, as the question that @KyranF has linked to points out. \$\endgroup\$ – Dave Tweed Oct 24 '14 at 14:16
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    \$\begingroup\$ @DaveTweed This board is a prototype, and the only thing I am concerned is proper electrical connection. If the device will fall off in a month - I just might make another one. Is the entire ball made of the solder and it melts, or only a tip of the ball is covered with solder? My pads are slightly less in diameter than the half of the ball diameter, so I figured it would be enough solder on the balls if they are made of solder? \$\endgroup\$ – Nazar Oct 24 '14 at 16:33
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No, you do not need solder paste. In fact, if you add solder paste you will probably get some pins shorted. You might want to add some flux which will improve soldering but this is not a must.

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  • \$\begingroup\$ Are there specific types of flux with some features that are preferable for BGA soldering? I heard that some burn off before the solder melts, the other might remain on the board and affect the performance. \$\endgroup\$ – Nazar Oct 24 '14 at 21:50
  • \$\begingroup\$ I'm not that of an expert in fluxes but just do yourself a favor and don't buy cheap/fake stuff on ebay. A small jar should cost around $50 and will last for 2 years (or more). I use KOKI TF-M955 for all leaded lab & prototype work. \$\endgroup\$ – Gilad Oct 24 '14 at 22:26
  • \$\begingroup\$ I wish people could do some voting on your answer. If I do not need extra solder on the board (which I hope for) then why do they make stencils with BGA holes? Why some recommend fine ball size solder for BGA soldering? At this point I can only conclude that it is possible to perform soldering both ways, but which way is more likely to be successful if all other variables are the same? \$\endgroup\$ – Nazar Oct 27 '14 at 14:58
  • \$\begingroup\$ The 'balls' are the solder, this guarantees that the exact solder amount is applied. Most BGA (all that I have seen) arrives from the factory with balls attached, maybe in some manufacturing processes BGA arrives with no balls (pads only) and need extra solder paste. \$\endgroup\$ – Gilad Nov 25 '14 at 7:31
  • \$\begingroup\$ Hm.. I would also think that solder from the balls is sufficient enough. However, I had my board assembled by a company, and I know for sure they put solder paste on the BGA pads on the board. Though, all BGA components had solder balls by default from the manufacturer. I hope I will have some time to try soldering BGAs myself with and without adding extra solder paste. That's probably the best way to find out. \$\endgroup\$ – Nazar Nov 25 '14 at 16:45

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