Printed Circuit Board Assembly & PCB Design SMT Electronics Assembly Manufacturing Forum

Printed Circuit Board Assembly & PCB Design Forum

SMT electronics assembly manufacturing forum.


0201 and uBGA

Yannick

#20239

0201 and uBGA | 5 June, 2002

Hello!

I have a strage problem, we made some production with uBGA, BGA, 0201, 0805, and other type of component. We didn't put the uBGA and 0201 and BGA on the board at the end of the line we look a our solder joint and surprise the solder made a good dome on the pad of the BGA, and 0805 but when we look a the uBGA and 0201 we have like 3-4 bead of solder that did'nt melt...I don't have a really good joint on the other pad ( they are too much granular I think) but all the solder are melt except for those uBGA and 0201...

Did someone have ever face this kind of problem? we try to heat a little more our board but we saw the same result.

If someone could give me a good shrewdness I appreciate it.

Thanks you

Yannick

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#20243

0201 and uBGA | 5 June, 2002

Tough to say based on what you have told us. Things to Determine are: * Is the heat at the solder connections that are not reflowing properly adequate? * Is the pad surface of the solder connections that are not reflowing properly solderable?

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steveb

#21705

0201 and uBGA | 23 September, 2002

On an assembly reflowed in air saw the same thing: 0201's with a grainular solder joint, but 0402's and above with perfectly formed joints. Reflow profile all within acceptable tolerances. Reflowing in nitrogen solves this problem, but increases tombstoning significantly. We were using a leading no-clean solder paste. My guess is that there isn't enough flux vehicle to prevent oxidation when printing this small amount of paste, other ideas?

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CH

#21741

0201 and uBGA | 25 September, 2002

U may check your profile ramp rate. The flux may evporated and look like cold joint

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Pc

#21747

0201 and uBGA | 25 September, 2002

Yeah, perhaps lean more towards a ramp-to-spike profile - reducing the soak time and add a littel heat to your temp above liquid. This has worked for us with water soluable paste as we are not required to use no-clean and utilizing a 6-zone oven. Get your paste rep in there and have him/her create a new profile that falls within your particular paste tolerances. It works and takes the "magic" out of experimenting with profiles till you see good results.

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#21750

0201 and uBGA | 25 September, 2002

Yannick,

If we leave the 201 issue aside; have you checked where those BGA pads are connected to? Could those be power/ground balls connected to large (difficult to heat up) planes by any chance?

Erhan

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