Hey,
I am trying to reball the tegra / ram / emmc. I would like to know what solder ball sizes or solder paste you guys use. I have tried to solder paste with a stencil, the stencil “bulge” under heat ( I’m guessing it is not a direct heat stencil)? The stencil says T=0.2mm for Tegra and 0.12mm for bga and ram, do I purchase 0.2mm solder balls ? Any suggestions?
For the Tegra, that kit actually can use solder paste instead of solder balls.
I stick with solder paste all the time, so idk what solder ball size works best. 
For the SoC the ball size is 0.35mm, I don’t typically use paste as it typically butchers the chip due to issues keeping even and consistent pressure on and across the whole stencil, but it would seem the jig you’ve linked to eleviates a lot of these issues as it’s using a magnet to pull the stencil down… Though I will say, I’d question how long it retains it’s magnetism afer a few heat cycles.
as for the other ICs, sorry I’m not sure, as they’re small enough to use paste, I would guess the Ram is the same at 0.35MM (but you could check in the datasheets based on the packages), no idea about the EMMC.
do your stencil bulge after apply heat? which ones are you using now?
I have already ruined 2 magnetic PCB holder thingy (still have 4 good ones)
Ill try to look for the ram datasheet or stick with paste.
Thank you all for your suggestion
I have the same brand stencil like your link post, no bulge so far
I had a similar jig used in Xbox360 what I did was apply Flux paste on the gpu then put the stencil and fill it up with solder balls then remove the stencil and place the gpu on a preheater until the solder balls attaches to the gpu. I don’t use direct heat. But I guess you could use hot air after removing the stencil. Although it a bit tricky some of the solder balls will be removed as well when you lift the stencil.
Try getting a BGA jig like this one
Avoid the other types as most are not suitable for the switch SoC as the jaws are too low which means the stencil has too much height and the balls will roll around underneath. they also don’t grab the IC all that well.
and then a dedicated 90x90 stencil such as this
As @Solac03 mentions, you’d remove the stencil after filling the balls and then remove the IC from the jig, then reflow the balls.
Alternatively, you can just use the stencil you currently have with the preformed 0.35mm balls, and you can leave the stencil in place and directly heat and reflow the balls in situe, you don’t have to remove the stencil prior, it will still likely buckle when you apply heat as it has done while your using solder paste but unlike solder paste, this doesn’t have the same negative effects as, wheras the paste will try to run and merge together below the stencil with the preformed balls won’t
The only issue with this aproach is it will be messy and you’ll have a hard time getting the balls into the stencil without the bronze jig above, as you can’t swirl them around.