- Joined
- Dec 21, 2011
- Messages
- 4,991
Removing the RF shield (as seen along the outlines in the work-area) was challenging enough. Enough heat must be generated to make the seam molten, without melting the plastic jacks on the board. (I use tin-foil to insulate against heat radiation/damage)
Once the shield is removed (very carefully! If I bump it, the components under it can get moved!), I let the board cool down.
A tiny dab of flux gets put onto the 6x6 area of the board where the chip will go.
I then use a 40x magnification jeweler's loop to position the chip absolutely perfectly, then use a tiny amount of paper towel to remove excess flux (while looking through jeweler loop) as too much flux will 'boil" when the heat is reapplied, causing bubbles which knock the chip off-center.
When I'm sure everything is ready, I heat up the area with a very hot (about 1100 F) but minimal-flow, hot-air gun, at a perfect angle which would not cause the component to move in either direction. The weight of this particular chip is also almost nil; other FBGA/VFBGA chips I've worked with are much easier to put in place.
After about a minute, the BGA solder balls become molten, and the chip "sucks itself" into perfect alignment.
I work on BGA/FBGA/VFBGA all the time. It's not a big deal. But I have to say, this is the tightest pitch/smallest package, I've ever manually worked on. The pictures are deceiving: It looks like a big board. I shot those pics with a super-macro lens. One could fit about 20 of those chips (if lined up edge-to-edge) on the face of that penny. American and Canadian pennies are the same physical size.
Once the shield is removed (very carefully! If I bump it, the components under it can get moved!), I let the board cool down.
A tiny dab of flux gets put onto the 6x6 area of the board where the chip will go.
I then use a 40x magnification jeweler's loop to position the chip absolutely perfectly, then use a tiny amount of paper towel to remove excess flux (while looking through jeweler loop) as too much flux will 'boil" when the heat is reapplied, causing bubbles which knock the chip off-center.
When I'm sure everything is ready, I heat up the area with a very hot (about 1100 F) but minimal-flow, hot-air gun, at a perfect angle which would not cause the component to move in either direction. The weight of this particular chip is also almost nil; other FBGA/VFBGA chips I've worked with are much easier to put in place.
After about a minute, the BGA solder balls become molten, and the chip "sucks itself" into perfect alignment.
I work on BGA/FBGA/VFBGA all the time. It's not a big deal. But I have to say, this is the tightest pitch/smallest package, I've ever manually worked on. The pictures are deceiving: It looks like a big board. I shot those pics with a super-macro lens. One could fit about 20 of those chips (if lined up edge-to-edge) on the face of that penny. American and Canadian pennies are the same physical size.
