Simple process - we use similar Kester solder brands of "no clean" low residue solder wick to clean our pads, then brush with isopropyl, and apply Kesters brand of tacky flux under a Leica 6x microscope. We do this on 7x7mm and 9x9mm packages. This works well with our failures from test, where we use BGA pre-form solder quik reballing templates.
In feedback from engineers I have not had any reports of thermal failure in logic ICs or passive/active components. The neat part is that I don't require a BGA camera or scope to peer 3-4 rows in for alignment, the natural tension generated by the "flowing" solder pulls it into place. ----------------------------------------------------------
John here at Volterra we use a standard reflow profile for our BGA rework & placement. I like the reflow oven for consistent results, it's a 4 zone convection oven. Our boards go 4-7 layers, 1"x4" modules up to load boards going 8"x12". All have a mix of 402/603 caps/res and usually have inductors plus fuses/diodes/in mixed packages.
160 170 190 270 top heaters 160 170 182 250 bottom heaters
Belt speed set between 17-19 resulting in a 4:20 - 4:30 min/sec profile. Thermal profiling on the curve reads 175` at start of 3rd zone and peaking in 4th zone at 225` C .
Regards, Phil Johnson Senior Engineering Technician http://www.volterra.com/
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