I have done BGA's at work. I used a hot plate and a hot air gun. use flux and the solder on the part. Dont use any paste because it will make it ununiform, possibly lifting one side leaving unsoldered balls, unless you have a paste plate. We had a test fixture for the board to confirmed it worked.
There was a silkscreen to help me align the part, not the best idea since the silkscreen can be off. inspecting position on each corner should be good. Once done inspect the distance of each corner from the board to make sure it is uniform.
Brian
--- In Homebrew_PCBs@yahoogroups.com, "mcjonster" <mcjonster@...> wrote:
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> I want to use a Xilinx Spartan 3A XC3S200AN
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> It comes in 256-FTBGA.
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> I've done .5mm pitch SMD parts with my hot air gun but never BGA.
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> I understand I won't be able to inspect the part but is BGA that difficult?
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> Can I solder it with a hot air gun?
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> My current technique is to put the biggest tip on my hot air gun then I just watch until all the solder has reflowed.
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> For the BGA, I was planning on carefully aligning it under the microscope then just hitting it with hot air from on top. I was going to place some dabs of solder paste around the side and I figure if I heat it a minute or so after the solder dabs have reflowed then it should be ok.
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> I did some SMD parts with an exposed thermal pad underneath and this seemed to work fine so I guess the BGA parts will be too.
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> Should I invest in one of those cheap Chinese reflow ovens on ebay or is my hot air gun good enough?
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> Thanks.
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