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Working with the Xilinx Virtex-E FPGA in a huge BGA package

Working with the Xilinx Virtex-E FPGA in a huge BGA package

The blank boards have arrived

It’s normally about three or four weeks from the date of the design upload to it arriving back in the UK and this was no exception. Patience is a virtue when using the HK Post shipping service. Here’s how they look, top and bottom. I’ve grown to like the mustard-yellow soldermask with white silkscreen and will probably use it more in the future.

The choice of finish for your pads can either be HASL or the more expensive ENIG (that’s the gold coloured one). ENIG has the advantage of producing a totally flat finish but costs a fair bit more. I did some research and ENIG is favoured for BGA footprints of less than 0.8mm pitch. Above that HASL is fine. Mine is a 1mm pitch BGA so I went with HASL to save on the costs.



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At first glance the PCBs appear to be as well manufactured as I’ve come to expect from PCBWay’s four layer service. Drill registration is spot on and all the narrow soldermask slivers are intact. However, inspection under the microscope did show that a few of the boards had minor manufacturing defects in the BGA footprint area.

As you can see from this close up the soldermask has spilled over to partly obscure one of the pads. This is not good, but I did expect that I wouldn’t get a 100% result from a prototype service on a BGA footprint this large and that was the main reason for me ordering 10 boards and not the cheaper 5. Most of the boards were defect-free though, and now I could move on to the reflow process.

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