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I have a JEDEC 1.0mm pitch 27x27 device. The only missing information I need to build a footprint for it is the size of the pads.

What size of pads should I use for a JEDEC 1.0mm pitch 27x27 device?

Randomblue
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    What is the device? – Leon Heller Mar 07 '13 at 18:07
  • Please see [this question](http://electronics.stackexchange.com/questions/59291/pcb-footprint-of-xilinx-kintex-7-fpga). – Randomblue Mar 07 '13 at 18:11
  • Since you already have the package spec, look it up to see where the pins are, then make the footprint accordingly. Why are you asking us? – Olin Lathrop Mar 07 '13 at 20:38
  • @OlinLathrop: Pad size. – Randomblue Mar 07 '13 at 20:40
  • @Random: But the pad size is up to you. There is no such thing as a single standard pad size for each package. You have to decice how much extra you want past each pin, how much solder mask clearance you need to leave, etc. You would have been done by now if you'd just sat down, read the datasheet, and made the footprint in whatever your ECAD program is. – Olin Lathrop Mar 07 '13 at 22:56
  • @OlinLathrop: You have no idea of what I've done. I have read datasheets, and I have used my CAD software to quickly build packages. However, I still have full control over the padstack; this is not done automatically for me. Since this is my first board layout, I had no idea that the pad size is "up to me". What's more, it's obviously not just "up to me". I'm sure there are rules and guidelines that should be followed (for which I have no clue about) and which I was trying to understand from asking the question. Why is it that I asked two questions, got both closed, and still got no answer? – Randomblue Mar 08 '13 at 08:31
  • Re: the "duplicate" question : its answer says the pad size is the same as every other (similar) device, which is technically correct, but not especially useful. Said question was then closed before any useful answers could be added. –  Mar 08 '13 at 10:29
  • @Random: If you wanted general guidelines about how to look at a package definition and decide what a good pad layout is for particular circumstances, then you should have asked that. However, you asked what the "right" footprint is for a particular package. That's very different. – Olin Lathrop Mar 08 '13 at 12:53
  • @OlinLathrop: Yeah, well I didn't know that was the right question to ask in the first place was, since I didn't know there was no concept of "right". – Randomblue Mar 08 '13 at 14:00

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Xilinx application note XAPP426 "Implementing Xilinx Flip-Chip BGA Packages" is probably your best place to look for an answer.