| General > General Technical Chat |
| Missing row labels in BGA package datasheets? Why? |
| (1/2) > >> |
| MarkS:
I'm working on a GUI-based utility to speed up the creation of complex parts in KiCAD (I am aware of KiPart, hence the "GUI-based"). Anyway, I downloaded the largest BGA datasheet I could find for eventual testing. I found a Xilinx UltraScale FPGA with 2892 balls. What I noticed is that on the row/column grid, the labels 'I', 'O', 'Q', 'S', 'X' and 'Y' are missing and this also goes for when the labels double, so, for example, 'AO' is missing. Checking other datasheets for other parts from other manufacturers turns up the same results. What I need to know is why this is, and if it is a standard, can I be directed to said standard? Is there ever a time where this will not be the case? I wasn't expecting this and it will complicate GUI creation a bit. I need to make absolutely sure that the GUI will match any datasheet on this issue. |
| dmills:
Same reason car number plates don't use the letters I,O,Q.... Far too easy to mistake them for numbers. I would assume this is a JEDEC standard, but do not know which one. Note that BGA packages with some balls missing are very much a thing, look at DDR memory packages for examples of this particular source of 'fun', you will need to support this. 73 Dan. |
| Cubdriver:
I don't know if it's a standard, but would guess that I, O, Q and S are not used because they're too similar in shape to 1, 0, 0 and 5, respectively, and could be misread. X and Y perhaps because they're commonly used for axis labels and/or variables. -Pat |
| MarkS:
--- Quote from: dmills on February 04, 2017, 06:23:08 pm ---Same reason car number plates don't use the letters I,O,Q.... Far too easy to mistake them for numbers. I would assume this is a JEDEC standard, but do not know which one. --- End quote --- --- Quote from: Cubdriver on February 04, 2017, 06:26:14 pm ---I don't know if it's a standard, but would guess that I, O, Q and S are not used because they're too similar in shape to 1, 0, 0 and 5, respectively, and could be misread. X and Y perhaps because they're commonly used for axis labels and/or variables. --- End quote --- That makes sense. --- Quote from: dmills on February 04, 2017, 06:23:08 pm ---Note that BGA packages with some balls missing are very much a thing, look at DDR memory packages for examples of this particular source of 'fun', you will need to support this. --- End quote --- Most definitely. I was aware of this and am planning on a way for the user to quickly select and discard missing balls/pins/pads (whatever). |
| MarkS:
One more question. With SIP, DIP and quad packages everything is referred to as a "pin". Does this naming convention still apply to ball grid, pin grid and land grid array packages? Is the grid position "J5" referred to as pin "J5" or ball/pin/pad/land "J5"? |
| Navigation |
| Message Index |
| Next page |