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Rant: Top View vs Bottom View on Datasheets.

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TerraHertz:
With any multi-leaded through hole component (eg TO-92) I have to layout on a PCB, I do a little 3D sketch to make sure I have the pins ordered right. Usually put this on the schematic too.
So, I don't care at all which way the datasheet shows it. Just so long as it's correctly labeled top or bottom view.

Prabhat:
Oh. This is a common problem. Thank god. I am feeling like shit today because I just destroyed a 15k Euros PCB board because of pinout top/bottom views.

I have done many passive antenna PCBs before but this was my first active antenna board (12 layers, RF at the top and bottom, analogue, digital and baseband at middle layers, 20 GHz antenna array PCB with electronics for beamforming). Unfortunately, the whole PCB is a piece of junk now because I assumed that the beamforming chip pinout was top-view but it is actually a bottom view and my chip layout in the PCB is flipped (It is a BGA chip with 9x11 400um bumps). The worse part is that the datasheet does not say if the pinout is a top or bottom view. When the prototype did not work during testing, we guessed that the pinout might be wrong and when we asked the chip manufacturer they say "It is a bottom view". And puff.... 15k Euros gone. The last 12 months of my work gone. |O |O |O

tggzzz:

--- Quote from: Prabhat on April 14, 2023, 09:37:41 am ---Oh. This is a common problem. Thank god. I am feeling like shit today because I just destroyed a 15k Euros PCB board because of pinout top/bottom views.

I have done many passive antenna PCBs before but this was my first active antenna board (12 layers, RF at the top and bottom, analogue, digital and baseband at middle layers, 20 GHz antenna array PCB with electronics for beamforming). Unfortunately, the whole PCB is a piece of junk now because I assumed that the beamforming chip pinout was top-view but it is actually a bottom view and my chip layout in the PCB is flipped (It is a BGA chip with 9x11 400um bumps). The worse part is that the datasheet does not say if the pinout is a top or bottom view. When the prototype did not work during testing, we guessed that the pinout might be wrong and when we asked the chip manufacturer they say "It is a bottom view". And puff.... 15k Euros gone. The last 12 months of my work gone. |O |O |O

--- End quote ---

Shame it wasn't a through-hole component. If it had been you could have tried the board simply by mounting it on the other side of the board.

That does work; I saw it used 35 years ago when the manufacturer (AMD IIRC) issued a preliminary datasheet for a prototype component with the pinout as viewed by the semiconductor mob :)

MarkS:
This has bitten me before. I learned the hard way to pay attention to that. It's very annoying.

SiliconWizard:
What is top and bottom anyway? Do the australians not live upside down? :-DD

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