Where can I find documentation that will tell me about polarity on components as it relates to pin numbers? For example, I'm in the process of making the librairies consistent but I have components that will have the cathode of a part either pin 1 or pin 2. This is specifically with 2 pin components (tantalum caps, diodes, etc.)I've been instructing the board house to follow silkscreen markings to make sure parts get stuffed correctly.
Ron Scott CID+
Why not use A and C instead of 1 and 2?
EMA Design Automation
In reply to BillZ:
I've used that nomenclature in the past. However, I'm working with a library that uses all 1 & 2. I know there is a document out there somewhere that states the industry standard and I need to provide this info to my boss.
In reply to Goblin59:
See the following PDF file.
In reply to mike1coppercad:
This is exactly what I was looking for! Thanx.
BillZHi Why not use A and C instead of 1 and 2?Regards,BillZ EMA Design Automation
Bill -- have you ever walked a PCB through its requisite steps on the assembly line? Ever seen how many hoops the assembly folks jump through because of misnamed pins? 1 and 2 is much preferred for diodes, resistors, and caps and the assembly folks do use that "common knowledge" when information is missing to determine where the cathode on a diode or negative pin on a cap goes.
The IPC suggested document above is a good starting point but there is a history to the old 1 & 2. :)
In reply to redwire:
We used to use A and C for diode pin numbers, but many SM didodes
used today come in SOT23 three pin type pakages, so we moved to
1, 2, and 3 for the pin numbers and A and C on the silkscreen layer only.