IPC-7351B Sets a Universal Zero Orientation for Electronic Components
IPC-7351B Electronic Component Zero Orientation [pdf]
This application note from Mentor Graphics defines a consistent zero orientation for electronic components in CAD libraries, aligning with IPC-7351 and IEC 61188-5-1 standards. It specifies pin 1 locations for various component families—chips, molded parts, MELF, SOT, QFP, BGA, and more—to enable global automation and a 'One World CAD Library'. The goal is to eliminate proprietary standards and reduce industry waste.
The land pattern standards clearly define all the properties necessary for standardization and acceptability of a 'One World CAD Library'.
- exmadscientist
Why is this posted here? It's old, and it's not terribly relevant, though it's not useless.
For anything larger than 2 pins, pin 1 at upper left and pin 1 at lower left are both quite common. Components are also reeled more or less randomly. (There are some patterns, but you'll be better served by pretending there aren't.)
Put that all together and it means... it's all a cluster and gets manual intervention for every build. You can't automate it, but you can automate the intervention (that's what JLCPCB has done to enable scaling to lower volumes).
Just pick "lower left" or "upper left" for your library and stick to it. That's the best you can realistically do.
Also, LEDs are terrible and everyone hates them.
- brotchie
Luckily never been bitten by component orientation issues. But every time I get a PCB assembled at JLCPCB with WS2812b or WS2816b LEDS they always email me to confirm LED orientation. I'm assuming customers have messed this up frequently enough to require a customer ACK.