3 ms·

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 c

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.

15155 2mo ago
They will send this email for all LEDs and generally all polarized components (capacitors, diodes, etc.) JLC is also extremely unique because they offer the component orientation configuration GUI. This GUI's output is likely used for PNP tape orientation configuration as well.
Karliss 2mo ago
ws2812 family is a mess. The pin 1 is not the pin which has the corner mark and pinout varies between specific packages and variations.
- CableNinja 2mo ago
  What an awful set of things to do!
  - exmadscientist 2mo ago
    All LEDs are like this. It's horrible. The only good thing about it is that every professional in the entire industry has come to expect that if it's an LED, something somewhere will be wrong with it.
    - Karliss 2mo ago
      By all LEDs do you mean addressable and other multipin LEDs? Never seen anything weird with classic 5mm/3mm. The flat side+leg length is quite reliable. 0805/1206 smd LEDs also seem mostly fine.
      - exmadscientist 2mo ago
        No, I mean all LEDs. The cathode marks are basically randomly assigned. This is because each company more or less designs one leadframe/package structure per size or type of LED. Sounds reasonable, right? But LED dice aren't made of silicon. They're made of weirdo high-bandgap materials, and every color is different in its own way. From physics alone, some of the colors end up with cathodes on top of the dice and some of the colors end up with anodes on top. They all get bonded in to the package the same way. So... that marking built in to the package? That's always the "top of die" wire next to it. But "top of die" might be cathode, or it might be anode. Flip a freaking coin! If you want to see this clearly, find a datasheet that covers an entire series of LEDs. Vishay often does this, here's one: https://www.vishay.com/docs/82437/vlmo1300.pdf https://www.vishay.com/docs/82437/vlmo1300.pdf . They'll tell you the marking locations for each color individually. Notice how they're all completely different? Yeah. Could the manufacturers do better? Yes. Yes, they could. We all wish they would do better. But they do not. So LEDs are the stuff of nightmares for people who assemble boards. Through-hole parts are somewhat better (but there are certainly rogues!), but this is 2026: the volume's in surface mount. Multipin LEDs are no better. The SMD no-lead versions are again fairly randomly marked. The PLCC-4 types are usually "cutoff corner near pin 1", but I've seen it as pin 4... or pin 2... constant vigilance is the only solution. Constant vigilance!

15155 2mo ago

They will send this email for all LEDs and generally all polarized components (capacitors, diodes, etc.) JLC is also extremely unique because they offer the component orientation configuration GUI. This GUI's output is likely used for PNP tape orientation configuration as well.

Karliss 2mo ago

ws2812 family is a mess. The pin 1 is not the pin which has the corner mark and pinout varies between specific packages and variations.

CableNinja 2mo ago
What an awful set of things to do!
- exmadscientist 2mo ago
  All LEDs are like this. It's horrible. The only good thing about it is that every professional in the entire industry has come to expect that if it's an LED, something somewhere will be wrong with it.
  - Karliss 2mo ago
    By all LEDs do you mean addressable and other multipin LEDs? Never seen anything weird with classic 5mm/3mm. The flat side+leg length is quite reliable. 0805/1206 smd LEDs also seem mostly fine.
    - exmadscientist 2mo ago
      No, I mean all LEDs. The cathode marks are basically randomly assigned. This is because each company more or less designs one leadframe/package structure per size or type of LED. Sounds reasonable, right? But LED dice aren't made of silicon. They're made of weirdo high-bandgap materials, and every color is different in its own way. From physics alone, some of the colors end up with cathodes on top of the dice and some of the colors end up with anodes on top. They all get bonded in to the package the same way. So... that marking built in to the package? That's always the "top of die" wire next to it. But "top of die" might be cathode, or it might be anode. Flip a freaking coin! If you want to see this clearly, find a datasheet that covers an entire series of LEDs. Vishay often does this, here's one: https://www.vishay.com/docs/82437/vlmo1300.pdf https://www.vishay.com/docs/82437/vlmo1300.pdf . They'll tell you the marking locations for each color individually. Notice how they're all completely different? Yeah. Could the manufacturers do better? Yes. Yes, they could. We all wish they would do better. But they do not. So LEDs are the stuff of nightmares for people who assemble boards. Through-hole parts are somewhat better (but there are certainly rogues!), but this is 2026: the volume's in surface mount. Multipin LEDs are no better. The SMD no-lead versions are again fairly randomly marked. The PLCC-4 types are usually "cutoff corner near pin 1", but I've seen it as pin 4... or pin 2... constant vigilance is the only solution. Constant vigilance!