I have not done a lot of work with SMD LEDs and have a question about the pad layout. I have done quite a bit of research and haven't found much helpful info yet.

I am working with 7030 SMD LEDs purchased from eBay https://rover.ebay.com/rover/0/0/0?mpre=https%3A%2F%2Fwww.ebay.com%2Fulk%2Fitm%2F182474024179

There are 3 pads on the bottom of the LEDs, as pictured below. As I understand it, the center pad is used for heat dissipation (though I'm not sure of that). The problem I am having is that the center pad on the bottom of these LEDs I purchased is the anode. While the LEDs that I am replacing look identical but the center pad is the cathode. Is anyone familiar with this style of LED and know whether this is normal? It doesn't make a lot of sense to me to have a heat sync connected to positive voltage. So I am wondering if I just purchased a bad batch of LEDs or if I just need to search harder for 7030 LEDs with a datasheet and cathode on the middle pad. Most similar SMD LEDs datasheets I've seen seem to only have that bottom center pad as the cathode.

So are these abnormal LEDs, or did I just buy the wrong ones? Thanks for your help! I hope this is on topic enough.

New LED pad configuration

New LED pad configuration

  • \$\begingroup\$ Always look for the datasheet led.lginnotek.com then similar. for PCB layout and heatsink for 7030 LED \$\endgroup\$ – Sunnyskyguy EE75 Apr 17 at 23:04
  • \$\begingroup\$ The best layouts will use Alum. MCPCB like these venture-mfg.com/led-pcb-assembly The pad designs will be somewhere for these old styles (>5yr) I might suggest these are going obsolete \$\endgroup\$ – Sunnyskyguy EE75 Apr 17 at 23:16

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