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.