It’s a thin (0.15~0.2mm) flex board DTP adapter for soldering 3535 LEDs onto a 5050 board, sometimes using another MCPCB is not possible, or in the case of Zebralight for example there is no MCPCB to swap at all.
3535 to 5050 : OSH Park ~
5050 to 7070 : OSH Park ~ (not tested)
That is so awesome. I could have used a few 3535 to 5050.
What a great idea! Have you tested how heat transfer will be affected?
Also, do you suggest reflowing both the adapter and emitter onto the MCPCB at the same time, or in 2 steps?
I didn’t compare performance, with the adapter the only difference is a 0.15~0.2mm solder layer between the copper base and the thermal pad of the LED, while solder has lower conductivity (50W/m.K) than copper (400W/m.K) it probably doens’t affect much heat transfer over such a thin layer.
I reflowed in one step, for the thermal pad I think it’s preferable to add solder to it before reflowing instead of paste though, since it need a certain amount to fill the gap, with a lot of paste it might make a mess.
Thanks for the feedback.
Tinning the thermal pad should be easier, which I'll trial on one sample. But applying paste with a fine tip applicator with a stencil should offer more consistent results. I'll report back if I try these out.
Looking at Oshpark’s flexpcb data it says it is using Panasonic R-F775 substrate. That is a polyimide film with a poor thermal conductivity of 0.16 W/m.K. Oshpark’s is 0.1mm thick.
So in all this is adding 1 extra layer of solder (0.15mm = 3.3e5 W/K each) and 2 extra layers of copper (35um = 1.1e7 W/K each) and the plastic film (0.1mm = 1600 W/K). Those combine together for a thermal resistance of 1590 W/K. Which is about 90x worse than the thermal resistance of a 1.5mm copper mcpcb with a layer of solder.
I would be very careful running this at high power!
There’s a cutout for the thermal pad :
Oshpark PCB viewer doesn’t display cutouts well, the black lines indicate the edge cut and cutouts, even if it’s filled with purple color.
Edited the title and description to add “DTP”.
Ah okay. Carry on 
Wow this is exactly what I’ve been looking for to use in my Zebralight sc600 mk2, I have a dedomed xm-l2 currently but looks like it’ll be getting a 519a!!
Interesting idea! Though with a dremel I’ve so far always been able to swap out the MCPCB.
What’s more challenging is to find boards for 3030 or 4040. Here an adapter would be awesome.
Interesting. I have a Nitecore HC60 headlamp with a 3v XM-L2 that I’d love to swap out with a 519A. This could be the trick. Thanks for coming up with this.
Thanks for designing these, I don’t have a project that needs them just yet but they were so inexpensive I couldn’t say no.
good idea
I have an Olight w XM-L2 that Id love to swap to 219b..
thanks to your good example, I just copied you
thanks to thefreeman for my first OshPark Order
Thanks to thefreeman for my second OshPark Order!
So, SC700 with 50.3 HI?
Very nice adapters, how have I not come across them until now?
Unfortunately the flex PCB option has been “temporarily suspended” for quite a while now at OSH Park (since at least early August 2025, according to the Internet Archive), it seems unlikely to me that it will be available again in the near future.
Since I could really use some of the 5050 to 7070 adapters for a current project, does anybody now a good alternative to OSH Park for flex PCBs?
I know there a many PCB manufacturing shops, but I have no idea which is a good/cheap option for flex PCBs and is ideally located in the EU or uses IOSS for hassle free shipping.
@thefreeman do you still happen to have the necessary gerber files for these adapters and if so, might you be willing to share them so I could check the pricing at different PCB manufacturing shops?
I was just wishing something like this was available and then this thread pops up. I need a 9090 to 7070 adapter. Anyone know if those exist?
Sorry for the late reply, here are the gerbers (remove the .pdf)
5050_to_7070.zip.pdf (10.4 KB)
Hi,
I’m in the same boat as Noir, also in EU and OSHpark is not making flexPCBs anymore, I asked them a few days ago and they still don’t know when it will be resumed.
I could use the 3535 to 5050 adapter, linked above on OSHpark for a Sofirn HS21 to convert the 5050 LED to a high CRI 519A which is 3535 as there are no high CRI 5050 LEDS even decade+ later.
(It’s probably my 3rd account with similar name here, always forget the password and old email service to recover it is nonexistent now. JackCY, did some reviews and Nanjg modding and ATTiny13 flashing guides long ago.)
I would like to try and order the 3535 to 5050 from a different flex PCB maker but need the files as I am way too rusty to design PCBs. Not sure what the standard and formats are this year.
Would you be so kind and share the necessary files so I can try and get the adapter made?
Thank you 
Jack
