Jumping the Gap: That pesky P60 driver-pill contact point.

My very first attempt at building a light was a P60 in which I failed miserably. Part of the problem was my cheap soldering iron, the other was bridging the gap between the driver and the pill. No matter how much I tred, the bridge kept failing. My solder was always breaking away from the pill when the large spring rubbed against it. The solder always failed where it had to jump accross that dead void where the driver press fits into the pill. Being nothing but air, and the fiber edge of the board presents a very iffy soldering territory.

I'm much better now, but I also developed a little technique I use to guarantee a solid negative connection to the pill with no weak solder gap.

A 1.4A Nanjg driver and P60 pill

I then attach copper braid to the neg. edge on the top of the driver in a few places.

I then snip the copper braid and bend it to the bottom side of the board, and press the driver into the pill. I've never used a 1.4A driver in a P60 before, but it sure makes things easy. Without any chips on the bottom side, I could just whack it in with a mallet.

Crop the copper braid short and bend it over the board, using a tweezers to squish it down.

The braid comes pre-impregnated with flux, but I add more anyway. Heat the braid with the tip of your soldering iron, touch the solder to it, and it will absorb the solder from the bottom of the driver to the top, filling the gap and ensuring a complete circuit and a strong bond.

That's just one way to do it. I hope this method can help someone.

I like your technique .

It might be worth it to get a better soldering iron. Bridging a small gap like that shouldn’t require a wire or any other type of gap filler other than solder. It should be very easy with a decent iron.

I also found using the right solder helps. haha

I got some 62/36/2 solder for reflowing LED’s cause of the better heat transfer abilities. And I was using it for everything, including bridging gaps. It was hard.

Then I tried regular 60/40. Wow, I forgot how easy it was to solder with that. Gaps are easy.

I have an excellent soldering station, and use proper solder. I don’t have problems any more with gaps, but just the same, this technique is still superior. A straight solder bridge accross an empty void will never be as strong as this. No one has to employ it, I’m just putting it out there as an option.

Looking at it, would it make sense to put the copper bent out towards the pill ? Dunno how the out spring would like that……

The braid is connected to the top and bottom of the board, and filling the gap tight against the inside of the pill for the full width of the board. The solder has been absorbed entirely through the braid, fusing it to the inside of the pill. You can’t get any better than that.

Gotcha. On a few driver boards I was a little to aggressive in cleaning off the crap on the edges and the fit is now loose, I’ll have to give that a try when I get around to using them

Thanks for posting this. This is similar to what I ended up doing on a Tiablo:

Hopefully what you posted plus some of the stuff I tried will make it easier for others!

I have decided to use the solid wire press-fit-only method from now on, as 1) I hate soldering to the pill even though I have figured out how to do it cleanly by now; and 2) I fiddle with things so often, being able to get at the backside of the driver with no soldering? That's like... amazing.

Spring? Who still uses those awful outer springs?! Use a solid spacer instead. Better heat transfer AND better ground path. And swapping dropins is still just as easy, unlike when you wrap them with foil/tape.

Thanks for the link comfychair. I was searching for that tip, but couldn’t remember where I saw it. I may PM you if I have problems with fitting.

great idea Comfy!

I recently used a single strand of copper wire to ground a star on a nanjc driver… i was trying to blob my way to ground out the third star but it was a mess… i stripped the end of a piece of scrap wire and separated the strands of copper wire. Using a single strand I soldered it to both the star and the pill, then trimmed the excess… works much better/cleaner….

i will have to try the press fit… as soon as my new drivers come in…. i just ripped the positive contact right off the board trying to solder a heavier gauge wire on…. |(


When you solder the braid to the traces, how do you get the solder to now flow into the whole braid?

When I working that Tiablo and tried something like this, in just a sec of contact with my soldering iron, about .5 - 1 inch of the braid would get impregnated with solder, so I just had one stiff piece of soldered braid. When I tried to bend that, it pulled the traces off of the edge in several places :(….

Funny, l have the same problem but you all know I’m a crappy solderer so come on ouchy, we need help.

Phew! I’m glad that it’s not just me :)!

I’m worried about soldering electrical stuff. Kind’a risky. Well done, anyway.

/begin thread hijack

Or, if you have too much free time, or need to fit a ~20mm driver in a p60, you can do this:

So would the heat transfer be better, since it has a much better connection to the pill, or worse, since it has less contact with the light body (it's a loose fit, and only sits on the little shelf)? It's definitely less convenient as you'd have to do this for each dropin while the split ring spacer stays in the light.

/end thread hijack


On my first dropin, when I couldn't get the solder to stick I put down the iron and grabbed the butane torch... and melted off all the components on the backside of the driver. :Sp

I lightly tin the small area where the braid is to adhere to, then wipe off any excess solder from the tip of the iron, and press it down on the braid until it sticks to the tinned area.

Why does that sound so easy? Thanks.

Actually, you don’t even need to solder it to the top side of the board. You can fold a piece of braid and hang it accross the edge of the pill, press the driver in tight, and trim and fold the braid from the outside of the pill, back over to the trace on the driver. Then flux and solder. It accomplishes the exact same thing.