What did you mod today?

It has been reviewed, and verified that is a 10mm copper pill.

Besides, technically, since copper’s thermal mass is about the same as brass, it wouldn’t really matter in terms of heat capacity potential if it really was brass instead of the verified 10mm copper.

Although the heat dissipation would be slower, quite a bit slower in fact.

The thermal conductivity of brass is less than half of copper. It might hold similar amounts of heat once saturated, it’ll just transfer the heat slower.

What about Graphite sheet? https://m.newegg.com/products/9SIA2W07HJ7968?ignorebbr=true&nm_mc=KNC-GoogleMKP-Mobile&cm_mmc=KNC-GoogleMKP-Mobile-*~~pla~~*~~CPU+Thermal+Paste+%2F+Grease~~\_–9SIA2W07HJ7968&gclid=Cj0KCQjw3ebdBRC1ARIsAD8U0V5CNQAOifhjwXDWYUpPdQ37plWSGkvUpqq2aa54aaqS2INPohycNxQaAp6REALw_wcB&gclsrc=aw.ds

Also, does lead transfer heat better than indium Gallium?

Also Based on looking at numbers the graphite beats lead by 5 w/mk. Also Aluminum beats Brass, and is easier to machine/dremel. Copper wins total at around 385 w/mk, but liquid metal is almost 50 more than that of leaded solder. At 73 w/mk, vs 50 w/mk. This is all from googling out of curiosity.

It’s not only thermal conductivity which matters.

Liquid metal is better yes, but being electrically conductive, if it flows out, there is a high chance of shorting out a component. It can’t also be used to stack copper layers for obvious reasons, so can’t use it to fuse multiple copper layers if you aren’t a machinist.

Another thing is that you do not want to mix liquid metal and aluminium, at all. You have been warned.

Liquid metal is also very expensive. It’s also hard to apply. Finally, thermal performance(not thermal conductivity) is usually better with solder, unless you apply a very thin layer of liquid metal.

You can simply remove any excess liquid metal after screwing down whatever pieces you’re using.
Nothing else will flow out.

As long as something is holding the copper layers together, like the screw holes in regular MCPCBs, of course you can use liquid metal.

It’s not hard to apply at all, just rub it around with a Q tip.

Liquid metal is literally just that, a liquid, there is no “you need to apply a thin layer” because any excess will simply be squeezed out when you tighten the MCPCB down or whatever it is.
It will always be the minimum thickness necessary.
Unlike soldering, which can cool too quickly (especially when soldering large pieces of copper) causing excessive layer thickness, cold welds, and other problems.

Liquid metal is basically solder that doesn’t harden when cool, that’s why it is so good.

Maybe I’m a bit biased because I, well, ummmm… did something bad to a friend’s PC a while back. :person_facepalming:

Yeah. Liquid metal is the best in this case. I’d still go with a hot air reflow+preheating+solder paste for the best results, for me of course.

Liquid metal , as far as I know….is Gallium, which corrodes aluminum. So if you’re applying it to copper or brass then yes it works great. Otherwise, not so much. I have some and use it sparingly on special lights. :wink:

So, proven to be copper huh, on a light they are willing to sell for $38. With the cost of copper being what it is, I’m suspicious of those findings. Nonetheless, that light does look interesting for it’s fins… I’d love to see pics of that “copper” pill.

I’m pretty much done with soldering Luxeon V’s to 3535 boards :weary:

After succesfully modding a 21700 Sofirn C8F with Luxeon V’s a few weeks back, over 5000 lumen output, after a day or so I noticed that one of the leds lost half of its die working, and so output went down with that, 4500 lumen. Can’t stand that of course so I spent a few hours last week swapping the faulty led to a new one. After assembly: again one led that only lit up half (I did not registrate if it was the new led or one of the others). I really want this mod to work, so yesterday evening another go, new led, of course also some tiny wires broke off driver, resoldered them, minuscule solder pad ripped off, created new solder pad further down the trace and fixed wire, closed head, led-minus was shorted to body because of some twisting action while screwing reflector tight, opened up, changed led-wires, closed again, all was working….except one led only half lighting up :person_facepalming: , still 4500 lumen.

The probable reason is that for one 4040 led to be reflowed correctly on these wrong 3535 pads, it has been reflowed, checked, removed, and reflowed again on average 8 times before succes, times three (it is a triple) is 24 cycles of heating up and cooling down of the board, while far from following the adviced thermal regime for reflow from the datasheet. Apart from the heat stress, it makes the solder brittle and likely less thermally conductive.

So being many hours and three expensive LuxeonV leds down, and I’m going to find new leds for this host :frowning:

Post #6000!

(at the moment)

My modding vibes are so bad at the moment that I even did not manage to grab post 6000 :cry:

Well done raccoon! :slight_smile:

raccoon, nice job on modding the thread to a 6k one! :wink:

As you might remember there were several members reporting the problem with the half lit Luxeon V in the beginning of this year, including me. I haven’t even reflowed this LEDs by myself, I bought them already reflowed to MCPCB. Meanwhile I believe they are either all of bad quality or quality is not constant during batches. I don’t consider buying more of this LEDs.

Perhaps you could try LH351Ds?

They don’t have as low of a forward voltage of course, but they are still very good.

That is one of the options indeed, but still tinkering…

Where could I buy LH351D in good price to ship central europe free or very reasonably shipping cost?
I asked Sofirn if they want to make 4040 and 5050 MCPCB for C8F sold separately or option at buying host.

If you want 4000K 90CRI: led4power.com - got mine there

If you want 5k 90CRI you can get some DOG FARTS from here:

https://www.arrow.com/en/products/sphwhtl3da0gf4rts6/samsung-electronics

Also, less desirable but tons of selection:

Split a 50 euro order (free shipping minimum) with someone and choose multiple CCT’s from a large digikey selection. They have 18 different bin/color choices (check datasheet for models cause not all are categorized properly):

I feel your pain djozz. Sometimes nothing goes right, other days unbelievably fluid.

CRX says it true, just the way it is…

Forget who said it but it’s SO true… sometimes when you’re on the cutting edge you just gotta bleed a little.