Idk people seem to think the sink pad technology is pretty good.
Apparently Brass will work sometimes, aluminum better, copper better still, silver even better.
If you need a better heatsink than copper, here is something better. Plus the dimes are about 18mm in diameter, which is about the right size. Kind of the ultimate heatsink.
I wish I could find the thread that I was reading about heatsinks and the link therein showing the different values….
That would be here
This one too
Along the lines of the cost of the material for mass production, brass, aluminum, and copper are the “best” heat conductivity to cost ratio…but copper and brass are the only two easily solderable
Copper and aluminium sinkpads are well used in these parts, Noctigons are a made product fitting the description and they come in a variety of specific purpose made sizes. There is also an alternative product named Sinkpad, which is also copper. There are aluminium variants too.
There are ‘pills’ these are then attached to, also made from copper or aluminium. A cheap source of silver would interest some of the modders Im sure, but I was doubting there being an untapped source circulating in US currency. I assumed if they had value, they would be officially pulled, added to collections at the new value, or defaced as scrap silver.
If a quarter is worth a dollar in silver, and they are available at face value ($0.25) then I can see a lucrative business idea. Although I assume defacing US currency is illegal too?
Oh yeah no you have to buy them. I find them now and then but I’d probably look on eBay if there’s no local coin shop.
You might check the Australian coinage. Probably some 90% silver there too.
Saw a thread where someone said if you’re loaded ($$$ aussie or us) use silver. But you dont have to be.
I’ve heard defacing coinage is illegal but they seem to melt them by the ton. And people are sanding pennies.
It is a better heatsinking material. Maybe for your best lights.
Yeah that’s it, I think, war hawk! The second one is even better, because it shows the density. A bit better than copper. What thread was that on?
ummm…Google
Seriously, just searched thermal conductivity of metal and thermal conductivity in heatsinks
It doesnt matter all that much. The most critical point is where the LED contacts the PCB, so use a copper PCB and if the pill is made from aluminium, screw it down. If its made from brass or copper, solder it down. Solder instead of glue will make a bigger difference than the material. Thats why I really like to see more and more hosts come with brass pills. :)
90% silver alloy has significantly reduced thermal conductivity compared to pure silver(just like any metal alloy),and that number is lower than pure copper for sure.
Yes better eliminate the thermal paste and solder it down to brass or copper if you have a copper mcpcb. I see people put a lot of paste under the LED "to heatsink better". that is the worst thing you can do, a thick layer of thermal grease or glue. On top of that I see many using the poor thermal conductivity Fujik glue, rated at 0.88W/m.K
This is viffer750's graph:
Sterling Silver (92.5% Ag, 7.5% Cu) has a Electrical conductivity (IACS) rating of 96% where pure copper is 100% and pure silver is 105%.
It is is not a thermal conductivity rating, but shows that silver alloyed with copper (only) loses those absolute proprieties and usually electrical conductivity goes hand in hand with thermal conductivity in alloys. http://www.substech.com/dokuwiki/doku.php?id=sterling_silver
Absolutely!!!
A very very thin layer, as a way to fill the gaps in the uneveness of the materials, barely matters what the material is, something there to keep the insulative air out…NOT as a gasket!
Good call!
It IS illegal to melt CURRENT u.s.a. coins, for their melt value. xample? illegal to melt the current use ZINC pennies, because the zinc sometims becomes 2 cents in value per cent piece…
money not CURRENT in circulation? (example, old copper pennies…) is not current anymore… it s properly referred to as BULLION. It MAY be worth somthing collecting wise? or it MAY b worth something for its metal content…
but if its not current circulation? its legal to do what you want with it.
silver dimes, and copper penies, are fair game to do what you want to with them.
now, that said?
i HAVE taken a handful of zinc pennies before, and melted them, and poured them into a mold to make something. The secret service did not come crashing down my door, LMAO… but, i would NOT make a “business model” around getting the half-price ZINC by melting zinc pennies, when th price of zinc spikes… good way to end up in the federal pen, lol…
although it is illegal to “deface” us currency? The ARE vending machines you put a PENNY into, and pay a fee… and turn a CRANK and it makes a CHARM for a bracelet out of it… ad ther is also companies that specialize in putting “photographd faces” onto “real” US paper money? and th money is still legal tender…
just remember… ANY coins no longer IN CIRCULATION? are simply bullion to do with as you see fit…
This document says 86% IACS for 10%copper:
http://www.thessco.nl/assets/files/fichesthesscopag2.pdf
In any case,conductivity is lower than pure copper which is much cheaper.So I don't see the point using more expensive and slightly inferior material.
Kind of a big difference, even though there is no direct comparison between the sources (10%Cu vs 10%Cu content).
You can see here a whopping 78W/m.K for the SnAg 96.5/3.5 alloy from a study (seems too high in my opinion), while 2 manufactures rate it much lower at 55W/m.K and 33W/m.K. https://budgetlightforum.com/t/-/24901
Sure would suck to use a coin and then find out that it might have been worth thousands as a rare strike.
I have wondered what silver rod might cost, as compared to copper.
But hey, onlinemetals.com has started using USPS flat rate as a shipping option! I just ordered a 1” long 1.375” dia copper bar and a 2” long .75” copper bar with $6.xx shipping for a total of $24.37 shipped. Easy enough now to get the copper you need, why deface old coins?
The 1.375” piece will be going into a D MagLight, the little one cut up for AA MiniMags. 
why bother?? it does not do much good anyway.
i do think good HTR of sinkpads and noctigons, are more result of soldering led directly, than because it is made from copper. old stars had delectric layer that had single digits HTR, direct path has same rate that of solder that is used to reflow led, which is about half of auminium. so why bother with stars\pills that can do 400+ when heat does not transfer any faster than 50?
the way i see it, no matter how many windows in your house you open, a person with a plastic bag over his head will still not breathe any better.
It's NOT illegal to melt US coins. It IS illegal to remove part of a coin or make a fake coin and pass it off as a real unmodified coin. Go ahead and do whatever you want to your coins. It's legal as long as it doesn't go back into circulation.
“Under the new rules, it is illegal to melt pennies and nickels. It is also illegal to export the coins for melting. Travelers may legally carry up to $5 in 1- and 5-cent coins out of the USA or ship $100 of the coins abroad ”for legitimate coinage and numismatic purposes.”
Violators could spend up to five years in prison and pay as much as $10,000 in fines. Plus, the government will confiscate any coins or metal used in melting schemes.”
There is also that age old “Give unto Caesar that which is Caesar’s” , the currency actually belongs to the US Government, we use it in a sort of barter system. Our tax base supports the minting of coinage and as such, the government (we the people) owns the coinage. Debatable all around of course.
And directly from USMint.gov (April 17, 2007)
“WASHINGTON - The United States Mint today announced a final rule to limit the exportation, melting, or treatment of one-cent (penny) and 5-cent (nickel) United States coins, to safeguard against a potential shortage of these coins in circulation.
United States Mint Director Edmund C. Moy had approved an interim rule on December 12, 2006, to be in effect for 120 days. Enactment of the final rule was pending public comment, solicited during a 30-day period from the date of the interim rule’s publication in the Federal Register on December 20, 2006.
“The new rule safeguards the integrity of U.S. coinage and protects taxpayers from bearing the costs to replace coins withdrawn from circulation,” said Director Moy.”
Cool news about online metals. Finally!