What do you find works to get a connection soldered to an aluminum pill?
I have an old low-end Hakko temperature controlled soldering iron.
I have a “Little-torch” jewelry-sized oxygen-propane torch that can make a pinhead-sized very hot flame for controlled heat.
I’m just messing with some 3-mode “next level memory” SK-68s after getting tired of chasing through modes every time.
I realize I probably need to ‘wet’ the aluminum pill edge with solder while there’s no driver or LED so I don’t cook those.
I know aluminum always has an oxide skin and the idea is to get something (flux? solder?) melted on top of the aluminum, to keep the air away, then poke something thhrough to scrape off the oxide layer through the liquid so the solder bonds to the aluminum.
I’ve in fact done that years ago with something called “alumiweld” to fix cracks in aluminum, and it worked ok.
But — dealing with an SK-68 pill as the example at hand — advice would be welcome.
So far I mostly seem to discolor it and get it so hot that solder just skitters off.
I’ve tried using electronic fluxed solder — tried 4% silver-96% tin, and tried some old 40 lead/60 tin.
I see I can probably buy solder meant for aluminum-to-copper from a welding shop
Ideally, I think, I’d like to get some of these pills and solder little copper tabs onto them, so I could later on drop in a driver,
bend the tab down and solder that onto the driver and have a good electrical contact. (I’ve seen some flashlights made that way).
I’m probably overthinking. Advice welcome.
(hmmm, what about that liquid circuit writing pen stuff … does that fill gaps between a driver and a pill?)
I have a very old budget soldering iron with no adjustments, just a bimetallic strip to regulate temperature, a propane torch and an old large iron, for bigger work than electronics, that I can heat with the torch (no gas stove). These have served my needs nicely so far, the little iron for connection and the torch for re-flow and disassembly.
Due to the difficulty of soldering aluminum the connection seems to always be made through pressure. Often its a brass ring that is pressed into the aluminum pill, the driver is soldered to the ring. Fasttech sells some rings. http://www.fasttech.com/product/1143102
If your just needing a good ground connection and not actually wanting to solder a star/solder a driver in you can drill and tap a hole for a copper/brass head screw then solder your ground wire to that screw. That's how foursevens and eagletac do it.
I drilled and tapped a whole butt-load of holes in the ends of Aluminum plate for an industrial robot controller I built. IMNERHO, (with a fairly significant amount of drill-&-tap experience) I’d almost rather drill & tap one of my own teeth.
You’d have a better time taking the edge of the board, soldering a blob on each side, in several places around the board, then laying in a solder bridge between the “top” blob and the “bottom” blob, across the edge of the board, then let those bridges achieve connectivity to the Aluminum.
For the few Al pills I’ve modded, with a really hot iron, you can attach a solder blob to the bare pill first, at points which will match where you want to bridge to the board when it gets put in, then put a blob at “that” point on the board, then quickly bridge them just before you finish assembling the light.
aw come on, drilling/tapping Al isn't bad at all, used to think so then I got into making/modifying knives. You know what really sucks?! Drilling a #51 hole in a steel and/or Ti knife handle and tapping them to 2-56. Last Ti handle knife I did it took me (no joke) 14 #51 screw machine [short] bits and 3 taps to drill/tap 6 holes, I'll gladly drill & tap Al any day.
After a couple of decades, I’ve forgotten the sizes, but I’ll never forget the heartsick feeling of breaking a tap in the “important” edge of an expensive plate of Al. Fortunately for me, Vice Grips saved my bacon. AFAIK, the robot is still working, somewhere in Jolly-old England, QC-inspecting nuke fuel envelopes for Westinghouse.
To be fair, drilling & tapping the face holes was easy enough, and I’m sure the edge hole I almost screwed up was my own danged fault, but every single edgewise hole was a nightmare, before and after the heart-stopping ‘tkkkk’ sound.
As long as you drown it in cutting fluid, keep constantly back-turning to break chips, frequently remove the tap to flush chips (which will weld themselves in place and jam the tap) from the hole, and forget the entire rest of the world while you’re working, sure, why not.
As for me, that idea (which I literally came up with as I was writing that — perhaps well after the rest of you already knew) of laying a solder bridge across the edge of the PCB just came to me, and I think that’s The Solution for me, from now on. Good contact and no-tool removal and simple to do? Why not?
There is some sort of household chemical that will dissolve the broken tap out of Al/Ti, forget what, I'm sure one day I'll be on the internet franticly looking it up Lol.
Chuckle. Ok, I don’t want to lead this too far away from “soldering iron” discussion.
I appreciate the various suggestions about how to get good contact between board and pill.
I know the problem with aluminum is that it always has an aluminum oxide layer on the surface — aluminum is extremely reactive in air, the aluminum metal oxidizes on the surface and seals itself away.
The “Lumiweld” stuff I’ve used in the past melts, sits on the aluminum, and then you scratch through the liquid with a sharp piece of steel, which breaks through the oxide layer. At that point you can see and feel how the liquid changes from sitting on top to sticking to the aluminum. Lots of discussion, ’oogle finds it. But it does not bond to copper.
JOINING COPPER OR BRASS TO ALUMINUM - TECHNO-WELD forms a strong bond with copper or brass rather like a hard solder, although it does not form a “fusion weld” as with Aluminum Alloys.
The brass or copper is “tinned” with TECHNO-WELD, and “keyed” by brushing the molten “TECHNO-WELD” into the surface with a Stainless-Steel brush. The Aluminum Alloy is prepared in the normal way [see description, using a scraper through the melted material], and the “tinned” brass or copper can then be “sweat” together, and a good fillet of TECHNO-WELD added for extra strength…
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and someone else there wrote:
“HTS-2000 can also be used for copper to alloy joints.”
found that company’s website: www.aluminumrepair.com/faqs.asp
Does HTS-2000 work on … copper …? Yes
hank - I messed around with soldering aluminum -- just didn't work out.. You may try some miracle alum solder solution like I did, but it didn't work for me. With SK68 pill/driver issues, you may try some DIY crimping method - like using a metal chisel and gently notch the edge of the pill so the driver press fits in. Not a great solution but works pretty well, as long as you can get metal-to-metal contact. Other techniques used/posted here is little bit of wire or solder briad in the joint, but must be careful with inadvertent contacts.
I got good results with original Lumiweld years ago (with practice, bad results at first!) fixing cracks in aluminum. Haven’t touched it for years. Maybe I’ll get some of the new stuff and see.
I’m getting OK results with pressure fit, and capturing a little bit of tinned copper in between driver and pill. Just wondering what might improve on that connection and stay good over time.
I found rubbing graphite powder into the gap improved brightness with one LED. It was messy, not permanent, just tried and it convinced me improvement is possible in that electrical connection.
Glad to see you are going to get your feet wet and try some modding, I have the same kind of iron as your link and I know that limits what I can do , but my mods are very very rudimentary and I am still not very good lol any how someone on this board told me you could get the mechanical helping hand with magnifying glass for 2.99 at harbor freight so that is where I bought mine best of luck to you!
0.2ML silver conductive glue / paste for electronics repair applications. Great for repairing defect traces / tracks or creating smooth jumpers on PCB board.
I didn’t even think to look until this thread came up, but I always thought it was strange how hard some people had it. A minute ago, I just looked. < stunned silence >
I kept my original soldering gun, plus inherited one from SWMBO’s grandfather. “Gun”, not “Iron”. I think this is why I never thought soldering to Al was hard.
Mine is a Weller Model 8200N, which is a two-speed model running at 100 or 140 Watts. < eeeek!!! > Tin it and touch it and Aluminum has a solder blob stuck to it!
The inherited one is a Wen “Quick Hot” Model 199. It isn’t even rated in Watts, but the UL listing claims 120VAC at 1.1A, meaning it should show me 132 Watts, and that right soon.
Sorry, I know that doesn’t help, but either of these will flat-out put solder on anything you can touch with them, NOW. That includes human flesh. Ask me how I know that!
My “normal” electronics-only pencil iron is another two-speed, but it’s a no-name generic 15/30W. I only switch to 15W while I’m dinking around between solderings, to save money. It works great for almost everything I solder indoors…
I’ll stop hijacking now & read along like a good boy!
