Easier and less critical to melt and flow, lets me get in and out of a joint quickly (to minimize component and trace damage).
It is easier to get a good joint formation using eutectic solder, flows better and doesn't have a pasty stage. Most commercial soldering is not done with traditional wave solder any more, but re-flow and selective soldering (which is hand soldering done by a machine).
At the end of the day it doesn't matter whether its DIY commercial or the flight controller for a jet, EVERY solder joint is critical.
As I have said there is more than enough information out there on solder joints, with billions of components placed every day...
Jneutron mentioned Toyota and Tin Whiskers, here is a brief overview, for the masochist I have the full report somewhere (700+ pages).
http://nepp.nasa.gov/whisker/reference/tech_papers/2011-NASA-GSFC-whisker-failure-app-sensor.pdf
Iron too cool for lead free is one possible cause, flux not aggressive enough, but mainly because lead free solder is a PITA.
have a look at this it may help...
http://www.kester.com/Portals/0/Knowledge_Base_Articles/Lead-free Handsoldering.Final.4.19.06.pdf
Better still just get proper solder (ie with lead in it).
have a look at this it may help...
http://www.kester.com/Portals/0/Knowledge_Base_Articles/Lead-free Handsoldering.Final.4.19.06.pdf
Better still just get proper solder (ie with lead in it).
You can't always guarantee metal-metal contact with no solder in between. Certainly normal DIY soldering for PCBs or point-point would allow for some metal-solder-metal joints. Even if you wrap the lead around a tag there is always the possibility that molten solder could wick between them.
I don't get worked up about solder. I use mainly Ersin Multicore, because I find it makes soldering easier than cheaper types. But what do I know? I am just the usual deaf scientist.
I don't get worked up about solder. I use mainly Ersin Multicore, because I find it makes soldering easier than cheaper types. But what do I know? I am just the usual deaf scientist.
I'd like to ask a question about fluxes, if it's not too OT. It's in the context of starting to experiment with PB free solders. I've been curious and decided to try some small jobs with Pb free to see how it handles. I normally use Kester 186 mildly activated rosin flux, which Kester says is good for Pb and Pb free. But I've read a few bits that suggest Kester 2331 might be better for Pb free work. Anyone have thoughts or experience in this area?
I have used MANY different solders for work and I have always come back to Kester 44 63/37.
That being said......I will only uses Cardas Quad Eutectic for my home projects.
It flows well and melts low, I have yet to have a cloudy joint with the CQE.
I don't subscribe to the idea of how solder sounds, but, I DO care about how it performs & flows through the PCB holes.
That being said......I will only uses Cardas Quad Eutectic for my home projects.
It flows well and melts low, I have yet to have a cloudy joint with the CQE.
I don't subscribe to the idea of how solder sounds, but, I DO care about how it performs & flows through the PCB holes.
Solder joints have various intermetallic layers that are critical to the joint being correct, you very rarely get metal to metal contact with parts and wires, and with SMD, almost never (and if using wire you usually tin it first before making the joint if you want a decent joint).
As most of the components you use have a tin coating on them anyway don't worry about it, it will not be a problem if the joints wet properly
As most of the components you use have a tin coating on them anyway don't worry about it, it will not be a problem if the joints wet properly
If you look at the diagram I posted, you can see the difference in temperature range for the two eutectics. While the 38 degrees C looks close, they can be a problem with the flux.
A flux designed to work only with tin/lead will begin to activate and attack the surface oxides below 183C. If that flux is used with tin/silver, it may burn before the temperature of 221 C is reached.
If a flux good for tin/silver is used for tin lead, the solder may melt entirely before the flux begins to clean the oxides.
In both mismatch cases, the soldering process will not be good.
In Home depot, flux will state "lead free". That is not an indication that there is no lead in the flux, it indicates it will work within the lead free range of soldering temperatures.
Fluxes will have a chemistry related to the materials that are to be bonded. Nickel requres a slightly different chamistry from bare copper, silver, tin, gold, even aluminum. Sometimes you just gotta experiment.
jn
Thanks for the responses on the eutectic solders. I can appreciate those user advantages. I have quite a bit of 60/40 in different sizes so it has been many years since I've purchased or used anything else. With prepared surfaces it doesn't give me problems, but with careful inspection one can see the pasty stage. Since I avoid lead-free I'll have to buy a stash of 63/37 eutectic.
Multicore solders, the Cardas is nothing special, have a look at Digikey or similar, and if you want copper in your solder like Cardas, look for "bit saver" solders, because that is why copper was added to tin/lead solder.
Multicore is a good brand, rosin fluxes are also generally better, just have some ventilation as it is the flux fumes that are not good, I developed asthma with my exposure to the chemicals etc from electronic production in the mid/late 80's.
Multicore is a good brand, rosin fluxes are also generally better, just have some ventilation as it is the flux fumes that are not good, I developed asthma with my exposure to the chemicals etc from electronic production in the mid/late 80's.
Agressive maybe. It could also be that the chemistry better targets the base metals you use.
If anybody is really having a problem with a specific app, get a tin of flux from home depot. Make sure is type RMA, or rosin mildly activated. You'll see zinc chloride in the label. Use this to pre-tin leads or pads to achieve the metallic bond. Then clean the daylights out of everything... The acid byproducts will not be very nice to the components long term. Superior flux had a neutralizer I used back in the late 80's. Baking soda weak solution, whatever...Sy would be far better at the chemistry part...
Do NOT use that flux on stranded wires. The flux WILL wick into the strands, you will NEVER be able to clean it out from under the insulation...
Ah, just remembered. I believe I used superior #95 flux for nickel surfaces..
jn
Good info, jn. Thanks.
I pulled the data sheets for Kester 186 and 2331. In 186 I found the following:
This flux possess high thermal stability for soldering multi-layer assemblies which require a high preheat temperature. Exposure to high preheat temperatures does not degrade solubility of the residue in normal cleaning solvents.
and
The optimum preheat temperature for most circuit assemblies is 90-105°C (194-221°F) as measured on the top or component side of the printed circuit board.
By comparison, Kester 2331:
Kester 2331-ZX has good soldering properties for improved productivity without sacrificing reliability of the assembly.
and
The optimum preheat temperature for most circuit assemblies is 82-88°C (180-190°F) as measured on the top or component side of the printed circuit board.
From the other stuff in the 2331 data sheet it seems like it was designed primarily to be eco and user friendly, and be water soluable - not necessarily to be a "better" flux. But in the case of Cardas Quad, because it has a lower melting point and Kester 2331 has a lower preheat temp, does it potentially make 2331 a better choice for Cardas?
Hmm, I just also noticed 2331 has a much smaller optimum preheat temperature window.
Nice, thanks.
I wouldn't worry too much about the window size. The instant you put in larger or smaller mass components, those numbers would probably change anyway.
The preheats may correlate to the eutectic temp, but the info doesn't state that.
My thinking would be to try them.
One area I am always warning people of is tip temp vs tip mass. If you use a low mass tip and high temp solder, most people will raise the tip temp way up to speed the process. As a consequence, the work temp can be forced too high before the joint is complete. My preference it to use the largest tip size I can get away with for the job, and not go crazy with the temp.
The other thing I recommend is to use the molten solder to transfer the heat to the work..yes, everybody was taught to heat the work...but I do not necessarily recommend that for tin/silver work especially. Use the tip to melt the solder, and let the molten solder heat the work. That way, the vast bulk of the work heating is performed by metal which is at exactly 221 C.
jn
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