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another vote for Cardas Quad!
Sounds like maybe the new Cardas with no lead isn't as nice to work with as the old with lead stuff?
Quote from: JoshK on 25 Jul 2007, 12:44 amSounds like maybe the new Cardas with no lead isn't as nice to work with as the old with lead stuff?I'd have to say it's not surprising at all. When I was in the SMT & electronics assembly industry we had all kinds of problems with lead-free solder, many of which were a pain the butt to solve. The lead in tin-lead solder acts as a mild flux & wetting agent, and helps wick the solder into the joints along with making it flow nicely. Without lead, the wicking and wetting action is reduced, plus the melting point of the solder goes way up which leads to much faster oxides formation, which requires more aggressive flux fomulations to keep the joint clean while the solder tries to wet and stick.In industry, we solved the problem with new temperature profiles for the reflow ovens along with using an inert nitrogen atmosphere in them, oh, and new cleaning & handling procedures and flux formulations. Even then, we still had more problems with bad solder joints using lead-free solder than we did with conventional tin-lead formulations.To make a long story short, I hate lead-free and I will never use it in my personal projects.
To make a long story short, I hate lead-free and I will never use it in my personal projects.
ps...sorry for the long post, guys..
Some interestingly incorrect information.So here's the differences.Lead free solder is a higher melt formulation. That has several problems.1. Lead free solder requires a flux which activates at higher temperatures. If you go to Home depot and look for flux, you will find packages which are marked "lead free flux". THIS DOES NOT MEAN THAT THE FLUX IS LEAD FREE... It means that it is formulated to activate at lead free temperatures. Typical lead free solders melt in the 221 C (eutectic tin/silver) range, whereas lead based solders go at 183 C. The 38 degree C difference is VERY significant when soldering. Using a flux which is formulated to activate at leaded temperatures will have terrible results if you are using lead free solder, as the flux will activate, then char, prior to the solder melting.Conversely, if you use "lead free" flux with leaded solder, the flux will not activate until long after the solder has melted. Again, not good.2. Lead free solders, due to their higher temperatures, are harder on the parts, on the insulation, and force one to alter the tip temp and generally the method for heating the parts to be soldered. I have found (and teach) that it is best to use a little of the melted solder to transfer heat from the tip to the part. That prevents overheating the part prior to the solder melt. Small switches like pushbuttons, typically have the terminals epoxy bonded to the back of the switch..when they are heated to lead free temps, the epoxy will exceed it's glass transition point, become soft, and will allow either the solder or the flux to wick into the component, essentially destroying the part reliability.3. The capability of the solder to wet to the parts is essentially independent of the alloy constituents of the solder. It doesn't matter. It is entirely dependent on the flux clearing the oxides from the surfaces. If that doesn't happen, the surfaces will not wet.4. Some surfaces, especially cold rolled ones which were rolled using a lubricating oil in the process, will outgass volatiles during the soldering process. If this happens, the surfaces will de-wet, and there is nothing you can do to stop this. For these cases, one must re-wet multiple times with fresh flux, and work the solder to the areas.5. The use of copper or silver to prevent leaching (dissolving) of the primary surface, while in theory good, is essentially useless. At a specific temperature, there will be a maximum solubility of either metal within the melt. Raise the temp a degree, and the melt will consume more of the basis metal. If you cannot control the melt temperature to within a degree or two, then using added metals to control this will result in a trivially small control over the dissolution. Temperature has an order of magnitude bigger impact on the scavenging process than the starting alloy composition.6. The older the roll of solder, the more oxide on the roll. I've had rolls age out, both because of the solder itself, and because of the flux.7. Three fluxes are available. R, RMA, and RA. R (Rosin) is the least active, and is primarily petrolatum jelly (vaseline), and white water gum rosin (tree sap). You will find that there are no halides present...halides are chlorides, flourides, bromides, and iodides. The most widely used is zinc chloride. RMA is Rosin Mildly Activated, and contains halides. Typically, this is also a paste with vaseline and rosin, though several manu's will use different activators to reduce the need for cleaning. RA is the most aggressive, is typically water based, and leaves rather corrosive residues. These absolutely require cleaning afterwards, and have a propensity to wick wherever it can, like into stranded wires, between a lead and a plastic body, wherever it can do the most damage.8. Fluxes can be formulated to target different basis metals, like gold, silver, nickel, copper, zinc, aluminum. Sometimes this can amke a significant difference.9. The look of the final solder surface will be very dependent on the alloy formulation. Eutectic tin'lead will have a shiny surface, we are all familiar with that. Non eutectic alloys of lead/tin as well as lead free, trinary and quadrenary (sp) mixes, will usually have a frosty appearance. This makes cold joints more difficult to spot, and raises holy heck with visual inspection.10. Excessive copper, gold, or silver, can impart a grainy or pebbly appearance to the solid surface of the solder. For copper, this is because the copper-tin intermetallic solidifies two degrees before the bulk of the melt, and it forms little grains. It looks really bad. Heavy gold does the same thing, but also has an embrittlement issue.If you can't solder to a clean metal, 99.9% of the time, it's either surface preparation, bad flux, or incorrect flux.Cheers, Johnps...sorry for the long post, guys..pps..I had to go lead free 14 years ago, and have used several thousand pounds of tin/silver eutectic, in solid wire form, wire with flux core (custom kester production run), and bar stock for solder pots. You guys are waaay behind me in making all kinds of mistakes ...trust me, there are many..
Ray, Successfully using lead free solder require advanced soldering skills and a high wattage soldering station. I have been using lead free solder for about four years. It helps to turn your soldering station up to about 750 degrees F and us as large a tip as possible consistent with the size of the joint you desire to make. You basically get one chance to do it right. Heavily pre tin your tip and if it is wires, those also. I actually start with a small glob of solder applied to the tip just before I make contact with the work. You want to use the maximum heat possible and rapidly heat the work make your joint and get off of it. Overheating the work by applying heat for too long will guarantee a brittle joint. You will need to practice soldering non-critical things together to acquire proficiency with lead free solder before attempting to solder parts on to a circuit board or make vital connections.Scotty
Hi john,Ok, sorry to be a bit dense here. Some of that was way over my head. So then, are you saying just to get some standard 60/40 solder and be done with it. Or do you have any specific brand(s)/formulations. The world is going to this lead free stuff. So, I thought since I just got a new soldering station, I'd ask around to see what to get for soldering. I had tried this Cardas lead free utektic solder, and was not pleased at the result. The stuff almost broke off, and it did not flow well. Others say this stuff is great. Not my experience. Now is it the same for the rest of the lead free stuff? I still have some old Kester solder that I've had for years. So yur further thoughts on this issue might help here. My understanding with some of the "audiphile" type solders is with the Silver content. Supposed to help make things sound better. Also, without the lead, removes the subtle glare that is there. I can't speak for experience here. Only going on what I've been told. i was curious to see what people like John Curl, and other manufacturers have to say. Hence my asking. Regards,Ray Bronk
Quote from: *Scotty* on 7 Oct 2007, 06:15 pmRay, Successfully using lead free solder require advanced soldering skills and a high wattage soldering station. I have been using lead free solder for about four years. It helps to turn your soldering station up to about 750 degrees F and us as large a tip as possible consistent with the size of the joint you desire to make. You basically get one chance to do it right. Heavily pre tin your tip and if it is wires, those also. I actually start with a small glob of solder applied to the tip just before I make contact with the work. You want to use the maximum heat possible and rapidly heat the work make your joint and get off of it. Overheating the work by applying heat for too long will guarantee a brittle joint. You will need to practice soldering non-critical things together to acquire proficiency with lead free solder before attempting to solder parts on to a circuit board or make vital connections.Scotty Hi Scotty...nice post.I do it a little different. I also use the largest tip possible, but try to keep the tip temp as low as possible. I would rather use the mass of the tip for it's heat capacity where possible, that way the tip doesn't continue to raise the temp during the soldering.I dislike the stations with extreme tip temp control, as they tend to fight the part heat capacity with power, and that really causes overheating, as it's not very easy to control the process if you have a quarter second or so between done and overheat..I'm not that good...I found that teaching the techs to use the molten solder to transfer heat to the work rather than using the tip to heat the work directly is a self limiting process that worked extremely well....with about 100 thousand joints made using the stuff, we found only one bad solder joint.Cheers, John
Saw this article posted at another site and thought it was interesting. http://news.yahoo.com/s/ap/20071005/ap_on_hi_te/tin_whiskersOf course in most cases whiskers won't be a problem, but maybe in some close quarters with 1mm spacing or less, one might consider the implications.
I switched to lead free solder four years for sonic reasons only. Silver-tin solder just didn't sound as good to me as copper bearing lead free solder. Not a big difference but definitely there and verifiable with single blind testing. John, thanks for the comments regarding my post. I should have qualified it by admitting that I didn't have the best soldering station and it could use more mass in the tip and barrel, you get what you pay for. Your approach is the way to go if dealing with delicate heat sensitive parts. I haven't fried any parts yet, but I use small clamp-on style heat sinks from RS when ever it seems prudent.Scotty