A Guide to Soldering for the Newbie Modder Introduction Soldering is “the joining of metals by a fusion of alloys which have relatively low melting points". It’s used in plumbing, sculpting, metalwork, but probably the most important to the modder, electronics. This guide goes over some of the aspects of soldering, and what you should think about, and should answer some common questions. Table of Contents: Part 1 Introduction (duh) The Soldering Iron Solder Part 2 Sleeving How to solder a simple joint Other considerations Conclusion The Soldering Iron. This is the part that you hold The iron is the tool that you use to melt the solder to make the joint. There are two main types of iron. The Electric Iron These are probably the most common type of iron. They plug into a power supply, sometimes have interchangeable tips, and are rated by Watts. The heat they give off and the time it takes to heat up depends on the wattage of the iron. Some irons are “temperature controlled”, which means they have a thermostat that keeps them at a certain temperature, in order to prevent any damage to sensitive components. The power of these irons range from about 10W to over 100W. Generally, the higher the wattage, the more the iron will cost. As a rough guide, 10W irons are generally good for working with sensitive components, but will not melt the solder very quickly, which means you have to hold the iron on for a long time, which is usually very inconvenient. A good iron would be anything from 30W upwards, and a budget iron can be bought at Maplin’s for just a fiver ( http://www.maplin.co.uk/Module.aspx?ModuleNo=32909&TabID=1&source=15&WorldID=&doy=31m1 ). A Budget 30W Iron Electric irons work by passing a current through a resistant heating coil in the main body of the iron, which heats up, thus heating the tip. They are very simple to power up, as all you have to do is plug in and turn on. Electric irons can be mains powered (230/120V~ AC) or another supply (such as 12V DC for car battery supplies) Gas Irons Less common and more expensive, these irons can get very very hot, and usually have a selection of attachments, including soldering tips, blowtorch nozzles and heat-gun nozzles. Gas Soldering iron tips In their specifications, they usually have Max tip temperature, max operating time and gas capacity. They will also have a “mains iron equivalent wattage”, which gives you an idea of what their electric equivalent would be. They usually run on butane, which can be purchased from tool shops or tobacconists (its sold as lighter refill gas (must be in a pressurized container, NOT liquid!). A Butane refill A gas soldering iron works somewhat similar to a Bunsen burner in the first stage. When first setting up the iron, the valve is open, which gives the iron 100% oxygen intake. Inside the iron, gas burns with a blue cone flame, which is aimed towards a small element in the tip of the iron. This blue cone heats up the element, until it glows, and heats the tip. Once the element has been brought up to temperature, the value should be closed, which extinguishes the flame. Now the gas is blown directly onto the catalytic element in the tip, which will be seen to glow brightly. The element catalyses the reaction between the butane gas, being blown onto it, and the air, and so the gas is “burnt”, with no flame, which is an exothermic reaction which keeps the tip at the desired temperature. These irons are best used when you are not near a mains outlet, and need to solder something quickly (e.g. a running repair “in the field”). Generally they’re not good value for money for a home hobbyist user, as they get through a lot of gas (which is expensive) require prepping before use and can easily damage components if set up incorrectly. NOTE !!!, this is NOT a gas “Soldering Gun”…. Though it may have an attachment for this. A soldering gun is basically a gas torch which burns with a large flame to melt the solder. This is best used for plumbing, making joints between pipes. This is not good for electronics, as the heat cannot be applied accurately enough to the connection, and would likely fry any surrounding components. Not at all useful. On COLD SOLDERING IRONS They run on 4AA batteries, probably got a max power rating of about 10W, if that. The nature of them being only temporarily hot means you can get inconsistant heat if you don't have a steady hand. The tips are made of a special compound which conducts heat extremly well, which is extremly expensive! IMO, not worth the bother. But, it would be suitable for quick solder joints, I suppose... There is a thread in electronics about this. Cold Heat Soldering Irons? Desoldering Personally, I think “Desoldering irons” are a complete waste of money. Basically, a desoldering iron consists of a soldering iron and a suction hole to suck up the melted solder. You can get exactly the same effect by using a normal soldering iron and a desoldering pump ( available from Maplin’s here http://www.maplin.co.uk/Module.aspx?ModuleNo=3937&TabID=1&source=15&WorldID=&doy=31m1 ) You can also buy “Desoldering braid” which attaches to the solder and will help free components from a solder joint. ( http://www.maplin.co.uk/Module.aspx?ModuleNo=29016&TabID=1&source=15&WorldID=&doy=31m1 ). They can be useful when desoldering a particularly large joints, but most of the time are unnecessary. Solder Lead-free Silver solder Types of Solder There are many kinds of solder available, which are widely categorised into two different types: lead and lead free. You can get a small list of types of solder here : http://www.efunda.com/materials/solders/types.cfm The types of Lead solder are shown in composition by the percentages of tin to lead. Common compositions are 50/50, 60/40 and 63/47, all have the same melting point (361 ºF), but the transitional range (pasty range) is different. At 63/47, the solder turns directly from solid to liquid, but at 50/50, the solder is “pasty” up until 421ºF. Generally when soldering electronic components it is best to have a fairly fluid solder, to allow the placement of small components easily. However, the properties for lead-free solders are different. My personal preference for solder is Tin-Silver solder, which is non-toxic and lead free, gives a good connection and is very accurate. It can be bought at Maplin’s here : http://www.maplin.co.uk/Module.aspx?ModuleNo=34965&TabID=1&source=15&WorldID=&doy=31m1 . They also sell copper lead-free solder which contains copper instead of silver and is slightly cheaper, Many solders have a fluxed core, which is very handy for fiddly electronics jobs (we’ll come to flux in a minute!), such as the above fluxed silver solder from Maplin’s. The best way to choose your solder is to experiment with different brands and compositions, and see what you prefer working with. The thinner gauges work best for intricate electronics work, than the larger gauges which work well for...uhh... plumbing. LOL Flux Flux is a sticky compound paste which melts when heated, and takes away any oxides on the surface of the contacts, and allows the solder to flow over the contacts to make a better joint. It is also used when brazing (though a different kind of flux) for the same purpose: to allow the brass to flow between the two pieces of metal and adhere correctly. There are several types of flux, but the best for electronics work is acid-free plumber’s flux. It can be purchased from hardware stores or specialist plumbing stores. In my opinion, flux is the best way to make a strong contaminant free joint. There are other methods for getting rid of oxidants, such as sanding the contacts with fine wet+dry paper, but in my experience they aren’t as effective as using flux. The flux should be applied to un-tinned wires/contacts prior to soldering. As the solder is applied (and the contact heated) the flux will melt and evaporate, and the solder will flow everywhere that the flux is applied. Use sparingly!! The fumes that it gives off are toxic, and so you should be working in a well ventilated room (as you should when soldering anything), ideally under a extraction-hood. As stated earlier, some kinds of solders have flux cores, so extra flux is not required when using this.