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Mixed Reef: Tips and Tricks of Soldering

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Chad

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Do you have the acro "red bugs" or flat worms  

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  1. 1. Do you have the acro "red bugs" or flat worms

    • I have the acro "red bugs"
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    • I have the red or brown flatworms
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    • I have both the acro bugs and flatworms!
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    • I have none
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Unless you have been living in your own cryptic refugium, it is unlikely that you have missed the impact that LEDs and other electronic DIY projects have made upon the hobby. Perhaps you have considered trying one of these projects, but are a little intimidated by soldering? Well, I am here to say that soldering is easily accomplished by a few simple techniques and inexpensive equipment. You can do it!To achieve a great solder joint you need to know a few things about what solder is... so, what is solder? Solder is a low melting point metal that is used to metalurgically bond metallic surfaces. In order to achieve proper bonding, the joint must be made on clean and un-oxidized metal surfaces. This is where flux comes into the picture. Flux removes the layer of oxidation that occurs on most metals so the liquid solder can adequately flow into the joint and make a good metal to metal connection.What do you need?The picture below shows everything that you need to make great solder joints on your projects:gallery_2632346_867_17060.jpgSoldering iron: For the joints that I made in this article, I used a variable wattage soldering iron. The variable wattage feature is nice, but not necessary. In general, any handheld soldering iron (not the "gun" type) around 25-50 watts will work for smaller electronics projects. However, if you are going to be doing a lot of soldering (especially if you will be working with sensitive semiconductor components), I recommend getting a soldering iron with a temperature controlled tip. In most single-wattage soldering irons, the tip temperature continues to rise until a loss/input equalibrium is reached (sometimes >1300F); this is fine for most work with wires and electrical components, but can damage semiconductor based components very quickly. For most projects, a small, bladed tip like the one shown below will work well; however, if you are doing fine electronic work on a printed circiut (PC) board, switching to a pointed tip will better suit your needs. Finally, ensure that the soldering iron comes with a stand and USE IT! The tip is 650F+ which can very easily burn you, your counter top or the floor; using a stand will minimize the chance of burning you or your stuff. These range in price from $15-150 and can be found many places. Desk clamp: Having an extra hand is usually the most difficult part of soldering, these help a great deal. I found this one for $15 at Radio Shack.Isopropyl alcohol: Cleanliness is THE most important thing to getting a good solder joint, clean everything before and after you solder. Skin oils from your fingers can interfere with getting a good solder joint and flux is corrosive which can degrade your solder joints over time. Rubbing alcohol >90% isopropyl is ok, just check the ingredients to verify the rest is water and it does not contain oil since some rubbing alcohol does.Solder: There are two main choices here: 60/40 or 63/37. This is the lead/tin ratio of the solder mix. Without getting too technical I recommend that you get the 63/37 because the transition from a liquid to a solid occurs at a single point meaning there is less of a chance that a crack will occur while the solder is cooling and transitions from liquid to solid. Also, the 0.032 thickness (the smaller one) is more than adequate for most small project needs. Silver and lead-free solders are safer (from a hazardous material point of view), but are more difficult to work with. Silver solders melt at a higher temperature which presents a higher risk of heat damage to components and lead-free solders have a larger plastic region between the liquid and solid state which results in higher risk of cracks. If you have a specific reason to use one of these alternative solders (perhaps you are soldering on something that you may want to lick?), understand the weaknesses and use it. But otherwise, go with a flux core 63/37 lead based solder.Flux: Make your life easier and get flux cored solder. It works well and is the least messy type. Keep in mind, though, flux is corrosive, clean it off when you are done. That being said using a separate flux almost guarantees great wetting action, but it will make a big mess to clean up.Misc stuff: Alligator clips for heat sinks, de-soldering braid for poor joint repair, rolled up and taped paper towel to replace the useless sponge that comes with most soldering irons that is used to wipe oxidation from the tip of your soldering iron (I find that using the paper towel you do not need to moisten it since it becomes a disposable tool), hair dryer or heat gun to shrink the heat shrink, masking tape to hold things in place, hobby brushes with the bristles cut short for cleaning and applying isopropyl alcohol.Preparing the soldering iron:The tip of the soldering iron needs to be clean, covered with solder, and shiny. To accomplish this, plug in the soldering iron to get it hot. Once hot, cover it with solder and wipe it off with your rolled up paper towel (throw away that useless sponge that come with the soldering iron!!!). Immediately prior to using the soldering iron, wipe the end with your rolled up paper towl so that it looks like this each time you use it:gallery_2632346_867_24427.jpgTinning:Tinning adds a small amount of solder to the lead that you plan on connecting prior to connecting it. This does three things, it keeps individual strands of a wire together so you can easily wrap the leads, it makes it "sticky" when you solder and it minimizes both the heat input and the solder that you need to use when you are on the component (which is likely to be more heat sensitive than the wire). To tin, wrap some solder around the index finger on the hand that you will hold the lead with, apply heat to the lead for 1-3 seconds (time depends on the wattage of your soldering iron, but NEVER apply heat for longer than about 10 seconds to a wire or 6 seconds to a electronic component). Then apply solder, the solder should not wick underneath the insulation on the wire. You should apply enough solder to cover all of the bare wire, but not enough to prevent you from being able to pick out individual wire strands beneath the solder. To help prevent wicking of solder below the insulation, you can clamp an alligator clip to the bare wire up next to the insulation. gallery_2632346_867_10505.jpgWire to wire connection:Once both leads are tinned, make a hook on both wires and thread a piece of heat shrink onto one of the wires then clamp one of the leads into your desk clamp. gallery_2632346_867_2733.jpgApply heat to BOTH wires at the same time, apply solder, remove the solder, remove the heat (work in a well ventilated area and use a face mask or hold your breath so you do not inhale the smoke because it contains lead oxide and can result in lead poisoning, more info on the hazards of lead poisoning can be found here). gallery_2632346_867_2474.jpgYou should apply enough solder to make a solid joint, but the shape of the wires should be visible beneath the solder:gallery_2632346_867_13432.jpgClean the joint with isopropyl alcohol. Cleaning can be performed by covering the joint with a paper towl and applying isopropyl alcohol to the paper towl, then blot at the joint through the paper towel using the hobby brush. Visually inspect the joint to ensure it is clean and shiny. Finally, move the heat shrink over the joint and apply heated air from a hair dryer or heat gun to cover the joint:gallery_2632346_867_4142.jpgAnd there it is! Easy, right?PC board or starboard:Soldering to a PC board or starboard is very similar, but the risk of heat damage to components is much more. Use an alligator clip whenever you can as a heat sink (it is under the board and not visible in this picture). Solid leads from electronic components do not need to be tinned and should be restrained such that the lead protrudes through the center of the board. Using masking take to hold components in place before soldering them (just don't forget to clean the residue off when finished!) helps with this. Note: many preprinted PC boards similar to that shown in the picture below are heavily oxidized when procured, using a fine grade steel wool (e.g., 0000) to lightly sand the board will help significantly to achieve proper wetting action. Here is a sample picture (it doesn't take very much solder on a board!):gallery_2632346_867_15296.jpgThe bad, and ugly:This a picture shows some poor solder joints:gallery_2632346_867_5798.jpgThe joint on the left uses too much solder, is cracked, dull in appearance and shows heat damage on the board. The joint on the right does not have enough solder and shows poor wetting action (dirty joint).In review:Prepare the soldering iron, clean everything, apply heat, add solder, remove solder, remove heat, clean, done. This cycle should always take less than 10 seconds for wires and 6 seconds for PC boards (or LEDs), but will usually take 1-3 seconds. Clean the flux off and the joint should be shiny, show good wetting action and the outline of the components should be visible underneath the solder. Did I mention you need to clean it? A great solder joint is achieved 95% by cleaning and preparation and 5% by actually laying solder down.A poor solder is dull, cracked or shows poor wetting action. If you do get a poor solder, don't fret too much, you just need to remember a couple of things: minimize heat input by allowing the parts to completely cool before attempting repair, remove the solder by applying heat through the de-soldering braid (wicking action will draw most of the solder into the braid), and remove the component. Clean everything, ensure it is completely cooled and try again. Any Questions?

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