Each tip cleaning method has its advantages and disadvantages. We will look at the four common tip cleaning methods and the downsides and upsides associated with each. These are use of a regular damp sponge, brass sponge, sandpaper and tinning.
A regular sponge is cooled before being used to clean soldering iron tips. Basically, the tip is placed or rubbed against the sponge after operation. This causes rapid cooling of the tip and thus removes any solder or residue stuck on the tip. This happens due to the differences in contraction points of the metal and the alloy making up the solder. However, the use of regular sponges as a means of cleaning is discouraged due to the possibility of tip damage from continued rapid contraction. Despite this shortcoming, it is by far the easiest and most convenient tip cleaning solution.
A brass sponge is a thin winding of brass strips bundled together to resemble a sponge. Cleaning with this involves moving the iron tip against the sponge as would happen while sharpening a knife. Among all available metals, brass happens to be the best at cleaning ironing tips without causing damage. However, the fact that this is usually bought as a separate accessory makes it an expensive tip cleaning option as compared to using a regular sponge.
This is a cheap yet very effective method of restoring soldering tips to previous working conditions. After sometime, tips become covered in solder or metal oxides. This prevents heat from transferring from the thermostat to the tip as intended. Brushing your tip against grained sandpaper removes these coatings revealing a shiny coating as was in the new tip. This is however the most damaging cleaning option and drastically reduces the tip’s life.
Most soldering work is usually carried out on electronics. It is therefore important to understand the different types of solder and the effectiveness with which they can be used to join electrical components. Solder is the metal alloy commonly used to join work-pieces that include sheets of metal, wires, plumbing and other elements common in soldering. The alloy is designed to have a melting point that is lower than that of the components it joins. Without this characteristic, the work-pieces would probably be damaged by the solder or even before the solder effectively binds them. Depending on the type of work and desired outcomes, one can choose from a wide range of solder. The most common include lead-free solder, rosin-coated solder, lead solder, flux-core solder and hard solder.
Lead-based or lead-free solder?
For household electronics, your best choice would be lead-free solder. This is due to the regulations that govern the use of lead on household appliances. Since the allowed level of lead has constantly reduced, it is safe, even for you, to use the lead-free variety of solder. However, besides the regulations, you could use lead-based solder for your electronic soldering tasks.
Resin-coated or flux-core solder?
Well, this depends entirely on your tastes and preferences. These coatings do not really affect the outcome of your electronics soldering in any significant manner. Flux is the element used to reduce the oxidized metals to their metallic state. It is in essence a reducing agent that undoes the effects of oxidization. Rosin-coated solder on the other hand is a type of flux extracted from the sap of pine trees and exhibits various electrical characteristics depending on its temperature. In its natural state, it does not conduct electricity and is non-corrosive. However, at higher temperatures, it becomes corrosive and has the ability to reverse oxidization in metals.
Solder is basically a low-melting point alloy that is used to seal joints between metals and other components. The main components of solder are therefore various metals mixed in different quantities. We will look at the three main types of solder and the respective components.
60-40 solder (Lead-Tin)
The 60-40 type of solder is basically a metal alloy containing 60% lead and 40% tin. This used to be the most common type of solder but this is gradually changing due to the strict regulations governing the use of lead. Lead is known to have a very low melting point and thus a larger proportion of lead in the alloy will cause it to have a lower melting point. 60-40 solder typically has a melting point of about 370 degrees Fahrenheit. This is quite low as compared to other metals and alloys that can be used as solder. Taking into account that lead generally has the lower melting point of the two, an increase in the amount of lead in the alloy will lower the melting point even further. An increase in the amount of tin will on the other hand raise the alloy’s melting point.
After the enforcement of anti-Lead regulations, most manufacturers changed to this alloy as a replacement. The tin silver copper alloy is used by more than two thirds of manufacturers in Japan. Like the 60-40 alloy, this alloy has a very low melting point though not as low as that of lead-tin alloy.
Solder exists in a very wide range of forms. The above-mentioned alloys are or rather have been the most commonly used. However, there are other metals that are used to make solder. These include solver, zinc, antimony, cadmium, bismuth, chromium and so on. There are usually variations in melting points, liquidus and solidus of each alloy depending on the type and proportion of each metal in the alloy.
In soldering, a cold joint is the point of a bond formed by molten solder that did not melt fully or as required. Cold joints can be caused by a wide range of factors including incorrect soldering temperatures, poor contact between the solder and iron tip and use of poor quality solder. A cold joint often develops cracks with time, forms poor bonding of components and is thus generally unreliable as a contact point especially in soldered electrical components. Let us look at these causes of cold joints and the possible solutions you could use should you ever encounter a cold joint.
Incorrect temperature settings
This basically involves use of temperatures below what would effectively melt the solder and cause it to flow or use of inconsistent heat. This causes the solder to partially reach liquidus and then afterwards solidify without having fully melted. This forms a lumpy point that is known as a cold solder joint. To avoid this, always ensure that the tools, techniques and settings you use match those suggested by the solder manufacturer.
Poor tip and solder contact
This may arise if you use a defective tip or a very narrow tip while working on a relatively wide solder wick. The narrow tip forms contact with a very small part of the solder thus causing the other part to melt partially and reach solidus after a very short while. The resulting joint will be rough and uneven in shape and texture. A defective tip will also transfer heat inconsistently and thus cause the same problem.
This may be caused by factors such as power interruptions or wrong use of the soldering iron. The variations in heating cause the solder to melt unevenly and solidify causing a cold solder joint. Cold joints can be easily rectified by reheating them and resoldering.