Have you ever had a bad solder joint?
If yes, then be sure you are not alone. Soldering works come with various problems and challenges. Not all solders bond well with all components. Sometimes, a bad solder joint is inevitable or no joint at all. However, this does not imply that your soldering skills are diminishing. So, how do you solve the problem of bad solder or no solder joints at all?
OK, try to incorporate solder flux and the right temperature to solve these problems. This brings us to an interesting question, what is a soldering flux?
The search for a solution is over. In this article, we will give details on what flux is made of and its importance in soldering works. It will be of no harm if we additionally elaborate on how to use flux when soldering electronics. That's sound cool.
Does it? Probably a yes from you.
What is Flux?
We all have come across the term "flux" and it is essential in making good solder joints. But, what exactly is flux? Why the struggle by solder manufacturers to stuff it within the core of the solder wire?
Probably you are yearning for an answer. Right, solder flux is simply a chemical cleaning agent used during soldering to clean oxides on metal surfaces.
Can you solder without flux?
You might be tempted to ask this question. The answer is yes, but the results may be really disappointing. Solder flux is important due to its ability to remove metal oxides leading to the perfect solder joint. Metal oxides are not good for solder joints. In the presence of metal oxides coating, the solder will not effectively wet a joint. Flux paste for electronics is designed to aid in the removal of metal oxides.
The electrical soldering flux is usually made of rosin hence termed as rosin soldering flux.
Rosin is a natural product derived from loblolly and longleaf pine trees especially for the US made rosin.
Rosin is well known for being less inert at room temperature. Despite being highly acidic when liquefied, it has other advantages that make it suitable for making flux such as having a lower melting point than solder. Therefore, the rosin core solder will melt before the solder, flowing into and around the joint.
Additionally, the acidic liquid flux will react with the metal oxides and converts it to metal salt and water. When the flux solidifies, these reaction products (metal salt and water) are locked up in the flux and are generally harmless at that point. However, there are some processes that will still require removal of the used flux.
Types of solder flux
There are different solder flux types currently available. Choosing the best soldering flux will entirely depend on the type and nature of soldering project. These soldering flux come in different forms and state. Just to mention, we have soldering flux paste and liquid solder flux. The following are the various types of flux available.
1. Rosin soldering flux
This one of the oldest type of flux still being used to date. It is based on refined and purified pine sap commonly known as rosin. However, the modern rosin is usually blended with different fluxes so as to optimize its performance.
2. Organic acid flux
It is the most common flux being used since it is water soluble. It employs the use of weak acids such as stearic, citric, and lactic acids. The weak acids are always combined with solvents like water and isopropyl alcohol. The organic acid flux cleans the oxides more effectively and stronger than rosin fluxes.
3. Inorganic Acid Flux
This is another solder flux type that works better with stronger metals for instance brass, stainless steel and copper. In case you will employing the use of inorganic acid flux, then you need to completely clean the surface to remove any corrosive residues from the surfaces. If the residues remains on the surface, then a perfect solder joint will not be achieved.
Alternatives of soldering flux
What happens if you have no access to the solder flux yet you really need to solder? Does this mean the end of the road for your soldering work? No! There are several soldering flux alternatives that can be used to clean up the metal oxides from metal surfaces.
Can I use a Vaseline instead of flux?
This question might just linger in your mind at the moment. The answer is yes. Using petroleum jelly as a soldering flux is an effective soldering flux alternative. Others include lemon juice flux. This can be made at the comfort of your home. Finally, solder flux is a very useful material which removes oxides that form on electrical contacts and helps the metals being soldered and bonded together more effectively.
Image & Video Credit: https://www.howcast.com/videos/504730-What-Is-Flux-Soldering/