Soldering : Soldering Method
Soldering in electronics is analogous to fixing of a component using glue. It is actually a general phenomenon in the field of electronics which involves fixing of electronic components into a special board called PCB with the help of instruments like soldering iron and electrical solder commonly called as ‘Solder wire’. Like glue, soldering establishes a secure connection between PCB and components. One must be careful enough to follow the correct procedure to perform soldering to avoid possible consequences due to failure. You should not heat the solder wire directly with the soldering iron as it fuses only to the component lead, copper pad of PCB if they are hot as well and doesn’t establish connection required. The central idea to perform soldering is to get the component lead and the copper PCB pad hot enough that the solder will melt right away as it touches them.
Multiple types of solder wire are available at the market varying on dimensions and quality. Different wires are assigned for different uses. For example, in electrical connections, it is highly recommended to use a rosin-core electrical soldier as shown in figure. The less is the diameter of the soldier wire, the circuit becomes simpler since less heat is enough to melt the solder and thus fusing component to PCB becomes easier.
Only the heated iron melts the wire so it is a must to let the iron heat up completely before following the soldering procedure. With soldering process, the gaps around the lead are completely filled by the melted solder. However, soldering takes time and can be an annoying process if not followed properly. If the iron is not heated enough, then the solder will not melt and if the solder melts excessively, it gets messy and spreads around the copper board. Also, the excessive amount of melted solder forms bubbles and can possibly touch another component lead or copper trace resulting short circuit or component damage. So, measures for extra precautions need to be taken before implementing this process.
In context of Nepal, soldering iron is available under budget of Rs. 400 at most hardware stores or Radio Shack. Though it works for most projects, this type of iron takes a while to heat up (around 10 minutes) and is difficult to solder in tight spots since it constitutes typically a large tip.
Another type of soldering iron can be found which has adjustable range of temperatures with multiple heating elements and heats up in around 1 minute. It is provided with typically a smaller tip for soldering on small projects or tight spaces as shown in figure. For the extended features and flexibility during application, this type of iron is highly recommendable. The estimated cost is Rs. 1500 to Rs. 5000.
Lately I was obsessed with a soldering iron worth of Rs. 6,000 until Hakko 936 came on my hands. Hakko 936 is not the best iron available but it is comparably better than others in context of heating time. It heats up in few minutes and on top of it, gets much hotter than a typical iron, making soldering quicker and smooth.
Like mathematics, soldering requires long time practice to excel at this particular process. Rather than spoiling the expensive designs, we would love to advise you to practice soldering on perforated prototyping board before making attempts to build your own PCBs. Also, you can buy an electronic kits from various suppliers that come with all needed parts, PCB, and instructions– only thing they require is you to have a soldering iron and an hour or two of assembly time. I too bought several kits in early days to make my soldering skill clean and the interesting thing about doing this is that they provided both an entertaining project and valuable hands-on learning experience on the other side.
When soldering is performed on a board, sometimes we have a clear path on the copper-side of the board from one electrical lead to another. To simplify the overall soldering process and to prevent the cluttered wires in the circuit, some soldering shortcuts can be followed to make the connections easier as shown in figure.
Option 1″”Pooling solder: During soldering, heat the adjacent (but separated) copper pads and apply solder, then you will notice the solder will tend toward both pads while avoiding the gap between them. This is because the solder cannot stick to the fiberglass PCB without any copper coating. If you add “too much” solder to these two pads, you will notice that the molten solder will try to jump the gap over to the other pool of molten solder on the other pad. If you are careful, you can let the solder solidify between the two pads creating a simple solder connection. This can be a helpful method of creating a jumper-wire between two or three adjacent pads. For high-power connections, this is not a suitable option because the solder is not capable of transferring large amounts of current.
Option 2″”Wire traces: If you find soldering tiresome or you cannot perform clean soldering then as alternative to this you can replace solder wire with a piece of solid bare copper wire (16-20awg) and placed directly on the copper pads that you would like to connect as shown in figure (see A, B, and D in Figure 1-27). If the connection will span several pads, it is desirable to apply a small amount of solder to each pad that the wire touches to ensure that it will not move after the circuit is complete. The plus point of this method is that you can bend the wire around other components to make a curved or angled line. This method yields results similar to a homemade PCB trace. Because each wire is connected directly from one lead to another, there can be no crossing wires from other components on the underside of the PCB. This method is acceptable for higher-current applications.
Let’s take few examples of different kinds of soldering process; Trace A is a bare wire with no insulation, but is soldered only at each end. Trace B is bare wire, but is soldered at each copper pad, making it far more secure than trace A. Trace C does not even have a wire–it is just solder that is pooled across all six pads. Trace D is a wire that has its insulation intact, but soldered only at each end. Among these traces, Trace C is difficult to accomplish across more than two or three pads and is not acceptable for high-power applications.