When it comes to soldering PCB components on the surface of PCBs, the process is hectic. Also, it takes a lot of time to solder each and every component on the PCBs, especially when you are using soldering irons on your own.
Besides, the harmful emissions that arise during the process are also a factor that you cannot ignore. However, there is no need to compromise your health since here is a quick and no harmful method of soldering that we are going to discuss in this post.
So what is it? The process is wave soldering. It helps you in the mass production of PCBs without consuming extra time and maintains the quality as well.
What is Meant by the Wave Soldering?
SMT has undergone many evolutionary changes. In the past, the concept of soldering was common and stood among the widely accepted soldering methods as well.
In those days, wave soldering was used to make simple to complex PCBs in a short period of time. The process includes taking all the PCBs through a liquified solder material. After this, the PCBs interact with a pump that functions to form a solder beam that looks similar to a wave or normally called a solder wave.
The process helps to apply this wave on the PCBs and also adheres the individual PCB components on the surface with accuracy. One factor that is the game changer in this whole process is the connection between the PCBs and their components developed through a fine solder material during wave soldering.
After this, you need to cool down the PCBs through water spraying and blowing air. The cooling step is important since it ensures a strong attachment of the components on the PCBs. The external factors for the wave soldering process are important to consider too.
The best environment for soldering is a protected gaseous atmosphere packed with nitrogen. The purpose of nitrogen is to lower the possible faults in wave soldering.
Technical Characteristics of Wave soldering temperature
It is important to shed some light on the technical part of the wave soldering process. The process takes place in a fine enclosure made of industrial-grade tin. Such a container is helpful for welding, which is a crucial step in wave soldering.
The container is helpful to endure hot temperatures where the excessive heat melts the tin bars, and this way, you can get molten tin through this process. Now this molten tin is in a liquified form, aka lake water. Now the tin on this step is leveling of waves, similar to the lake when it’s in a calm position.
When you disturb the lake, it will create waves in it called spoiler waves. To make the technical part of wave soldering more perceivable, consider PCB as a boat. Then, it floats on the leveling and spoiler waves that allow the molten tin to connect the PCB components on their surfaces.
One more advantage of using tin is that it cools fastly and gives enough room to the solder to perform its function, which is to combine the PCB components on the surface of printed circuit boards. There is no margin of negligence regarding the temperature regulation in wave soldering.
The inaccurate temperature can compromise the PCBs by exerting mechanical stress on them. It compromises the entire PCB structure and develops cracks in it. If the temperature is too low, it will not let solder form accurate thickness, which also contributes to putting stress on PCBs.
What Is The Exact Time To Utilize Wave Soldering Temperature?
There are some important applications that you must consider while using wave soldering. It comes in handy for PCBs made from methods of SMT & through-hole. When using SMT, it is crucial to use glue for attaching the PCB components to the surface of the board using different tools for the process.
After this step, you pass the entire board through a liquid solder wave. Another interesting use case of soldering is welding the through-hole PCB components. However, in some cases, when you weigh down different factors, you will see that you can replace wave soldering with reflow soldering as well.
We will discuss reflow soldering in detail in further sections. The bottom line is that soldering is always applicable for components.
The Procedure Of Wave Soldering
1. Machine for Soldering
Today, the PCB industry relies on different types of wave soldering equipment, including special machines. These machines can be lead or free from lead, depending on your needs and requirements.
However, there are some similarities between these two types, for instance, their purposes, components, and style of functioning. A conveyor belt is an important part of all types of machines that performs to take PCB components through different phases during the process.
A duo of pan and solder is for creating the initial solder wave. A sprayer of flux and preheating pad are also among the essential components of a wave soldering machine.
Such machines use a metallic solder mixture that is a fundamental component of the entire wave soldering process. However, advancements in technology can also be fatal to human health.
Owing to this fact, there are now lead-free machines available in which tin, nickel, and copper are the main alloys.
2. Wave Soldering Temperature
The purpose of using tin in the wave soldering process is its special metallic qualities.
Experts believe that setting temperatures around 260 degrees with the exception of ± 5 °C is beneficial and maintains the overall quality of the final product as well. Also, while regulating the temperatures for the wave soldering process, it is better to keep the individual weight of PCB parts and boards themselves in mind.
If the components are heavy, the temperature has to be over 280°C. If the components are not heavy, the accurate temperature would be lower than 230 °C. Other factors like preheating and setting the pace of the conveyor belt are also important to consider.
It is not beneficial to alter the tin’s temperature since it will create a negative impact on the joints developing between PCB parts and the board surface. It’s better to play with the pace of the conveyor belt to avoid any problems.
3. Fluxing
Another important step in the soldering process is fluxing. The flux used in this process is in a liquid form which you have to apply on the PCB surface when the soldering process takes place.
The motive for using flux is to boost the formation and solder quality for connecting the PCB components on the board surface. Doing this protects the shape and quality of the PCB parts and boards them when you cool them after the step of soldering.
The benefits of using flux include erasing the debris and dirt on the components. The flux also develops a thin layer on the components to block the space to react to the metallic components during hot temperatures.
There are two basic methods of adding flux to PCBs. One is by spraying and the second is by using foaming change.
If you rely on foaming change, the flux can also face some complications. These complications include inappropriate application of the flux on PCBs. Due to this reason, it will not let solder do its job in the areas where the change is less or completely missing.
A spray bottle is important to use when you are adding flux through the spraying method. However, spraying can also compromise the flux where the gaps are present on the PCB. Due to this, corrosion can take place on the board, making flux and invading the PCB parts as well.
4. Preheating
Preheating takes place prior to the initiation of the wave welding step. The purpose is to boost the temperature of the upper plate through preheating and maintain it between 65 degree centigrade and 121°C.
The preheating has to be adequate so that you can make the most out of soldering at the end of the process. The flux has to adhere to the tiniest of gaps, and preheating the upper plate helps a lot in this pursuit. It is better to regulate the preheating temperature to not compromise the no-clean flux.
5. PCB Cleaning
The role of cleaning is to tidy up the PCB and make it ready to use with the help of deionized water and other appropriate chemical solvents to exclude the remaining fragments of fluctuation on the board.
Now, this step can be time-consuming; however, there is a type of flux that does not need cleaning at all, which is called no clean flux. It is a benign flux, but there are some special applications to implement no clean flux.
Types of PCB or Wave Soldering in Electronics
· Dip and Wave Soldering
Soldering (Dip) is a special form of wave soldering process. However, this method has little or no applications in the industry, which means it is not widely accepted. It has similar applications to the basic wave soldering process.
In this soldering, the solder trickles on the metallic portions of the PCBs. It forms a combination of electrical & automatic elements during the process. It is similar to the automated soldering process but in a manual manner.
· Reflow and Wave Soldering
Reflow or conventional soldering is the best possible soldering method to attach SMT parts on PCBs. It uses flux to withdraw solder paste and powder of solder to ensure positive results. The extracted paste is beneficial to solder the PCB parts on the pads present on PCBs.
The PCB needs sufficient heat, and for this, an IR lamp or a specially designed reflow oven proves to be helpful. It melts the solder and solidifies the connection between the PCB components and the board surface.
Experts believe that reflow soldering is much simpler to use than wave soldering. Wave soldering needs a lot of time, attention, and precise temperature regulation. Any negligence can alter the final product as well.
Reflow soldering does not need you to regulate external factors like heat/temperature regulation at all. However, soldering is affordable and can adjust with your budget. Reflow soldering is useful for small use cases. These use cases are not affordable and don’t require bulk manufacturing of PCBs as well.
In some cases, you can combine both methods for your own good, depending on the situation. Apply the reflow soldering upon one part of the PCBs and wave soldering on the other. Now you know how you can leverage both methods to procure multiple advantages.
Defects & Problems of Wave soldering temperature
The problems in the wave soldering process normally arise due to ignorance of temperature regulation and faulty soldering atmosphere. If this happens, you need to know what major defects can occur during or after the process finishes:
- Cavities can still be left between the PCB parts
- In case of cracks develop, these can compromise the overall structure of PCBs
- Poor Conductivity damaging the functioning of PCBs
- Inadequate solder thickness that will form loose and weak connections among the PCB parts
- Following are some major downsides if you consider wave soldering:
- Higher consumption of electricity, flux, solder material, and nitrogen gas that can disturb the budget leading to higher manufacturing cost
- Might require solder reworking in case of any mishap or error
- The process includes masking of points that takes a lot of time
Cost
There is no doubt that wave soldering is a fruitful process to consider. However, there are some definite drawbacks that come with the wave soldering process. So, in this case, you must know the best use case for wave soldering to avoid future complications. The process is expensive and needs a large budget to give desired results.
Conclusion
Hopefully, now understanding the wave soldering process will be a smooth sail for you after going through this article. It covers all the key factors regarding wave soldering.
The post also compares different types of soldering processes and sheds light on their pros and cons as well. You can without difficulty evaluate what type of soldering would be the best fit for you by considering the strong and weak points of the alternatives mentioned.
If you require assistance with PCB manufacturing or assembly, please get in touch with RayPCB.
