The basics of PCB assembly & soldering
Printed circuit board (PCB) manufacturing involves soldering. It's an essential step in the PCB assembly process. With this, it's important to use clean, pure nitrogen. The reason is that (compressed) air contains oxygen, which in turn contains oxides, which can be detrimental. Nitrogen is a much better gas when assembling PCBs. We’ll explain further in this article.
PCB assembly falls under electronic manufacturing services (EMS). If you'd like more information on that topic, consult our WIKI. It explains more on why PCBs are a big part of the ever-changing global landscape. This includes electric vehicle (EV) manufacturing.
To continue learning about PCB assembly, read on to learn about what is a PCB, technologies, applications, soldering, SMT vs THT, and nitrogen supply.
Printed circuit board (PCB) overview
Before diving into the technologies and processes, including soldering, used in PCB manufacturing, it's important to better define a PCB. It is a board made of insulating material, such as fiberglass or plastic, and contains conductive pathways. These pathways are made of copper and connect various components like capacitors, resistors, LEDs, transistors to the circuit board.
It's also worth mentioning that before anything can be added to a PCB, the board must be stenciled and cut to size. Also, during this stage solder paste is added. This allows for components to be mounted before soldering takes place.
With that out of the way, we'll go on to discuss applications to explain the relevance of PCB assembly as well as through-hole technology (THT) versus surface mount technology (SMT). In addition, there are different types of soldering methods, which apply to each technology.
Applications
As mentioned in the introduction, PCB manufacturing is used in EV production. This is because of the many electronics EVs and the related infrastructure require, including charging stations. Within an EV, PCBs connect the battery, motor controller, and charging system. They are also used in dashboards to operate systems including air conditioning and infotainment systems.
PCBs are also used in charging station production. With this, there are many other applications for PCBs. These include healthcare, robotics, consumer electronics, power and energy. The reality is that there are ever more connected devices in the world, and PCBs play a major role in them. They can adapt to most applications due to their lightweight design, as opposed to traditional wiring.
Soldering
The right type depends on whether you're using THT or SMT. Wave soldering is generally used for THT. On the other hand, reflow soldering is only used for SMT and is preferred for this type. The main difference between wave and reflow soldering is that reflow has a hardening process in an oven around 250° C. This is because the solder needs to be set after it’s applied.
By comparison, wave soldering involves passing the PCB over a solder bath to secure the metal components. It’s also worth stating that, while less economical, selective soldering is sometimes used for PCBs with THT. It offers the benefits of hand soldering with an automated process. It is carried out similarly to wave soldering with more precision.
Technologies: SMT vs THT
SMT production has largely replaced THT, which is where the components are guided through the mounting holes of a PCB. SMT assembly is fundamental for PCB production in the semiconductor industry.
This is because SMT assembly places components on the surface and uses reflow soldering to ensure stability. This is much easier than drilling holes to secure elements to a PCB. Below you'll find some advantages of using SMT in PCB manufacturing.
They explain why SMT will continue to become the preferred method to power smaller and more powerful electronic devices. The following benefits directly apply to the EV market, which, as stated, is dependent on PCBs.
Advantages of SMT
- Eliminates the need to drill holes, saving space and enabling the production of smaller electronic devices.
- Components can be placed closer together on both sides of a PCB. This allows for more compact, dense circuits.
- Allows for shorter and more direct connections between components, enabling faster processing and communication.
- Faster PCB production as the circuit boards pass through the oven like in an assembly line.
Nitrogen for the PCB assembly process
When assembling PCBs, pure, clean nitrogen is needed. It's used in stencil laser cutting, as well as soldering. The reason nitrogen is preferred is due to its inert, as well as its low oxide properties (vs air and the oxygen it contains). Oxides can break down the properties of solder, as well as cause corrosion. In addition, nitrogen enables better solder flow. On top of that, nitrogen generates less heat which is better for electronics. Overall, it’s beneficial for high PCB quality.
For optimal results, it’s important to pay attention to nitrogen purity and flow in accordance with the soldering type. That said, the best way for any PCB assembly company to guarantee optimal supply is with a nitrogen generator. Aside from delivering cost efficiencies and supply control, it is generally more sustainable. This is due the fact that no delivery transportation is required, and the related emissions can be avoided. You can read more in our related article.
Conclusion
The PCB manufacturing process is becoming more advanced due to increasing demands in the global market. This is seen with SMT increasingly being used over THT.
We hope the above information is helpful in better understanding the process involved and how nitrogen plays a role - especially with soldering. In general, a finished board is one where all the components are properly installed and soldered, ready for use.
Would you like any additional assistance? Click the button below and one of our experts will contact you shortly.
Do you want to learn more about Nitrogen Generation?
Read more about Nitrogen generation on our eBook:
