Contents
Methods of PCB welding
What is PCB welding?
Welding is the method to place one or more electronic components on a PCB using a solder. The solder melts and fixes the electronic components at their places.
The melting point of solder metal is smaller than that of parts and the PCB. Hence, PCB welding is also called PCB soldering.
Therefore, the welding process has a vast number of applications. It can be utilized in plumbing, repairing home electronics, electronics, and electrical projects, among other things.
The working and performance of your electronic circuit greatly depend upon ideal PCB welding. First, you must be an expert in developing the entire PCB circuit.
And if you are inexperienced, you need to know about welding hacks. Welding hacks are suitable methods of soldering.
The following sections describe different methods of PCB welding. Could you read them carefully and get started?
You will need a printed circuit board, soldering iron, lead, and flux. Figure 1 shows a soldering iron welding on a printed circuit board.
Types of Methods of PCB Welding
There are two types of welding methods: complex welding and smooth welding. Furthermore, hard welding is also divided into two more brazing and silver welding categories.
Hard Welding
This category of welding or soldering involves connecting two components of metals with a solid solder, which spreads into the gaps of the elements that are visible because of high temperature.
The gap filler metal holds high temperatures, which may be over 840◦F. This was the basic concept behind hard soldering. Now, we will discuss brazing and silver welding.
Silver Welding
You will need to buy a silver alloy that will act as a gap filler metal. This spotless method is helpful for manufacturing small elements, built-up tools, and periodic maintenance.
However, silver soldering is not recommended for gap filling. We suggest using a different flux to get accurate results from silver welding.
Braze Welding
In Braze welding, two components are connected by creating a liquid metallic gap filler. This filler follows the vessel and runs through the joints.
Then, it will cool down to provide a solid union to the electronic components.
Atomic magnetism and diffusion are the processes responsible for this solid union. You will see that this type of welding makes a reliable connection.
Brass metal is mainly used for gap filling. Figure 2 illustrates the close view of the challenging brazing copper element.
Soft Welding
Smooth welding is used for placing very tiny compound parts with low melting points. The compound’s features would have been cracked during the welding process. Can you guess why? This is because welding is done at high temperatures.
Thus, in this case, you will need to get a tin alloy for the gap-filling metal. The melting point of the gap filler metal should not be smaller than 752◦F.
We suggest you buy a gas torch if you are looking for a heat source recommendation.
Don’t worry if you are unfamiliar with welding terms like soldering flux, iron, etc.
In the next chapter, we will explain these terms in detail and give you some tips for the welding process.
Tools and Tips for Welding
Some of you will already be familiar with all the tools required for soldering the PCB. However, beginners in electronics often suffer because they start working without getting the necessary information.
Knowing everything beforehand is the key to reducing the various welding problems.
This chapter will tell you all about the required tools and tips for PCB soldering.
Thus, as a beginner, you can solder your electronics components even on the first attempt successfully.
Tools required for PCB welding
Soldering Iron
A soldering iron is the essential tool required for the welding or soldering. It acts as a heat source for the soft solder. You can use it to solder electronic components manually.
It melts the soldering wire so that it can run into the gaps between two connections.
For the majority of electronics projects, soldering guns with power capacities from 15W to 30W are best.
Moreover, if you want to weld heavy cables and elements, buy an iron with a higher power capacity.
A 40W power capacity or higher will usually suffice the purpose.
Figure 3 demonstrates a soldering iron and its stand, and Figure 4 shows a soldering gun.
You can easily observe the difference in their shapes. The weapon will always have higher wattages and need an electric current to pass through them.
A soldering iron placed on its stand
A soldering gun ready to solder electronic components
Soldering Flux and Soldering Paste
It would be best if you also bought a soldering paste or cream for perfect welding. This soldering cream will contain solder flux.
The soldering paste attaches the legs of integrated circuits (ICs) to the connection points on a PCB. The legs are the leads of your ICs or chip packages.
The included solder flux is a chemical purifying agent. It is beneficial for the welding process as it has three primary functions.
First, it removes rust from the electronic elements that are to be soldered.
Second, it keeps the air out and thus removes extra rust.
And third, it advances the soaking capability of the fluid solder. Figure 5 illustrates the soldering paste.
The soldering paste
Soldering Wire and Wire Stripper
Lastly, you will undoubtedly need a soldering wire and its stripper.
The soldering wire is the metal wire that will act as the soft solder. It has a low melting point and fills gaps in the joints on the PCB.
In other words, it is simply a “solder.”
For electronic projects, you would encounter tin and lead soldering wires. Figure 6 shows a reel of soldering wire, and Figure 7 demonstrates its stripper.
Reel of Soldering Wire
A wire stripper
Tips for Avoiding Welding Problems
Here, we will discuss a few tips that will help you avoid many welding problems. First, you should use heat sinks.
They are necessary for attaching wires to sensitive electric components like integrated circuits and transistors.
Secondly, try to keep the soldering iron tip neat and clean.
An excellent iron tip will ensure better heat conduction and result in an improved joint. To clean the end, use a damp sponge.
Thirdly, make sure that the soldered joints are correct. In complex circuits, there is a chance that some of the soldered connections are not there.
So, checking after soldering each electronic component will save frustration in the end. You need to confirm that the joints are there.
Fourthly, you should first solder the tiny electronic components. Small components include diodes, resistors, jumper wires, and similar items.
Significant features include transistors and capacitors. This tip will make parts assembling on the PCB easier for you.
Further, you should also solder the sensitive electronics components at the end. This will help prevent any damage to them while you are soldering other components.
Sharp features include MOSFETs, CMOS, ICs, microcontrollers, etc.
Ultimately, this is a health tip: work in a room with sufficient ventilation. It would help if you avoided the smoke generated from the soft solder.
This smoke is toxic, and plenty of ventilation will ensure it doesn’t build up in your room.
Figure 8 illustrates the smoke that forms during the soldering process.
The smoke that forms during the soldering process
Common Problems of Welding
Some welding problems can occur when you are modeling a printed circuit board.
These problems can increase your costs and decrease manufacturing yields. Worst of all, your product will encounter delays from the drawing board to the user.
These problems mainly result from faults in your projects’ manufacturing or design process. Luckily, there are solutions to avoid these problems.
In this chapter, we will discuss the common soldering problems, and in the next chapter, we will discuss their solutions.
Problems of Welding Caused by Soldering Manually
The following are the six common problems caused by soldering by hand:
The next point defines what a cold joint is. 1. Disturbed Joint: A disturbed joint results from solder movement as it is solidifying.
The joint may have a crystalline, rough, or frosted surface. It is also sometimes called a “cold joint.” The figure below shows a disturbing joint.
An uneven or rough surface often categorizes the joint. 2. Cold Joint: You will cause a “cold joint” if you don’t let the solder melt completely.
The solder connection will be poor, and the breaks may increase with time. The figure below illustrates a cold joint.
Overheated Joint: If the solder has not run well, you will encounter an overheated joint. Fixing this joint becomes difficult because of the remains of the burnt flux.
The figure shown below illustrates an overheated joint.
Insufficient Wetting: The solder nicely wets the leads but doesn’t form a mature connection with the pad. This problem can be caused if you don’t provide heat to the pin and the place. The figure shown below demonstrates insufficient wetting.
Starved Solder: If you don’t use enough solder, you will cause a starved solder joint. This will result in a weak joint and may cause stress breaks and damage with time. The figure shown below demonstrates the starved solder joint.
Too much solder: You should not put too much solder at a joint as this also causes a problem. There is a chance that neither the pad nor the pin gets wet. Ensure you give the solder joint a concave surface, as shown in the figure below.
Problems of Welding Caused by Manufacturers
You’re mistaken if you wonder if welding problems are only caused by working manually. Even PCB manufacturers, using machines can cause soldering problems that should be tackled. The following are the four common problems caused by manufacturers:
1. Solder Bridge: In a solder bridge, two solder joints make an unexpected connection, which can result in short circuits in your circuit. The figure shown below demonstrates a solder bridge.
2. Lifted Components: During the wave soldering process performed by the manufacturers, electronic components can rise off the surface of your PCB. The figure shown below illustrates lifted components.
3. Lifted Pads: When manufacturers try to de-solder components, their pads can get lifted from the surface of your PCB. The figure shown below demonstrates raised pads.
4. Solder Ball: In solder balling, a small piece of solder gets stuck to your PCB during the wave soldering process. The figure below shows a solder ball.
Techniques to Reduce Welding Problems
This chapter will explain how you can quickly repair all the previously mentioned soldering problems.
1. Repair Disturbed Joint: You can re-heat it and give it time to cool down without interruption.
2. Repair Cold Joint: You can reheat it again until the solder starts to flow.
3. Repair Overheated Joint: Clean your PCB using a toothbrush or a little isopropyl alcohol. It will reheat the burnt flux.
Repair Insufficient Wetting: Simply put the hot iron’s tip at the end, preheating until the solder starts to flow. This liquid solder will then cover the pad.
1. Repair Starved Solder: After re-heating the joint, add more solder.
2. Repair Too Much Solder: Excess solder can be pulled off with a hot iron tip, wick, or a solder-sucker.
3. Repair Solder Bridge: Excess solder can be pulled off with a hot iron tip, wick, or a solder-sucker.
Prevenreheatingomponents: The manufacturers should use a robust PCB during the wave soldering. The PCB should not bend if the elements are staying flat.
Repair Lifted Pad: Soldering connects the lead to a still-in-place copper trace.
Prevent Solder Ball: Again, it can be repaired by reheating it. The manufacturers should not set too high temperatures in the wave soldering machine for prevention.
Conclusion
In this article, we have explained everything that you need to know about PCB welding. We mainly aimeds to tell you about treheatings and techniques to reduce welding problems.
But before jumping to it directly, we have also mentioned the required background information. Moreover, we have also included tips that will help you avoid these problems in the first place.
If you still have questions, you can contact us at [email protected]. Our team of experts and engineers will be more than happy to help.
