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Wave Soldering in the THT and SMT for electronics manufacturing


Wave soldering is a welding process used in the batch production of printed circuit boards or PCBs. Wave soldering is to use a pump to spray molten solder into the solder wave peak, and then the pins of electronic components to be welded pass through the solder wave peak to realize the electrical interconnection between electronic components and pcb board. It’s a technique for large-scale PCB assembly that uses SMDs and lead components to solder boards quickly.

How many types of soldering techniques are there?

The three types of soldering techniques are listed below:

Wave soldering

In this type, a solder connection is formed with this approach by filling holes in a PCB using molten solder and flux that is rolled across the region that is to be bonded.

Hand soldering

This method creates each union by hand through the simultaneous application of hoe soldering iron and a solder-coated wire to the required surfaces.

Reflow soldering

Firstly, a solder paste is made, then the paste is used for the attachment of components with the contact pads. Next, using the reflow oven, the entire assembly is heated for the connection of the joint and to melt the solder.

What is wave soldering?

Wave soldering is to make the welding surface of the plug-in board directly contact with the high-temperature liquid tin to achieve the purpose of welding. The high-temperature liquid tin maintains a slope, and the liquid tin is formed into waves by special devices, so it is called “wave soldering”. Its main material is solder rod.

Wave soldering is frequently used as a fast approach to produce large numbers of boards. Not only this, but wave soldering is also a reliable and stable way of attaching components to PCB.
What is wave soldering and its purpose

What is the purpose of wave soldering?

Wave soldering is a process in THT and SMT assembly technology. Through wave soldering, the welding surface of the plug-in board directly contacts with the high-temperature liquid tin to achieve the purpose of welding electronic components and PCB.

For welding purposes, the board’s soldering surface must be in contact with the hot liquid. Wave soldering is done to fulfill this condition. It is referred to as “Wave Soldering”, the reason is that high-temperature liquid tin maintains a slope and generates a wave-like phenomenon using particular techniques.

What are the advantages and disadvantages of wave soldering?

1. Good welding reliability
2. PCB board cleanliness is high
3. Reduce the cost of welding
4. Reduce the thermal shock of the board

1. The price of equipment is high
2. Low production efficiency
3. High maintenance cost
4. Produce more oxides, which will cause various forms of welding defects

What is the wave soldering process?

A procedure in which the act of passing the PCBs to be soldered over a wave of solder occurs, hence the name “Wave Soldering “.This technique makes it possible to quickly and effectively solder a complete board, producing junctions that are both mechanically and electrically reliable.

Both traditional through-hole installed components and surface-mount components can be soldered during PCB construction using wave soldering.The steps in the wave soldering process are as follows:

Step 1- Fluxing
Step 2- Pre-heating
Step 3- Wave solder
Step 4- Cleaning

What defects are there in the wave soldering process?

The fact that wave-soldering uses technology does not make it any less error-prone than manually soldering each joint. You must treat soldering like the exact science it is, carefully managing where and what you solder, whether you’re using a solder tank or a hand iron. Otherwise, you’ll end up with the following defects:

● Insufficient hole
● Lifted Components
● Excessive Solder
● Solder Balling

Why wave soldering is the best choice for THM components?

Wave soldering is considered as the best choice for THM components because it is easy to set up and moreover, can quickly solder a large number of circuit boards, this is why wave soldering is the favored method. However, due to some limitations, wave soldering is not suited for all types of circuit boards.

What is the difference between reflow soldering and wave soldering?

Both of these are types of soldering. However some of the major differences between reflow soldering and wave soldering are listed below:

● In wave soldering, the components are combined using a wave crest made of melted solder, whereas in reflow soldering, the components are connected using a reflow made of hot air.

● The wave soldering technique is less expensive as compare to the other methods for PCB soldering. However, the reflow soldering method is more time- and money-consuming.

● Wave soldering is the optimum technique to use for soldering through-hole components, while reflow soldering is appropriate for surface mount devices on the PCB.

FAQ about wave soldering

What are the three regions of a solder wave machine

What are the three regions of a solder wave machine?

The hot solder tank in the machine is kept at the temperature needed for the procedure of soldering. Creating a solder wave inside the tank, PCBs are then passed over it with their undersides just touching the solder wave. Care must be used when adjusting the wave’s height to prevent it from flowing over the board’s top side, which could drive solder into unneeded locations.

The wave soldering machine consists of the following main parts:
During this step, flux is sprayed onto the PCB to clean the component leads and copper tracks. Fluxing clears away any oxide that may have built up on component leads and the copper tracks of the PCB. This flux may be water soluble, no-clean, RA (rosin activated), or RMA (rosin mildly activated).

The conveyor belt then proceeds to the preheating zone after passing through the Fluxing Zone. The board is preheated in this instance to prevent any thermal shock when it is moved to the extremely high temperature of the molten solder wave.

Solder bath – solder wave:
After that, the Conveyor travels to the Pan where a Pump creates solder waves. As the Board passes over the wave, the electronic component leads are soldered to the PCB.

This completes the wave soldering procedure. This stage involves cleaning off any flux residues that developed during the process. Deionized water and solvents are used to clean and wash the circuit board.

What is wave soldering temperature?

What is wave soldering temperatureDuring wave soldering, proper temperature control is crucial. The wrong temperature can prevent the required solder thickness from being achieved, which could increase the board’s susceptibility to stress.

What is dwell time in wave soldering?

The time that passes between the point at which the solder and the components to be soldered make their initial and last contacts. This time frame should be between two and four seconds.


When PCBs are assembled, wave soldering is used far less frequently than it once was. Despite this, there are still many uses for wave soldering, especially when a mix of leaded and SMT components is used in the PCB assembly. To summarize the whole process, wave soldering can rapidly solder typically leaded components and some surface mount boards for mass production. Additionally, the procedure wave soldering is inexpensive and it results in sturdy joints.



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