All you need to know about SMT PCB Assembly

SMT PCB Assembly

The production of Printed Circuit Boards (PCBs) comes in different forms. From the SMT PCB Assembly to the use of the Flexible PCB variant, there are many options out there.

For good reasons too, many PCB buyers are always looking out for the SMT PCB Assembly. The interest in this is not unconnected to the many impressive qualities that SMT PCB Assembly has to offer.

That is why we have taken time to look at all there is to the SMT PCB Assembly. In this article, you will find answers to those questions you have been meaning to ask about SMT PCB Assembly.

What Is SMT PCB Assembly?SMT PCB Assembly

The first thing is to figure out what SMT PCB Assembly means. With that in mind, you will not have challenges in unravelling the other important aspects of this innovative method of assembling Printed Circuit Boards (PCBs).

Surface Mount Technology (SMT) is a dedicated method of producing electrical circuits. It is actualized by placing the relevant components directly on the surface of the Printed Circuit Boards (PCBs).

Once the components have been placed, the production phase will continue. The Surface Mount Device (SMD) is an example of a device that can be made by the process of the SMT PCB Assembly.


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Important Points to Know About SMT

There is some confusion about the overall implications of the SMT PCB Assembly. That is why we have made some bullet points you need to know about it.

Here are some of them:

  • SMT Is Different from SMD

Some people confuse Surface Mount Device (SMD) to be Surface Mount Technology (SMT). That is wrong.

One is the head and the other is the body.

Ideally, Surface Mount Technology (SMT) is meant to be the “head” because it is the primary component. This is the technology that enables the development of every Surface-based device.

On the other hand, the Surface Mount Device (SMD) is the derivative or the finished product that was made via the Surface Mount Technology (SMT).

  • SMDs Can Be Mounted on PCBs

From another perspective, Surface Mount Devices (SMDs) can be mounted on the surface of the Printed Circuit Boards (PCBs).

This is bolstered by the fact that the mounting can be achieved by deploying some techniques, as well as putting some materials in place. After that, the SMDs will be soldered, cleaned, and tested to ensure they are ready for the PCB Assembly.

  • SMT Replaced Through-Hole

Before the advent of the Surface Mount Technology (SMT), the Through-Hole Technology held sway. It was after the industry players opted to find an alternative that SMT was considered.

SMT is considered a better alternative because it delivered consistent results. Because Surface Mount Technology (SMT) has to do with the soldering of elements, it made it easier to reduce the hassles associated with driving the leads through the components of the PCB.

Besides, the components of the Surface Mount Technology (SMT) are considered smaller because they have smaller or no leads to be driven through the PCB.

SMT Procedure

Here, we will be looking at the procedures or processes of manufacturing Printed Circuit Boards (PCBs) using the Surface Mount Technology (SMT).

These procedures have been detailed alphabetically so you can have a good idea of the first step to take and the last thing to do when considering SMT PCB Assembly.

  1. Component Replacement

The replacement of components is the first step that should be considered in the SMT PCB Assembly.

In as much as it can be easy as mounting the components on the Printed Circuit Boards, it can be complex too.

The first basic step to take is to ensure that the designing process is free of errors. The reason is that an error-filled SMT PCB Assembly designing process can mar the success of the project.

When the designer gets to work, the primary focus is to ensure that the positions of the components are carefully considered so they do not affect the outcome of the production phase.

Also, it is advised that the designing of the components should commence from simple structures. The idea is that by designing the simpler parts, the SMT designer can then progress upwards to design the complex parts.

  1. SMT Printing

It is time to print the Surface Mount Devices (SMDs). Here, the concentration is on how to add the solder paste to the pads of the Printed Circuit Boards (PCBs).

The first step is to stir the paste for soldering. While at it, make sure that the viscosity and the uniformity of the paste are in place so that you wouldn’t encounter challenges.

Second, store the paste in an ideal environment. Ideally, a low temperature ranging from 0 to 5 degrees centigrade is recommended. Once you do that, you can be confident that there will be a natural separation of the segments of the paste.

When the paste is ready for use, remove it from where it was stored and allow to rest at room temperature. With an interval heating of about 30 minutes and about 15 minutes of stirring, the paste will be ready for use.

  1. Reflow Soldering

The reflow soldering phase that we have here is basically all about the things you need to do in order to maintain the optimal temperature of the SMT PCB Assembly.

Here are the highlights of the process, which also includes the welding phase:

  • Pre-Heating Phase

The pre-heating phase has to do with the steps taken to heat the temperature to the desired height.

For example, a balanced temperature of about 180C is required. The humidity should also be kept at 50% at most.

  • Heating

The main heating phase comes next. One of the things you should be looking for is how to ensure that the paste melts in 183 degrees centigrade.

In addition, make sure that the temperature doesn’t surpass the standard 245-degree centigrade.

  • Cooling

Now, the Printed Circuit Board (PCB) has gone through the production phase. It is time to allow it to “settle” or cool. This is the last stage.

It involves the systematic reduction of the PCBs temperature. This can be achieved by setting in a cool environment.

Also, the essence of the cooling phase is to reduce the potentialities of extreme changes in temperature, which will, in turn, affect the Printed Circuit Boards (PCBs).


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Benefits of SMT PCB Assembly

You stand to gain a lot by using Surface Mount Technology (SMT) as one of the ways to assemble Printed Circuit Boards (PCBs).

Here are some of the upsides or potential benefits that come with making use of SMT PCB Assembly:

  • Cost Saving

Since you are looking to save costs, SMT PCB Assembly will be the best way to assembly your Printed Circuit Boards (PCBs).

Ideally, preferring SMT PCB Assembly over the Through-Hole Technology has the potentiality of cutting down your PCB Assembly by 30% or more.

This is bolstered by two facts. The first is that the required materials are fewer than those of Through-Hole Technology. The second is that there is little or no drilling of leads into the Printed Circuit Boards. This, will, in turn, reduce the labour costs.

  • Compact Design

Indeed, the overall idea of the Printed Circuit Boards (PCBs) is to “disentangle” wires that will be lurking around. In the stead, electrical components are either drilled or placed on top of the other to minimize the bulk of the boards.

However, SMT PCB Assembly happens to have a more compact design than the other forms of PCB Assembly. This is because it involves placing more components on top of the other instead of creating a different space for them.

Hence, you will enjoy the reduction of sizes, as well as have just enough space to put more elements in a limited space.

  • Low Defect Rate

Since PCB Assembly isn’t entirely free of defects, there is a need to reduce the defects.

Now, SMT PCB Assembly has a low defect rate. This is partly because of the soldering process and mainly because of the sturdiness of the soldering points.

The Future of SMT

The future of the SMT PCB Assembly is bright. The development trends already in motion are testaments to that.

Here are some of the trends that can shape the future of the SMT PCB Assembly for more positive tidings:

  • Lead-Free Soldering

Lead can be used in SMT PCB Assembly. But, with the look of things, it may no longer be needed in the future.

This is partly because of the toxicity of the metal that causes many environmental and health challenges and mainly because of the measures that are in place to ban it.

With the prohibition of electronic equipment produced via lead soldering in the European Countries and the banning of the same in Japan, it is obvious that lead will soon fizzle out of SMT PCB Assembly.

Therefore, the development trends point to a “lead-free soldering” process as far as SMT PCB Assembly is concerned.

  • Automation

With the advancements in technology, the future of the SMT PCB Assembly looks good to work on automation.

Then, the assemblage processes will be automated and that means there will be more productions.


Surface Mount Technology (SMT) is taking the lead as far as Printed Circuit Board (PCB) fabrication is concerned.

With the reliability and the efficiency over the other models (including Through-Hole Technology), SMT PCB Assembly looks good to remain relevant in the PCB industry as long as it can sustain its current tempo and make the needed adjustments in the future.


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