SMT Assembly vs. Through-Hole Assembly: Their Pros and ...

As you know, once fabricated, PCBs (printed circuit boards) can be assembled using either one of the two technologies, i.e. SMT assembly and through-hole assembly, or using a combination of both. However, you may wonder how these two technologies differ from each other and which one you should opt for. In this case, check the comprehensive guide prepared by the experts at Viasion describing the two technologies and their pros and cons. This quick guide will help you understand the subject better to make the best decision for your next PCB-based project.

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What is SMT Assembly?

PCB assembly is a step based on PCB bare board which is fabricated as designed. Similar to this concept, SMT assembly (Surface Mount Technology)  is the process of mounting some parts on the surface of the bare PCB using specific auxiliary apparatus. These components are solidified in their patch positions by melted solder paste with the help of reflow soldering ovens. Engineers carry out various inspections to ensure the final assembled PCB is devoid of any flaws or errors. Let&#;s learn more about the knowledge of PCB SMT assembly.

What is Through-Hole Assembly?

Unlike the SMT technique, the components are not mounted directly in this case. Instead, holes are first drilled in the PCB board, in which the leads of the components are inserted for connections. PTH or through-hole assembly process is comparatively more time-consuming and costly than SMT due to the extra steps involved. SMT technique is a newer technology, and it is faster, cheaper, and more efficient than PTH. SMT makes people think that the PTH is no longer required for assembly. However, the through-hole assembly technique continued to stay in demand due to its various benefits over SMT technology. Continue reading to understand the difference between the two technologies.

What is the difference between SMT and PTH assembly techniques?

The key difference between the two assembly processes is the drilling of holes. As mentioned earlier, SMT does not require the drilling of holes, whereas PTH cannot be carried out in the lack of drilling. This makes SMT a faster process but the extra steps of hole drilling, plating of holes, component lead insertion, etc. involved in PTH are more time-consuming.

The fewer steps in SMT assembly have also helped reduce the processing and handling costs. However, PTH is still quite in demand as many components cannot be mounted via SMT assembly, therefore, through-hole assembly is used for them. While SMT is more efficient, the PTH process can increase the durability of the PCBs. Devices that require high reliability are made with PCBs with stronger connections between layers. To achieve this, through-hole components are the best suited.

On the other hand, for small-sized electronic devices, SMT assembly is usually opted because SMT components are much smaller in size compared to PTH components. Additionally, a higher component density can be achieved via SMT, which further helps increase the functionality of the device without increasing its size.

In short, both SMT and PTH assembly have their benefits and drawbacks. Which assembly technique would be more suitable for a PCB depends upon the requirements of the electronic device. Below, their pros and cons are explained in detail for your better understanding.

Pros of SMT Assembly

SMT assembly process is quite sought-after for PCB fabrication due to its various benefits, such as low costs, assembly speed, high reliability and so on. Some of them are listed below:

1. This technology allows automation as a pick-and-place machine can help carry out most of the process. This reduces the need for manual labor and thus, reduces the overall costs. Additionally, automation speeds up the assembly process.
2. SMT also allows the assembly of small-sized components (surface mount devices or SMDs) that do not require a large-sized board for mounting purposes. This helps fabricate lightweight and portable PCBs.
3. Since SMDs are quite small in size, a large number of them can be mounted on one PCB. Therefore, a high component density can be achieved by the SMT assembly process. This is especially useful for manufacturing small devices, like the handheld ones.
4. Unlike through-hole technology, SMT does not require the drilling of holes and lead forming, which are quite time-consuming processes. These processes are not only more difficult to carry out but also add to the cost of the entire PCB. Thus, SMT assembly is much faster, simpler and cheaper than the PTH method.
5. SMDs are less prone to vibration and shock as compared to their through-hole counterparts. This increases the reliability of a PCB fabricated with SMT technology.
6. SMT assembly technique allows the combining of other assembly techniques. In other words, mixed technology PCBs that require a combination of both SMDs and through-hole components can be fabricated by using SMT along with PTH technology on the same PCB.

Cons of SMT Assembly

This assembly process is not 100% foolproof and has some disadvantages. However, an informed decision and a team of expert technicians can help avoid any losses due to these drawbacks. So, consult Viasion Technology Co. Ltd. professionals to understand how you can make the most of your money.

1. Since the components are soldered directly, these soldered joints may be affected under extreme temperature or pressure conditions. Therefore, the technique is usually avoided to assemble PCBs for the devices that are expected to heat up too much.
2. The SMT assembly process requires state-of-the-art equipment and trained staff. This requires a considerable investment of money.
3. If the equipment is not programmed correctly or if the staff is not trained well, a lot of errors may occur in the PCB assembly. Solder-bridging, electrical opens, &#;tombstoning&#;, solder balling, and de-wetting are some of the common errors.
4. Numerous joints and miniaturization may increase the difficulty in carrying out manufacturing and inspections.
5. The strength of the solder joints is also subject to mechanical stress, therefore, a PCB SMT assembly is comparatively less reliable than a through-hole assembly.
6. For small circuit prototyping or testing, SMT assembly processes are not suitable. This is because component switching or replacement is not possible in this assembly type. Engineers would need to assemble an entirely new PCB to test other combinations and design possibilities.
7. Since SMDs are quite small in size, it becomes challenging to identify in case of repairing the PCB.
8. Some components are not suited for SMT Assembly. As you know, pick-and-place machines are used to carry out the SMT assembly process. Many components are not suited for this automated technique, therefore, they require either PTH assembly or manual assembly.

• Such components cannot withstand extreme temperatures because the SMT process includes conveying through the reflow soldering oven. These components may get damaged when exposed to extreme temperatures in the reflow oven.
• Heavier components or the components with connector leads that require sturdier joints are better to not mount via surface mount technology.
• While most SMDs are small, lightweight and delicate, too-light components may not be possible to assemble via SMT assembly. This is because an adequate mass-to-adherence ratio is required for this automated technology.

Pros of Through-Hole Assembly

Through-hole assembly technique (PTH) is an older technology than SMT. However, it is still prevalent and could not be completely replaced by the latter due to its distinct features. Below are some of them.

1. As mentioned earlier, PCBs assembled via the PTH assembly process are more durable than those assembled by SMT assembly. This is because the connections made using component leads are sturdier and can withstand environmental stress better. Therefore, through-hole assemblies can resist extreme heat and pressure conditions. This makes them the go-to choice for devices used in defense and space applications.
2. Heavier, large-in-size and bulkier components that cannot be mounted using the SMT process require through-hole technology for their assembly.
3. Component connections made with leads are easier to replace and adjust. This simplifies the process of repair and replacement. Specialized equipment is not required to replace any component as they can be mounted simply with a soldering iron.
4. Since the parts assembled by PTH are interchangeable, the through-hole assembly process is the go-to choice for prototyping and small circuit testing. It is also preferred for easy manual operations.
5. PTH PCB assemblies have better power handling as the bonds between the board and the components are quite strong, which allows the PCB to handle high power and voltage easily without the risk of circuit failure.

Cons of Through-Hole Assembly

As every coin has two sides, this immensely beneficial assembly technology &#; PTH, also comes with some drawbacks. Find them below.

1. The extra steps involved in the through-hole assembly process, like drilling and plating, make it more time-consuming. Therefore, the manufacturing and production efficiency is low in this case.
2. Drilling holes and component connections require more space compared to the surface mounting technique. Therefore, small or miniature PCBs cannot be assembled via this process. PTH assembly boards are generally larger, which makes them unsuitable for small-sized devices.
3. The component density is lower in through-hole assemblies due to the large-sized components and lead connection process.
4. While the ease of manual operations makes it the preferred choice for many applications, the same feature increases the turn time and chances of human error. Skilled staff is required to carry out this assembly process.
5. Like the SMT assembly process has a high chance of errors, through-hole assembly processes have a high risk of damage to the components. This is because the lead insertion process is tricky and may lead to bent or broken leads.

How to Select the Right Assembly Process for Your Project?

Both SMT and through-hole technology are extensively used in various applications ranging from consumer applications to defense and space industries. You may wonder if the two technologies have such drawbacks then how they are used in such crucial applications. This is because PCB engineers study the requirements of a device in detail and then choose a technology that best suits the device&#;s requirements. They use the right components and take necessary measures to avoid drawbacks like chances of error and damaged components. To determine which process is the right choice for a project, engineers consider points like:

• The scale of the project
• Device application
• If the device is made for prototyping purposes
• The components to be mounted
• Size of the device
• External and environmental conditions the device is expected to be exposed to
• Reliability and durability needs
• Budget and expected turn-time
• Component density required
• Device power handling capacity

In many cases, a combination of both technologies is employed to minimize the drawbacks and increase the advantages. So, talking to industry experts and hiring experienced professionals can make the most of your investment, considering the above-mentioned criteria. If you want to know more about the SMT assembly and through-hole assembly processes, get in touch with us today!

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Almost everyone uses devices that incorporate printed circuit boards every single day. It might not be known that these are being used, but they are so widespread and offer so many benefits that  almost everyone has them in nearly all of their electronic devices. Used to create electronics, there are many applications for printed circuit boards, many of which use surface mount technology (SMT) to integrate components faster and more efficiently than past technologies.

The Basics of Printed Circuit Boards

A printed circuit board or PCB is a board used to connect electronic components. These are essential parts of all the electronics that people use at home and work each day. PCBs are made using non-conductive material and come with pads, lines, and other features that are etched from a sheet of copper that can electrically connect various components inside of a device. When SMT technology is included, things like resistors and capacitors are soldered onto the board rather than using wires.

Today, PCBs in electronics are common and the most popular way to create new products. The boards themselves can be single-sided, double-sided, or multilayer. They also come in flexible or rigid configurations or can combine both based on need.

PCB Assembly Options

There are two typical methods for assembly of PCBs and their components, including through-hole and surface mount.

• Through-Hole Mount &#; With this kind of mounting, an assembler will put components leads into holes that are drilled into a PCB. This is an older technology that is not used as often as it used to be. It has a strong connection since the leads run through the board, but it takes more time and effort to work with this kind of mounting technology.

• SMT Technology &#; With surface mounting, the components are connected to the PCB directly through soldering. The method was first created in the s and gained popularity in the 80s. It&#;s the most common method of adding components today. Surface-mounted components are smaller so more parts can be placed on a board. This helps with the cost and has led to the proliferation of smaller devices year after year.

Common Uses for Printed Circuit Boards

It might seem like only a few sectors and industries would use printed circuit boards, but that&#;s not true. These little boards can be found in everything from massive pieces of machinery to small consumer devices. We want to share some of the most common applications for PCBs to give a basic idea of just how integral these items are for pretty much everyone.

LEDs

LEDs or light-emitting diodes are often used for lighting in both commercial and residential locations. LEDs are also used in many industries including computer technology, automobiles, and medicine. The biggest benefits of LEDs are their long life, energy efficiency, and compact size. PCBs are great for LEDs since they can help transfer heat away from the bulb. High temperatures make LEDs burn out faster, so the PCBs for them are typically made of aluminum to offer the best results. This eliminates the need for an extra heat sink and allows small, compact designs.

Industrial Equipment

The industrial sector uses printed circuit boards and SMT technology in many different ways. Electronic components are used for much of the powering of equipment in distribution and manufacturing centers, as well as other kinds of industrial environments. PCBs in industrial environments need to be exceptionally durable and high powered to handle harsh conditions since they may be around extreme temperatures, rough handling, harsh chemicals, or vibrating machinery. Many of them are made with thermal-resistant durable metals and are often thicker than typical PCBs.

Aerospace Components

Aerospace applications of PCBs require them to be capable of handling extremely harsh conditions. These printed circuit boards may be used in all sorts of equipment ranging from planes to satellites, space shuttles, and communication systems. The materials used for these PCBs need to withstand harsh conditions like extreme temperatures and large amounts of vibrations. Some are made to be used in outer space and are even more durable. Lightweight PCBs made of things like aluminum can also be useful in some situations.

Security and Safety Equipment

Whether used for homes, government buildings, or commercial businesses, security systems often rely on the use of PCBs and SMT technology. They have a huge effect on security and safety beyond what many are aware of. The PCBs used for these applications can vary based on the actual application, however, all should be reliable since these products must operate correctly at all times. Since some security devices operate outside the home or business, they need to be able to withstand that type of environment, as well. PCBs are used in everything from modern electronic door locks to security cameras, and even smoke detectors.

Medical Devices

New technology is constantly being incorporated into the healthcare sector and PCBs add additional capabilities to devices. Printed circuit boards are used in devices for diagnostics, treatment, monitoring, and more. These PCBs need to be exceptionally reliable since they are used to improve patient health. They also often need to meet specific sanitation standards and tend to work best when very small. Some of the devices that use PCBs in healthcare include medical imaging systems, infusion pumps, monitors, and even internal devices.

Electronics for Consumers

Computers, tablets, smartphones, and various other devices that people use every day need PCBs with SMT technology to function. As more electronics become part of everyone&#;s daily lives, PCBs are there to ensure they operate correctly. The boards allow smaller laptops and other devices while still creating the option of numerous capabilities. Most consumer electronics PCBs are relatively inexpensive to keep product prices low. However, the boards also need to be reliable to keep consumers satisfied.

AdvancedPCB offers a wide variety of printed circuit boards that can use SMT technology. We operate as a one-stop manufacturer and assembler of PCB solutions. We offer innovative technology with quick manufacturing and assembly for a wide variety of industries. Individuals and businesses can reach out to us with an order of any size to see what options we can offer.

The company is the world’s best Smt Soldering supplier. We are your one-stop shop for all needs. Our staff are highly-specialized and will help you find the product you need.