How To Complete Your SMT PCB Assembly, These 9 Detailed Instructions

When it comes to electronic components' manufacture, especially printed circuit boards, you may hear of SMT or Surface Mount Technology PCB assembly. But what does SMT PCB assembly mean? SMT PCB assembly is a method whereby a printed circuit board's components get placed or mounted directly onto the surface of a printed circuit board.

When it comes to the assembly of electronic components, SMT comes in as one of the industry's most commonly used processes. Many PCB designers, learners, and PCB assembly engineers might not understand the basics of PCB assembly. This article provides nine aspects that can guide you through the SMT PCB assembly.

（The welding robot solders the circuit board in a light blue scene with lighting effects.）

1.Development of SMT PCB Assembly Technology

The development of SMT PCB assembly technology is a short one, having come in the market during the 1960s. In the 1960s, when this technology came into light, only a few players in the industry took advantage of the possibilities that surface mount technology provided. It took another 20 years for SMT assembly technology to turn into a widely used operation across many industries.

During the late 80s and early 90s, the development of SMT PCB assembly technology increased with placement equipment beginning to automate the entire process of surface mounting. When it reached the year 2000s, PCB assembly technology saw the combination of several “pick” and “placement” machines into one highly heads that perform the entire placement procedures.

(a board that uses SMT technology)

2.Advantages of SMT PCB Assembly

There are several benefits associated with the Surface Mount Technology PCB assembly. When it comes to the assembling printed circuit boards, SMT PCB assembly comes with the promise of reduced material handling costs, reduced board costs, and a unique manufacturing process.

Additionally, one of the most important benefits, especially in the design stage section, is massive savings not only in weight but also in terms of noise reduction.

Better yet, SMT components are excellent when it comes to space management. SMT components occupy minimal space on the printed circuit board. SMT permits easily allow the creation of small PCB designs as it enables the placement of components closer together on the PCB.

Unlike other forms of technology, the SMT process is swift to set for production. Moreover, PCBs made under the SMT process are compact and come with higher circuit speeds.

(capacitors attached to a board with SMT technology)

3.Disadvantages of SMT PCB Assembly

Even though surface mount technology comes with plenty of benefits, some disadvantages are associated with SMT PCB assembly technology. First, the small lead spaces may make repairs to be a little bit difficult.

Secondly, SMT PCB assembly cannot assure that the solder connections will withstand components used during potting.

Thirdly, when it comes to SMT PCB assembly, components that bear high electrical loads or happen to generate a lot of heat can’t be mounted using SMT because the solder can melt under high temperature.

Lastly, another disadvantage associated with surface mount technology printed circuit board assembly is that solder quickly weakens due to instances of mechanical stress.

It means that those components that directly interact with the user need attachment with through-hole mounting's physical binding.

SMT is also unsuitable for high-power, large, and high-voltage parts, not forgetting that component-level repair or manual prototype assembly is more tasking and requires expensive tools and skilled operators.

(PCB on fire)

4.How does SMT Machine Work?

As mentioned earlier, electronics manufacturing by using surface mount technology means the assembly of electronic components with automated machines that place different parts on a printed circuit board.

In contrast to conventional or traditional through-hole technology processes, SMT components get placed directly on a printed circuit board's surface instead of soldering to a wire lead. While an SMT machine may look somewhat complicated, it works very quickly.

A surface mounts technology machine has a head and an arm that reaches all the tubes, reels, and every other part. It picks all the pieces up and then perfectly places them on the board.

The SMT machine's head mainly uses a small vacuum head to pick up the components before precisely placing them on the board. Known as “pick” and “place” machines, these machines pick individual pieces from a reel magazine and put them on an empty printed circuit board. Of importance to note is that proper programming of such devices plays an essential role in quality and performance.

(close up image of a processor)

5.Important Technology in the SMT Process

As mentioned earlier, surface mount technology, short for SMT is a method used to attach electronic components on the surface of a printed circuit board instead of inserting parts or elements to holes as with traditional printed circuit board assembly.

Surface mount technology is unique for plenty of reasons. Still, the idea behind this technology was to reduce the costs of manufacturing printed circuit boards and make more efficient use of written circuit board space. With SMT's introduction, it is now possible to build highly complex circuits into smaller assemblies with excellent repeatability based on high levels of automation.

SMT process consists of six essential steps that require the use of the latest technology.

I. Solder paste stenciling followed by

II. Pick and place then followed by

III. Reflow soldering

IV. Inspection and quality control developed by

V. Through-hole component insertion, and lastly,

VI. Final inspection and functional testing.

3D technology is one of the most critical technologies in the SMT process because it allows more accurate measurements and brings about a more stable inspection process on a PCB.

(an SMT assessment device)

6.What can SMT Printing Technology can Bring to us?

People expect SMT printing technology to advance in the years to come. Even though we currently have better performing printed circuit boards, the future looks bright with SMT printing technology expected to improve.

With SMT printing technology, there will come novel manufacturing methods of printed circuit boards for better system integration, cost-saving, and lightweight boards. Additionally, SMT printing technology will bring about new assembly possibilities, shorter development times, and new assembly technologies.

With technology continuing to advance, there are expectations that surface mount printing technology will bring about better and high-performing printed circuit boards than the ones that currently run our electrical devices.

(futuristic trends of SMT technology)

7.Difference Between SMT and SMD PCB Assembly Technology

Fundamentally, there is a massive difference between surface-mount technology, SMT in short, surface-mount device, or SMD. The first distinguishing factor is that one is a process –surface-mount technology-, while the other is a device –surface-mount device.

Secondly, SMT is not tangible to the final consumer, and most people that don’t understand PCB might not even know. But SMD is more physical and tangible. These are the day to day electronic products from laptops, washing machines, and military-grade electronics.

Thirdly, surface-mount technology, and surface-mount devices differ in terms of technology. Surface-mount devices can be manually soldered using hands, but the situation is not the same when it comes to surface-mount technology.

(a board that uses SMT technology)

8.Technologies that PCB Suppliers can Provide for SMT Assembly

Surface mount technology assembly seems to have gained significant popularity, especially in recent years, due to several beneficial features that the SMT assembly offers. As mentioned earlier, these printed circuit boards are compact and perfect in meeting the growing demand for small electronic devices.

Over the years, plenty of printed circuit board suppliers have improved their technologies concerning SMT assembly. However, there are technologies that PCB suppliers can provide for SMT assembly. There are plenty of techniques that printed circuit boards suppliers can offer when it comes to surface mount technology assembly. Some of the most common ones include the following:

• Custom-retained thermal profiles
• Miniature Chip
• BGA repair and real
• Leadless devices
• BGA, SCM, and Pop

(an SMT assembly line)

9.Development Trends of SMT PCB Assembly

Looking around, you’ll notice that when it comes to surface mount technology printed circuit board assembly, most products are heading towards the development of small, short, multi-functional, and lightweight printed circuit boards. Surface-mount technology has transformed, turning out to become the mainstream of the manufacture of electronic components.

SMT PCB assembly is continually evolving, and some of the latest advancements here include increased speeds, soldering paste, and the development of LED technology, to mention but a few. Currently, there seems to be a fierce competition across various PCB suppliers, with the cost of pressure being relatively high.

However, when it comes to surface-mount printed circuit board assembly, the primary development trend is to come up with flexible, high-performing, and ease-of-use printed circuit boards. There are plenty of development trends that are shaping the SMT PCB assembly market. Some of the common include the rise of some smart consumer devices that require tightly packed PCB boards, the impact of cyber hacking across the PCB board assembly industry, and the excessive usage of unconventional substrates that include stretchy and flexible printed circuit boards.

（ High Tech Factory Facility.）

Summary

For a decade and counting, we at WellPCB have been an industry provider for the provision of printed circuit board assembly services - supplying both flexible and rigid products to customers across the industrial, automotive, telecommunications, medical, aerospace, and other markets.

Our SMT PCB assembly services include the design of printed circuit boards and prototyping, Design for Manufacturability, low-volume, and high-volume to low-mix production. Our testing and inspection services feature state-of-the-art equipment coupled with some of the latest practices when it comes to testing your boards in addition to our automated machines.