Advantages and Disadvantages of SMT

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Surface mount technology is a part of the electronic assembly that deals with the mounting of electronic components to the surface of a PCB. Electronic components mounted this way are called surface-mounted devices (SMD).

SMT was developed to minimize manufacturing costs while making efficient use of board space. The introduction of surface mount technology has enabled manufacturers to fabricate smaller size complex circuit boards. There are various advantages and disadvantages of surface mount technology which we will discuss over the course of this article.

The advent of surface mount technology

Surface-mount technology was developed in the s and was broadly used in the s. By the s, they were used in most of the high-end PCB assemblies. Conventional electronic components were redesigned to include metal tabs or end caps that could be attached directly to the board surface. This replaced typical wire leads which needed to pass through drilled holes. SMT led to much smaller components and enabled component placement on both sides of the board. Surface mounting enables a higher degree of automation minimizing labor costs and expanding production rates that results in the development advanced of boards.

Salient features of SMT and through-hole technology

SMT allows electrical components to be mounted on the board surface without any drilling. Most electronic applications prefer to use surface mount components since they are compact and may be installed on either side of a printed circuit. They are suitable for applications with higher routing densities. These components have smaller leads or no leads at all and are smaller than through-hole components.

The process involved in SMT assembly is:

• Apply solder paste to the fabricated circuit board using stencils. Solder paste is made up of flux and tin particles.
• Attach the surface mount components.
• Use a reflow method for soldering.

In through-hole technology, the component leads are inserted into the drilled holes on the board. These leads are then soldered to pads on the opposite side using wave soldering or re-flow soldering tools. Since through-hole mounting offers strong mechanical bonds, it is highly reliable. However, drilling PCBs during production tends to increase manufacturing costs. Also, through-hole technology limits the routing area for signal traces below the top layer of multi-layer PCBs.

Major differences between through-hole technology and surface mount technology

• SMT frees up the limitation on board space posed by the through-hole mounting manufacturing process.
• Through-hole components involve higher manufacturing costs than SMT components.
• You require advanced design and production skills for using SMT when compared to through-hole technology.
• SMT components can have a higher pin count as compared to through-hole components.
• Unlike through-hole technology, SMT enables assembly automation which is suitable for high production volumes at lower costs when compared to through-hole production.

• SMT components are more compact leading to higher component density as compared to through-hole mounting.
• While surface mount leads to lower production costs, capital investment for machinery is higher than needed for through-hole technology.
• Through-hole mounting is better suited to the production of large and bulky components that are subjected to periodic mechanical stresses or even high-voltage and high-power parts.
• SMT makes it easier to achieve higher circuit speeds because of its reduced size and fewer holes.

Factors to consider before choosing SMT or through-hole technology

• Stability of the component when exposed to external stress
• Ease of thermal management/ heat dissipation
• Availability of the part and its alternative
• Cost-effectiveness of assembly
• High performance and life-span of the package
• Facilitate rework in case of board failure

Advantages of surface mount technology

SMT has many advantages over conventional through-hole technology:

• Surface mount technology supports microelectronics by allowing more components to be placed closer together on the board. This leads to designs that are more lightweight and compact.
• The process for SMT production setup is faster when compared to through-hole technology. This is because components are mounted using solder paste instead of drilled holes. It saves time and labor-intensive work.

• Components can be placed on both sides of the circuit board along with a higher component density with more connections possible per component.
• Due to the compact size of the package, higher-density traces can be accommodated on the same layer.
• The surface tension of molten solder pulls components into alignment with solder pads, which automatically corrects minor placement problems.
• Compared to through holes, these do not expand in size during the operation. Hence you can reduce the inter-packaging space.
• Electromagnetic compatibility is easily achievable in SMT boards because of their compact package and lower lead inductance.
• SMT enables lower resistance and inductance at the connection. It mitigates the undesired effects of RF signals and provides better high-frequency performance.
• More parts can fit on the board easily due to their compactness, resulting in shorter signal paths. This enhances signal integrity.
• The heat dissipated is also lesser than through-hole components.
• SMT reduces board and material handling costs.
• Enables you to have a controlled manufacturing process. This especially opted for high-volume PCB production.

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Disadvantages of surface mount technology

Even though SMT has several advantages, the technology also comes with it certain disadvantages:

• When you subject components to mechanical stress, it is not reliable to use surface mounting as the sole method of attachment to the PCB. This is because you need to use component connectors to interface with external devices that are periodically removed and re-attached.
• Solder connections for SMDs might be damaged through thermal cycles during operations.
• You would need highly skilled or expert-level operators and expensive tools for component-level repair and manual prototype assembly. This is because of the smaller sizes and lead spaces.
• Most SMT component packages can&#;t be installed in sockets that enable easy installation and replacement of failed components.
• You use less solder for solder joints in SMT, therefore the reliability of solder joints becomes a concern. Void formation might lead to solder joint failures here.
• SMDs are typically smaller than through-hole components leaving lesser surface area for marking part IDs and component values. This makes identifying components a challenge during prototyping and repairing the PCB.
• The solder can melt when exposed to intense heat. Therefore, SMT cannot be implemented in electrical load circuits with high heat dissipation.
• PCBs that use this technology requires more installation costs. This is because most of the SMT equipment such as the hot air rework station, pick and place machine, solder paste screen printer, and reflow oven are expensive.

• Miniaturization and a variety of solder joints can make the procedure and inspection more difficult.
• Due to compact size, there is an increased chance of solder overflow that can result in short circuits and solder bridge.

 

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When to use surface mount technology?

The majority of products manufactured at this time utilize surface mount technology. But SMT is not suitable in all cases. Consider SMT considered if:

• You need to accommodate a high density of components.
• The need is for a compact or small product.
• Your final product needs to be sleek and light despite component density.
• The requirement specifies the high-speed/frequency functioning of the device.
• You need to produce large quantities with automated technology.
• Your product should produce very little noise (if any at all).

Guidelines for SMT component placement

Here are some recommendations for SMD placement to maintain good signal and power integrity for your board.

• Keep the components as near as possible to minimize the routing distance.
• Adhere to the signal path as per the schematic while placing the components.
• Never place the components in the return path of sensitive signals. This leads to signal integrity issues.
• For high-speed devices, place the bypass capacitors closer to their power pins. This will reduce parasitic inductance.
• Arrange the SMD together for power supply circuits. This will help you to provide shorter routing and reduce the inductance in the connections.
• Try to keep SMT components on one side of the board to reduce costs associated with stencils and assembly.
• Maintain the minimal spacing between the test points and SMT components as specified by your manufacturer. This spacing may vary depending on the component&#;s height.

To facilitate the assembly process ensure that all component names, polarities, orientations, and placements are marked properly in the assembly drawing. The footprints present in the drawings should match with the actual parts. Consult your manufacturer for their kitting guideline if you are considering consigned assembly. Prepare your BOM accordingly.

 

 

Soldering techniques employed in SMT

Solder reflow and wave soldering are widely used to mount components onto the board. Depending on the nature of the components, the designer can choose one of these methods for surface mounting technology.

Wave soldering: Since the solder will flow through the holes to form a connection, wave soldering is mostly used for through-hole components. You can use wave soldering for most of the surface-mount components also.

Solder reflow: This process is generally preferred in SMT. Here, the solder on one pin melts and reflows faster than the other. The only disadvantage is that it causes a tombstoning effect, where the component peels away from the non-melted pad. This effect is common for surface mount components like resistors, capacitors, and inductors.

Surface mount device packages

SMD packages come in a broad range of shapes and sizes as given below:

Common passive discrete components: These components are mostly resistors and capacitors and are a part of most electronic devices available today. Given below are SMD package details for capacitors and resistors.

Transistors: The common type of packages for transistors are as follows:

• SOT-23 (Small Outline Transistor) with dimensions 3 x 1.75 x 1.3mm
• SOT-223 (Small Outline Transistor) with dimensions 6.7 x 3.7 x 1.8Mmm

Integrated Circuit (IC) packages

Integrated Circuit packages come in a wide range as given below:

• Small Outline Integrated Circuit (SOIC)

Small Outline Package (SOP)

TSOP (Thin Small Outline Package)  is thinner than SOIC

• Quad Flat Pack (QFP)

Quad flat packs are generic square, flat IC packages.

• Ball Grid Array (BGA)

BGA packages include an arrangement of solder balls on the chip underside in the place of pins. The ball spacing typically is 1.27, 0.8, 0.5, 0.4, and 0.35mm

• Plastic Leaded Chip Carrier

The chip is enclosed in a plastic mold. It can either be square or rectangular in shape.

Measurement of SMD size

Surface mount component standards are specified by the Joint Electron Device Engineering Council (JEDEC) Solid State Technology Association (JEDEC.org). JEDEC is an independent semiconductor engineering trade organization and standardization body that has its headquarters in Arlington, Virginia, United States.

You can measure SMD size in inches in the Imperial system and millimeters in the Metric system. For the imperial components, the dimensions are 0.02 x 0.01 inches. For the metric components 0.2 x 0.1 mm.

Understanding the advantages and disadvantages of surface mount technology is essential to comprehend its role in the electronics industry. This will always help in optimizing your design and assembly skills. Follow the guidelines listed in this article to completely benefit from the SMT process for component placement. Please comment below if you have any queries on employing surface mount technology for your design. We will be happy to help you.

 

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What's Inside:

• Recommended layout for components
• Common PCB assembly defects
• Factors that impact the cost of the PCB assembly, including:
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Surface Mount Technology (SMT) manufacturing is a method for constructing electronic circuits in which components are mounted or placed directly onto the surface of printed circuit boards (PCBs). [1]In this article, we&#;ll take a look at the process, its benefits, factors that influence the SMT market &#; and, of course, how skills management can help improve SMT manufacturing processes.

What is SMT manufacturing?

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SMT manufacturing has largely replaced through-hole technology, in which components are inserted into holes drilled in the PCB. It&#;s also become a fundamental part of the semiconductor industry&#;s assembly and production processes. According to market analysis, the SMT market is predicted to grow from USD $5.7 billion in to $8.24 billion by . [2]

Here&#;s a bit of insight as to why:

• SMT eliminates the need for holes to be drilled into PCBs, saving space and enabling the production of smaller electronic devices
• SMT components can be placed on both sides of a PCB, and be placed closer together, meaning it is possible to create more compact and densely populated circuits
• SMT is compatible with automated assembly processes, which are more precise and efficient compared to manual assembly
• SMT results in the connections between components becoming shorter and more direct, better enabling higher-speed processing and communication in electronic devices.

 

What factors are influencing the SMT market?

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The predicted dramatic growth of the SMT market in the near future is due to myriad factors, but several of them play more prominent roles. They include the following.

 

Automation and robotics

Because SMT manufacturing can be used in automated production processes, the integration of advanced automation and robotics technologies in SMT assembly lines enables higher precision, faster production rates, and improved quality control, leading to enhanced overall manufacturing efficiency.

 

Miniaturization of electronic devices

The increasing demand &#; on both a consumer and commercial level &#; for smaller and more powerful electronic devices requires increasingly precise and intricate components and manufacturing processes, such as those used in SMT manufacturing.

 

Electric vehicles

Research from the European Free Trade Association showed a 57.4% jump in new electric vehicle registrations in the first quarter of . [3] As the motors of electric cars heavily rely on PCBs, the demand for SMT is expected to continue to rise.

 

How skills management can help navigate the SMT industry&#;s challenges

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Despite a highly positive outlook for the SMT market, the industry nevertheless faces challenges that hold the potential to delay or stall production.

The right skills management software, however, can play a critical role in helping organizations navigate them, providing a clear overview of the skills necessary to ensure smooth SMT manufacturing processes &#; thus ensuring that skills gaps are easily identified and closed before they become an issue.

Let&#;s take a look at a few of the most prominent challenges facing the SMT industry, as well as how proper skills management might help an organization through them.

Supply chain challenges

Disruptions in the global supply chain, including shortages of raw materials, electronic components, and semiconductor chips, have significantly impacted SMT manufacturing, leading to production delays and increased costs.

Here, skills management could help an organization track and maintain certifications critical to managing the supply chain. They include &#; but are not limited to &#; the following.

Explore more:
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• Certified Supply Chain Professional (CSCP). Offered by APICS

  [4]

  , a CSCP certification validates professionals&#; expertise in supply chain management, including areas such as supplier and customer relations, international trade, and logistics. AG5 offers a free certification guide for CSCP certifications.
• Certified Professional in Supply Management (CPSM). The Institute for Supply Management (ISM)&#;s

  [5]

   CPSM certification demonstrates proficiency in strategic sourcing, negotiation, supplier relationship management, and supply chain planning.
• SCPro certification. Offered by the Council of Supply Chain Management Professionals (CSCMP)

  [6]

  , the SCPro certification program assesses professionals&#; end-to-end supply chain knowledge, including areas such as supply chain concepts, analysis, and design.
• Certified Warehouse Logistics Professional (CWLP)&#;. Offered by the International Warehouse Logistics Association (IWLA)

  [7]

  , the CWLP demonstrates proficiency in warehouse management, distribution operations, and inventory control, essential for effective supply chain management.

 

 

Environmental regulations

As environmental concerns continue to gain prominence, the SMT market is under increasing pressure to adopt sustainable manufacturing practices and comply with stringent environmental regulations. This includes reducing the use of hazardous materials, minimizing electronic waste generation, and implementing energy-efficient manufacturing processes.

Here, you can use skills management software to track the statuses of a wide range of qualifications and certifications related to environmental compliance. These might include the following.

 

• ISO certification. ISO&#;s

  [8]

  globally recognized certification demonstrates a company&#;s commitment to implementing and maintaining an effective environmental management system, including practices for reducing environmental impact and complying with relevant regulations. AG5 offers a free certification guide for ISO certifications.
• Certified Energy Manager (CEM). Offered by the Association of Energy Engineers (AEE)

  [9]

  , A CEM certification validates professionals&#; expertise in managing energy efficiency programs, implementing sustainable energy solutions, and ensuring compliance with environmental regulations.
• Certified Hazardous Materials Manager (CHMM). Provided by the Institute of Hazardous Materials Management (IHMM)

  [10]

  , this certification demonstrates proficiency in managing hazardous materials, including their safe handling, storage, transportation, and disposal, essential for ensuring compliance with environmental regulations.
• OSHA 30-Hour General Industry Certification. While not specific to environmental compliance, an OSHA

  [11]

   general industry certification demonstrates knowledge of workplace safety and health regulations, which are essential for ensuring a safe and compliant work environment in the context of environmental regulations.

 

Skilled labor shortage

 

The SMT industry requires skilled technicians and engineers with expertise in operating advanced manufacturing equipment and handling complex assembly processes. Addressing the shortage of skilled labor in the manufacturing industry and investing in workforce development and training programs are essential for sustaining growth and innovation within the industry.

 

Skills management software plays an especially key role here, helping you monitor certification statues, training needs, and other important skills related to SMT manufacturing. Certifications that prove especially valuable here include the following.

 

• IPC-A-610 certification. The IPC

  [12]

  is a global trade association for the production and assembly requirements of electronics. The IPC-A-610 certification focuses on the acceptability criteria for electronic assemblies, covering topics such as component installation, soldering criteria, and surface mounting criteria. It is highly valued in the electronics manufacturing industry.
• IPC J-STD-001 certification. Focuses on the requirements for soldered electrical and electronic assemblies. It covers soldering materials and processes, including surface mount and through-hole technologies, as well as the handling of electronic components.
• IPC-/ certification. A certification related to the repair and rework of electronic assemblies. It covers the best practices and techniques for reworking and repairing printed circuit board assemblies, including both surface mount and through-hole components.
• J-STD-020 certification. The JEDEC Solid State Technology Association&#;s

  [13]

  J-STD-020  certification focuses on the requirements for moisture and reflow sensitivity classification in surface mount devices (SMDs). An SMD refers to an individual component that is mounted during an SMT manufacturing process. A J-STD-020 certification is particularly important for ensuring the reliability of SMDs during the manufacturing and assembly processes.

 

Get started with your skills management strategy for SMT manufacturing

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Are you ready to get started streamlining your SMT manufacturing processes and ensuring compliance and safety along the way? Book a free, live, 15-minute demo with AG5 today for a front-row seat!

Additionally, we also provide free certification guides &#; such as those linked in the above section &#; and Excel skills matrix templates, such as these for the semiconductor industry and manufacturing industry. You can use them to effectively manage and assess the skills and certification statuses of individual employees or teams before fully onboarding to AG5.

 

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Source number Source title Description Date retrieved Source URL 1SMT Manufacturing: Everything You Need to Know.Wevolver19 Apr 14:07:40https://www.wevolver.com/artic..2Surface Mount Technology Market - Growth, Trends, COVID-19 Impact, and Forecasts (-)Research and Markets19 Apr 14:08:38https://www.researchandmarkets..3European Free Trade AssociationEuropean Free Trade Association19 Apr 14:10:14https://www.efta.int/..4Association for Supply Chain ManagementAPICS19 Apr 14:11:42https://www.ascm.org/learning-..5Institute for Supply ManagementISM19 Apr 13:36:03https://www.ismworld.org/..6Council of Supply Chain Management ProfessionalsCSCMP19 Apr 13:36:03https://www.ascm.org/learning-..7International Warehouse Logistics AssociationIWLA19 Apr 13:46:03https://www.ascm.org/learning-..8International Organization for StandardizationISO19 Apr 13:46:03https://www.iso.org/home.html..9Association of Energy EngineersAEE19 Apr 14:43:03https://www.aeecenter.org/..10Institute of Hazardous Materials ManagementIHMM17 Apr 15:23:02https://www.ihmm.org/..11OSHAOSHA19 Apr 13:36:03https://www.osha.gov/..12IPCIPC19 Apr 14:46:23https://www.ipc.org/..13JEDEC Solid State Technology AssociationJEDEC19 Apr 14:21:02https://www.jedec.org/..

• SMT Manufacturing: Everything You Need to Know. Wevolver. Retrieved 19 Apr 14:07:40, from https://www.wevolver.com/article/smt-manufacturing-everything-you-need-to-know

• Surface Mount Technology Market &#; Growth, Trends, COVID-19 Impact, and Forecasts (-). Research and Markets. Retrieved 19 Apr 14:08:38, from https://www.researchandmarkets.com/reports//surface-mount-technology-market-growth?utm_source=BW&utm_medium=PressRelease&utm_code=w7v7sq&utm_campaign=+-+Insights+on+the+Surface+Mount+Technology+Global+Market+to++-+Featuring+Yamaha+Motor%2c+Panasonic+and+Nordson+Among+Others&utm_exec=jamu273prd

• European Free Trade Association. European Free Trade Association. Retrieved 19 Apr 14:10:14, from https://www.efta.int/

• Association for Supply Chain Management. APICS. Retrieved 19 Apr 14:11:42, from https://www.ascm.org/learning-development/certifications-credentials/cscp/

• Institute for Supply Management. ISM. Retrieved 19 Apr 13:36:03, from https://www.ismworld.org/

• Council of Supply Chain Management Professionals. CSCMP. Retrieved 19 Apr 13:36:03, from https://www.ascm.org/learning-development/certifications-credentials/cscp/

• International Warehouse Logistics Association. IWLA. Retrieved 19 Apr 13:46:03, from https://www.ascm.org/learning-development/certifications-credentials/cscp/

• International Organization for Standardization. ISO. Retrieved 19 Apr 13:46:03, from https://www.iso.org/home.html

• Association of Energy Engineers. AEE. Retrieved 19 Apr 14:43:03, from https://www.aeecenter.org/

• Institute of Hazardous Materials Management. IHMM. Retrieved 17 Apr 15:23:02, from https://www.ihmm.org/

• OSHA. OSHA. Retrieved 19 Apr 13:36:03, from https://www.osha.gov/

• IPC. IPC. Retrieved 19 Apr 14:46:23, from https://www.ipc.org/

• JEDEC Solid State Technology Association. JEDEC. Retrieved 19 Apr 14:21:02, from https://www.jedec.org/

Author

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Rick van Echtelt

Rick van Echtelt is the Co-Founder and CEO of AG5, where he leverages over two decades of experience in entrepreneurship and developing skills management software.

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