The process of PCB fabrication is impressive, and even those familiar with PCB design might not know all the ins and outs of how PCBs are made. Learn more about the different PCB fabrication techniques that make your design go from the virtual image on your computer screen to the tangible, green board in your toaster.

The Basics

Before diving into PCB fabrication, it’s important to know what makes up a PCB. Often, people will describe PCBs as a layered cake. The most basic PCB designs have four layers: the substrate (base), copper, solder mask, and silkscreen. These layers all work together and must be in total alignment for the final product to work.

Once you’ve designed a PCB and sent your PCB design off to the manufacturer, what will they do with it? For starters, they use your PCB design as the blueprint for the entire process.

Through-Hole Method

One of the earliest forms of PCB fabrication was the through-hole method. This tried-and-true method is quickly being replaced by a more modern PCB fabrication, known as surface mount technology (SMT). While each has its advantages and disadvantages, SMT PCB manufacturers seem to be able to produce smaller and cheaper PCB boards.

We’ll take a look at the intricate work that goes into a through-hole PCB design first. The most significant difference of the through-hole method is that manufacturers drill a hole into the board so that factory workers can double-check that each layer is aligned before moving onto the next step. With the through-hole method, manufacturers will print your PCB design onto special laminate paper. The manufacturers can attach a thin sheet of copper once the design is captured onto this special paper. This will be the basis of your substrate, or the base of the PCB.

Creating Layers

The next step is to start working on the copper that will form the layers of your PCB. This process is a bit similar to how photographs are developed – to the point that at-home PCB makers will use the same processing chemicals. Essentially, the special laminate paper is covered with photo-reactive chemicals, and when a UV light passes over it, it hardens the desired areas. This shows manufacturers which parts, based on your design, should be kept for the final PCB board and which bits of copper should be chipped away.

When the chemicals dry and harden, the board is washed in an alkaline solution and is ready to be inspected. If the board is good to go, a technician uses a powerful chemical to remove unnecessary copper, leaving behind only the copper needed per your PCB design.

Next, the copper layers are laminated together. Technicians must keep a keen eye for detail and always watch that each layer is perfectly aligned with the last. The result is a beautiful, half-finished board.

Factories can use an x-ray machine to uncover where the holes are meant to be drilled and then use a high-powered drill for precise execution. The board is finally plated, and the layers are fused with a series of chemicals. There is one last etching that occurs before the solder mask is attached. This etching ensures that your PCB has the right connections to make your creation function.

Surface Mount Technology

Surface mount technology (SMT) has become more commonplace in the PCB fabrication process because it allows for easier mass production. With an SMT outfit, the PCB fabrication process is more automated and thus less prone to human error. SMT-designed PCBs also do not have the same hole that is prominent in the through-hole method. Here’s a brief glimpse into how these PCBs are produced.

Simple As a Stencil

By using high-powered computers and technology, machinery takes your PCB design and creates a stencil. The stencil contains all the information the automated process will need to finish up your design. The stencil also allows machines to trace solder paste onto the board only in the designated areas.

The board is now ready to run through a pick-and-place machine, which takes the guesswork and error out of the PCB design process. The pick and place machine holds various components in their reels and reads the solder paste to place the proper components onto the board as directed by the PCB’s design. The solder paste will also hold everything in place so that components cannot be knocked off-kilter, thus resulting in a faulty product.

Once this process finishes, the PCB is heated and melts the soldering paste so that the layers meld together. The PCB is then ready for a clean-up, to ensure there is no residual solder paste on the board. At last, the board will receive an inspection of any potential defects.

Advantages of Surface Mount Technology

As you can see, SMT is a much more straightforward and more automated process. Its simplicity is what makes it best for the mass production of PCBs. Once a stencil is created for a design, you can print countless boards. Since the process relies on computers and machines rather than technicians, it’s also less vulnerable to human error. If there’s a mistake with a PCB board, it’s likely because the pick and place machine needs some reconfiguration.

Another big advantage of SMT fabrication is that they tend to allow for higher density component placement while still maintaining smaller boards. Since the board is smaller, the connections have a shorter distance to travel for better power.

The most significant disadvantage of the stencil-based process is that it makes it more challenging to produce prototypes quickly. This system works best if the same stencil is being used repeatedly, rather than creating one stencil that will change.

However, given the automation of the SMT process, it’s no wonder that the SMT fabrication method has gained greater momentum in the PCB world than the through-hole. Whichever route you go, make sure you’re aware of the PCB fabrication process that your manufacturer uses. In today’s world of making everything faster and smaller, you’ll want to make a decision that gives you the best return on investment.

To distribute electricity, PCBs are made with a series of copper wires (called traces) that connect components and allow electrons to flow. Understanding PCB fabrication is important, whether you’re teaching students the basics of electronic device operation or you’re designing the next hit Internet of Things device. In this guide, we’ll explore some of what you need to know about PCB fabrication.

Types of PCBs

Today, there are three types of PCBs manufactured. The PCB fabrication process is similar for each, although the more complex the board, the more complicated the fabrication process will be. The three types you’ll find today include the following:

• Single – Single-sided PCBs are the simplest of the lot and are made with an FR4 base and a rigid laminate made from woven glass epoxy. One side of the laminate is covered with copper, while the other side is left uncovered. The copper layer can be of varying thickness to suit the usage needs and design of the board.

• Double – Double-sided PCBs use the same epoxy as single-sided PCBs. The primary difference here is that both sides have copper added so that traces can be etched. Each side has the potential to either act as a separate circuit board, or to integrate with the other, creating a more compact form factor for what would be a larger board if it were only single-sided.

• Multi-Layer – Some PCBs have multiple layers. They begin with the same substrate material, but use copper foil instead of a copper coating. Foil and base material are interleaved to create a sandwich effect that allows multiple layers of functionality.

Of course, the PCB fabrication process is more complex than this. There are four primary parts to a PCB. These are the substrate, or base material, the copper layer (or foil), the solder mask, which protects the copper from damage during the soldering process, and silk-screening, which denotes part numbers, symbols, and other important information. Getting these four components into place is the purpose of PCB fabrication, and there are multiple steps involved.

Design

The first step is to design the PCB. Usually, you’ll use design software, such as PCB Artist, which is a free, full-feature tool that delivers powerful capabilities and ease of use. During this process, you lay out the board, indicate where components go, route traces, add capacitors, and more. However, this is all theoretical. No actual PCB fabrication occurs during this stage – it’s all about planning, prep, and basic testing for functionality.

The Design and Fabrication Process

With the design work out of the way, you now need to choose the bare PCB boards and create the traces. This process will remove unwanted/unneeded copper, leaving you with the characteristic thin lines to carry current from component to component. In most cases, a chemical etching process is used – ferric chloride is the most common etching agent, although there are other agents, and even other etching processes that may be used.

On top of the base material, copper is laid, either as a full layer, or as a foil. Over that, a film is placed. This film has a photograph/image of the completed circuit. The film is exposed to light to detail the traces and component mounting locations, creating what is called a photo-resist. This is then placed in a developer solution that removes any unneeded material.

The next step in the PCB fabrication process is to use ferric chloride to etch the area without copper. If the ferric chloride solution is too strong, or if the PCB is left in the solution for too long, damage may occur, so timing and proper solution mixing are both critical considerations.

Note that this is just one option when it comes to PCB fabrication. There are other methods that do not rely on ferric chloride at all. For instance, milling machines are able to remove copper from the areas where it is not needed without damaging the underlying board. Another option is to use inks that resist the etching solution rather than a film.

Drilling Holes/Vias

Numerous holes, or vias, must be drilled through the PCB during the fabrication process. These are used for a couple of different things. One is obvious – mounting components by their pins. However, another is to ensure that the individual layers of the board can be lined up. This is particularly important with multilayer PCBs.

Soldering and Silk-Screening

The final two steps of the PCB fabrication process are soldering and silk-screening. A soldering mask is put in place over the PCB to protect the copper from damage and to ensure that soldering is done accurately. Then, the board is flipped over and names, numbers, symbols, part identification information, and other text elements are silk-screened onto the board.

Decades of PCB Manufacturing Experience

In the end, PCB fabrication is a complex process. Accuracy and proper planning are essential from the very beginning. Whether you’re designing your first PCB ever or you’re hard at work on yet another prototype, it pays to have the right PCB design software, as well as the right manufacturing partner.

At Advanced Circuits, we have decades of experience working with clients ranging from individuals to international corporations. We can help with prototyping, design, testing and offer full PCB fabrication services with minimal lead time and highly flexible minimum order requirements. Contact us today to learn more about how we can help.

Before Sending

Before you send your design to the PCB manufacturer, there are a few things that you should do. Remember – this is your final chance to make sure that your board design lives up to your expectations. To that end, make sure that you:

• Print Out the Layout: Physically print the board design on paper and make sure that everything fits. If there is even a small amount out of tolerance, it’s time to address that.

• Check for Functionality: Make sure that your components are all in place, that your traces are properly sized, that you have no 90-degree angles (to avoid partial etching and the resulting shorts), and more. As much as you can, check functionality and placement one last time before sending the design out.

• Double Check Tolerances: Verify with your PCB manufacturer what their tolerances are and then ensure that your design meets those requirements. In most cases, you can simply build those tolerances into your design with your PCB software, such as our free PCB Artist software. Just run a quick manufacturability check based on those tolerances and you should be alerted to any issues, which can then be rectified.

• Double Check the Space Requirements: When adding components to your PCB, make sure that you leave enough space between them. You need to account for traces, but also to help alleviate heat buildup, to reduce resistance, and more. Don’t forget that you will also need to leave room for things like buttons and other components that are not part of the PCB layout, too. Accurate size estimation from the beginning stages is essential to success.

Know the PCB Manufacturing Process

It is important to understand the process followed by the PCB manufacturer once you send your design to them. After design, which is the part you handle, the next step is printing. The PCB manufacturer will check your design to ensure that it meets design tolerances. Note that this check does not necessarily mean that your board works to your expectations – most DFM checks are strictly to ensure that the board fulfills the tolerances necessary for manufacturing. (When you work with Advanced Circuits you can take advantage of our FreeDFM tool, to ensure your design is free of manufacturability issues.)

A plotter printer will then be used to print the PCB. This type of printer uses a transparent film to create a negative image of the board. Black and clear ink are used to represent traces and circuits, as well as non-conductive areas of the board (clear ink). With outer board layers, the colors are reversed, with black indicating non-conductive parts and clear ink used for components. A soldering mask is added, and then a registration hole is punched through the film to help align each one into the appropriate layer.

Next up, the manufacturer prints the copper layer for the board’s interior layers, then unnecessary copper is removed. Finally, the entire thing is sandwiched together into a single board and inspected, the layers are laminated, drilling takes place, and plating occurs. A final etching then occurs, followed by the application of the solder mask, silk-screening, and a final reliability test.

Of course, it helps if you have chosen the right PCB manufacturer in the first place. What should you consider when choosing one?

Choosing a PCB Manufacturer

You’ll find many important considerations when choosing a PCB manufacturer. There are numerous fabricators available, but they are by no means created equal. Some are budget-oriented options, while others are geared for working with major tech companies. Here are a few of the more critical considerations to make before choosing a partner:

• Lead Time: Some PCB manufacturers have very long lead times. Make sure you know the lead time requirements of any you are considering working with, as this will have a huge impact on your overall project.

• File Type: Make sure that the PCB manufacturer that you choose accepts the file type(s) that you want to send. Some of the more common types used today include KiCad, Gerber, and EAGLE.

• Minimum Time to Shipment: In addition to lead time, you’ll need to think about the company’s minimum time to shipment. Basically, this is a specified period that occurs before your order can be shipped. Some companies have very low requirements, but others have lengthy periods that may be a week or more.

• Order Quantity: How many boards do you need to print? Are you interested in one or two prototypes for testing? Do you need a full production run? Make sure that the PCB manufacturer you choose is able to meet your quantity requirements. Some companies will only print larger quantities, while others are more flexible.

• Software Availability: Ideally, you’ll work with a PCB manufacturer that makes design software available to you. At Advanced Circuits, we offer one of the most robust design tools in the industry – PCB Artist – free of charge. It can handle all of your design needs and seamlessly export the design when you’re ready to print.

Our Position as an Industry Leader

Ultimately, the right PCB manufacturer will help you bring your designs to life. Make sure that you check their reputation, the quality of their manufacturing process, their lead time and minimum time to shipment, minimum order quantity, and whether they offer access to free design software or not. At Advanced Circuits, we’re proud of our position as an industry leader, as well as our ability to offer our customers the flexibility they need. Whether you’re printing off a handful of prototypes, or you’re ready to go to market with a full production run, we can help.

Yet, turnaround times, costs, and one-off capabilities have not been available to the average designer…at least, not until now. While the professional level fabrication of circuit boards doesn’t involve the prototyping board but instead takes many steps (design, DFM checks, film creation, mapping of copper paths, and all of the way to V-scoring and testing, among other steps), it can now be done on the same day!

Advanced Circuits has turned PCB design and manufacturing on its head, and has made the classic prototyping board look as out of date as the Model-A Ford does to the Tesla.

A One-Day and One-Stop PCB Opportunity

With more than 25 years in the circuit boards industry, Advanced Circuits has real-time capabilities that ensure anyone eager to make a single board or conduct an experiment prior to marketing a design or concept can do so quickly and flawlessly. We have thousands of square feet of production space, we offer clients an in-house PCB assembly system from start to finish, and we can also provide:

• One day PCB – We are one of the few PCB makers that can manufacture and assemble circuit boards and ship them out in as little as a single day – including items that would once have required someone working in a lab using their outdated prototyping board.
• Quality – Most in the modern PCB industry approve of Advanced Circuits’ design resources, the company’s inspection process that begins with a full CAM review before any manufacturing begins, and the services that include visual inspections of the final circuit boards.
• Clear pricing – Also unlike many other producers, we do not ask for stenciling fees, setup fees, and other charges.
• Comprehensive support – Our team works with you every step of the way. We begin with a quote based on initial design uploads and then work with an order of any size (one to one thousand, or more PCBs) to final production and assembly phases.

We are an authentic “one-stop” and often “one-day” shop, with a completely seamless process under a single roof. Whether it is a single board or an array of options, everything remains in the hands of the company’s designers and engineers. Don’t worry about outside vendors looking at a concept or messing up a design, and also don’t worry about delays, problems, and errors. Advanced Circuits’ in-house production and assembly make these risks a non-issue.

Amazing Resources Well Beyond Replacing Prototyping Boards

It is great to toss that prototyping board, but there are even greater benefits for clients of Advanced Circuits. As noted, we impose no minimum orders, making us an ideal solution for  small to mid-sized producers or designers. We make design nearly foolproof thanks to our  “eyes at all times” approach, and our remarkable resources for clients to use free of charge. We include:

• Free Design Software – The cost of PCB design software is part of doing business, but the Advanced Circuits PCB Artist software is available in an unrestricted format and entirely for free. It is a free download (Windows only at this time) and is capable of up to 28 layers in a single design. The program has over 500k parts from which to choose, integrates a controlled auto-router function to speed up design processes, and offers multi-page schematics for more complex projects. With a complete library of tutorials to train those using the program, there is no reason not to take advantage of it (and the discounts given to clients who opt for the use of either free software). It makes the use of that prototyping board unnecessary.
• Free Evaluation Software – For those already using a CAM program of ours, use of FreeDFM allows any design to be tested. The files are exported in a Gerber format and the entire file will be reviewed. The software can correct any glitches and generate a report indicating changes or potential problems. Troubleshooting the flawed prototyping board is now a permanent relic of the past.
• CAM Engineer Evaluations – All products are evaluated by one of the in-house engineers before production begins in order to spare clients any costly mistakes.
• Clients always have access to tech support – Our around the clock customer support includes the help of a CAM engineer, and these experts are available 24 hours a day.
• Ordering through the software – When a client runs the proprietary software available through the site, they also have the choice of ordering at the same time. They still get that CAM engineer review and checks for errors and get a discount code as an incentive.

Everything is done in-house – from customer service to final production. This eliminates most of the problems in the design process. Why remain an advocate or user of prototyping boards and breadboards when the resources from Advanced Circuits are available? With them, clients enjoy the same kinds of hands-on attention they might in a real-world lab. Production is never outsourced. Evaluation is never outsourced, and there are no risks as there are in the “no-touch” approach used by a lot of fabricators (who want to receive your pre-tested files and get to work).

Rigorous Quality Checks & Premier Client Support

We do rigorous examinations of a design before we begin. We are never a broker that sends the work elsewhere. Rather, designers and clients enjoy a one-stop answer to their circuit board needs, and troubleshooting is part of the equation. This is one of the biggest benefits to those who would otherwise use the clunky prototyping board option. Instead, it is free design tools, free testing, and one-day manufacturing of even a one-off item.

We are quick turn specialists with some of the fastest turnaround times and shipping. In fact, Advanced Circuits offers the BEST ON-TIME SHIPPING RECORD in the industry, and is now shipping 50% of orders early! In fact, we ship Standard Spec orders on time or they’re FREE!

Clients who want to toss the prototyping board and enjoy a flawless design process full of support and even corrections and adjustments that guarantee success, rely on Advanced Circuits!

Below is a list of the common types of printed circuit boards.  For a complete list of Advanced Circuits’ PCB manufacturing capabilities, click here.

Single Layer PCB

Single layer printed circuit boards are among some of the simplest to design and manufacture.  These boards have a single layer of conductive material (such as copper) on only one side of a non-conductive substrate.

Double Layer PCB

Double layer PCBs have one conductive layer on top of a non-conductive substrate and another conductive layer on the reverse side (top and bottom layers).  The two conductive sides can be connected using plated holes in the substrate that connect to pads on both sides of the circuit board; these are called vias.

Multi-Layer PCB

This term refers to a circuit board that has three or more conductive layers.  The conductive layers are at the top and bottom, as well as at least one conductive layer sandwiched between non-conductive substrate.  Advanced Circuits has the capability to fabricate up to 40 layer boards, but the most commonly used have lower layer counts such as 4, 6, or 8 layer boards.

High Density Interconnect (HDI) PCB

HDI PCBs take advantage of precision based manufacturing technology to pack as much functionality into a small space.  This is done by using many conductive layers, laser drilled microvias, fine lines and tolerances, and advanced laminate materials.  HDI PCBs can accommodate the complex routing of high pin count chips and other high-tech miniaturized components.

High Frequency PCB

The main difference in manufacturing high frequency printed circuit boards pertains to the design itself.  These PCB are designed to facilitate signals over 1 gigahertz.  Depending on the application, high frequency printed circuit boards may require the use of advanced laminate materials and controlled impedance.

Advanced Circuits’ PCB manufacturing capabilities range from the simplest of designs to the most complex builds with rigorous design requirements.  Our capabilities include laser-drilled microvias, cavity boards, heavy copper up to 20 oz., via-in-pad, microwave & RF boards, up to 40 layers and others.  We are your one-stop solution to all of your printed circuit board manufacturing.  For more information about our PCB capabilities and services, contact your Sales Representative or call 1-800-979-4722.

Due to the fast-paced technological advancements of today’s world, many PC boards are designed with a very compact layout and require higher functionality and performance standards.  In order to achieve optimum PC broad performance and quality, a careful review of the circuit board design must be done to ensure it meets the minimum manufacturing requirements as well as verifying that the manufacturer has the precision capabilities, industry certifications, and qualifications required.

PC Board Quality Starts with its Design

Our PC board Tolerance Guidelines are accessible online and make it easy for design engineers to adhere to the required tolerances and specifications for a smooth PCB ordering and fabrication process.  Every PC board design submitted to Advanced Circuits receives a detailed review by our CAM engineers prior to production to ensure all minimum design requirements are met.

We also provide free tools to ensure your PC board design is ready for manufacturing and meets the requirements to produce quality boards.  Simply upload your circuit board design’s Gerber files to our FreeDFM online tool to perform an automated review prior to placing your order.  Within minutes, you will receive a graphical report that includes any possible manufacturability issues found in your PC board design that will cause a production hold.  The FreeDFM report will also highlight any design elements that do not meet our manufacturing and tolerance requirements but will be Automatically Fixed by our CAM engineers before production.

PC Board Fabrication Capabilities

Advanced Circuits offers expanded capabilities and certifications to meet rigorous design requirements.  Our PC board fabrication capabilities include:

• Stacked Microvias
• Blind & Buried Vias
• Laser Drilled Microvias
• Up to 40 layers
• Laser Direct Imaging (LDI)
• .00275″ Trace/Space
• Down to .3mm Pitch
• Air Pockets Between Layers
• Heavy Copper (up to 20 oz.)
• Via-in-Pad
• Multilayer RF Designs (up to 8 layers)
• Cavity Boards
• Oversized Boards (up to 37″ x 120″)

Click here to download our full list of PC board fabrication capabilities [PDF].

For more information about our printed circuit board manufacturing capabilities, ordering process and services, please contact your Sales Representative or call us at 1-800-979-4722.

Our powerful PCB fabrication solutions range from the simplest circuit board designs to the most rigorous design requirements for the medical, commercial, defense, and aerospace marketplaces.  Advanced Circuits is committed to U.S.A. manufacturing with three facilities in Arizona, Colorado, and Minnesota totaling over 200,000 square feet of manufacturing space.  Providing enhanced support to the military/defense and aerospace industries for PCB fabrication, Advanced Circuits has made significant capital investments over the years to meet stringent standards and fabrication requirements of some of the most technologically advanced circuit board designs for mission-critical applications.

Advanced Circuits’ Three PCB Fabrication Facilities are ITAR Registered

All three of Advanced Circuits’ PCB fabrication facilities are are fully compliant and follow strict security protocols with the United States International Trade in Arms Regulations (ITAR) which is an important factor for our aerospace and defense industry customers.  To download our industry certifications and review our ITAR documentation, please visit our Certifications page on our website 4pcb.com.

Advanced Circuits’ Minnesota PCB fabrication facility is also DOD contracts ready with elevated security measures and compliance protocols that only few PCB manufacturers in the U.S.A. meet for Department of Defense contracts.

Expanded PCB Fabrication Laminates and Capabilities

Advanced Circuits sources many types of PCB laminates from top industry providers to bring you a wide range of options such as enhanced epoxy laminates, ultra-low moisture materials, high-frequency ceramic filled laminates, RoHS compliant, and more.  As North America’s third largest PCB manufacturer, we are able to work closely with laminate providers like Isola, Nelco, Arlon, Rogers, Taconic, 3M, Panasonic, and others to quickly source the materials our customers demand.  We carry laminate materials suitable for applications such as:

• Radar systems
• Mobile communications
• Complex microwave
• High speed digital
• RF components
• Phased array antennas
• Automotive radar & sensors
• High reliability aerospace & defense
• High frequency performance
• Direct broadcast satellites
• Power backplanes
• GPS antennas

Our advanced PCB Fabrication capabilities to support advanced designs with demanding requirements include: laser-drilled microvias, cavity boards, heavy copper up to 20 oz., via-in-pad, microwave & RF boards, up to 40 layers, IPC Class 3 Etchback, and others.  To view a complete list of Advanced Circuits PCB fabrication capabilities, click here.

For more information about our advanced PCB fabrication capabilities, certifications, and facilities, please call 1-800-979-4722 or find your Advanced Circuits Sales Representative by clicking here.

Benefits of Advanced Circuits’ PCB Board & In-House Assembly Services

Our quickturn, small quantity assembly service was created to offer our customers a better PCB prototyping process that eliminates shipping delays and communication issues from one vendor to the next.  Since Advanced Circuits controls the entire process from beginning to end, you can be sure that your bare PC boards start the assembly process as soon as the fabrication process is completed.

Here are just a few reasons to choose Advanced Circuits’ in-house PCB assembly services for your next turnkey prototypes:

• PCB + Assembly As Fast As One Day
• Superior Quality Assurance
• One Seamless Process
• Easy Parts Procurement
• Single Vendor
• No Set-Up Fees & No Stencil Charges
• Industry’s Best On-Time Shipping Record
• 24 Hour Tech Support

Advanced Circuits’ PC Board Assembly Capabilities

Advanced Circuits maintains a reputation for high quality, reliability, and a hands-on approach to customer service.  This is what you can expect from our assembly services along with industry leading certifications and capabilities.

Assembly Turn Times

• Same day through four week turns
• Scheduled deliveries

Technology

• Surface mount (SMT)
• Thru-hole
• Mixed technology (SMT/Thru-hole)
• Single or double sided placement

 Stencils

• Laser cut stainless steel
• Nano-coating available

Passive Components

• As small as 0402 package
• As small as 0201 with design review

Ball Grid Arrays (BGA)

• As small as .35mm pitch
• All BGA placements are x-ray inspected

Fine Pitch Components

• As small as 15 mil pitch

Volume

• No minimum order quantity
• Engineering prototypes
• Low cost first article builds

To learn more about our PC board fabrication and quickturn assembly services, click here to connect with your regional sales representative.

Get an Instant Quote or contact your Regional Manager to get started with your PCB and Assembly order.

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Surface mount technology (SMT) is a design and fabrication process that replaces the through-hole mounting of PCB components with direct placement on the printed circuit board surface.

Fortunately, SMT components and packages are largely standardized in size such that uniformity in components can be realized. These standards are specified by the Joint Electron Device Engineering Council (JEDEC) to simplify the development processes for PCB designers, component manufacturers, and companies that manufacture and utilize SMT fabrication equipment.

SMT Assembly Benefits

SMT is now utilized in the vast majority of printed circuit boards being designed and manufactured for modern electronics, including computer boards, smartphones, televisions, and even home appliances such as refrigerators and laundry machines.

Creating mass-produced PCBs built with SMT construction requires highly-technical design tools such as CAD software and specialized PCB development programs. Design engineers now have software products at their disposal that interact with fabrication tools, such that consideration for manufacturing capabilities is integrated into the initial design. This closely-coupled process from design to fabrication is often referred to as design for manufacturing (DFM).

Once the design is completed for a PCB, an initial prototype is created to prove the intended functionality of the end product. SMT is sometimes not considered for this phase of development, due to the flexibility provided by less automated fabrication techniques to more readily rework the PCB. This accommodates any changes required in the board design prior to full-scale manufacturing.

Approved designs are most often released for manufacturing incorporating SMT assembly processes. SMT provides many advantages for manufacturing, as well as for the company designing the board for a product:

Reduced cost – through surface mounting of components, manufacturers eliminate (or significantly reduce) operations for hole drilling to affix components and devices to board materials.

Weight/Size – lighter boards are produced through the attributes of smaller devices. Capability of installing SMT components on both sides of the board results in fewer or smaller boards to take less space in the end product. This is a very important factor in today’s shrinking electronic devices.

Automated fabrication processes – Manufacturers can leverage efficient fabrication equipment to provide high-quality PCBs that utilize surface-mount components consistently and reliably.

SMT Assembly Techniques

SMT assembly can be done very efficiently with high-speed specialized equipment that place SMT components on boards quickly and accurately.

Solder pads on the board surface have a solder paste or similar substance applied to the points where SMDs are to be placed. This is typically done through utilizing a stencil process similar to silk-screening, in order to control application of the solder mixture.

Mechanized equipment then places the designated components onto the corresponding solder pads at high speed, eliminating manual processes of placing component leads through holes that have been drilled in the board material.

Soldering ovens then warm the board to the proper temperature to melt the solder paste, forming a permanent bond to the solder pads on the board surface. Several techniques are in practice for performing this operation, partly due to environmental concerns raised by lead content, generating more strict controls over lead-based soldering. Additional methods for accomplishing the solder connections include infrared reflow, convection reflow, and vapor phase reflow. Each of these methods has its own advantages and disadvantages, and application for use.

When a PCB includes dual-sided application of SMDs, this process will be repeated for the subsequent side. If there are heat-sensitive components included, they may be installed manually after these heat-generating processes are complete.

Residue is typically removed from the PCB surface through a washing and drying process.

Quality inspection is performed to examine boards for missing components or those that may be misaligned during the manufacturing process. This is followed by functional testing to ensure the PCB circuit works properly.

Rework is one of the biggest issues for SMT boards. SMDs that are defective, incorrectly positioned, or missing must be installed manually using very precise operations for installation of the faulty component. This can be tedious work that requires both considerable time and significant skill.

SMT Fabrication Considerations

SMT design and manufacturing has taken over the market for PCB providers, due to the call for miniaturization, speed of manufacturing, and cost reductions. Advanced in the development of equipment that can place components consistently at high speed has further escalated the popularity and use of SMT for printed circuit board manufacturing.