PCB Assembly (PCBA) Design Guide

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Ultimate PCB Assembly Guide

PCBs, or printed circuit boards are the unsung heroes of modern electronic devices. Most end-users have no idea how the components inside the electronics they know and love work together. However, for engineers, OEMs, and designers, there’s a lot to know — and love — about PCBs.

This PCB design guide was created to help new and seasoned engineers make more informed design decisions early on so they can end up with the perfect components for their products.

Let’s start with the basics:

PCBA FAQs

Common questions about printed circuit boards

What is a PCB?

A printed circuit board or PCB is a central piece of any electronic device. It has two primary
functions:

• House the electronic components
• Connect components for operation

The board itself is made of a non-conducting substrate, such as fiberglass, that is coated with copper on one or both sides. The copper conducts electricity and is etched away from the board leaving the appropriate components to be connected to each other through the circuit.

PCB. PCBA. PCA. What’s the correct name for a printed circuit board with all the components?

There are many acronyms that industry pros use when it comes to printed circuit boards. The most common question head-scratcher being, what’s the difference between a PCB and PCBA?

Here’s a breakdown of what they mean:

PWB – printed wiring board. One of the first terms used when the connectivity of electronic components was simply point-to-point instead of circuit operation.

PCBprinted circuit board. Technically speaking, the term PCB refers to the etched wiring board itself without any of the components installed yet. In 1999, this term was mandated by the IPC Technical Activities Executive Committee as the go-to term for new document development, as the printed circuitry design often has an impact on device function.

PCAprinted circuit assembly. Used after the IPC change in 1999 for clarity. 

PCBA printed circuit board assembly. It’s the printed circuit board with all of the electronic components installed.


PCB is the most popular term when referring to the whole, assembled shebang. So be sure to clarify which type of PCB you need when communicating with manufacturers and outside vendors — the basic board, or the fully connected printed board assembly (PCBA).

For a deeper dive on the acronyms used for all things printed circuit board, check out this discussion from industry experts.

How does a printed circuit board work?

PCBAs are designed to provide a central hub for integrating all electronic components within a device. Using multiple layers to create the board, conductive pathways or tracts are laminated onto a substrate material. These copper tracks are used to conduct electricity, acting as a circuit for all components soldered to the board, thus powering the device while providing insulation and safe transmission of electric current.

What are the components of a PCB?

Each of the PCB hardware components has a vital role to play in powering the electronic device. PCB components include:

Diode

A component that allows electricity to run through in a single direction while blocking the other

LED

Light-emitting diode, which lights up when an electric current runs through it

Resistors

Color-coded controls that allow the electric current to pass through

Capacitors

Designed to hold an electrical charge for operation of the device

Switches

Allow or prevent current from moving, depending on whether they are open or closed switches

Inductors

A passive component that resists a sudden change of current

Battery

Links voltage to the circuit

What is PCB made of?

The board itself is made of four key components:

  • Substrate – the foundation of the PCB, a substrate is usually made of fiberglass or some other non-conductive material. Substrates can be single or multiple layers.
  • Copper – used to transmit electric current, the copper within a PCB takes the place of wires.
  • Solder mask – the metal used to create connections between the surface of the PCB and the electronic components. The solder mask protects the electronic traces underneath from unfavorable conditions.
  • Silkscreen – a layer of ink traces that are used to label electronic components, warnings and other features unique to that device’s connectivity.

Before moving into the production of final PCB production, a prototype must be validated to ensure all components are connected and work properly to power the device.

Need a quick PCB prototype or design validation?

We can handle those in house.

What are the different types of PCB available?

To accommodate your device’s design, application and complexity, there are a couple of design decisions that need to be made upfront. First, which type of PCB do you need?  Much like light pipes, PCBs can be rigid or flexible, depending on the design and application of the device. 

  • Rigid PCBs – designed not to bend or move from their original shape or placement.
  • Flexible PCBs made to fold, twist and flex into the desired configuration. They are thinner and more lightweight and can accommodate unique shapes.

 

Flexible PCB vs. Rigid Cost

Here’s how the two compare from a financial perspective:

Rigid PCBs

Are typically a more cost-effective solution because they are simple to mass produce due to automation.

Flexible PCBs

Eliminate the need for other connectors, which can drive down total production costs. However, they require additional steps to secure components and automate assembly, which make them cost-prohibitive.
Cost isn’t the only deciding factor when choosing between a rigid or flexible PCB — design constraints like weight and space also come into play.

Next, how many layers do you need to get the job done?

Single Layer PCB

A board made out of a single layer of base material or substrate. Typically, one side of the base material is coated with a thin layer of metal on one side of the substrate. Single-layer PCBs are ideal for rapid production due to their simplicity in design and ease of automation.

Double-layer PCB

A board that contains soldered electrical connections on both sides. This is achieved when copper or another conductive material is applied to both sides of the board. For added flexibility, double-sided PCBs can utilize a through-hole or surface mount (SMT) design.

Multi-layer PCB

Used in more complex designs, multi-layer boards include up to four layers. Multi-layer PCBs provide added benefits of a smaller footprint and fewer wiring harnesses, which reduces the overall weight. These PCBs are ideal for aerospace, handheld devices, cell and signal transmission, and many other applications.

What are the advantages of using a printed circuit board?

PCBs deliver many benefits for engineers, OEMs, and designers of electronic devices, including:

  • Minimal space requirements – because all electronic connections occur on the board, there’s no need for multiple wires to carry the current and take up valuable real estate on the device.
  • Simplified installation and troubleshooting – all components are housed on the PCB and clearly labeled, allowing for easy access during assembly and maintenance.
  • Streamlined assembly – PCBs allow for quick assembly compared to other means, such as wired connections.
  • Secure placement and connectivity – with a PCB, all electronic components are soldered to the board, ensuring they will stay in place.
  • Manufacturing efficiency – PCBs are more cost-effective than other connectivity methods when mass quantities are needed.
  • Reliable operation – the design of the PCB ensures steady operation, as the connections are made via copper tracks that will not come loose.

What color are circuit boards?

It may seem like it’s the substrate is what gives the PCB the color, but it’s actually the solder mask. The substrate will typically be green, but the solder mask that goes over it can be blue, yellow, orange, purple, red, black, white, or of course, green.

Does the color of the PCB matter?

There are several reasons to choose a specific color for your PCB’s substrate — whether it’s branding or if you have a system where pre-prod is one color and production-ready boards are another color. Plus, certain colors make it easier to see the contrast than others with the naked eye, which could be an advantage when inspecting your boards. 

However, if you’re working with illumination, choosing a white surface of the PCB can help reflect the light. In certain instances, this additional control provides a wider selection of LEDs to choose from in optimizing your design. 

Depending on the application, there may be a time when you want to reflect the light. In those applications, a white PCB is ideal. 

A white PCB is commonly used for LED light engines or LED illumination systems.

On the other hand, there may be an application where you don’t want the light to reflect, such as DJ equipment being used in a dark night club. 

The color of the substrate is just one factor to consider during the schematic phase of your PCB design.

What does the PCB design process look like?

Fabricating a PCB is an 8-step process, which can vary in complexity due to the design of the device:

PCB Designing Basics

Concept of the electronic device

Before putting components to paper, the process begins with an idea. What will the electronic device be? How will it work? 

Once the core electronic needs are determined, it’s time to map out what the PCB would look like.

Electronic schematic creation

Using advanced PCB software, the manufacturer will create a design schematic that acts as a blueprint of the circuit. 

All logical connections between the PCB components within the circuit are laid out, and the electrical connections between each component are identified. 

Once the components are identified, a bill of materials (BOM) can be initiated to secure the appropriate components for the device.

Printed circuit board layout design

With the BOM in progress, the PCB manufacturer will use the schematic to start building the layout of the circuit board design. The components are arranged in an ideal configuration, then footprints of ALL the necessary components are added to ensure they all fit. 

It includes the tracing and placing of all components, including the copper tracks and hole layout. Once this information is finalized, a Gerber file is generated, which acts as an industry standard to communicate PCB specs with manufacturers.

Final Bill of Materials (BOM)

Once the layout of the PCB and its mechanical constraints have been determined, it’s time to move into full production of the BOM. 

Often generated by the schematic design software, the BOM includes:

  • All part numbers needed
  • Component locations on the board
  • Design specifications and limitations
  • Quantities of each component

Prototyping the PCB

The prototyping process can be simple or complex, depending on your needs. There are two main paths the prototyping can take:  
^
Prototyping only the printed circuit board (PCB)

Gerber files are used to quickly create a simple, two-layer copper PCB prototypes without any of the electronic components attached.

For more complex designs, additional materials are used to create rapid prototypes used for design validation.

^
Prototyping the board + electronic components (the PCBA)

To prototype the fully assembled PCBA, each component on the PCB must be soldered to the board. Designs can include surface-mount components, through-hole components, or a combination of the two.  

Using a combination of automated and manual processes, a prototype is created to validate the design as a fully assembled PCBA.

  • By hand – any aspect of the process that cannot be automated is soldered manually
  • SMT machine – used to apply solder to a high volume of surface-mount components 
  • Wave solder – Used to “solder” through-hole components to a PCB

For more complex designs, additional materials are used to create rapid prototypes used for design validation.

Evaluate Prototype

The next step is to test the custom prototype PCB in an engineering lab. Chances are, it won’t be perfect the first time. Your manufacturing team will continue to test, evaluate and optimize the design until it is ready to be programmed and brought to life. 

Installing firmware/Programming

If the electronic circuit has programmable components such as microcontrollers and FPGAs, the manufacturer can upload the firmware for prototyping as well as full production. 

From how to turn it on to how the illumination will communicate with the HMI, our team can upload the relevant software.

Full Production

After the custom PCB prototype has been approved and any necessary components have been programmed, it’s time to move into full-scale production.

This extensive process can be a combination of automated and manual assembly. Machines used include:

  • Plotter printer – a specialized printer used to create the design which becomes the foundation of the substrate
  • SMT pick and place – for fast, automated placement of surface-mount components
  • Wave solder machine – used to quickly apply solder and seal the connections in place

The production process is made up of the following steps:

1. Printing the PCB design

Plotter printer is used to print the design, which is made up of multiple layers for the conductive and non-conductive areas that hold the components of the structure.

2. Printing the copper for the interior layers

The design of the PCB is printed to a laminate that includes a film designed to react with ultraviolet light to properly align the board and the layout of the electrical components.

3. Getting rid of the extra copper

Because the design has been cooked and processed with ultraviolet lights, certain areas are hardened and the copper is bonded to the board. The next step is to use a chemical solution to remove the unnecessary copper from the board.

4. Inspection and layer alignment

Once the extra copper is removed, the design must be scrutinized to ensure all the layer and drill holes align properly. A machine drills a pin through the layers to keep them aligned. Then another machine tests the board for errors.

5. Laminating the layers

Once the board passes inspection, an epoxy resin layer is applied to laminate the board. Another layer of the substrate is applied, then layers of substrate resin and copper foil are applied and pressed together.

6. Drilling appropriate holes

A computer-guided drill is used to drill holes through the substrate and inner panels at the appropriate places for the design. Once drilling is completed, any leftover copper is removed.

7. PCB plating

An additional copper layer is added to the board, followed by a thin tin guard to protect the outer layer of copper from being etched off. From there, the PCB receives a solder mask, silkscreen with critical information and placed with a solderable finish.

8. RoHS compliance

The final step is to prove compliance with the European Union’s Directive of the use of certain Hazardous Substances in Electrical and Electronic Equipment (“RoHS”). Our team provides documentation of RoHS compliance, as well as any other regulatory requirements

PCB Fabrication + Assembly

In house. Affordable. On-time delivery.

How long does it take to design and produce a custom PCB?

The turnaround time for a custom PCB will depend on the supplier you choose, as well as the complexity and quantity of your project. 

At VCC, our in-house PCB capabilities start at design and end at final completion, allowing us to deliver turnarounds in as little as four weeks.

Dedicated warehouse space and advanced tools like a 3D printer empower our team to provide rapid prototyping and expedite the process.

Explore our PCB possibilities

PCB production. PCB assembly. FAST.

What to Look for in Printed Circuit Board Assemblies Suppliers

Not all PCB assembly partners are the same. To make sure your boards stack up, ensure your vendor provides:

  • PCB assembly, all in one place – one central point of contact for everything from concept and design to final assembly, including:
    • Preliminary design and layout
    • Prototype development
    • Manufacturing integration
    • Production
  • North American manufacturing – facilities close to home can cut down on product lead times, as well as shipping and production costs.
  • In-house capabilities – if your PCB manufacturer is sending your work out, you are likely paying more in time and production costs. Find a one-stop-shop with the core capabilities to handle every aspect of your PCB assembly, including surface mount technology and 3D printing for expedited prototyping and production.
  • Stringent quality control processes – don’t take a chance on quality. See proof and documentation of testing and regulatory compliance, including ROHS. 

Proven track record – make sure your PCBA partner has an outstanding on-time delivery so you get your components when you need them, every time.

We Never Compromise on Quality

Read more about VCC’s commitment.

Advanced Equipment Drives Better Outcomes

We combine the latest manual and automated techniques to ensure you get exactly what you need. But our advanced equipment and processes aren’t the only reasons to work with us.

  Solder Paste Application
  Automated Pick and Place Machines
  Automatic Dispensing Carts
  8-Zone SMT Solder Reflow Ovens
  Automatic Wave and Soldering Machine

  Advanced PCB and Stencil Cleaning Machine
  Advanced ESD Control System
  Conformal Coating Equipment
  Visual Scanning Microscopes
  Visual Camera for Quality Check

Custom PCBAs Real-World Applications

Custom PCBAs are ideal for a variety of industries and applications, including:

  • Automotive and aerospace
  • Medical devices
  • Industrial machinery
  • Consumer products

Here are a few examples of custom printed circuit board assemblies (PCBAs) we’ve created for clients around the globe.

In-theater Food Service: Custom PCBA Design and Prototyping

To help moviegoers indulge in popcorn and other treats without missing any of the action, VCC created an innovative indication solution for the in-seat call button.

The client’s previous indicator created hot spots and light loss, ensuring a performance that didn’t receive rave reviews.

Our team designed, prototyped, and perfected a small light engine with eight SMTs to accommodate the client’s needs. And we did it all in only three weeks. 

Now, the call button doesn’t distract from the main action happening on-screen.

In-seat theater foodservice button

It’s light engine, for the win.

Lighting for Patient Rooms at Hospitals: Component-Level PCBA Customization

Being a patient in a hospital is hard enough without harsh downlighting. The VCC team worked closely with our client to develop a custom transistor assembly that would enhance the patient experience while minimizing energy consumption. 

The over-molded circuit board and photocell unit also had to withstand harsh hospital conditions. 

We designed and prototyped a custom circuit board and photocell unit, then designed and shipped the custom product in only 12 weeks.

Lighting that facilitates healing

VCC created the ideal custom assembly on an accelerated timeline.

Slight Product Modifications Deliver Ideal Solutions

Sometimes, you don’t need a fully-customized solution to get exactly what you need. Look for a PCB supplier that can create component-level modifications for existing LED products

For example, we’ve helped clients in the farming, heavy machinery and security industries modify our existing panel mount indicators to:

  • The transition from single color to bi-color indication
  • Update the lens color 
  • Upgrading from a single color to a tri-color option
  • Change voltage options 

Put Our In-House PCBA Skills to Work for Your Next Project

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PCB Terminology: Definitions You Can Use

There’s a lot more to PCB design terminology than PCB vs. PCBA. Here’s key PCB terminology to become familiar with:

Double-sided PCB: also known as a two-layer PCB, a double-sided PCB features components for connectivity on both sides.

Flexible PCB: a flexible printed circuit board is designed to move and bend to accommodate the design of the device. Flexible PCBs provide OEMs with more compact, lightweight and customizable solutions to suit their needs.

FPGA: a field-programmable gate array (FPGA) is an integrated circuit that can be programmed to execute one or more operations.

FR4: low-cost printed circuit board material commonly used for the substrate layer. FR4 is made from fiberglass cloth that has been embedded in epoxy resin. The term FR4 is a type of substrate, and also the rating used grade epoxy laminate sheets.

Gerber File: computer-aided manufacturing (CAM) file used to provide an industry standard for communicating board specifications with multiple manufacturers.

Light engine: similar to a PCBA, a light engine is a small board that contains a combination of LED modules and an LED driver.

Multi-layer PCB: a board that features more than two conductive metal layers. Multi-layer PCBs enable a range of interconnections ideal for many applications and industries.

Pad: the connection point for the electronic component terminal in the PCB. Components are soldered to the pad.

Rigid PCB: the opposite of a flexible PCB, a rigid circuit board made of a solid substrate material such as metal or FR4 that can not bend. Depending on the design of the device, rigid PCBs can be the most cost-effective solution for mass production.

Single-sided PCB: a simple board with electronic connections on one side.

SMT Pick and Place Machine: High-speed, automated equipment used to place surface-mount technology (SMT) devices onto a printed circuit board. These machines are highly precise and efficient, helping reduce the costs of PCB production.

Solder Paste Printing: using a printer and a stencil, solder paste is applied to a PCB and baked in an oven to seal the bond.  

Substrate: the material used to create the foundation of the PCB. This base material is usually made of fiberglass, but can also be comprised of epoxy, metal, ceramic or other materials. The material selection of the substrate is dictated by the primary function and design of the PCB and its components.

Stencils: used to aid the application of solder paste to surface mount (SMT) component pads during the printed circuit board assembly (PCBA).  

Wave Solder Machine: wave soldering is a bulk soldering process used in the manufacture of printed circuit boards. The wave solder machines move each board into a pan where a wave of melted solder covers it, bonding all the components of the board together.   

Stay Ahead of the Competition with Custom PCB Assembly

The right PCBA partner can help you:

  • Get to market faster
  • Save on overall production and installation costs
  • Streamline the whole process — from design to assembly
  • Shrink design and development timelines 
  • Deliver high-quality, reliable devices
  • Reduce the number of vendors required 

We have a dedicated team and best-in-class technology to deliver low-cost, high-quality design, fabrication and PCB assembly from a single source.

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VCC can customize your components with full PCBA design and production capabilities — right here in North America

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