PCB design is an intricate process requiring careful consideration of a variety of factors and attention to the tiniest details. Fail to pay attention to these minute details, and you may end up tossing aside weeks of work to start anew when you realize that your failure to account for a material consideration or a functional requirement makes your current design unworkable.
The first step in any complex process is often one of the most crucial, and the same holds true for PCB design. That’s why they say that failing to plan is planning to fail. To help you get started on the right path, we reached out to a panel of electrical engineering and PCB design experts and asked them to respond to this question:
“What’s most important first step in the PCB design process (and why)?”
Meet Our Panel of Engineering and Design Experts:
Kyle Muir is the President and Co-Founder of FuzePlay, an adventuring health guru and builder all things of startups. He specializes in hardware design, manufacturing, and supply chain management. Kyle is a renegade entrepreneur – a curious lover of ideas and dreams.
“For starters, Printed Circuit Board (PCB) Design is an elementary step in the larger PCB fabrication and assembly process…”
You may think of the PCB as a pre-configured wired card that enables signals and power to flow between electronic parts and devices. The PCB holds everything together, connects all the circuits, and provides the functional reliability we expect in purpose-driven smart devices during repeat usage.
The process and knowledge base required for electronics design and fabrication is technical. To get good requires a lifetime of continued education and hands-on practice. This is said not to discourage – the art, when practiced, can be extremely powerful. It is something ironic that these same artists are not your typical gallery patron. Rather the artist designing a PCB is an engineer who has determined control over a mix of physical laws and properties that can be reproduced in a controlled and
stable environment – the Printed Circuit Board.
More variables more problems. That is my experience. And, when it comes to electronics the variables are infinite. So, where to start? The answer is really no different than in any other product development process. Ideation, Definition, and Validation – all before starting a design and/or prototype.
PCB design often takes place in sync within the context of a larger hardware project. More often than not the champion of the project will have little to no experience in the technicalities of PCB design. This means that a well ‘Ideated’ and ‘Defined’ project may still be open-ended in the technical realm leaving unstructured leeway for the savvy engineer. This especially holds true in new or earlier stage ventures.
For the engineer, this leeway is double sided. By playing the Maverick card you may be successful in surprising the team with a slick new feature, some novel innovation, or a leap in product functionality. On the other hand you may be the cause of scope creep, increased costs, or delays getting to market. Unless you have been approved to run wild in an R&D lab no one likes surprises in Product Development – even good surprises introduce risk.
The single most important first step in the PCB design process is Ideation, Definition, and Validation – all before starting a design and/or prototype. Regardless whether your team is large or small, this one simple rule accomplishes two things: 1) Lets you highlight your ability to be Maverick, and 2) Ensures balanced congruence among the projects various hardware elements.
Not only will applying these two points make you a team player, but the preemptive knowledge share should result in a synergy of talents among all cross-collaborators relative to budgets and timelines over time.
With scope clearly defined, the Design and Prototype process can begin!
There are many PCB design software solutions available. The software you use should be able to draw both schematics and printed circuit boards. You can take a look at some of the more popular PCB design software; Cadsoft Eagle, KiCad, and gEDA-project.
PCB Design Tips:
1. Use the entire surface area of the PCB Note how densely you concentrate parts matrixes on the board. You will want to avoid parts so close together they require hand solder or use of a pick and place machine relative to available resources.
2. Make traces wide enough. The minimum trace width might not be wide enough if the required current is greater than a few hundred milliamps. A number of factors play into this like whether or not the trace is external versus internal – external layers can carry more current than an internal for the same thickness. Use a trace calculator for properly determine your trace width.
3. Surface Mount Technology (SMT) vs. Through Holes. Not only does SMT have a nicer aesthetic, but larger components only come in SMT format.
4. Errors in landing patterns. Prepare, print, and review a document of all connections. Most PCB software packages include libraries of electronic parts to ensure all components and pins align. However, it is easy to make mistakes on the landing pattern, especially if your Bill of Materials calls for components not found in the provided libraries. Time and money will be saved by double checking this step.
5. Print 1:1 Scale. This is a simple, easy step to make sure all your components fit on your board.
6. Capacitor placement and decoupling. Decoupling capacitors should be as close to the pin requiring clean, stable voltage as possible. Place your decoupling capacitor on the power supply rail to help serve this purpose.
7. Optimize layout of switching regulators. There are two types of electronic voltage regulators; linear regulators and switching regulators. Linear regulators are inexpensive, simple to layout, but can waste a lot of power. Switching regulators are more
complex, but much more efficient for applications requiring higher power and lower noise.
8. Blind and buried vias. Avoid them if you can. A blind via connects an external layer to an internal layer and a buried via connects two internal layers. No matter what, a via passes through all layers of the PC board to connect traces from one layer to the next. Both types of vias can result in the size of the PCB increasing as well as the cost. Each via has limitations based on how layers stack on the board and should be avoided.
Ivan Arakistain is a Spanish researcher who has specialized in ultra-low power electronics. Ivan graduated from UPV/EHU in Electronics Engineering and completed his education with a degree in Industrial Organization. He has been conducting his research in Tecnalia over the last 10 years, with a focus on energy-harvesting circuit design. He is involved in AIOTI forum.
“In my view, to start with a PCB design, there is an extremely important ideation process…”
This is a first brief draft of the expected outcome, the way it is going to function, an approach to the most relevant parts, and product economics. This first draft does not have to be extensively detailed; it only needs to cover the most relevant aspects.
The PCB design could be a process to industrialize a prototype that has been tested before or to start a new product from scratch. If the latter is the case, you would want to first study feasibility aspects such as the expected battery life (which will give some orientation regarding the current available for the circuit & main components), environmental conditions such as operation temperature range, input voltage range that it should tolerate (what will happen when discharged batteries voltage goes under 1V instead of the initial 1.5V?), signal integrity, delay tuning for high speed interfaces, etc.
Along with the feasibility study, you would also think about some particular parts. These are by no means definitive, but it will be helpful to pick parts for the next design stages considering many other aspects (price of the reel or MQT, features, future availability, supplier and alternatives, etc.). For the ideation process, you would only want a first approach.
Regarding hardware economics (it is of paramount importance to consider this from the ideation process as you would want to design a successful product), there is an often thrown-around figure of 2.5 times for hardware products. This is the Cost Multiplier. And 2.5 is not bad number to work from as a baseline. Generally, you’d want a good reason to go below this number. If something costs you $50 in true cost to manufacture, you’ll likely want to sell it for 2.5 times that, or $125.
Any distributor will want at least a 60% markup. Markup is the retail price divided by what it costs the distributor to buy it, minus one. All this means that for every $100 as retail price, the developer will get about $28/unit for getting parts purchased, manufactured, tested, packed, shipped, and chasing distributors to pay invoices.
In brief, before even starting the schematic capture, make sure you have consistently covered most important aspects in the feasibility study.
Nick’s professional background consists of electrical engineering and physics. His work in condensed matter physics has been published in two prestigious peer-reviewed journals, Applied Physics Letters (APL) and Physical Review Letters (PRL). His company, PiMios, develops embedded systems and applications for companies entering into Internet of Things (IoT) markets.
“The most critical piece in any hardware design is a full understanding of the end use case…”
It’s easy to break down the process into some boilerplate, rudimentary steps:
1) Requirements Specification
2) Schematic Capture
3) PCB Layout
4) Manufacturing Files
5) Spin Copper
6) Populate PCB
If a company prides itself on QA and/or is ISO certified, they have engineering reviews in between each of those steps. That entire process can take months – 1 month if you’re fast. It is also expensive. The greatest cost to any company designing hardware happens when they have to change something in the hardware and go back through the process. Each iteration costs more time, money, materials and, in most cases, motivation.
There are many PCB design houses that have inexpensive technicians to layout circuit boards. But unless the technician has visibility to the conversations with the end user (customer), then re-working the design is a very high risk. Simply passing down requirements to a technician will generate an output, but it is much more important to provide requirements with context and to give the PCB designer the freedom to make changes in the requirements to better suit the needs of the end use application. This requires higher caliber PCB designers with an understanding of the full engineering and manufacturing process. As a result, this will cost more money up front. However, the quality is much higher, and the risk of re-work is minimized.
To summarize, the most important first step in any PCB design process is to gather requirements with full context and user experience needs. In order to fulfill this first step, a competent PCB designer with an understanding of the engineering process is critical. Outside of those two things, the rest of the process can be very rudimentary.
Sergio Flores is the Technical Product Manager for Samsung Electronics.
“There are several important steps in designing a PCB…”
As a member of a Product R&D Team at Samsung, designing PCBs is a process we always go through from the very beginning of the design of our products. Although there are dozens of processes that happen at the beginning of the PCB design process, two steps are key in making sure that the process is done successfully:
1. Appropriately sourcing the components needed to meet your product requirements. One of the key steps in correctly designing a PCB board that fits your product requirements is choosing the right components according to your product specifications and expected user. It is important at this stage to perform a thorough sourcing of components so that you can find the ones that accurately meet your electrical and general requirements. Specifications like component performance accuracy, ESR at high frequencies, temperature stability, packing size and so on are among the factors you should stress the most when making a pick.
2. Correctly defining the board requirements. Second, proper board requirements have to defined according to these components. Although there are dozens of factors that can affect the performance of electronic circuits, not defining board requirements properly when designing the PCB is one of the most common ones.
Apart from basic things like matching board dimensions and mounting hole locations to your prototype needs, it is important to consider height restrictions and restrictions imposed by the assembly method used to define part placement considerations. It is very important that at this stage noise and shielding requirements are properly defined and that the component mounting technology is also decided (SMT, THT, etc.). Based on this, correct trace width and trace spacing requirements are very important to be decided early on so that PCB layout errors (capacitive, inductive or electromagnetic interference) don’t come up later in the design. Finally, required vias and fan-outs must be defined accordingly and the number of ground planes and routing layers must be set so that next stages in the development are not affected.
Making sure that these two steps are done correctly are definitely important to be sure the first step in PCB design is done correctly.
Ken Kok is the CTO of BK Technologies, a technology company that does product design and consulting. He is an Electrical Engineer who specializes in designing IoT systems and firmware engineering. He is passionate about creating “invisible technology” – that is, technology that integrates well into your life and just works.
“When I am designing a PCB, the first thing I consider is…”
What product my PCB is going into. There’s a big difference between designing a PCB for manufacturing equipment and designing the PCB that goes into a handheld consumer product. This determines the size and shape of my board which also helps determine what components I can use. The next thing I consider, which is equally important, is how many layers the board will be. This is determined by things like the product budget, the complexity of the board, required analog performance, and compliance standards, such as FCC. Finally, I will look at the technologies I’m using and determine if any of them require special placement considerations, such as USB, magnetics, RF, or anything with a large bus.
Scott Deuty is a 30 year electronics expert who writes for Planet Analog, a worldwide electrical engineering website that is a division of the most popular Electrical Engineering website and publication EETimes.
“The most important first step in the PCB design process is to understand the physical aspect of the components that will be on the board…”
This will help to steer the three most crucial design parameters: package size, heat dissipation, and signal flow.
A board layout is much different than a schematic. A schematic works in a manner similar to how we read. Signals start in the upper left hand corner and terminate in the lower right section of the schematic. When transitioning to the more physical board layout, this theory quickly dissipates and logic must take over.
Physical layout is dictated by component size. Everything has to fit while terminating properly at the connectors. This is true for the x-y layout of the board as well as the z direction for the height of the packages and those space consuming magnetics.
Even though the packages may fit from a dimension standpoint, layout is dictated by the signal flow. Cross conduction of signals can create unwanted effects due to EMI. Large signal loops can also cause EMI issues. Finally, proper ground referencing and ground plain shielding can reduce noise generation.
Heat dissipation can be an issue especially in power electronics and as LED lighting increases in popularity. Case construction is also a heat flow factor. Components must be placed in a manner that has optimal air flow or can dissipate heat to the case.
In high vibration environments such as space and automobile application, mechanical stresses are a factor. Boards can actually flex and crack if not properly mounted with adequate support.
Lisa Myers is working as a Marketing Head at Game Period, a gaming website.
“The most important first step when designing a PCB board is…”
Arranging parts on the board. It is crucial because the location of the parts will have the significant influence on the performance of the board. Here are few things to consider when placing the parts:
1. Put the most connected parts in the middle.
2. There should also be enough space between the parts, if there isn’t any, make some by rotating or moving the parts.
3. If you think the board is too small, redesign its size.
Baoguo Wei is the founder of IoT design kit Blink’r (about to be launched on Kickstarter).
“For PCB design, designers need to consider the design from a manufacturing standpoint…”
A PCB design will need to be able to be produced (at the least) by a PCB house, so taking design for manufacturing (DFM) into account is the first step.
DFM involves quite a few factors, and designers should know the answers to the following before the DFM process starts: how many layers of does the PCB have; what is the PCB’s base material; what are the design’s smallest components (a 0201 capacitor); what is the smallest IC pitch; what is the closest trace; what is the smallest via size; what are the requirements on impendence matching, board size, etc.
The second point to consider with a DFM is whether the PCB design could be suitable for a surface mount technology (SMT) process, including the components selection. In short, a PCB designer must design so that all components could be soldered by a SMT facility.
The final point with a DFM is to evaluate the design for testing. As a PCB design becomes more and more complicated and the components becomes smaller and smaller, the manufacturing testing requirements need to be considered from the start. Otherwise, the designer may have to start over to meet the manufacturing testing requirements. There are two types of testing for PCBA (printed circuit board assembly): one is ICT ( in-circuit testing), which typically happens right after the SMT and before the assembly process, after all of the components are soldered on the PCB. A well-designed ICT should be able to find misplaced parts, parts of wrong value, open/short condition and other sorts of SMT mistakes. The second manufacturing testing happens in the assembly and testing process, and the PCB design needs to consider what testing fixtures the PCBA needs to fit in.
Julian von Mendel
Julian von Mendel has 10 years of experience as an embedded developer, and is the CEO of jInvent. His start-up company develops innovative FPGA products and microcontroller utilities. In his career, analyzing and optimizing hardware development processes has been a primary focus.
“The first step of PCB design is also by far the most vital…”
Deciding purpose. Who is it for? What flexibility is required, what features should be included? Make it minimal and simple, or complex, expensive and multi-functional? Should it be easy to test?
What follows is component placement and mechanical decisions – more of a simple and technical process.
Routing is by far the most critical part, for software claims to automate it, but it can’t. Designs that include high speed signals, high power, or – even worse – big power spikes, may require enormous extra care of an engineer that understands the electrical effects behind it; the power distribution and capacitance, temperature limits and effects (e.g., on LED color or on chip performance). Correct decisions about layer thickness and order are also vital engineering decisions.
Prototyping and locating issues during careful testing may be time consuming, but with a good design, it is a rewarding process.
Most regret arises at this point, when a bad decision about the PCB’s purpose was made.
New designs should always aim for testability first; and be optimized for cost-efficiency and space only at a later point, after experience has been collected. If this general rule of development is not observed, costs have a tendency to explode. But this is part of defining purpose correctly.
Other decisions may include whether the PCB should be easy to repair at a later point; if it does include self testing features or test points; whether chips are reprogrammable or not. What connectors to expose, and what chips to use. The exact connector interfaces have huge influence on the schematic design, production cost and overall project complexity.
All of these subjects have direct influence on the cost of the PCB production. But it is a mistake to worry about this before a product is ready for mass production, and it rarely pays off.
Ken Carter is MIS Manager at WARDJet, a manufacturer of waterjet cutting machines and industrial automation solutions. He’s passionate about technology, innovation and using business intelligence to drive growth and profitability.
“The single most important thing when designing a new PCB is simple…”
Collaborative design review.
After years of designing and making our own circuit boards in-house, we can say with the utmost certainty that having more people involved in the early stages of PCB design ultimately leads to a better product. Cross-functional design review teams allow engineers to bring innovative PCBs to the market as quickly as possible.
Rocco Tuccio is the founder of Zippy Robotics and the designer of Prometheus, the company’s desktop PCB prototyping machine. While humans are creative and can make their ideas a reality, a human with a computerized machine-tool can take their ideas further, faster. It’s a tool that amplifies ability. His mission is to empower as many people as possible with this technology.
“In my view, testing that your design actually works in the real world is the most important step…”
Because it will either validate your design or tell you that you need to go back and fix something before going into production. There are other key areas that need attention as well, like verifying that the parts you want to use in your design are in high-supply and not marked end-of-life by the manufacturer, but at Zippy Robotics we focus on the prototyping problem.
Prototyping is typically done by sending your design files to one of many board houses and waiting a week or so to get your physical board in the mail. A week can be a long time and if it takes a few versions to get the design right, we’re talking a month or more. Instead, we make a desktop machine called Prometheus that can prototype two-layer boards in about an hour. For their board material, users can select FR-4, FR-1, Rogers, or MCPCBs.
Ihor Baranovskyi is a 44-year-old Senior PCB Designer at Ricker Lyman Robotic.He finished Vinnitsa State Technical University with the qualification process engineer designing computer systems. He started in 1995 as a Engineer-Assistant of the Department, in 2002 became PCB Designer, from 2009 worked as a Chief of PCB Design Department, and in 2017 joined Ricker Lyman Robotic in Lviv, Ukraine.
“The very first step in designing PCB is to…”
Clearly understand the customer and the requirements for the operating conditions of the device.
Development of PCB design is not just the development of board with its components. Every board is a part of product that should provide value to a user.
The choice of base materials for the board, the definition of reliability class, design rules for design and technological standards for production depend on how clearly the engineer understands under what conditions the product will be used, such as its climatic conditions, mechanical loads, electrical parameters, etc. This allows you to gain reliability, reduce the number of defects in the production of boards, minimize losses during assembly, and ensure high-quality operation of the device.
Jared has brought several consumer products to full production and managed millions of dollars worth of equipment and inventory to make it all a reality.
“The most important first step when designing a PCB is the prototyping stage…”
This where you take your proposed design, splay out all the important development boards on a table and connect them all together. This is the basis of design validation before spending lots of money and spinning a board.
There’s also the step of capturing that prototype and putting into a schematic. No complex circuit board design can exist without its corresponding schematic. Schematics consist of symbols that represent different circuit elements like resistors, capacitors, integrated circuits, switches, etc. This is typically the job of a “system integrator” which takes all the components and connects them so they work in the conditions specified by a product specification. Engineers who designed the electronics for the iPhone, iPad, iPod, etc are called “system integrators.”
If you already have a design that is captured in a schematic, the first important step would be to create the library for all the parts on the board. This involves working with one of my awesome librarians to create all the footprints. In the meantime, a mechanical engineer is creating the board outline which constrains how big the circuit board can be in all dimensions. Without those two things, you can’t move forward with designing a PCB.
Nicholaus Smith is an applications engineer at Integrated Device Technology with more than 10 years of experience working on printed-circuit boards (PCBs) and in semiconductor engineering. He was educated at the University of Arizona and San Jose State University while working as a technician and PCB designer. During his career, he has designed and used PCBs for engineering evaluation, customer demonstration, IC qualification, and automatic test equipment.
NOTE: The following information is excerpted from The Engineer’s Guide To High-Quality PCB Design via ElectronicDesign.
“The ideal PCB design starts with the discovery that a PCB is needed and continues through the final production boards…”
After determining why the PCB is needed, the product’s final concept should be decided. The concept includes the design’s features, the functions the PCB must have and perform, interconnection with other circuits, placement, and the approximate final dimensions.
Ambient temperature range and concerns regarding the operating environment should be addressed and used to specify the materials selected for the PCB. Components and PCB materials must be selected to guarantee operation under all expected and potential forms of duress the board may be exposed to during its lifetime.
The circuit schematic is drawn based on the concept. This detailed diagram shows the electrical implementation of each function of the PCB. With the schematic drawn, a realistic drawing of the final PCB dimensions should be completed with areas designated for each of the circuit’s schematic blocks (groups of components closely connected for electrical reasons or constraints).
Circuits Today provides useful content on Electronics Engineering topics.
NOTE: The following information is excerpted from PCB Manufacturing Process via Circuits Today.
“Once you have decided which electronic circuit is to be made on a PCB, you will have to make the design for the board on your PC…”
You can use different PCB designing CAD software like EAGLE. The most important point to note is that everything has to be designed in reverse because you are watching the board from above. If you need the circuit to be designed on a PCB, the layout must have a 360 degree flip.
The next step is to print out the layout using a laser printer. You must take special care in the type of paper that you are going to use. Though a little expensive, photo basic gloss transparent papers are known to be the most suitable for the process.
You must also make sure that you are able to fit all your components on to the print. First take a copy of the print on ordinary paper and lay down all the IC’s and other components. The size of the layout must also fit the size of the PCB.
Michigan State University, Department of Electrical & Computer Engineering
The Michigan State University College of Engineering is engineering a healthier, safer, and more sustainable world.The college has recently embarked on a number of initiatives designed to ensure our leadership in many new and exciting areas of research and education as we address the National Academy of Engineers “Grand Challenges for the 21st Century.”
NOTE: The following information is excerpted from How to Create a Printed Circuit Board (PCB), prepared by John Kelley, via Michigan State University Department of Electrical & Computer Engineering.
“There are several basic steps involved in producing a printed circuit board (PCB)…”
Most designs begin with a hand drawn schematic and design plan. With these, the circuit is prototyped and tested to verify that the design works correctly. Then, using software, an electronic version of the schematic is created. A netlist file is created from the electronic schematic and used in other software to create the physical layout of the PCB. Next, the components are placed and routed in the physical layout software and Gerber files are created. These Gerber files are used in a prototyping system to mill, drill, and cut the PCB substrate. The components are then placed and soldered to the substrate. Finally, the board is tested to verify that it works as expected.
The major steps in the PCB design and fabrication process are as follows:
1. design and test the prototype circuit— by hand;
2. capture the circuit’s schematic— using OrCAD Capture or similar software;
3. perform the physical layout of the circuit— using OrCAD Layoutor similar software;
4. fabricate, populate and test the PCB— done by ECE shop personnel or similar personnel.