Top 5 Common PCB Prototyping Errors & How to Avoid Them

Estimated reading time: 12 minutes

Prototyping Hardware Development is an essential step in developing hardware, however, it is also a phase where the majority of the time frame will slip. Statistics show approximately one-third of PCB prototypes fail after their initial iteration leading to expensive respins and weeks of delays.

Unlike many failures that occur due to complex design flaws, these types of PCB prototype failures are frequently due to simple oversight. This guide will show you five common errors made when designing PCBs that will undermine a prototype’s success. We will also describe the reasons these errors occur and present you with actionable solutions for making certain your next PCB design will operate properly on its first attempt.

Incorrect Component Footprint Design

The failure to accurately design the PCB footprint of the components you are using is one of the most prevalent and most frustrating mistakes made during PCB prototyping. The footprint is a two-dimensional outline that represents the external shape of the component, including the locations of the solder pads and the pins if applicable. If your footprint does not correspond to the actual outline of the component you purchased, there is no way that you will be able to properly attach the component to your PCB and the prototype will be rendered useless.

Why This Error Happens

The three main sources for most footprint errors arise from how designers work. Designers often use the same PCB designs for their next project without making any edits to the associated component libraries. The design for a component in 2022 could look very different to the actual dimensions of the foot or pin (for example, 0.1 inch) of that same component in 2024, as the components evolve almost yearly. In addition, confusion occurs when mixing two types of measurement systems—imperial and metric (e.g., a resistor with a pin spacing of 0.1″). The resistor will not fit onto a footprint that has been designed for a part with a pin spacing of 2.5 mm, even though the measurements appear very close to one another. Lastly, many designers fail to check the manufacturer’s datasheets for the precise dimensions of their PCB footprint and therefore rely on their own assumptions as to what footprint sizes they will need and do not utilize the manufacturer’s resource.

How to Avoid Component Footprint Errors

Fortunately, there is an easy way to avoid footprint errors by following some easy guidelines. First and foremost, make sure that you are using the most up-to-date component libraries available from your PCB design programme; For example: Altium, KiCad, & Eagle! The majority of those providers update their component libraries often, when new parts come out, therefore it is not a good idea to rely on a library that has not been updated in the past six months or so.

After cross-referencing the footprint with the component datasheet, check the datasheet sections labelled “Package Dimensions”, or “Footprint Recommendations”, to find the exact measurements for pin spacing, pad size and overall component width. If the component datasheet contains a 3D model of the component, you can import the model into your design software and see how the component fits when placed on the PCB.

Before you send the design out for production, be sure to complete a 3D Preview of your design. Most current PCB design tools allow you to rotate and zoom into the PCB, giving you an opportunity to look for interference from other components. It is critical to evaluate any adjacent components; while the footprint may be correct, a component that has a large physical size, like a capacitor, might inadvertently obstruct access to the solder pads on an adjacent component such as a resistor if the two components are positioned too closely together.

Our PCB prototyping service provides a complimentary check of all component footprints for added assurance. Engineers examine your designs and confirm that all components will fit according to the most current datasheets—eliminating the possibility of any expensive errors in the production of your prototype.

Poor Trace Width & Spacing

PCB Traces are the copper traces that connect all of the components on a printed circuit board by transmitting electrical signals and power. They may appear to be a small detail, but incorrect PCB trace width and distance on PCB traces results in approximately 25% of all PCB prototype failures. When you create a product and use the wrong PCB trace width or spacing, this may cause the PCB prototype to experience a short circuit, overheat or transmit a weak signal—none of which will allow the product to function properly.

What Causes This Error

A lot of designers do not accurately determine the amount of current a trace can carry. If a trace is too narrow for the amount of current flowing through it, the trace will become hot and may melt the solder or damage the PCB. For example, a trace that is 0.5mm will handle approximately 0.5A of current; therefore, if you are using that trace to power a motor that is pulling 1A, the trace will become too hot to handle. Conversely, using a trace that is excessively wide uses more board space than necessary and makes it difficult to place the rest of the components on the PCB.

Errors in spacing are another source of concern; when traces are placed closely together, and both carry significant voltage, the potential exists for electrical current to “arc” or jump from one trace to the other (which also results in an unwanted electrical connection) and create a short circuit. This is most frequently seen on densely populated PCBs where there is limited room between components.

How to Avoid Trace Width & Spacing Errors

Your project’s trace width should be calculated as a first step. Various online trace width calculators, including those offered by PCBINQ, provide recommendations for trace widths based on various factors such as PCB thickness, voltage and current. Input these numbers into these calculators, and receive a specific trace width recommendation. Generally speaking, the following standard trace widths correspond to:

• 0.5mm trace = 0.5A current
• 1.0mm trace = 1.0A current
• 2.0mm trace = 2.0A current

When determining trace spacing, you should adhere to IPC-2221 industry standard recommendations for minimum trace spacing of 0.1mm between traces in most instances. If your design utilizes high voltage signals (over 50V), increase trace spacing to 0.2mm or greater to avoid arcing.

Separating your project’s power and signal traces is also recommended. Power traces can carry a lot of currents and produce noise that could affect the operation of your signal traces. By maintaining a distance of at least 0.5mm between the two types of the traces, you will minimize noise interference, resulting in enhanced signal quality.

Our PCB prototyping service includes DFM checks that verify trace width and spacing. We also offer high-density PCB options with minimum spacing as low as 0.075mm for compact designs—ensuring your prototype is both functional and space-efficient.

Thermal Management Ignored

Heat generated by electronics is a reality that cannot be ignored, therefore failing to include thermal management into your PCB prototype design is an error that can result in overheating, damaged parts, and unpredictable operation, particularly if your prototype has high power consumption devices such as microcontrollers, amplifiers, or motors.

What Causes this Error?

Often times designers concentrate on fitting as many components as they can into the space available on the PCB without considering how those parts will release their heat. During operation the heat generated by these components will build up within the PCB and create a rise in the temperature of both the board and the components themselves. Most electronic components have a maximum temperature for operation (typically 85 to 125 degrees Celsius) and exceeding that may render them inoperable or even cause them to fail.

Another mistake designers also make is positioning heat generating components in close proximity to one another. For example, if an amplifier is placed next to a sensor, the sensor will be subjected to excessive heat and as a result will provide inaccurate readings.

How to Avoid Thermal Management Errors

Start by identifying the heat-generating components in your design. These are typically components that draw more than 0.5A of current, such as voltage regulators, amplifiers, and motors. Once you’ve identified them, follow these steps:

• Added Thermal Pads-The thermal pad is an area of copper on the PCB and one end of the thermal pad attaches to the “heat sink pad” of a heat generating electronic component. Copper is an excellent conductor of heat and, therefore, the thermal pad moves heat throughout the PCB and helps eliminate hot spots. For power components, use thermal pads that have at least 2x the surface area compared to the base of the component.
• Added Heat Sinks-For heat generating electronics like amplifiers, it’s helpful to add a small heat sink. Heat sinks are metal objects attached to the electronic component to dissipate heat to the surrounding air. They are inexpensive, easy to install, and they can lower the temperature of components by 20-30 degrees C.
• Optimized Layout of Components-Keep heat generating components away from sensitive electronics (i.e., sensors, Microcontrollers, Capacitors, Etc.). Leave at least 1-2 centimeters of empty space between components for adequate ventilation and do not place components in tight areas or in the corners of the PCB because this will create a “heat pocket.”
• Thermal vias are tiny holes in the PCB that serve as a conduit for thermal energy between the top and bottom copper layers. They allow heat generated on the top layer (where the components reside) to be routed to the bottom layer, which has a larger exposed area for dissipating that heat. To adequately provide for the heat created by high-power components, it is recommended to install 4 or more vias around the pad by drilling holes through the PCB that meet the thermal requirements of the component.

Insufficient Pre-Production Testing: A Problem Affecting Many Productions.

Testing is important in PCB prototyping, but many times it is neglected or done quickly in order to save time. Neglecting proper testing can result in prototype failures, delays in the project, and lost funds. Many designers believe that if a prototype can turn on and do what it’s supposed to do then it is ready for production. This assumption overlooks things such as signal issues, durability issues, and compatibility with other parts of the PCB system.

So why do designers ignore the need for complete testing? The biggest reason is that they feel rushed to get to production. They verify that their PCBs can power on and have basic functions. They have no way of knowing if there will be problems when the PCB is used in real-world situations, such as temperature fluctuations, vibration, etc. Some small companies and hobbyists do not have the proper equipment to conduct complete testing, including broken oscilloscopes and environmental testing chambers.

Choosing the Wrong PCB Material

The PCB material you choose has a huge impact on the performance and reliability of your prototype. Many designers choose the cheapest material (usually FR-4) without considering their project’s specific needs. This leads to prototypes that fail in harsh environments, can’t handle high temperatures, or have poor signal quality.

When choosing a material, consider the following factors:

• Operating temperature: What’s the maximum temperature the prototype will be exposed to?
• Signal frequency: Does the prototype use high-frequency signals (above 1GHz)?
• Mechanical requirements: Does the prototype need to be flexible or rigid?
• Environmental conditions: Will the prototype be exposed to moisture, chemicals, or vibration?

Our PCB prototyping service offers a wide range of materials, including FR-4, Polyimide, PTFE, and aluminum-backed PCBs. Our engineers can help you choose the right material for your project based on your requirements—ensuring your prototype is durable, reliable, and cost-effective.

5 Mistakes When Building PCB Prototypes

Creating PCB prototypes shouldn’t be a guessing game. You can avoid this by avoiding 5 of the most common PCB prototyping mistakes: incorrect component footprints; incorrect trace widths and spacing; neglecting thermal management; inadequate testing of your design; and selecting an incorrect PCB substrate material. If you avoid these basic mistakes, your prototype will work the way you expect it to, take less time and money to build, and help to speed up the design process for your project.

Pay Attention to Detail: The Most Important Factor

If you want to be successful at building printed circuit board prototypes, you must pay very close attention to every detail involved in the process. This means you will need to double-check all of your component footprints, calculate your trace widths accurately, design thermal management into your prototype, perform thorough testing on your designs, and select the proper PCB substrate materials for your specific project.

If you want a dependable partner for your PCBs prototyping efforts, please consider us. We have an experienced team that provides free DFM checks, verifies component footprints, designs thermal management systems, and conducts extensive testing. Our manufacturing facilities use only the finest quality materials and state-of-the-art equipment, enabling us to produce high-quality prototypes for our customers that meet or exceed the highest quality standards. Whether your prototype is for a personal hobby project or a large corporation, we will work closely with you to ensure your design becomes a reality.

Don’t let common PCB prototyping errors derail your project. Contact us today to get a free quote and start building better prototypes.

FAQ