The 3 Essentials of PCB Design Testing

Tempo Automation

July 3, 2018 , in Blog

As engineers and PCB designers, we live in fabulous times! It’s easy to take for granted the amazing software tools we have at our disposal and forget that our early predecessors weren’t as fortunate as we are. Instead of using software to draw circuit diagram models and simulate designs, they had to build everything using trial and error. If the design was a good one, they’d eventually develop a functional product after countless hours and significant expense, which we would consider a waste in today’s world. Although we are significantly more efficient nowadays, the final product must still be tested to ensure the board meets all PCB design requirements.

Through design testing, we can validate the design and verify the PCB will meet our quality, functionality and regulatory requirements. To meet these objectives, the board design must fall within the equipment capabilities of your contract manufacturer (CM), reliably perform tasks and adhere to industry standards. Typically, three design testing stages are included in product design and development: manufacturing, functionality and regulatory. To better understand their importance, we will review the three design testing stages in the order they are performed within the product design and development process.

PCB Design Testing for Manufacturing

The first design testing stage is performed by your CM during manufacturing, which consists of board fabrication and PCB assembly. PCB design testing for manufacturing is a major part of your CM’s quality control regimen and can be divided into three areas based on focus:

  • Fabrication – The primary concern here involves ensuring that the design specifications for clearances, spacing and drill hole sizes fall within acceptable tolerances. Depending on your CM, some electrical testing and optical inspections may also be performed, if requested.
  • Component Procurement – Here, your components are checked against your BOM for accuracy. The availability of additional checks, like component tolerance and solderability testing, varies among CMs.
  • Assembly – As the last manufacturing step, PCB assembly usually involves more inspections and checks. These may include internal and external optical scans, contamination testing and electrical testing.

In this stage, design testing is primarily conducted to ensure your board is manufactured to meet your design specifications. To ensure your specifications fall within acceptable tolerances, you should follow design for manufacturing (DFM) rules and guidelines as set forth by your CM. Failing to do so can delay board manufacturing or even prevent your boards from being fabricated and assembled at all. The types of circuit board testing available to you depend on your CM.

PCB Design Testing for Functionality

Following PCB assembly, you will have a prototype board ready for functional testing. This testing is typically performed by an engineer or PCB designer with the primary objective of determining the reliability of the PCB to perform the functions it was designed for. The testing process may be as complex and time-consuming as designing the functionality circuitry itself.

Although the specific types of measurement, methods and equipment employed will depend greatly on the board’s purpose, the following metrics may be important:

  • Trace currents
  • Pin voltages
  • Power supply levels
  • Switching and timing signals
  • Board temperatures

Some CMs perform functionality PCB design testing that may require design for testing (DFT) additions to your design. Although this testing may increase your board’s turnaround time and cost in the short-term, it is essential to verify your PCB’s functionality to prevent failure in the field and minimize time losses and costs, not to mention damage to your brand and client relationship(s).

Regulatory PCB Design Testing

The final PCB design testing stage is regulatory. The purpose of this stage is to ensure electronics products meet or exceed specifications for usage by targeted users or in particular industries. The underlying motivations for these requirements include protecting end users or complying with security requirements.

Below is a list of common regulations and standards for PCBs or electronics systems and devices that require testing.

Regulation / Standard Description Products Regulatory or Testing Body
UL 796 Tests bond strength, delamination, silver migration, conductive paste and plating adhesion PCBs Underwriters Laboratory (UL)
UL 746 Tests ignitability, ability to support components, insulation breakdown and environmental contamination PCBs Underwriters Laboratory (UL)
UL 94 Classifies plastics based on their flammability Devices and appliances that contain plastic components Underwriters Laboratory (UL)
IPC-A-610 Classifies PCBs according to reliability PCBs IPC Association Connecting Electronics Industries
FCC 47 CFR 15 Classifies devices based on their EMI All electronic devices that radiate unintentional emissions Federal Communications Commission (FCC)
AS9100 Quality management standard for the aerospace industry Devices that are deployed within aerospace systems Society of Automotive Engineers (SAE) International
IEC 60601 Standards for safety and performance of medical equipment Devices that are deployed within medical systems International Electrotechnical Commission (IEC)
IEC 61010-1 Standards for electrical testing equipment Devices that are deployed within laboratory or testing equipment International Electrotechnical Commission (IEC)

The above list isn’t exhaustive but if your PCB falls within one of the groups under the Products column, you may need to perform PCB design testing. Typically, device testing is done by a third-party laboratory, which furnishes a certification to the organization requesting the testing. This certification can be displayed on the device for verification purposes. Besides testing, your product must satisfy other standards that before it can be distributed, like the AS6081 standard for avoiding counterfeit components to qualify for governmental contracts. Specific standards and regulations may vary by industry or product purpose.

PCB design testing helps assure engineers, designers, OEMs, electronic products distributors and end users that the devices and systems they receive along the supply chain meet the necessary standards for normal usage or product operation. The degree of testing required is primarily based on the targeted industry or end user. Regardless of the intended deployment, however, your PCB will need to undergo some level of design testing.

Efficiently manufacturing high-quality PCBs is a standard at Tempo Automation. We can build your boards to meet or exceed the requirements for IPC Class 1, 2 or 3 and ensure that your PCBs satisfy necessary industry requirements.

Tempo‘s Custom PCB Manufacturing Service

  • Accurate quote in less than 1 day.
  • Performs entire turnkey process in as fast as 3 days.
  • Emphasizes DFM to eliminate time-consuming back-and-forth design corrections.
  • Sources components from the most reputable suppliers in the industry to reduce procurement time.
  • Performs multiple automated inspections during assembly to ensure PCB quality for prototyping.
  • Provides support throughout the PCB manufacturing process, beginning with design.
  • Smooth transition from prototyping to production.

At Tempo, we strive to form a symbiotic relationship with you by transforming the traditional black box of PCB manufacturing into an open, transparent white box such that your design is optimized for our equipment and process capabilities and the manufacturing process incorporates your design intent.

And to help you get started on the best path, we furnish information for your DFM and enable you to easily view and download DRC files. If you’re an Altium user, you can simply add these files to your PCB design software.

If you are ready to have your design manufactured, try our quote tool to upload your CAD and BOM files. If you want more information on PCB design testing or how to incorporate testing into your design, contact us.

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