Design Methodology for Hardware Prototyping: Product Requirements and Finalization

July 11, 2019 Cadence PCB Solutions

Man in steampunk equipment and dressage

 

During 1868, Edward S. Ellis wrote a science fiction dime novel titled “The Steam Man of the Prairies” with Johnny Brainerd—a young inventor—as its main character. While history has forgotten most dime novels of that era, “The Steam Man of the Prairies,” remains with us because it presented the first robot in literature. Johnny Brainerd’s Steam Man stood ten feet tall and used a steam boiler to produce the energy needed to pull a cart.

I suppose that we could call “The Steam Man” a prototype for the humanoid robot prototypes that have gained recent publicity. Unfortunately, 250 or so years is not rapid prototyping. Moving forward, hardware should not be moving as slowly as a steam engine through its production stages. Learning design methodologies for hardware prototyping can speed up this process tremendously.

Establishing a Design Methodology for Hardware Prototyping

By definition, a prototype is an early sample or model of a product built to test a concept or process.  We can use prototypes to learn if a model matches with the design or if the function responds to the expectations desired by consumers. Very basically, a prototype allows us to gather feedback and evaluate an idea.

In PCB design, we use software tools to engage in rapid prototyping. After the design team has determined the requirements of a project, team members use schematic and layout tools to develop and refine the concept into something tangible. Simulation tools included within the design software allow teams to demonstrate and test the design. 2D and 3D computer-aided design tools offer the capability to merge electrical and mechanical aspects of the design and quickly transition towards the prototyping stage. All this takes us full circle in that the prototype encourages design teams to compare the original requirements with the lessons learned from the prototype and gain a better understanding of everything that the customer needs or wants.

Define Your Requirements

Before your team can build a schematic or create a layout, you need to know what the customer wants. A good requirements document identifies the audience for the product and how the desired audience will use the product. For example, a PCB built for a drone needs to receive—and possibly transmit—signals from specific range. The signals may include information that tells the drone to fly from side-to-side or to change altitude.

 

Pulsation machine displaying heart rate monitor

Medical devices especially require intensive safety testing in prototyping

 

Next, a requirements document provides information about the environment for the product. A PCB used to control drilling in an underground mine may need to respond to specific tolerances and fit into a specially designed enclosure because of moisture or vibration. Compliance with safety rules may drive the use of special components for the mining application.

Having detailed information about the audience, the use of the product, and the working environment allows the requirements to respond to other key questions. Your team will want to know about the desired power supply and how the product can integrate with other operations, products, or systems. A PCB designed for wearable technologies will work within a small enclosure, require battery power, use sensors to capture heart rates and other medical information, run software applications, and may need to communicate with analysis software found in the Internet of Things.

A completed requirement document translates into a statement of work (SOW). Your design team can use the SOW to establish the project schedule, describe activities, define responsibilities, and set the deliverables for the project. All this leads to a collaborative understanding about the level of effort, the resources needed to complete the project, and the cost of those resources.

Build a Proof-of-Concept

PCB design software includes a broad suite of tools that can move a product from the idea stage to something that your design team can test and—if needed—modify. A proof-of-concept tests the function and the technologies used in the product. Design rules and Design Rule Checks establish parameters for the PCB. Electrical rule checks ensure that the electrical functionality of the concept operates as expected. Component libraries allow your design team to select the components that provide the best match for tolerances or any compliance issues. With some tools within PCB design software also providing real-time views of vendor inventories, design teams can select delivery dates that match the project schedule.

3D design tools found within many PCB design software applications allow design teams to match electrical and mechanical functionality. With these tools, a design team can ensure that the enclosure provides the clearance needed by the PCB and its components. Having 3D design availability also allows design teams to determine if the best option involves a rigid PCB, a rigid-flex PCB, or a flexible PCB.

Your PCB design software also supports Design for Manufacturability—and speeds the prototyping process—with accurate output documentation. Fabricators can move quickly with access to the correct Gerber files, layout diagrams, 3D mechanical design files, and Bill of Materials. Having this information also tightens the process by facilitating collaboration between the design team and the fabricator.

Create a Lessons Learned File and Deliver the Best Product

Prototypes can teach our customers and our design teams about the product and the requirements for achieving market success. Before a PCB design moves from prototype to fabrication, consider methods for improving the design. Feedback at this stage of the design/prototyping process should include all partners, stakeholders, user acceptance teams, researchers, and the design team.

 

Pile of electronics scraps on a table

Don’t forget all the mistakes made along the way, use them for future intelligence

 

After making any approved revisions, your design team will need to retest the electrical and mechanical functionality of the product. For some design processes, the feedback—retesting— stage may require several iterations to ensure that all members of the team remain satisfied. Your design team will need to carefully document all revisions and ensure that all members have access to current files.

Having a detailed and understandable design methodology for hardware builds interaction and collaboration between all members of the design team. Collaboration also extends to customers, researchers, and user acceptance groups and encourages honest appraisals of the PCB design and the product. A good design methodology also allows teams to detect errors early in the process and make modifications well in advance of building the prototype.

Keeping design for manufacturability (DFM) as a focus also speeds the transition from prototype to product. A smooth transition assists with controlling costs and ensures that clear communication between the design team and the fabricator exists.

If you’re looking for PCB design software that can resolve your layout and analysis issues, Cadence’s suite of tools is sure to help. OrCAD’s PCB Editor has the functionality you need to get through the mud in any design, and the processes in place to move your product through to manufacturing in short order.

If you’re looking to learn more about how Cadence has the solution for you, talk to us and our team of experts

About the Author

Cadence PCB solutions is a complete front to back design tool to enable fast and efficient product creation. Cadence enables users accurately shorten design cycles to hand off to manufacturing through modern, IPC-2581 industry standard.

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