What’s the Typical Hardware Design Process for a Professional Circuit Design Team?

Many professional PCB designers wait to create the schematic and the PCB layout. It's crucial first to complete a project requirements document (PRD)—the PRD documents components, production cost, performance, user experience, feasibility, and manufacturability. There are unlimited ways to make a circuit function, so this document helps the designer make decisions on par with the customer's expectations.

The PRD also helps set expectations regarding who's responsible for delivering what, development affordability, timeframes, mass production feasibility, and profitability. Other expected deliverables during this phase include a system-level block diagram and selecting production components to create a preliminary bill of materials (BOM).

The next step involves starting the hardware specifications document. The hardware spec document states the reasons behind all critical decisions during schematic capture and PCB layout. The hardware spec document is a living document that gets reviewed at the start and end of each hardware iteration stage. Some industries, such as medical, aerospace, and hazardous areas, require thorough documentation. Less complex designs may get away with simple documentation.?

Making the schematic is highly technical but requires some product developer experience. A schematic designer must grasp user behavior, cost constraints, size/shape goals, and user experience. They must know how and when to actively contribute insightful ideas to shape the ultimate use of the product.

Schematics are put into 'schematic blocks' segregated in a schematic design layout. Professional engineers will typically specify pass/fail for each schematic block. Engineers must pay close attention to detail, as minor errors can lead to functionality issues. The best advice is to ask for design reviews by a third person. The PCB design software ensures the layout adheres to design rules and matches the schematic. Engineers rely on component datasheets that go into detail about critical layout and routing requirements, if any.?

Ordering printed circuit board prototypes involves three steps: procuring components, producing bare boards (PCB fab), and soldering electronic components onto them (PCB Assembly). Our tips are to order the chips and ICs when you finish the schematic to avoid parts going out of stock and to get enough PCB fabs for as many prototypes as you need, but only build a couple to start with. If you discover an issue, you can more cheaply replace the PCB fab, and you don't have to rebuy all the parts.?

Prototype hardware testing is a crucial and sometimes the most challenging stage. Professional engineers know the importance of testing before releasing the design as "good." Our goal is to avoid the pain of troubleshooting an issue and not knowing if it's software/firmware related or if the bug is due to a hardware mistake. This process for testing we use is called "block testing." Professionals will plan the order of block tests to progress safely from one schematic block to the next.

At times, block testing may need firmware to test. In such cases, it's advisable to create a specific firmware version for each exercise, avoiding firmware issues caused by handling multiple routines simultaneously. Ultimately, if you find yourself troubleshooting a system-level bug and you're unsure if the problem is originating from the outside world, the latest software/firmware release, or the hardware or if you think you blew up something and want to know if it's still working after inspection/repair, you can refer back to your list of block test firmware and upload the simplified version and attempt to retest isolated sections.

This article is our quick overview of making a custom PCB prototype. I hope you enjoyed it.