If you have spent any appreciable amount of time around mechanics or working on your own car then you have probably heard the term jackleg. If not, this term is an unflattering description of those guys who work on cars on the weekend under a shade tree and take business away from the more skilled professionals. To add insult to injury, these guys also typically have limited tools and equipment, although that usually does not prevent them from tackling complicated jobs. Now, if you are brave enough (or cheap enough) to let one of these guys near your vehicle, you may get lucky and get good service. Or, you may not.
When developing PCBAs, it is imperative that you do not take the jackleg approach. You must know the purpose and intended use of the boards you are building. This is the only way that you can make design decisions intended to optimize manufacture and meet the performance and quality objectives for their utilization. And these objectives may vary depending on the type of board being developed, which consequently will affect your design choices. Let’s take a look at the similarities and differences of an evaluation vs development board and how these affect PCBA development.
What is the Difference Between Evaluation and Development PCBAs?
It is not uncommon for the terms evaluation and development to be used interchangeably when describing PCBAs that are or may not be intended for installation in a product or system for usage “as is.” In fact, there are a number of terms for these types of boards which makes it more difficult to determine for what purpose the board was developed. Therefore, clearly defining these board types should also provide some clarity as to the difference between evaluation and development PCBAs.
Non-production Board Types
- Proto (or prototyping)
Protoboards are usually bare boards with uniform sections of through-holes for connecting different size components. These proof-of-concept boards allow you to test various layouts manually using jumper wires as traces as opposed to the iterative process.
Breakout boards are PCBs that may contain headers or connectors to facilitate easy connection from one main board to other devices or boards. An example is an Arduino breakout board that allows you to connect to graphic displays or other devices.
- Reference Design
Reference design boards are layouts based on a circuit schematic that has been tested for functionality previously. These circuits can be copied and used “as is” or included as part of your larger design. The use of reference designs is an essential element of collaborative engineering that improves efficiency. These designs are also used in concurrent engineering to provide access to designs by different teams and as starting points for design enhancements or functionality extensions as they save development time.
Although they are often confused with other types of boards, evaluation boards are intended to aid in the evaluation of some major components. These boards typically contain a complex semiconductor, such as a sensor, processor, microprocessor unit (MCU), etc. In addition to the major component, there may be various types of common input and output connectors, memory, graphical displays, and an onboard power supply.
As all of the boards on this list are used at some stage of development, it is not surprising that most of them are at times called development boards. Actual development boards differ from the others, except reference design boards, in that they are basically fixed designs that have been vetted and they are used to demonstrate functionality, capability, and/or application for deployment into a larger system.
Understanding PCBA Complexity: Designing for Trouble Free Manufacturing
Upon a quick review of the list above, it is understandable how inconsistency in terminology usage can lead to confusion. Yet, after more careful inspection, it is obvious that each board type is distinct in its construction and/or purpose. In terms of the relationship between evaluation boards and development boards, we can make the following assertions:
- For evaluation boards, the focus is on a component.
- For development boards, the focus is on the entire board’s functionality.
- Not all evaluation boards go on to become a development board.
The Design and Manufacturing of Evaluation vs Development Boards
Now that we know the difference between PCBA evaluation and development boards, we can offer some guidelines for their development, as shown below.
Evaluation Board Design and Manufacturing
- Include as many types of interconnections as possible
- Use as much space as needed
- Provide test points to aid evaluation and analyses
Development Board Design and Manufacturing
- Include additional circuitry to maximize the range of functionality
- Manufacture as a production board
For evaluation boards, you should take advantage of prototyping assembly flexibility, while development boards should be considered production level. Are evaluation boards and development boards essentially the same? No. The evaluation board is used to determine if a semiconductor component is a good or the best fit for an application. The development board is the production version of the evaluation board with all pertinent components and connectors included.
|Tempo‘s Custom Demo and Evaluation Board PCBA Manufacturing Service
When building these boards you need to work with a PCBA manufacturer that has experience in both types. At Tempo Automation, the industry leader in fast, high-quality prototyping and low-volume production, we specialize in building these types of boards in the most efficient manner.
And to help you get started on the best path, we furnish information for your DFM checks and enable you to easily view and download DRC files. If you’re an Altium Designer or Cadence Allegro user, you can simply add these files to your PCB design software. For Mentor Pads or other design packages, we furnish DRC information in other CAD formats and Excel.