Electronic Product Design: Manufacture and Assembly Advice for a PCB CAD Tool
If you were to go grocery shopping at the beginning of the 20th century, you wouldn’t give a second thought to wandering all over town to find the bakery, the butcher, and the produce market. That’s just the way it was until 1916 when Piggly Wiggly opened as the first self-service grocery store. Here you could get your bread, meat, and vegetables all in one location, and the term “one-stop-shop” was born.
It has taken the one-stop-shopping concept a long time to permeate into the electronic product design industry. For years we’ve relied on individual contributors to finish their particular task, and then “throw” the design over-the-wall to the next person in line. This compartmentalized approach to design has sometimes led to problems in manufacturing.
Fortunately, there are new tools and methodologies that are creating a one-stop-shopping process in the regular PCB design cycle. With today’s CAD tools, engineers can work with both the layout and the mechanical design in one environment. Here’s how this is helping to create a new paradigm in electronic product design for manufacture and assembly.
PCB Layout for Manufacture and Assembly
Traditionally, a printed circuit board would be designed and manufactured for a new electronic product prototype. The goal would be to use the board to develop and refine the circuitry and prove the concept of the product. Often though the development of these prototype boards would be fast-tracked, and their design wasn’t optimized for mass production. This would require that the board would eventually have to be re-designed for production, which meant that the circuitry would have to be verified once again. With multiple design and verification passes to get through prototyping, the cost for the design could quickly get out of control.
Thanks to the capabilities of modern PCB design CAD tools however, prototype and new product introduction (NPI) circuit boards can be designed for mass production from the onset. Here are some of the features in these tools that can be used effectively for this level of design:
Online part searching: Instead of using preliminary symbol and footprint data in your design, the online part searching features of the tools will give you access to current part information. This will allow you to design to the actual part instead of using placeholders on your design that may be incorrect.
Rules and constraints: Not only can you set up design rules and constraints, but you can also set up rules that will govern your design for manufacturability (DFM). This will assure that you don’t violate minimum placement spacing or other assembly constraints.
Data exchange: In order to set up your rules and constraints, you need to know what values to use. With the ability to exchange data with your manufacturer using IPC-2581, you can directly import their manufacturing rules making sure that you have it right the first time.
3D viewing and checking: Having the ability to see your component placement in 3D during the design of the board can be extremely helpful. You will be able to see right away if a connector needs to be moved so that there is enough clearance to plug into it.
As you can see already, the list of benefits is impressive and will prove to be very helpful during the layout of the PCB to keep design costs down. But hold on, there’s still more electronic product design and development benefits to talk about.
Using OrCAD’s part search to find and place a correct component on a schematic
Mechanical and Electronic Product Co-Design for Manufacture and Assembly
PCB design CAD systems have had the ability to carry height information in their component footprints to export to mechanical systems for as long as they have been around. But now those footprints can also carry STEP model information as well.
This has opened up a whole new design canvas in 3D instead of only being able to work in the traditional flat 2D CAD rendering. With these capabilities, you can see how a connector will extend past the edge of the board so that you can place it at its most optimum location. You can also see how small parts can be grouped tighter around larger parts instead of basing their placement on a simple rectangle part outline for reference. And with the use of STEP models, there’s a lot more you can do now as well:
Import mechanical 3D models: Circuit board features that are typically not modeled in PCB footprints can now be viewed as a STEP model. This includes objects such as stiffener bars, fans, switches, and ejector tabs. Not only can you see these objects in 3D, but any moving parts can be manipulated to see how they will interact with the component placement.
Work with multiple system boards: Additional system level boards can also be added to the PCB design database. This will allow you to check and see how the different boards will fit together within the system.
Work within system enclosures: You can also add system enclosures as STEP models to your PCB database. This will give you the unique ability to verify what goes into the enclosure design for a manufactured electronic product before you send out your PCB data to be manufactured.
A 3D cut-away view of a flex circuit with multiple boards folded up and in its enclosure
E-CAD M-CAD Tool Support for Product Design
With the ability of design tools to create production ready circuit boards, along with the benefits of using E-CAD and M-CAD co-design methodologies, PCB manufacturing is better now than ever before. Manufacturers are able to build electronic products with fewer problems during assembly, which increases circuit board yields and lowers the final cost for you.
The way to start down this path of designing circuit boards that are production ready, is to use tools that come with these capabilities already built into them. An example of a PCB design system that has all of the abilities that we’ve talked about here is from Cadence. OrCAD PCB Designer has the features you need to design a board with the most up to date part information, as well as having those parts placed in the most optimum configuration for error free manufacturing.
If you’re looking to learn more about how Cadence has the solution for you, talk to us and our team of experts.