When I barbecue, I always lay the food out symmetrically on the grill. It’s a habit I just can’t break because, after all, I’m a PCB designer, and good placement is ingrained in me, whether it’s burgers or capacitors. The rest of my family laughs at this and will throw the food on the grill in any configuration, but I insist on keeping it orderly. My organization habit often provides me with more room to work, cuts back on waste, and everything gets cooked evenly.
In PCB design, we are accustomed to laying out components in the best possible configuration for circuit performance and manufacturability. However, the need for diligence in our board designs doesn’t stop there, as schedules and budgets encourage us to make designs more efficient. One such approach involves combining design for manufacturability (DFM) practices with design for assembly (DFA) standards, improving the products we build, and ensuring their assembly is simplified. Here are some considerations to keep in mind that can help DfMA, to design your product for manufacturability and high quality.
Design Your Product for Manufacturability
Design for manufacturability, or DFM, has long been standard practice in circuit board layout. The goal of DFM is to reduce the number of errors on the circuit board that slows down or pauses the manufacturing process. This goal minimizes the amount of time and expense needed for production while increasing manufacturing yields. Incorporating DFM standards into the board during PCB layout is the most efficient way to avoid costly alterations and redesigns. However, circuit board manufacturers will still review the design before production. Here is what PCB CMs will be looking for in their DFM reviews:
- Incorrect, unavailable, or expensive components and materials
- Design errors that will lead to fabrication difficulties
- Component placement is not optimized for automated assembly and soldering
- Incomplete or missing test strategy
- Board design not optimized for human interface and rework
Unavailable parts will cause the production line to stop completely, while an un-optimized component placement can lead to manufacturing errors that cost time and money to correct. Even an incomplete test strategy could lead to missing errors caused by automated assembly processes resulting in bad board builds being shipped back to the user.
If the PCB CM finds any of these issues present in the design they are preparing to build, they will typically consult with the client to determine the best course of action. Following that, they may make the corrections themselves or ship the design back to the customer. Best practice begins with a design optimized for manufacturing instead of redesigning it later to retrofit those standards. Therefore, next, we will examine the assembly design and how it is still equally crucial although different from DFM.
Design Your Product for Assembly
DFM is concerned with designing a circuit board to reduce manufacturing errors, thereby lowering costs and increasing yields, while the design for assembly, or DFA, simplifies the manufacturing process. This production simplification is accomplished by minimizing the number or types of individual components or parts and reducing the number of assembly steps required. The circuit board will take less time to assemble with fewer parts and production processes, thus lowering its overall manufacturing costs.
Once again, incorporate DFA at the design level for maximum efficiency, and circuit board designers should focus on the following:
- Reducing unnecessary components and circuitry
- Replace unique components with industry-standard parts when possible
- Optimizing the board design for human interface and rework
Notice that both DFM and DFA look for ways to optimize the circuit board layout for human interfaces and rework. They go through this process because the inability to plug connectors together or correct soldering problems will create errors for manufacturing and hinder PCB assembly.
Not only do designers need to be concerned with assembling the printed circuit board, but their DFA efforts must consider the assembly of the entire electronics system for which the board is intended. For instance, PCB designers should consider the following in their circuit boards:
- Are connectors and wire harnesses correctly pinned out to fit together?
- Are connectors and other interface parts placed where they are accessible for final system assembly?
- Are connectors, switches, pins, and other interfaces clearly labeled for assembly?
- Will other system circuit boards, enclosures, brackets, or braces conflict with the component placement on the board?
You can see that even though designing for manufacturing and assembly have their differences, their goals and purposes are closely aligned. Next, we’ll look at how DFM and DFA can be combined for the highest efficiency.
Combining the Two: Using DfMA to Design Your Product for Manufacturability and High Quality
When designing a circuit board according to DFM standards, it’s best to include DFA standards simultaneously for a full DfMA review. While good DFM rules ensure minimal manufacturing problems, a circuit board could still have assembly issues that can cost time and money. Fortunately, there are some steps to take that will help:
- Make sure to conduct your own DfMA reviews during the design cycle instead of waiting for the manufacturer.
- Involve all members of your design team in DfMA reviews, such as mechanical engineers and PCB librarians, to ensure that all critical points are examined and checked off.
- Use PCB CAD tools that feature 3D viewing and checking, and that will allow you to import mechanical features such as system enclosures and other circuit boards.
- Work with a trusted PCB contract manufacturer that is experienced in DfMA processes and standards.
At VSE, we have been helping our customers for over 30 years by building boards that are not only optimized for manufacturing but configured for ease of assembly. We also feature box builds as part of our manufacturing services. Our engineering teams are well versed in DfMA standards to design your product for manufacturability and high quality.
