In popular media, manufacturing often gets the short stick regarding inventions. How many stories have you seen where the genius idea becomes reality without so much as a montage? Now there’s certainly an egalitarian nature to an idea – anyone can have one after all – and some of the most engrossing stories are framed around an average person with that one-in-a-million proposal.
However, manufacturing sometimes acts as the cold dose of reality, returning concepts to drawing boards. Begrudgingly or otherwise, designers learn to respect the constraints of manufacturing technology or set to improve it themselves.
We at VSE believe in keeping the designer focused on the design: our engineering services support electronics development at every step. Close collaboration between design teams and manufacturers enhances the quality of the final product and minimizes overall production time. These design for manufacturing guidelines – implemented at the earliest point of product development – renders a design highly amenable to the processes, variations, and inevitable revisions associated with creating a PCB and its associated features.
Subsets of DFM
|Design for Test
|Design for Assembly (DFA)||Design for Logistics (DFL)||Design for Standards (DFS)||Design for Cost
|Qualities||Improves testing interfaces.
Increases the rate and speed of defect detection.
|Improves the assembly process of the board through soldering, component selection, or placement.||Checks that the items listed in the BOM are available/ sourced and replaced if not.||Enhances the universality of devices through component and protocol choices.||Reduces cost through component and material selection and design review.|
|Enhanced DFM by…||Increasing yield and simplifying test procedures.||Improving reliability and minimizing rework.||Ensuring the necessary amount of components is available.||Reducing the need for revisions owing to design choices.||Lowering per-unit cost of high-volume lots.|
Simulations: A First Look at Design Capabilities
Every great product begins as an idea, whether reenvisioning an existing device or something entirely new. At the outset, a simulation will feature heavily in the pre-prototype modeling of circuit response. There are many shortcuts that designers may employ (l1 mil trace widths, vias that violate the aspect ratio, etc.) for ease of routability. Some are infeasible for any production level but can more quickly arrive at early model results that will shape future revisions. Small design teams or individual designers will likely forego this interim layout for the prototype as the time spent redesigning may lead to bottlenecks. Still, larger design teams can effectively split a design among its different functions as it continues through development.
Prototyping and Design for Manufacturing Guidelines
Prototyping is a graduation of the project: design and manufacture are no longer just content to see if it works, but rather how well it works. Prototyping occupies a space of manufacturing that doesn’t require DFM. However, DFM practices improve and reach the desired outcomes of the prototype phase faster as it segues into final production. Importantly, DFM can be relaxed if it helps start manufacturing sooner for testing and measurements that can only be simulated.
“…a comprehensive DFT implementation minimizes yield losses while improving test outcomes with smooth system integrations.”
Product iterations employing design for test (DFT) methodology do so to reduce defect escape from production at the earliest possible point while also supporting simpler methods of interfacing connectors and test points with test equipment. Every board must submit to multiple tests throughout production to limit losses and prevent faulty or malfunctioning devices from reaching consumers’ hands. Thus, a comprehensive DFT implementation minimizes yield losses while improving test outcomes with smooth system integrations.
VSE’s San Jose facility is outfitted with all the tools necessary to bridge the gap from prototype design to a new product introduction (NPI). A collection of engineering services can handle everything from enclosure design to cable assembly; having a turn-key solution ensures that the assembly and box build proceeds seamlessly and is optimized for electrical, thermal, and mechanical performance. For particularly cramped design enclosures, printed flex circuits offer designers an additional implementation that can also reduce the chance of errors during cable harness mating.
The Role of DFM in Pre- and Post-Assembly Quality
When a board enters wide production, cost dominates the design process. Whereas a few redundant vias in the routing make little impact on the overall cost and time of the job during production, the additional processing cost over thousands of boards or more quickly can become significant. A DFM review is paramount, especially for manufacturing.
Design for assembly (DFA) is crucial for streamlining production whenever possible. Certain components are better suited for reflow or wave soldering depending on their packaging style (SMD and through-hole). Especially large components may even require hand soldering by trained technicians. Furthermore, different soldering processes require additional forethought. While wave soldering may be best suited for high volume, the layout will need to be cognizant of “shadows” cast in the wake of the solder flow by taller components that may affect the quality of the solder of components behind them (relative to the direction of travel). Manual soldering is the most time-intensive method and requires more clearance around the pads to avoid bridging connections.
Design for logistics (DFL) is closely related to DFA, which has taken on an even greater role due to component shortages impacting some of the most fundamental components of PCBs. A PCB manufacturer that has built a wealth of professional relationships with component manufacturers will have an easier time sourcing and building supplies to prevent interruptions to production runs.
In the event of obsolescence or inability to acquire parts within a reasonable lead time, VSE can find suitable replacements, draft an ECO, and update designs to maintain tight production schedules. At our high-volume Reno facility, we can establish a dedicated stock for your production supplies. You can scale up the lot volume without worrying about your parts being diminished in a central repository.
Your Contract Manufacturer Makes DFM A Cornerstone of Production
Design for manufacturing guidelines will vary between projects and evolve throughout the product development cycle. Designers and manufacturers are tasked with optimizing performance, reliability, and cost, often in increasingly smaller and more complex form factors. At any stage of development, designers need confidence in their manufacturer to deliver a high-quality product that is set to pass any expensive third-party compliance testing on its first try while still meeting all points of design intent. Here at VSE, we’re a team of engineers committed to building electronics for our customers across various life-saving and life-changing applications. We can deliver critical performance in demanding fields alongside our valued manufacturing partners.