PCB DFM (Design for Manufacturability) best practices are critical for getting designs from concept to production seamlessly. This will help eliminate errors, decrease costs and ensure a quicker turn around alongside being able to extract the most reliability and performance from the final product.
One important PCB DFM practice is the specification of trace width and spacing, which helps prevent shorts or opens that can interfere with functionality. For instance, typical PCB traces need a minimum width of 0.1mm for signal traces and even larger for power traces depending on their current specification. In dense layouts, the best practice is to maintain a trace spacing of 0.1mm to 0.2 mm helps prevent accidental connection between traces (about 20% production rework due short circuits & open connections traced back) when keeping within the recommended limit.
DFM equal importance of hole sizing and placement above. You must comply with minimum size requirements for vias typically 0.3mm in diameter and larger for standard vias, 0.1mm microvias for HDI (high density interconnect) boards, as they connect the layers of the PCB. DFM guidelines recommend keeping a certain distance between vias and the edges of the board (usually 0.5 mm away from any edge of the board),[e.g. cutting area] such that air pressure does not break them during handling or installation upon arrival at your facility. These guidelines help manufacturers improve PCB reliability and make sure they do not fail under high-stress environments, such as automotive or other nearby applications in aerospace.
Placement and orientation of components also play a crucial role in manufacturability. Sufficient spacing in between components to allow soldering, assembly and testing of a circuit. DFM practices, for instance, recommend a 0.5mm distance between components in an automated assembly line so that pick-and-place machines can accurately place each component with no interference [5]. With the proper orientation of components, specifically polarized parts (e.g. capacitors) we ensure there’s less change for assembly defects to occur, reducing assembly defect rates by up to 15%.
Design of solder mask and silkscreen is another subject that can be treated as best practices. Solder mask everywhere except the pads to control the solder flow and avoid bridging. When dealing with fine-pitch components (with pin pitches below 0.2mm), solder masks need to be cleared from the pads to avoid shorts. Avoid pads and vias with silkscreen markings to ensure that the marking remains legible, and prevent a peeling mask during assembly.
Another DFM must-do is balance copper within the layers. Copper asymmetry during the manufacturing process can cause warping, especially for 4+ layer boards and thicker copper layers — to learn more about through-hole plating check out our blog on this topic. Keeping even amounts of copper helps prevent warping and misalignments to provide added durability and reliability.
As a gruntled Michael Lasky—the non-gruntled veteran of the industry—pints out: “Good DFM practices are the backbone of reliable manufacturing. You not only ensure quality of your product, but also save on costs. By adhering to these principles, manufacturers minimize mistakes and maximize yield — ensuring the final product does what it is meant to do.
Implementing these pcb dfm design best practices will ensure better quality and reliability of the product, while also resulting in a smooth, economical manufacturing process. By focusing on these design details, engineers position their projects for success by enabling production and solid performance in the field.