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38 DESIGN007 MAGAZINE I JULY 2019 Optimizing your board using design for man- ufacturability (DFM) techniques just makes sense. But without formal training, this isn't as straightforward as one would hope. Every day, our team receives designs that are too com- plex, too thick, incomplete, with components placed too close together, among other things. When something like this happens, rejection of your design is a best-case scenario because it means your manufacturing partner has your back. If your design is just dropped into an au- tomated queue without concern for manufac- turability, quality, or functionality, the output can be a batch of unusable boards. This doesn't have to happen because you are in control of your vendor choice. While not a replacement for good design practice, care- fully picking a manufacturing partner and ser- vice level that meet your needs will help you achieve a quality result. Now, let's examine five design best practices that will help reduce costs, increase yield, and improve manufacturability. 1. Always Double Check Your Design It will save you time on the front end. Re- gardless of which partner or service level you choose, I strongly encourage you to be sure to review your design, taking a second look for issues, such as insufficient power trace widths or blind vias. Ditto if components are laid out too close together. It is easy to accidentally cut holes or route slots too close to pads or traces. Copper thickness is another biggie. Higher current may require thicker copper and narrow traces probably should be thinner, so be spe- cific about what you need to ensure your de- sign will not fail. Check land patterns against the part supplier's manufacturer data sheets (MDS) as well. Often, that's all it takes to avoid common design issues. 2. Always Consider Your Environment When you send your design for manufacturing, your part- ner does not know what type of device the board will be part of nor the conditions in which it will have to perform. It's com- mon for harsh environments or exposure to mess up a board's performance. If you call out ma- terials that will not tolerate the end-product's operating envi- ronment, bad things can hap- pen—such as a smoking board, Five Best Practices to Ensure Manufacturability Connect the Dots by Bob Tise, SUNSTONE CIRCUITS Figure 1: PCB production.