Issue link: https://iconnect007.uberflip.com/i/1525004
AUGUST 2024 I DESIGN007 MAGAZINE 37 Mouse bites can cause localized stress on the PCB edge and lead to component cracking. Serpens processus is a wily species, oen cohab- iting with other, beneficial process species. To avoid being bitten, designers must focus on design constraints, keep them simple, and be aware of design features that add processing. Common lairs for process cost adders are PCB outlines, hole definitions, unique sizing, fin- ishing, or coatings, especially ones requiring extended cure times. e anti-venom is applied topically and serves mostly as a repellent; PCB designers must apply heavily during times of early proj- ect planning and treat fellow stakeholders who might be unaware of the dangers. Signs of an early bite, however, will materialize via stake- holder team suggestions describing oversized, curvy-shaped PCB designs with both plated and unplated countersunk mounting holes. In rare cases, wild visions of PCB stackups capa- ble of carrying 80 amps and running down an ordinary soldering line must be treated imme- diately. In these cases, the venom of the pro- cess cost-adder has reached the brain tissue of this stakeholder and must be stopped before reaching the project budget and swelling it until it pops. Species: Serpens Apparatus (Machinery and Equipment Cost Adders) e safest way to avoid the bite of Serpens apparatus is to stay on the high ground, making quick hops between the machine stations that do the work of manufacturing the PCB. If a designer can clearly see and understand what it takes to hop to the next machine station without falling to the adder-infested jungle floor, the chances of being bitten by Ser- pens apparatus decrease greatly. But many PCB designers fail to study the equipment and capabilities of the fab and EMS providers, rely- ing only on the PCB design soware as a GPS guide. We see news stories about travelers not researching their destination and winding up in dangerous situations by relying solely on GPS. Unfortunately, designers oen suffer the same metaphorical fate. PCB design soware can convert almost any geometric feature into a process machine language. Via padstacks are not only identified as drilled and plated holes, but our layout tools now invite designers to select from several filling and capping options without identifying the added cost or equip- ment needed. Just last week, I had to rescue a designer who had fallen to the jungle floor in this manner. He'd pressed some via definition buttons and unknowingly stirred up a nest of Serpens appa- ratus. In the nick of time, I yelled, "Cost adder, watch out!" Once we scrambled back up on the DFM observation platform for a design review, we could clearly scope out the equipment that would have been required for the unnecessary filled and capped vias. We were lucky enough to avoid being bitten by Serpens apparatus and lived to tell the story. e anti-venom for Serpens apparatus does not yet exist. e best prevention for this type of bite involves traveling to PCB design and manufactur- ing trade shows and taking frequent tours of PCB and EMS manufacturing facilities. ere is simply no better way to get in touch with the equipment and the people who run it. To remain above the man- ufacturing jungle canopy and to know where to jump next, PCB design-