Design007 Magazine

PCBD-Mar2016

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10 The PCB Design Magazine • March 2016 internal layer, as they are "print and etch" for the most part. Their desired copper features are protected by the photosensitive resist and are simply printed, developed (to remove the resist not hardened by the light source), etched (to remove the unwanted metal) and resist stripped to remove the resist covering your desired cop- per features. So a 1 oz. callout for an inner layer is not at all uncommon. The 1 oz. finish for the outer layers, how- ever, is a bit unusual, given the fact that IPC rec- ommends a minimum of 8/10 of a mil of plated copper on the surface and in the barrel of the hole for continuity. So starting on .5 oz. or even .25 oz. copper foils would mean we would have to plate less than what IPC recommends to fin- ish at 1 oz. Some of you are probably wondering about the title of this article. "What could Mark pos- sibly mean? How can a lowly PCB designer like me increase our company's profits?" So can you truly increase profitability through PCB design practices? Yes, you can. And it starts with a philosophy that embraces DFM techniques. Then you must be ready for the initial release to a fabricator by ensuring that you are communicating all of your speci- fications and needs clearly to the fabrication house so that you get an accurate quote. Let's dive in, starting with Number 10 and working our way to the most important way a designer can increase company profits. 10. Accurate Fab Notes I cannot over-stress this one. Lets talk about some common fab notes that can cause confu- sion, sometimes delaying your quote. For instance, do copper weights refer to start- ing or finished weight? A standard note may read, "All copper weights listed on the stack-up detail are finished weights." But a glance at the provided stack-up shows both 1 oz. inners and outers. Remember, the first fab note speci- fied FINISHED weights. This is not a problem for an by Mark Thompson, CID Prototron CirCuits the Bare (Board) truth 10 The PCB Design Magazine • March 2016 The Top 10 Ways Designers Can Increase Profits

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