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Design007-Oct2018

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32 DESIGN007 MAGAZINE I OCTOBER 2018 occasions where a customer has sent files that were supposed to be the updated version but were not changed at all. All suppliers of PCBs, including assembly services suppliers, make great efforts to verify that the data they are using to build the product for a customer is the latest up-to- date version. Every manufacturing process is tied to an internal prod- uct control number and revision. In production environments, the mate- rial does not move forward unless it has been checked, verified, and inspected to the revision control process in place. But what happens when the customer design data is not identified? It is a fact that designing and engi- neering PCBs requires changes. But the trag- edy is that without organization and control, a quickly introduced change using data that is not clearly identified can wreak havoc on a supplier's manufacturing control systems. All too often in the rush to market a new PCB design, a customer's design layout template is used without the customer editing the file names to be appropriately descriptive. Here's an extreme example. Many designers send out data files for a "MAIN_PCB" design to suppliers (Figure 1). Within the data archive for this generically named design, the files may also lack descriptive naming attributes. To make a point, let's examine the data archive for this four-layer, single-sided assembly design (Figure 2). As a manufacturing stakeholder, could you quickly pick out the file that reflects the top-side leg- end (silkscreen)? How about the top-side solder resist artwork? Not a chance without importing the files into a manufacturing file viewer (Gerber) and putting the pieces of the manufacturing puz- zle together. In this case, the only file pro- viding a clue to its functional- ity is the .NCD file. The supplier will probably assume that this is an NC Drill file. The other files will need further investiga- tion. But even after assimilating the files into a viewer, determining the functional purpose of the files without any descriptive help is a chal- lenge. Let's use the viewer to plunge inside the design files to see if we can determine how to use this data. Is the view of the MAIN_PCB_1.pho file in Figure 3 the top-side artwork or the bottom side? How would your fabrication stakeholder know? Next, let's take a look at another file in the archive, the MAIN_PCB_6.pho file. It appears to be a power plane. Shall we assume that it resides on an inner layer (Figure 4)? If so, which one? There are two inner layers. I'm getting a headache. This is impossible! Figure 1: Many PCB designs are named "MAIN_PCB." Figure 2: Name your files in a way that lets the fabricator know your intent.

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