Issue link: https://iconnect007.uberflip.com/i/1417991
OCTOBER 2021 I DESIGN007 MAGAZINE 19 Johnson: It's not a file problem as much as it is a parts quality problem? Stans: Exactly. Tavernier: In the implementation of Gerbers, you see errors in the attributes. For instance, if the shape is a little bit more complicated than a rectangular shape, it is sometimes put in the parts library as different flashes that are over- lapping, or you would get the same thing in Gerber output, and it's not even the fault of the Gerber format or the CAD soware. It's just the way the part has been constructed. More errors come from database—user—errors than from weaknesses in the CAD soware. Stans: For assembly, the real drama is that the IPC, which has existed for a long time, never succeeded to convince the component manu- facturers to create one joint worldwide acces- sible database with all the components in it. e whole world is forced to do this work repeatedly, and that means mistakes are made repeatedly. at is a huge part of it. Johnson: Using an example, it's as if the word processors that we all use refused to supply fonts and made all of us make our own. Tavernier: at's a good analogy. Stans: It's exactly that. It's a scandal that com- ponent manufacturers are not willing to sup- ply the data component information in one standardized, unified database, accessible by everybody. It's a scandal. But it is what it is. behind it, doing things right the first time. I can only contribute for what I have the informa- tion for. But that really comes down to efficient CAD libraries. Nolan Johnson: Dirk, you said something I want to expand on. We've already discussed CAD tools and whether they support the formats, but you touched on CAD libraries as an issue just now. Can you talk more about that? Stans: It all starts with what the designer has in his CAD library. Where does his information come from? Does it come from a spec or from something that he downloaded on the inter- net? What is the quality of his information that he puts in his database? We see many mistakes. It's rare that we have a job for which we need to make the board and assemble it, that does not have a mistake in there. ese mistakes are very, let's say, down-to-earth mistakes, such as non-matching footprints. e customer designs the board, and says, "For this manu- facturing part number, that's the footprint," in his CAD system. en we do the DFM. We countercheck this with this manufacturing part number in our database and then the foot- print doesn't match. Subsequently you have an anomaly, and you need to find the problem. In many cases, the customer's footprint is wrong. Why? Because in many cases, we've seen this footprint already 10 times before, and that's a daily practice. If you don't do the virtual manufacturing before you start manu- facturing, then you get a situation in which the EMS companies order the part based on the customer's data, the board comes in, the com- ponent comes in, and then they say, "Hey, it doesn't fit." Now we have a problem. Johnson: So, that's a problem with selection of the footprint in the CAD system? e file export, the Gerber file format itself, is accurately representing what the user put in their database. Stans: Yes. More errors come from database—user—errors than from weaknesses in the CAD software.