Issue link: https://iconnect007.uberflip.com/i/1466505
22 SMT007 MAGAZINE I MAY 2022 Bennett: Yes, lighting issues do create chal- lenges. If the component body and termina- tions are similar in color, like on a ceramic BGA, it can be difficult to achieve proper con- trast with the vision system. Cameras with higher resolution are used when the compo- nent features are small, like fine pitch leaded devices or micro BGAs. Rowland: Kevin is the expert here, but there are two issues when you talk about cameras. One is the actual resolution of the camera to be able to image the size of the device that you're dealing with, but then an integral part of the camera system is lighting. In general, lighting tends to be a bigger issue than the resolution of the camera. Bennett: I would agree with that. It goes back to the contrast. e cameras we use have three different lighting angles: top, side, and angled view. Sometimes it's a trial-and-error process to find the right combination of lighting to achieve the desired contrast so the camera can distinguish the features of the component. Johnson: Do you have to change these settings job by job? Bennett: Once a component package is defined, we can test to make sure it will consistently pass with the vision system. If the same com- ponent package is used on another job, the set- tings do not have to be adjusted. Rowland: Devices like QFNs and ball grid arrays are the most challenging because, with a typical package—resistors, capacitors, things like that—you're looking at an outline that is easy to set up to get a clean outline. When you're dealing with something on the bottom of the component, it comes down to contrast. Getting the lighting such that you can spot the contrast differences is a big challenge, right? Bennett: at's correct. Another factor to con- sider is symmetry. If a component is symmet- rical—for example, a leadless device where all the terminations have the same geometry on all four sides, the camera will recognize the component even if the polarity is incorrect. e component will be placed on the board in the wrong orientation because there isn't a unique feature for the camera to distinguish as a polarity indicator. Tape feeders with a combination of very short and long strips of (white) carrier tape. A yellow cover tape leader has been added to the cover tape so it can pulled to the take up spool.