JAX

Vahid, What type of error are you talking about? If you mean accuracy I would stick to round fiducials. As far as machines, the only question is about active component placement. For passive components Fuji(CP-series) is the way to go. Otherwise the machine depends on volume and mixture. What will you use it for? What fits your needs the best? Sorry about not being direct but there is enough reps that cruise this site. Let them sale you on their own machines. Good luck,

reply »

Hello Vahid The most accurate fiducial for you depends somewhat on your board characteristics like contrast, spacing, inner layer features and obstructions. The more important consideration is what does the particular machine like best? The manufacturer will normally have a specific recommendation for the best shape. This will often be a SMEMA circle. If you wish to experiment to see what works best, Topline has a fiducial evaluation kit with 10 QFP100 footprints, each with a different set of local fiducials in different shapes. As Jax says, the "best" machine (or machines) will depend on what you plan to do with them.

reply »

Correct me if i am mistaken, I always hear the circle is better fid mark than any. Due to shape and dimension, one value of diameter is needed while square you need width and lenght. beside whichever fid mark, the accuracy will base on cad and technical setup of the board and surrounded area near the fid(contrast or another close fid) As for the machine, while fuji and panasonic is high volume is great. Fuji( the program have more control on their program because no one can change on the machine except by the transmit controller) as for other..like Jax said...

reply »

Fiducial recognition is based on finding the centroid of the gray scale density of the fiducial. Round fiducials are easier for the software to digest in most cases, but its more important what the camera sees.

Gray scale or color contrast of the fiducial and the background is the most important. Lighting, focus and brightness adjustments can affect the imaging capabilities of the vision system which in turn will screw with the software.

Ask any potential vendor to do a repeatability test with a fiducial of your choice (pick something you will actually use) and have the vendor printout the location coordinates as seen by the machine's vision system. Than compare for yourself, whose machine saw them the best. These things cost up to a million bucks, don't take any crap about running a test or producing location data. If your worried its their job to provide you with data to increase your purchasing confidence.

Beware, accuracy of placement is not necessarily tied to accuracy of vision/fiducial location. The placement mechanism has a list of things that have to use that vision location and get there accurately. Good Luck..Dan.

reply »