First, take a look at our 10/10/10 components attrition guidelines
Surface mount pick and place (PnP) machines are a marvel of technology. The PnP heads on the fastest machines can be so fast, that they travel just shy of supersonic speeds. The X/Y/Z computations need to consider the bending and swing of the hardened steel head and nozzle to place the part at just the right spot in the deflection arc.
Our machines are optimized for smaller runs with fast change over between jobs being the priority, but they’re still pretty speedy. They are precision devices, but even so, they have to contend with a number of unpredictable environmental factors when picking and placing parts. A component might have an extra rough surface. It might catch on a rough edge of the strip. Or it could be hit with random bad luck. Whatever the cause, all PnP machines occasionally drop a part, leaving it to end up in a catch bin in the machine, rather than solidly placed on your board.
Manufacturing shops that require full reels to assemble from don’t have to worry about a few lost parts, so no one ever hears about it. Screaming Circuits, however, wants to keep your costs down and convenience up, so we often assemble from short cut strips of parts.
If you send us just the exact number of parts being placed on your boards and our machines experience a mis-picks, we won’t have enough parts to finish building all of your boards. So, when you’re sending us a parts kit, at minimum, we ask for 10% extra parts, with a minimum of ten, for each part in your BOM. For the super tiny 0201 parts, we ask for 50% extra.
Sending in the right number of extras gives us the best chance to deliver everything you need, without much extra cost on your end. For bigger parts, we like to see one extra.
Sunstone Circuits and Screaming Circuits work closely together to take as much stress as possible out of your prototype phase. You can quote and order assembly at Sunstone.com or at ScreamingCircuits.com.
Duane Benson