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We have been working on two projects, and both of them are way over due.
The first started out with us finding a part that was supplied with a wrong value, not a big deal, but we are glad we caught it. Then the second was moved to a workable status. We had a large failure rate placing 0402/0603 parts (not actually the placement, more of the parts moving after placement). We had a few conversations with the customer, solder vendors, machinery suppliers, etc. The solder paste had been deemed the root of the problem. We ordered new solder paste, and suffice to say the new solder paste is a world of difference in more way than one.
We assembled both jobs with the new solder paste, and it solved the part moving problem.
We found another problem with our process, which is cut tape parts. This problem doesn't apply to all cut tapes, only cut tapes that are 8mm wide (and typically only plastic pocketed tapes). The parts would snap out of their pockets when the machine was picking other parts (typically the first item). We have devised a solution to the problem, but it will take a week or two to implement the solution.
There are two things we have found are very important in having a jobs assembled, good communication, and good information.
Everyone should be put on notice. We require information for job assemblies. If the customers will supply it, our job gets much easier. If the customers will not supply it, we will start charging for the information gathering necessary. This will also delay your assembly, because we will assemble jobs with the supplied information first (just good time management).
We must have the 4 following pieces of information for a job to go smoothly:
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The orientation of a part as it sits within the supplied container. It really takes time to look at every part and figure out the orientation of each part with respect to it's container. Typically, orientation is given (some datasheets contain this information) with the tape with the feed holes down, and reeling to the right. This is an industry standard orientation method. We will ask for customers to supply this information. If not we will implement a $100 charge per job if we have to do the research. It takes time to research each part, because every manufacturer doesn't orient the same.
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When creating a BOM, please include the thickness of the part. This reverts back to the first issue of part orientation. If this information is not included, we have to research every part to find it's thickness. We do ask, that the information is standardized either in inches or mm. (make the total list refer to inches or mm)
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Please make sure you supply enough parts to cover the entire job. We ask for 5% extra for passives, and small items like LED's. These items will some times require us to hand place an item or two. If you send the exact amount, the machine may drop one, then the job will be short. Small items dropped by a Pick and Place do "vanish" never to be seen again. This is due to the nature of the machine design. There are many nook and crannies these small parts can find their way into.
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A centroid data file is really a time saver. Even if the centroid data is wrong, it saves us a lot of hand entry. Please include a centroid data file for your boards. We try to sort centroid data from smallest to largest part size.
We are moving forward, and greatly appreciate the patience of our customers who have waited so long for their assemblies to return to them.
We have had problems that we hadn't expected, the cut tape problem being one of them. We are going to spend a significant amount of money to fix the problem. This is to relieve our rework (hand placing parts) and lost parts (money waisted).
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