In SMT assembly, it’s surprisingly common to find that a reel of resistors, capacitors or diodes has been mislabeled. If these components are placed on a printed circuit board assembly, the error can be hard to detect and expensive to correct. In this video we explain why and how Z-AXIS quickly checks these components before placing them on printed circuit boards.
Video Transcript
Simple components – like resistors, capacitors and diodes– are quite common on surface-mount printed circuit board assemblies. At Z-AXIS we buy hundreds of thousands of reels a year, usually from major distributors.
Several times a year we get a reel that is mislabeled– the value of the component is not what the label says it is. Sometimes it’s the manufacturer’s error, sometimes it’s the distributor’s.
At some electronics contractor manufacturing companies, entering the wrong part number in receiving is a common mistake. Here we’ve eliminated that potential source of error by scanning incoming parts rather than doing manual data entry. Because once a component with the wrong value is placed on a board, it’s very hard to detect it, and it can cause some very expensive problems.
The small SMT packages that we use most often are not individually marked, and so a 1 nF capacitor looks exactly like a 10 nF capacitor. Automated optical inspection won’t catch it. In-circuit testing may catch it perhaps half of the time. But it’s more likely to remain undetected until it causes problems, such as high EMI because a decoupling capacitor has the wrong value, or rapid battery drain because the current draw is higher than we expected due to a wrong-value pull-up resistor.
At Z-AXIS we think the best solution is to verify the value of these components before we place them. There are a couple of ways we do this.
One is that we’ve enabled an advanced option on our Mycronc pick-and-place machines, to test the first few components on a reel, whenever a new reel is loaded. This option checks resistors and capacitors for the correct value. It also checks diodes for correct polarity.
Here we’ve just loaded a reel of resistors that were mislabeled by the manufacturer. The Mycronic machine checks the first few components, detects that the value is not what it should be, and gives a “part value out of range” error. At 10,000 parts per reel, this fast and simple check just prevented a lot of bad boards – and costly rework – without significantly affecting our throughput.
Testing components before we place them is just one more way that Z-AXIS maintains high quality and keeps costs down for our contract manufacturing customers.
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Contact Z-AXIS to learn more about our high-quality SMT assembly services in the USA.