If you work in PCB assembly or electronics manufacturing environments, you're probably already familiar with PCB " panels," or multiple, identical PCBs arranged together in a grid. The process by which these grids are produced is appropriately called panelization, and there are key benefits to its practice.
When you get right down to it, PCB panelization is all about cutting costs and increasing assembly efficiency. If a manufacturer's aim is to assemble several devices with identical PCBs, then it stands to reason that processing multiple PCBs at once rather than each PCB one at a time could have a positive impact on the bottom line. Panels can be loaded into an assembly line and run through SMT operations much faster than single boards alone, maximizing a manufacturer's efficiency and yielding more PCBAs in exponentially less time.
So, panelization helps manufacturers do more with less (higher velocity). That's great! But the risk with any time-saving benefit is that it may come at the expense of product or process integrity. As with any advanced system, great care must be taken to ensure that there are appropriate mechanisms in place to support it.
What's the Problem?
Conscientious manufacturers know that the key to quality and efficient production is having a firm grip on production data. In electronics assembly, with so many parts in the mix, it's critical to ensure that a reliable system is in place to log and track components so that you always know what is coming in, where each piece is going, and how to pinpoint mistakes in order to prevent issues down the line or quarantine issues after production.
Typically, PCB tracking is done by way of barcodes or other encoded symbols marked or labeled on each board. These codes contain identifying information about the board (where it came from, what kind of board it is, and so on), which can be logged in an MES and used as a unique ID to track a particular PCB as it is scanned at several key points throughout the assembly process. When accurately logged and tracked by a network of barcode readers, PCs, and other equipment, a manufacturer can rest easy knowing that all of their material is accounted for and that they have traceability data on hand in case a problem arises - that is, the manufacturer can literally " trace" an issue back to a specific component or process.
But what happens when you need to process several PCBs at once - as with PCB panels? How can a manufacturer ensure not only that each individual PCB in a panel is accurately logged into a system, but also that panelized PCBs are logged in the correct order? Imagine what would happen if an operator scanned PCB barcodes from left to right on one panel, and then right to left on another - would each PCB find its way to the correct assembly? If there were a problem in production, could the issue be accurately traced back to the problem PCB? What if an operator neglects to scan one or more PCB barcodes on a panel?
These risks are only compounded when you're working in high-mix production environments. Here, not only are you tracking multiple PCBs at once, but new batches of PCB panels are continuously coming down the line. These panels will likely have varying grid configurations and contain PCBs marked with various codes in various places. It's virtually impossible to anticipate every scenario - as great as panelization may be for your bottom line, it demands great responsibility!
Since PCBs in a panel are identifiable by barcodes or symbols, it stands to reason that barcode readers would serve a role in the PCB identification and tracking solution. Theoretically (and in many places this is still the case), a human operator could be tasked with hand-scanning each PCB on each panel using a handheld barcode reader, for example, to log PCBs into a central system before they enter the assembly line. However, as we've discussed above, scanning each barcode on a panel by hand relies on the accuracy (and endurance) of a human operator to follow a multi-step process, which - despite our best efforts - does not quite compare to a fully-automated system.
Some clever automation engineers in the industry have produced systems that take the human element out of PCB panel scanning altogether. Using barcode imaging equipment, these engineers attempt to replicate a human's ability to " see" an entire PCB panel in order to anticipate the number of barcodes on a panel to be scanned and what order to scan them in. However, most imaging tools have limited fields of view and cannot capture an entire panel in one shot to ensure sequential decoding. To account for this, these engineers' custom solutions employ multiple imagers, robotic equipment, or mirrors to simulate large-area imaging and inspection. These systems, often fully customized, can be expensive and complicated for assembly line operators to set up and use. And when a new kind of PCB panel comes down the line, custom hardware configurations often need to be adjusted to read a new sequence of PCBs, resulting in costly downtime on the line and more room for error.
Enter: Line scan technology. Like a fax machine or copier, line scan cameras are able to compile large-area images of an object by combining line by line of pixels as the object passes below the camera's field of view. This is great for imaging large, flat objects like PCB panels, which can be captured in a single image as they move through the assembly line. What's more, these images can easily be served up to inspection equipment like machine vision systems that are able to analyze each image in full. Common machine vision software platforms have barcode decoding tools that can be applied multiple times on a single image to decode all barcodes on a PCB panel at once. For each new PCB panel, the machine vision system can be configured to read PCB codes in the correct grid arrangement, and then log each PCB code in the correct sequence to be tracked by the system. Since accommodations for each new PCB panel are made in the software only, no complicated hardware setup or reconfiguration is required, saving a big headache for the operators.
The only remaining problem with a line scan and machine vision solution for PCB panel scanning is the amount of time it takes to train the machine vision software on each new PCB that enters the line. Since a new panel typically means a new PCB grid arrangement, the barcodes that you need to scan are now likely in different places than your machine vision system expects them to be. This means you're going to have to spend some time repositioning the machine vision decoding tools applied to your PCB panel image to match up with the new barcode locations, and at this stage you may start to wonder: What's the point in automating a process to save time and cost if the automated system itself necessitates costly downtime?
As this is the Microscan blog, it is worth pointing out that Microscan has developed a turnkey solution to solve this very issue. The PanelScanâ„¢ PCB Traceability System, including GigE line scan cameras and machine vision technology, has a unique, user-friendly software interface that trains on a new PCB panel in less than 1 minute. PanelScan software is engineered to take advantage of the grid format of a PCB panel, relying on row and column data to allow it to easily anticipate the configuration of all panels in a batch. As an operator receives a new kind of PCB panel, the operator simply enters the number of rows and columns of PCBs in the panel into the PanelScan interface, identifies upper and lower barcodes on the image captured by the line scan camera, and then runs a complete set of panels through the assembly line. With PanelScan trained on a panel, lines are able to keep moving until the next batch of panels arrives - at which point an operator can easily input the next panel's sequence of rows and columns and virtually eliminate downtime on the line.
Operators do not need to be experts in automation or machine vision to use PanelScan. However, since the PanelScan system is based on machine vision technology, it also has the ability to be programmed in a host of useful ways. For instance, PanelScan can send an alert or stop production if a panel is missing a barcode, or if a PCB barcode is unreadable. With expanded capability in PanelScan's developer interface (brought to you by Microscan's VisionscapeÂ® Machine Vision Software), PanelScan can even go beyond standard decoding and barcode presence/absence functions to inspect barcode position or quality, verifying codes to ISO 15416, ISO 15415, and AIM/DPM standards.
All of this spells a big win for the manufacturer. Now the benefits of PCB panelization can be realized with a fully-automated system that supports the cost and time savings that panelization is meant to bring to the production floor. Panelization and automation together - it's a powerful thing!
Is your system responsible enough to handle the great challenges posed by panelization? Find out how to boost your assembly efficiency without losing any critical data - Request a Demo of PanelScan.
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