Benefits of automating post-SMT assembly
02 December 2019
With the dawn of SMT (surface-mount technology) components, and the associated vision of creating automated electronic assemblies entirely from SMT parts, many predicted the downfall of THT (through-hole technology) in the assembly of future PCBAs (printed circuit board assemblies).
This article was originally featured in the December 2019 issue of EPDT magazine [read the digital issue]. Sign up to receive your own copy each month.
This vision, however, has not yet become a reality. To this day, some components are still hand placed, hand soldered, hand inspected and hand packed by CEMs (contract electronics manufacturers) and OEMs (original equipment manufacturers) alike across the globe. But, as Joe Booth, Business Development & Marketing Manager at electronic manufacturing equipment distributor, Altus tells us, there are benefits to be gained in automating post-SMT assembly...
As all these manufacturers will tell you, THT processes demand highly-skilled operators, trained to the appropriate IPC standard to complete this function. Although typically a high cost process, THT assembly is usually the bottleneck to fully assembling a PCB product. Let’s consider the process...
Typically, PCBs go through the entire SMT process and are delivered to post-SMT in magazine racks in panels, or perhaps even broken out into individual PCBs, depending on how the post-SMT process is designed. In a common scenario, a row of operators would complete the many processes required for the final assembly of a product. These can include: hand placement; hand solder; visual inspection and test; all the way up to final assembly, labelling and packaging. The key benefit of a manual production line is its flexibility and reactiveness. The downfalls are that they are operated by humans, which means that, even with highly trained operators, there is still a high chance of error, they have a broad window of repeatability in terms of time and quality, and they are not optimised for profit.
So, having established there are significant issues when using a manual process, why aren’t more companies automating? Well, many companies are investing, because of huge advancements in recent technology. The most problematic area of automation during THT assembly has always been the placement of parts. And this is the area that the market has recently seen drastic improvements in capabilities.
Odd form placement by its name alone is ‘odd’. Parts weren’t traditionally placed this way because they are incredibly difficult to position accurately and repeatedly by robots. Early odd form systems did not necessarily have the level of robotics or software required to justify a huge spend for an unstable platform. Unless the process is reliably constant, accurate, repeatable, quick and offering a significant boost to production metrics, why would companies change? We are now finally at the stage where odd form placement solutions are becoming the area that manufacturers can look to make significant improvements in product profitability. This is because the systems’ capabilities are now far beyond the level that human operators could ever reach!
So why look at odd form? The main arguments a credible salesman will make are that: “you can increase volumes, improve quality and achieve significant savings with clever automation solutions.” And this ‘pitch’ is not just sales talk. Today’s systems are highly flexible and easy to changeover for higher mix low volume manufacturing. For example, let’s consider a popular solution from a market leading brand, Cencorp Automation.
The 1000OF odd-form placement platform can place through a variety of feeders, including axial, radial, tube, bowl and tray. It can undertake polarity and lead checks in the feeders, and design bespoke servo grippers, picking any component which requires placement. More than that, it has force detection sensors in the grippers and clinchers to ensure an accurate placement, and can position any component in approximately two seconds. This takes place consistently over a whole shift, which is why companies tend to find a two, or even three-fold, increase in production output.
Most people are now familiar with wave, selective and robotic soldering for THT to replace manual soldering – all of which deliver significant benefits over the manual method. Fewer people will be familiar with in-line physical test solutions and THT AOI that can inspect both the top and bottom of a board with 3D capabilities at once. This is another solution to labour-intensive methods and a growing part of the assembly process.
Another significant bottleneck in post-SMT where options are less clear is during the final assembly. Final assembly is a phrase used to describe a very broad range of activities required to pass a final product. For example, your customer may require an individual PCB assembled and placed into a blister pack. This may then need to be labelled, placed into packaging, and boxed, ready to be shipped. Some manufacturers might hire a couple operators to complete this task. However, this ‘add an operator’ approach is the best way to drive down profitability, and is not future-proofing production.
Does hiring a new person each time you increase production numbers offer you the best return on investment? The answer is clearly no, but many people aren’t aware of the alternative solutions. One of the key areas is a final assembly cell, broadly named because of the variety of processes that can be custom designed to suit an application. These cells are equipped with robots that can be customised with labelling robots, box-building robots, and blister pack dispensing and sealing robots, or whatever your application process might require. It may sound too good to be true, but robots are best utilised in processes that are repetitive and can be broken down into steps.
I imagine that you are now thinking about the price tag that comes with a robot or line that can fully automate your production. The question shouldn’t really be about the price of the line, but the speed of the return on investment. These capabilities typically replace the most manual and costly processes of PCB assembly. Imagine having one operator on an entire line, producing double the output of a variety of through-hole products. Aside from the time saving benefits, you now have a completely consistent process, producing the same product, to the same quality every time, with quality guaranteed.
Assembly solutions and the accompanying technologies are consistently improving, allowing manufacturers to get the best from their manufacturing processes. Automation is becoming the norm for electronic SMT assembly, and there are now methods available helping in the trend to becoming fully-automated across an entire PCB product. The vision of creating automated electronic assemblies entirely from SMT parts, without touching a board, is now there – not only helping to obtain high-quality and repeatability, but ultimately improving the bottom-line.
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