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FEATURE CONTRACT MANUFACTURING


Unlikely ways components impact the SMT assembly process


Andy Jones, business development & UK sales manager at Europlacer, looks at some of the unexpected issues encountered whilst using surface mount component pick & place systems


A


utomating the surface mount assembly process is critical to


productivity and competitiveness for any company whose business relies on building circuit boards. Today’s component design engineers will know that packaging requirements that minimise board real estate are driving miniaturisation to the point that some devices, those with 01005 profiles for example, are close to invisible. Assembly by hand is out of the question. The day-to-day issues faced by electronics manufacturers that relate to components broadly fall into two categories: counterfeits and shortages. Increasingly, you may find you are having to deal with both of these at the point of assembly.


FAKE NEWS Predominantly, it’s the large ICs that tend to be faked by less-than-scrupulous businesses, often based in the East. But even small passive SMDs are not immune. They are purchased in such volumes and rarely scrutinised, which means there’s still value for the fakers. Suffice to say that the pressures of


‘cost-down’ initiatives by product manufacturers to remain competitive in their end-user markets often squeeze the contract manufacturer assembling those items. Many such manufacturing organisations take responsibility for sourcing all components for an assembly project. Done correctly, there’s a margin to be had. In some cases, it’s the most profitable part of the contract. However, buyer beware! With that responsibility comes accountability. All that extra revenue can go down the drain rapidly if the components sourced are not up to scratch. More so if those erroneous components are placed and reflowed onto a sophisticated surface mount assembly and not discovered until system test, or worse: they cause a field failure. The cost of rectification at the former level, in the shape of fiddly and arduous SMT rework, is expensive. The cost of the latter scenario doesn’t bear thinking about. For manufacturers with the appropriate resources, or budget, incoming goods inspection is a first line of defence. But for counterfeit SMDs, that’s a challenge:


16 OCTOBER 2018 | ELECTRONICS


even if devices are visible, handling them is tricky. And optical inspection, whether by a trained eye or automated, won’t discern a fake component that looks the part. For passives, electrical test is the only reliable solution. Most high-end pick & place machines


include some kind of test facility. The Europlacer solution is especially robust, comprising a 4-wire, Kelvin-connected LCR bridge, built right into the heart of the system that returns a true measured value. Once picked from the reel or stick, usually by a precision vacuum nozzle, the X-Y motion gantry can steer a component to the electrical tester on the way to its final position on the circuit board. That slight journey diversion adds a


small amount of time to the placement process. Europlacer’s newest machine, the atom4, will place at rates up to a breath- taking 104,000 components per hour – but it can’t achieve those heady speeds if an electrical test is required every time. Testing at the point of use is perhaps the ultimate defence, not just against counterfeit or substandard devices that


get through to production, but also against those that were simply mislabelled in the stores, or where the wrong reel is inadvertently installed onto the placement machine.


Figure 1:


Europlacer’s built-in electrical LCR test bridge


Figure 2:


Component wall built using precision Z-axis control being knocked down by a feather


SHORTAGES Component shortages are more common than people realise. Contract manufacturers and OEMs with robust supply chains can often find alternate sources without breaking the budget or suffering non-productive idle time waiting for components to arrive. Idle time is one of productivity’s biggest enemies: imagine the frustration of running a high-speed assembly line with placement machines proceeding at 100,000+ components per hour, only to then stop the entire line while missing parts are located. One technique that has been deployed


Figure 3:


Europlacer’s atom4 high- speed placement machine


is based on a modern pick & place machine’s ability to not only place with micron-levels of precision in the X and Y axes, but also in Z height. Europlacer’s iineo, atom and XPii platforms all feature precision Z-axis control to cope with inevitabilities like board warpage, and to handle meticulous applications such as PoP (package on package), where stacking devices or even bare die during assembly is part of the production process. This Z-axis capability was recently


Figure 4:


Andy Jones (business development & UK sales manager at Europlacer


demonstrated at a Technology Open Day where a Europlacer iineo+ machine was programmed to build a ‘wall of components’ by stacking dry chips on top of each other. The proof of precision, and the delicacy with which these placement systems can operate, was highlighted by that wall then being demolished with a feather (Figure 2). This same technique of ‘stacking’


components has been used to great effect by some Europlacer customers to overcome shortages of passive devices of a specific value, by stacking a second available device (after applying solder paste from the built-in dispenser) on top of the first to create the correct ‘combined’ value. Long live Ohm’s Law!


Europlacer


www.europlacer.com 01202 266550


/ ELECTRONICS


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