Your choice

Your choiceDavid Buckley looks at the developments in SMD pick-and-place machinery aimed at meeting PCB assemblers’ current and future needs
Lying between the world’s fastest pick-and-place machine – the recently launched Fuji FQP 132E which places a staggering 143,000 components per hour (cph) – and Zevatech’s Micron 2 in-line machine, which places a modest 1500-2000cph, but with an accuracy of ?12 microns, there are over 100 different models from some 30 manufacturers available in Europe. Even allowing for the fact that different suppliers are competing in the same machine category, the choice is huge.
With a few exceptions, the vast majority of UK and mainland European electronics manufacturers are engaged in low-medium volume batch production – environments where the principal requirement is flexibility. Placement speed is certainly regarded as important, as are placement accuracy, product throughput and the ability to cope with the newer advanced components, but the ability to reconfigure a machine for the next job with the minimum of down-time is seen as essential. The latest machines seek to address these requirements.
Flexible mid-range machines typically employ either a stationary PCB/moving X-Y placement head configuration or a split-axis arrangement in which the board moves in Y and the head in X. Mydata’s TP11-UFP fine-pitch placer, for example, adopts the latter format and, by adding its new Hydra Speedmount eight-nozzle pick-up head alongside the existing fine-pitch head, the Swedish company has upped this machine’s placement rate from 6000 to 14,400 cph.
More typical of continuing incremental speed enhancement is the performance offered by Zevatech’s latest mid-range offerings, the FS 750 and the FM 760. These new machines deliver placement rates of 14,400 and 11,250 respectively, an increase over the company’s current models of some 10-15 per cent.
If yet higher speeds are needed, then linking a flexible placer with one of the much faster, though less versatile, chipshooter machines provides a commonly adopted solution. Line balancing software ensures that the work is efficiently shared between the two machines. Capable of placing up to 45,000cph, chip shooters employ a rotating turret containing multiple placement heads under which the PCB is moved in X and Y. Suppliers include Japanese firms Fuji, Panasonic and Sanyo. The chipshooter’s placement rate sounds impressive but, as with all types of placement machine, it is worth remembering that the quoted maximum rate is possible only under limited ‘ideal’ conditions. It is unlikely to be achieved in practice. Ray Bruce, Siemens’ UK business manager points out that a chipshooter’s benchmark rate of 40-45,000cph may have to be derated to around 19,000cph when difficult real life conditions are encountered.
Fuji’s new world speed record holder, the FQP-132E, achieves its impressive 143,000cph placement rate not with a super-fast turret, but by reverting to what is essentially a static PCB/moving X-Y head configuration. The PCB is palletised on entry to the machine and then indexed along beneath a row of 16 placement heads. “The machine is aimed at very high-volume, low-mix environments,” says Mark Hendry of Fuji’s UK distributor, Astro Technology, who readily admits: “We don’t expect to sell very many in this country.”
Fuji is, of course, a major player in the more flexible machine market where suppliers are now offering machines equipped with such features as intelligent feeders (which can be replenished while the machine is running), automatic nozzle changing, and software to optimise the placement sequence.
Improved throughput has received particular attention. Siemens, for example, has developed a dual-lane conveyor system for its placers which feeds two circuit boards into a machine for either simultaneous or back-to-back assembly. And Mydata has developed a conveyor system which, receiving boards from upstream, packs them side-by-side to create a ‘virtual panel’. This ‘panel’ is then transferred to the placement area. After population, the conveyor system unpacks the panel into individual boards and transports them downstream, one at a time.
Adapting existing flexible machine designs to physically handle BGAs, microBGAs, CSPs or even flip chips, together with providing the necessary enhanced lighting and vision systems needed to accurately place these devices, is not, in itself, an insurmountable hurdle – several manufacturers are already trumpeting their machines’ capabilities in this respect. But these capabilities can only be achieved at the expense of the hard won increases in machine speed.
Today these advanced components make up only a tiny proportion of the total number of SMDs placed. If they are used at all, they tend to be placed either off-line or in-line using a placement machine such as Zevatech’s slow, but highly accurate, granite-based Micron 2. But with the use of advanced components set to increase, and with I/Os increasing and pitches becoming ever finer, will this dual-machine approach continue? Or will the machine makers be expected to come up with equipment capable of placing the new devices at the sort of placement rates currently achieved for ‘conventional’ SMDs? It’s a debate the machine makers will be following closely.


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