Placement challenges of 0201s: the next generation of chips requires better motion control, machine vision, feeder design and nozzles.

The size and weight savings offered by adopting the 0201 form factor for passive components are attractive to designers of products such as mobile phones and portable computers. Component manufacturers have solved the majority of challenges to producing 0201s within workable tolerances and at acceptable unit prices. The assembly community must now demonstrate production-quality placement and soldering for 0201s to reach consumers' pockets.

Pick-and-place holds the greatest challenges, and the majority of end-of-line defects are likely to be traceable to this stage of assembly. The four dominant placement defects are the same as always: missing component; component on edge; component upside down; and component off pad. However, with the smaller component and pad dimensions, as well as closer component spacing, placement processes are more sensitive to smaller errors.

Generally, placing components spaced at 0.2 mm and below is considered a challenge from both a process and placement perspective. For system-in-package (SiP) applications, placement is feasible at 0.15 mm spacing. However, the 0201 form factor allows designers to target even closer spacing, as close as 0.1 mm, and the placement time per component must be significantly shorter. To achieve this, the hardware and software on today's placement machines are going to have to change.

First-generation 0201 placement processes recorded roughly double the accepted 0402 defect rate, at around 100 dpm. Also, it is much tougher for current AOI technology to detect defects when working with such small components. With this in mind, equipment vendors need to aim at reducing the typical dpm for 0201 placement, to at least achieve parity with 0402 rates (currently about 50 dpm).

The tiny dimensions and lower mass of an 0201 device hold the key to the likely increase in defect rates. Because the nozzle is almost the same size as the component, there is a higher probability of mis-picking the component from the blister tape; the components can also move significantly, relative to their size, in the tape, unless the tolerance between the pocket dimensions and component dimensions is tightened. Also, electrostatic effects resulting from separating the Mylar cover from the blister tape have a greater tendency to displace the component before it can be picked. Transferring the component from the nozzle to the board--the handoff stage--is also more sensitive to motion control in the z axis. Finally, since the smaller component dimensions permit closer spacing on the PCB, placement resolution must be twice as high for 0201s as for 0402s.

Ed.: For the full article, please see circuitsassembly.com/cms/content/view/1343/

Shawn Robinson is manager, GSM product sales, and James Lamuraglia is systems engineering manager with Universal Instruments Corp. (uic.com); [e-mail].