Quartz-based timing devices are the traditional, long-established components used to provide critical clocking signals in all electronic systems. It's a mature technology, with a track record extending back over 60 years. As such, it's normal to assume that there will be many credible vendors, numerous sourcing options, and fairly few technical surprises. However, this is not always the case.
Despite the maturity of quartz-based devices, the reality is that quartz can be a very challenging component to source. First, there are actually only three or four credible sources of quartz devices in the very high volumes needed for products such as smartphones and tablets, where global smartphone shipments alone are on track to reach around one billion units for 2013, and where there can be multiple quartz devices per smartphone.
Further, shifts in market demand often lead to frequent swings in the supply/demand balance, yet manufacture ring constraints can make the ramp-up time to increased production volume can require up to six months. As a result, maintaining a reliable supply chain requires that OEMs establish long-term relationships with their quartz vendors, along with careful and constant nurturing of the partnership, which means a significant time and personnel commitment.
There are also complicating technical issues to consider. For example, even if there are what seem to be viable second sources, in practice it is not feasible to change suppliers due to subtle differences in performance and specifications. For cellular OEMs, there are major cost and revenue implications as well. A common complaint occurs when OEMs or their contract manufacturing partners switch to an alternate quartz supplier, other than the one recommended by their cellular IC vendor, and suddenly a batch phones malfunctions.
Often, the first supplier to be contacted is the cellular IC manufacturer, who either spends tremendous resources proving that the quartz is the root cause of their cellular IC failure, or in the worst case simply loses the design and associate business when the OEM changes cellular IC suppliers.
Another complaint occurs due to an undesirable secondary parameter of quartz performance known as “activity dips,” where the quartz device simply fails to function at random operating temperatures. Once again, the end product will malfunction and a costly “blame game” begins: the phone OEM blames the chipset vendor; the chipset vendor then goes into costly failure-analysis mode only to determine that it is the OEM-supplied cheap quartz that is really the problem; meanwhile, millions of shippable units are at risk.
Such problems with this modestly-priced component — typically 35 cents or less — can result in product returns each costing $50 or more to service, often resulting in scrapping the phone entirely (especially if it is a low-cost smartphone or a feature phone). Of course, this can also damage the OEM's reputation with customers, who ultimately blame the OEM and switch to another brand.
Availability issues can hurt the OEM's ability to ship product, significantly affecting top-line revenue. A phone vendor that is able to deliver an additional five million phones within a quarter because of their superior ability to source quartz components, can capture an additional $750 million in top-line revenue (assuming an average price of $150/phone) due solely to the availability of this inexpensive part. Adding to BOM cost and sourcing headaches, most designs that use quartz for timing also require an additional component called a thermistor to measure inevitable variations in the ambient temperature.
The MEMS-based alternative
Fortunately, a viable and very different alternative to the quartz-based timing device is now available and is already serving mass-market, high-volume products. A micro-electromechanical system (MEMS) timing device is built onto a tiny silicon die, using manufacturing technology closely aligned with conventional integrated circuits (ICs).
MEMS-based devices offer several critical advantages compared to quartz. First, the production process leverages standard CMOS equipment, so it can be easily manufactured in one of the many existing 8″ IC foundries. As a result, time-to-market is quicker and ramp-up time to meet demand spikes can be greatly reduced by staging MEMS wafers in the fab process; typically, it can be less than half the time needed for quartz component manufacturing.
Looking further ahead, the MEMS-based die can be co-packaged and over molded with other ICs, such as cellular transceivers or GPS/GNSS connectivity products. This offers multiple benefits compared to using a separate timing component: it reduces required engineering work at the OEM side, it enhances consistency in performance by eliminating quartz variation from the equation, and it requires less PC board space. It also eliminates quartz and the thermistor from the BOM entirely, thus simplifying procurement and lowering assembly costs.
As a consequence of integrating the MEMS device within cellular and connectivity ICs, the chipset vendor can provide a higher-quality solution by eliminating the need for the phone OEM to use quartz-based devices. The chipset performance would be more reliable and consistent, thus reducing incoming quality issues and engineering support burden, lowering overall cost of ownership, and increasing profitability.
It's largely about the supply chain
Great engineering designs are important to market success, but being able to build them with an effective procurement and manufacturing chain is just as critical for financial success and ROI in high-volume markets. A secure and reliable supply chain that can respond to market conditions is worth a premium to many vendors. In addition, it can be a critical differentiator for any chipset providers who are trying to sell to OEMs.
As the OEM space consolidates with fewer large-scale manufacturers, sourcing and bill of materials issues become even more important. The availability of MEMS-based timing devices in place of traditional quartz-based units provides advantages in system design and test, improved unit performance and consistency, reduction in supplier-to-supplier variation, and more reliable field performance. OEMs also benefit from the other technical virtues of MEMS devices, including minimal hysteresis, superior thermal performance, and greatly improved shock and vibration tolerance (a serious problem with quartz devices).