T echnology is shrinking and, as

with any other component, the

electronics industry is being driven

to reduce product footprint for a number

of reasons. But miniaturisation comes

with a price, and nowhere is the effect felt

more keenly than in frequency control

product (FCP) manufacture. However,

innovative techniques have shown that

suppliers are tuning into customer

demands for a smaller footprint without

compromising performance.

A glance at the latest trends confirms

that miniaturisation is a big deal. Stefan

Hartmann, senior manager of Epson Elec-

tronics Europe’s QD division, begins:

“There is an increasing trend towards

miniaturisation as manufacturers pack

more functionality into smaller devices

such as mobile phones. This places certain

manufacturing demands on the physical

size of quartz devices, crystal oscillators

and filters.”

Manufacturers are then faced

with a number of exacting require-

ments in size and performance.

But, because many of the applica-

tions are now handheld and certainly

very mobile, the effect of both shock and

vibration must be considered in the spec-

ifications.

As an example, Hartmann

points out that improving stability,

performance and temperature char-

acteristics of quartz crystals requires

some mounting knowledge.

“Mechanically mounting a crystal

inside a package needs to have as little

impact on the oscillating device as pos-

sible and I see mounting technology

developing further.”

Euroquartz sales and marketing

director Andy Treble agrees, noting

that manufacturers must ensure that

the mounting is secure as possible. “One

of the things you can do is to increase the

number of mounting points on the crystal

to create a dampening effect. When the

crystal does become subject to shock and

vibration, it is better able to cope.”

Hartmann points to another trend.

“We are seeing a diversification of meth-

ods to obtain the range of frequencies and

specifications today’s customers require,”

he explained. “Some manufacturers tend

to implement more functionality in the

oscillation circuit, which means adapting

the external quartz device to the chip char-

acteristic as a result of changes in the chip

shrink. This can require additional devel-

opment time that some chipset manufac-

turers are increasingly reluctant to spend.”

AEL Crystals’ operations director

Shaun Mellors feels the technology within

FCPs is in a constant state of change, with

many factors affecting the device develop-

ment. “These include the usual push to

reduce package size and footprint, as well

as tighter specification requirements, ever

higher frequency demands, lower

power/voltage availability and pressure to

reduce cost and lead time.

“The ‘standard’ smd package for

higher technology applications has now

moved away from 7 x 5mm parts to 5 x

3.2mm devices. With packages now avail-

able in production volume at 4 x 2.5mm,

3 x 2.5mm and 2 x 2.5mm, the costs for

Size counts

How reduced component size avoids an attack of the jitters – if you catch my drift. By Mike Richardson.

I N T R A D E S I G NF R E Q U E N C Y C O N T R O L

45New E lec t ron ics www.newelec t ron ics . co .uk 27 Februar y 2007

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these smaller devices are starting to fall.”

Both crystal and oscillator devices are

experiencing tighter specification require-

ments and, whilst the ‘standard’ micro-

processor part is still in demand, there are

many silicon devices that require more

detailed specification FCPs for consistent

operation. Many silicon devices exhibit

low power start up, making esr and drive

level dependency (DLD) specifications

much more critical. In addition, the

increase in RF applications requires

tighter stability, aging and pulling require-

ments to be designed into the FCPs.

Treble noted concerns in other FCOP

areas. “Devices are becoming more

sophisticated, but as you reduce product

size, components become more densely

packed. Suddenly, problems like noise

generation become an issue because you

can get crosstalk.”

“For oscillator products in particular,

phase noise, power consumption and

overall stability budgets are often much

tighter,” continued Mellors. “There is an

increasing requirement for more flexibil-

ity in the range of applications a device

can be used. Although many FCP appli-

cations are extremely cost sensitive, the

main problem is in using a part that sig-

nificantly overperforms for the require-

ments of the application because it has

been specified incorrectly.”

Hartmann notes that manufacturing a

crystal to a reduced footprint changes its

characteristics, leading to increased equiv-

alent series resistance and crystal imped-

ance. “It then becomes harder to achieve

a stable oscillation, so there is a certain

physical limit – unless you change your

manufacturing process significantly.”

Epson developed its QMEMS semi-

conductor like process for manufacturing

smaller crystal oscillators by etching the

crystal using a photolithographic process.

Clearly, technological advances

impact on the manufacturing techniques

required to meet customer expectations.

Advanced Crystal Technology and ACAL

Components’ quality assurance and tech-

nical manager Dave Mullins takes up the

story: “It is important to minimise the

changes in characteristics exhibited by

quartz due to the requirements of higher

assembly reflow temperatures necessary

for use of solder alloys that comply with

the RoHS legislation.”

Total Frequency Control sales and

marketing manager Craig Wells concurs:

“Lead free solder and RoHS compliant

components force the redesign of long

established parts. It can be very time con-

suming and expensive to source and

replace some inferior components.”

Precision Devices’ business develop-

ment manager Neil Floodgate offers a

commercial view: “Manufacturers are

being placed under increasing pressure to

reduce lead times and prices, whilst main-

taining a first class service and fully acces-

sible technical support,” he intoned.

“However, this is real ‘chicken and egg’

situation, as most manufacturers are

looking to reduce stocks of components

whilst trying to cut lead times.”

If it’s all about timing, what can we

expect to see between the tick and the

tock of advancing FCP technology?

“TCXO and VCTCXO parts continue

to push into market areas previously only

supported by OCXO parts and this trend

will continue with increased stability and

aging characteristics as well as higher fre-

quency availability,” stated Mellors.

Floodgate: “New developments will see

smaller packages becoming available at

higher frequencies and tighter tolerances.

We will also see higher reliability products

for avionics and space applications.” Wells

sees a growing requirement for more strin-

gent tolerances within applications that

supports a trend towards digital frequency

adjustment. “This technology can prove

invaluable to the customer by preventing

accidental adjustments of the frequency set

points,” he claimed.

“The demand for higher frequency

quartz devices like those used in satellite

communication applications is increas-

ing,” Hartmann observed. “Products like

surface acoustic wave filters and res-

onators are best suited for this high fre-

quency range. In addition, the

technology to design and form electrodes

is developing further for ongoing charac-

teristic improvements like narrower filter

bandwidth.”

Mullins suggests that smaller crystal

sizes are gaining acceptance in some space

sensitive applications and this will con-

tinue to grow – especially in the consumer

markets as demand for ultra small sized,

battery operated personal devices grows.

Treble concludes: “Where is the tech-

nology going longer term? The aim is to

try and reduce things to a single chip.

But the variations of frequency require-

ments are endless and whether we’ll actu-

ally achieve this remains to be seen.”

New E lec t ron ics www.newelec t ron ics . co .uk 27 Februar y 200746

“New developments will see smallerpackages becoming available at higherfrequencies and tighter tolerances.”Neil Floodgate, Precision Devices

I N T R A D E S I G NF R E Q U E N C Y C O N T R O L

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