Quartz Crystal handling notes

Handling Notes for Quartz Crystals
Generally, quartz crystals are designed to be quite insensitive against environmental conditions,
nevertheless care should be taken during transportation, storing and production to avoid deteriorations of the crystal performance, or even destruction of the crystal component.
1. Storage conditions and moisture
A crystal is a hermetically sealed device, therefore no humidity gets inside the cavity of the
crystal package. As the handling conditions and the pre-production conditioning being defined in JEDEC J-STD-020 do only apply to non-hermetic devices, they basically do not apply to quartz crystal components.
Nevertheless, long storage of quartz crystals at hot and humid conditions should be
avoided. Therefore, we recommend to store our quartz crystals with tinned wires within the
conditions described as MSL level 2, to avoid slight oxidation of the component’s contact
SMD crystals with gold-plated contact pads are even less susceptible to pad oxidation, and
storage temperature and humidity conditions according to MSL level 1 may be applied.
During storage of the component, the storage conditions should never exceed the temperature limits as specified in the catalog or datasheets. Please note that the storage temperature range applies to the component only.
Preferably, please keep the storage temperature between +10° ~ +45°C (50°F ~ 115°F)
and below 60% RH as long as the component is packed and reeled.
If the components were stored over a long period or the storage conditions were not appropriate, before using please make sure that the crystal components still comply to their specifications by performing visual and electrical inspections.
2. Transportation and Handling
During transportation and during the manufacturing process, please avoid high shock and
vibration levels to the component, which are exceeding its maximum specifications. Severe
drops or being hit with a hard object could also cause damages to the component.
Crystals which have suffered from excessive shocks and vibrations may show partial or full
cracks of their internal crystal plate (crystal blank), or partial cracks of their cementing
points, which might lead to intermittent failures of the component.
3. Mounting
SMD components
Please make sure not to exceed the appropriate reflow conditions as recommended in the
component specification, such as the peak temperature, the maximum duration, the number of exposures, the rate of temperature change vs. time, etc.
Hand Soldering can be performed at a temperature of 350°C max. for 3 sec. max.
Soldering of the metallic package surface (for example for mechanical fixation) is not allowed.
Please avoid extreme deformations of the board. Deformations may result in a detachment of
the PCB contact pad, a detachment of the SMD crystal terminals or cracks in the solder joints.
Full attention is requested especially when splitting the board with the component already
mounted. Any deformation or bending of the board should be avoided.
Should an automatic mounting system be used, please select an equipment with minor shock
generation, and check for the intensity of the shock before use.
Pin type components
Please do not apply excessive soldering heat or soldering duration on crystal terminals.
Please refer to the recommended wave soldering conditions.
Hand Soldering can be performed at a temperature of 350°C max. for 3 sec. max.
Soldering of the metallic package surface (for example for mechanical fixation) is not allowed.
Do not apply excessive force to cut or bend leads. Doing so could crack the glass insulation
or resin seal and cause a leak, which deteriorates the crystal performance.
When bending crystal leads for SMD mount, please do not bend the pins directly at the
crystal package, which might cause a crack in the glass insulation at the body of the package. We recommend to use an appropriate bending tool to keep a safe distance between
the component body and the bending point.
4. Cleaning
AT-cut quartz crystals (not tuning fork crystals)
Ultrasonic cleaning should be avoided due to the risk of damage to the crystal blank.
If ultrasonic cleaning is used, there is a risk of generating mechanical resonances, which may
cause an intermittent or permanent damage of the crystal component. Please be aware that ultrasonic waves propagate over a board in a way which is not under control of the crystal
Therefore it is impossible for us to confirm each customer's mounting and cleaning conditions,
such as the mechanical resonance conditions of the board, the cleaner's type, the applied power, the time, the placement in the cleaning tank and so on. Consequently, we are unable to define general conditions for cleaning or guidelines to protect our component against damage.
If ultra-sonic waves are used during cleaning or manufacturing, please make sure to perform an appropriate inspection to make sure that the quartz crystal still meets its specification.
Moreover, if there is a change in cleaning conditions, board or placement of the component after
a redesign of the board, please be sure to perform the same inspection for confirmation.
Tuning Fork Crystals
It is strongly recommended not to apply ultrasonic waves during cleaning or manufacturing
to tuning fork crystals, as their resonance frequencies lie close to the ultrasonic frequencies
being typically used during ultrasonic cleaning or manufacturing. Tuning fork crystal blanks
might easily get partially or fully cracked by ultrasonic cleaning or welding.
Cleaning Solvents
It is recommended that aqueous cleaning methods such as demineralised water or high
pressure water cleaning is used in order to avoid physical damage caused by solvents.
Some aggressive solvents (such as those containing Chlorine), may cause an oxidation of
the metallic crystal packages or a discoloration on the component surface or marking. Do
not exceed a temperature of +50°C (120°F) during cleaning.
5. Packing Method (ESD)
Although quartz crystals are not ESD sensitive, we deliver our products in anti-static bags
for better protection in ESD compliant production environments. We use various ESD compliant packing methods such as anti-static tube, foam, tape and reel, ammo packing on our
products. We recommend opening packaging tubes or bags with care to avoid damage to
6. Operating Conditions
Operating temperature
All crystals should be operated within the temperature limits as specified in the catalog or
Drive level
All crystals should be operated within the maximum power as specified in the catalog or
datasheets. Excessive drive levels could affect the long-term frequency stability or even
destroy the crystal blank.
Side Note for Tuning Fork Crystals
Please note that tuning fork crystals have a max. drive level as low as 0.5µW ~ 1.0µW (depending on package size). Please make sure that appropriate driving circuits are used
which limit the drive level. In case of doubt, please contact the IC or circuit supplier. Please
be aware that if drive levels over ~ 2µW are applied to a tuning fork crystal, the frequency
may shift down and the internal crystal blank may be broken.
PCB layout
We recommend to layout crystal connections close to the chip or driver circuit inputs. Preferably avoid long traces, and signal traces which could interfere to the crystal clock signal.
In multilayer boards, avoid stray inductance and capacitance by leaving out inner traces in
the area of the crystal.
Please be aware that our pad layout suggestions are given for your reference. Please use
them as a design suggestion and apply your companies’ design rules. Pins that are identified as NC should remain unconnected.
Oscillation Safety Factor or Negative Resistance
Please refer to the appropriate documents which you can find on the technical section of
our homepage (www.jauch.de / www.jauchusa.com / www.jauch.co.uk / www.jauch.fr).
© Jauch Quartz GmbH
Ch. Buechler