AN-1001 - Cymbet Corporation

Application Note
Handling & Soldering of Cymbet™ EnerChip™ Batteries
Cymbet™ EnerChip™ thin film, solid state batteries feature
all solid state construction, are packaged in standard integrated circuit packages, and can be reflow soldered for high
volume PCB assembly. They are ideal as rechargeable backup
power sources for clocks, memories, microcontrollers and
other low-power circuits where data or timing information
must be retained in the absence of primary power.
• The maximum number of times the battery may be reflow
soldered is three times.
• The surface temperature of the battery must not exceed 260°C.
• The recommended solder reflow profile is shown in Figure 1
below; refer to Table I for time and temperature requirements.
This document provides general handling guidelines and precautions for the batteries. These include device handling and
storage, protection against electrostatic discharge (ESD),
reflow solder, and in-circuit use.
Device Handling & Storage
• EnerChip batteries are packaged and shipped in moisture
barrier bags, and are sensitive to moisture absorption. They
must be kept in the sealed bag until ready for board mounting
and reflow soldering.
• If the batteries are removed from the sealed bag more than 12
hours prior to board mounting, they must be baked at 125°C
for a minimum of 24 hours prior to board mounting and
reflow soldering.
• Store the batteries in an environment where the temperature
and humidity do not undergo large fluctuations. Store at 10°C
to 30°C and at less than 60% relative humidity.
Electrostatic Discharge (ESD)
• Similar to integrated circuits, the batteries are sensitive to
ESD damage prior to receiving a charge cycle. Therefore,
adherence to ESD prevention guidelines is required.
• Remove devices from protective shipping and storage containers at approved ESD workstations only.
• All equipment used to process the devices must be configured
to minimize the generation of static charges. This includes
soldering and de-soldering equipment and tools, pick-andplace equipment, test equipment, and all other tools and
equipment used to handle or process the devices.
• Failure to observe these precautions can lead to premature
failure and shall void product warranty.
Figure 1. Recommended solder reflow profile.
Max ramp-up rate
Soak temperature, min, TSMIN
Soak temperature, max, TSMAX
Soak time, max, TS
Liquid temperature, TL
Max time above TL
Max peak temperature, TP
2 min
150 sec
3 min
150 sec
Max time at peak, TP
30 sec
30 sec
Max ramp-down rate
Table 1. Solder reflow parameters.
In-circuit Use Guidelines
• Do not connect these batteries to other types of batteries
except through an approved charging circuit.
• To increase battery life, avoid installing near heat generating
PCB Layout & Board Contamination
• Electrical resistance of solder flux residue can be low enough
to discharge the cell at a much higher rate than in the normal
backup mode. Therefore, solder flux must be thoroughly
washed from the board following soldering
© Cymbet Corporation • 18326 Joplin Street, Elk River, MN 55330 • 763-633-1780 •
DOC-111001 RevA
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• The PCB layout can make this problem worse if the cell’s
positive and negative terminals are routed near each other and
under the package, where it is difficult to wash the flux residue
• In the example in Figure 2, the negative connection is routed
from the negative pad to a via placed under the package near
the positive pad. In this scenario, solder flux residue can wick
from the positive solder pad, covering both the positive pad
and the via, resulting in a high resistance current path. This
current path will make the cell appear to be defective or make
the application circuit appear to be drawing too much current.
• Make sure positive and negative traces are routed outside of
the package footprint to ensure that flux residue will not cause
a discharge path between the positive and negative pads.
Figure 2. PCB traces resulting in a low resistance leakage path.
© Cymbet Corporation • 18326 Joplin Street, Elk River, MN 55330 • 763-633-1780 •
DOC-111001 RevA
Page 2