14
04.18
D
Solder Paste
To achieve reliable soldering results one of
the following solder alloys have from case
to case proven being workable:
Lead free solder paste
Sn - Bi
Sn - Zn (Bi)
Sn - Ag - Cu (suitable for SMD-PET 5040/
6054, SMD-PEN and SMD-PPS)
Solder paste with lead
Sn - Pb - Ag (Sn60-Pb40-A, Sn63-Pb37-A)
Washing
WIMA SMD components with plastic
encapsulation - like all other components
of similar construction irrespective of the
make - cannot be regarded as herme-
tically sealed. Due to today’s common
washing substances, e. g. on aqueous
basis instead of the formerly used halo-
genated hydrocarbons, with enhanced
washing efficiency it became obvious that
assembled SMD capacitors may show an
impermissibly high deviation of the electri-
cal parameters after a corresponding
washing process. Hence it is recommended
to refrain from applying industrial washing
processes for WIMA SMD capacitors in
order to avoid possible damages.
Initial Operation/Calibration
Due to the stress which the components
are subjected to during processing, reversi-
ble parameter changes occur in almost all
electronic components. The capacitance
recovery accuracy to be expected with
careful processing is within a scope
of
DC/C 5 %.
For the initial operation of the device a
minimum storage time of
t 24 hours
is to be taken into account. With cali-
brated devices or when the application
is largely dependent on capacitance it is
advisable to prolong the storage time to
t 10 days
In this way ageing effects of the capacitor
structure can be anticipated. Parameter
changes due to processing are not to be
expected after this period of time
Humidity Protection Bags
Taped WIMA SMD capacitors are shipped
in humidity protection bags according to
JEDEC standard (ESD/EMI-shield/water-
vapour proof).
Under controlled conditions the compo-
nents can be stored two years and more
in the originally sealed bag. Opened
packing units should immediately be used
up for processing. If storage is necessary
the opened packing units should be stored
air-tight in the original plastic bag.
Reliability
Taking account of the manufacturer‘s
guidelines and compatible processing,
the WIMA SMD stand out for the same
high quality and reliability as the
analogous through-hole WIMA series. The
technology of metallized film capacitors
used e.g. in WIMA SMD-PET achieves
the best values for all fields of application.
The expected value is about:
Û0 2 fit
Furthermore the production of all WIMA
components is subject to the regulations
laid down by ISO 9001:2008 as well
as the guidelines for component specifi-
cations set out by IEC quality assessment
system (IECQ) for electronic components.
Electrical Characteristics and
Fields of Application
Basically the WIMA SMD series have the
same electrical characteristics as the ana-
logous through-hole WIMA capacitors.
Compared to ceramic or tantalum
dielectrics WIMA SMD capacitors have a
number of other outstanding qualities:
” favourable pulse rise time
” low ESR
” low dielectric absorption
” available in high voltage series
” large capacitance spectrum
” stand up to high mechanical
stress
” good long-term stability
As regards technical performance as well
as quality and reliability, the WIMA
SMD series offer the possibility to cover
nearly all applications of conventionally
through-hole film capacitors with SMD
components. Furthermore, the WIMA SMD
series can now be used for all the deman-
ding capacitor applications for which, in
the past, the use of through-hole compo-
nents was mandatory:
” measuring techniques
” oscillator circuits
” differentiating and integrating
circuits
” A/D or D/A transformers
” sample and hold circuits
” automotive electronics
With the WIMA SMD programme avai-
lable today, the major part of all plastic
film capacitors can be replaced by WIMA
SMD components. The field of application
ranges from standard coupling capacitors
to use in switch-mode power supplies as
filter or charging capacitors with high vol-
tage and capacitance values, as well as
in telecommunications e.g. the well-known
telephone capacitor 1mF/250VDC.
Recommendation for Processing
and Application of SMD Capacitors
(Continuation)