Syfer Technology Ltd. SFJE Issue 2 (P108893) Release Date 04/03/14 Page 4 of 4
Resin filled screw mounted EMI filters
General
The ceramic capacitor, which is the heart of the filter, can be
damaged by thermal and mechanical shock, as well as by
over-voltage. Care should be taken to minimise the risk of
stress when mounting the filter to a panel and when soldering
wire to the filter terminations.
Mounting to chassis
Mounting torque
It is important to mount the filter to the bulkhead or panel
using the recommended mounting torque, otherwise damage
may be caused to the capacitor due to distortion of the case.
When a threaded hole is to be utilised, the maximum mounting
torque should be 50% of the specified figure which relates to
unthreaded holes. For details of torque figures for each filter
range, please see below.
Tools
Hexagonal devices should be assembled using a suitable
socket. Round bodied filters may be fitted to the panel in one
of two ways (and should not be fitted using pliers or other
similar tools which may damage them):
Round bodies with slotted tops are designed to be screwed
in using a simple purpose-designed tool.
Round bodies without slotted tops are intended to be
inserted into slotted holes and retained with a nut.
Grounding
To ensure the proper operation of the filters, the filter body
should be adequately grounded to the panel to allow an
effective path for the interference. The use of locking
adhesives is not recommended, but if used should be applied
after the filter has been fitted.
Minimum plate thickness
Users should be aware that the majority of these filters have
an undercut between the thread and the mounting flange of
the body, equal to 1.5 x the pitch of the thread. Mounting into
a panel thinner than this undercut length may result in
problems with thread mating and filter position. It is
recommended that a panel thicker than this undercut length be
used wherever possible.
Maximum plate thickness
This is specified for each filter in order that the nut can be fully
engaged even when using a washer.
Soldering to axial wire leads
Soldering temperature
The tip temperature of the iron should not exceed 300°C.
Dwell time
Dwell time should be 3-5 seconds maximum to minimise the
risk of cracking the capacitor due to thermal shock.
Heat sink
Where possible, a heat sink should be used between the solder
joint and the body, especially if longer dwell times are
required.
Bending or cropping of wire leads
Bending or cropping of the filter terminations should not be
carried out within 4mm (0.157”) of the epoxy encapsulation,
the wire should be supported when cropping.
RoHS compliance
All surface mount filters, resin sealed panel mount filters and
power filters are fully RoHS compliant through material
exemption, although care must be taken not to exceed the
maximum soldering temperatures of surface mount parts.
Standard hermetic sealed panel mount filters use SnPb solders
as part of their assembly, and are intended for exempt
applications such as aerospace or military. Substitution of the
SnPb solder with Pb free solders is possible to create a RoHS
compliant part – please contact factory for further details.
