mec
General Information
How to get the best results with MEC Switches
Usage Guidelines
These guidelines are offered to users of MEC switches as an aid to ensure
successful and reliable switch operation.
Temperature
Both UNIMEC and MULTIMEC switches are produced in standard and high
temperature materials. Please see the technical specifications for details on
operating and storage temperatures and soldering guidelines to make sure
you select the switch best suited to your application. When flow soldering,
MEC strongly recommend that the temperature profile is analysed and
compared with the temperature rating of the switch. In case of doubt always
select the high temperature version 3XXH9.
All accessories for both UNIMEC and MULTIMEC switches are made from
ABS plastic with a maximum operating temperature of 65擄C. Care must
be taken not to overheat the accessories during the soldering process. In
soldering processes exposing the switch to high temperatures it is strongly
recommended that accessories are mounted after soldering.
LED鈥檚 have their own temperature specifications. When fitted in a high
temperature switch the LED will determine the max. operating temperature,
i.e. 3FTH922 has an upper temperature limit of 85擄C - not 160擄C!
When infrared reflow soldering is used, it is very important to monitor the
surface temperature of the switch during the pre-heat stage to prevent
excessive heat buildup and overheating during soldering.
Mounting
If switches are to be mounted in rows it is critical that the recommendations
regarding spacing are followed. PC board thickness should be 1.2 to 1.6mm
and terminal hole diameters should be 0.9mm.
All UNIMEC and MULTIMEC caps and bezels are easily snapped onto the
switch modules and can be changed at a later time with the exception of
the UNIMEC 16.700 cap. Once this cap is installed it is not designed to be
removed. To do so may cause damage to the switch and the PC board if
not done with extreme care. If the 16.300 or 16.700 cap must be removed
from an alternate action switch, make sure that the switch actuator is in the
released, upper position before attempting to remove the cap. This will
prevent possible damage to the internal latching pin.
Care must be taken when inserting the 3FT switch and LED assembly into
the PC board. Do not press direct on the LED. This will force the LED down
into the actuator and cause the switch contacts to remain in the closed posi-
tion. To correct the fault, the LED must be raised slightly and centered in the
actuator to assure unrestricted movement of the actuator.
Soldering and Cleaning UNIMEC
Most assembly and field problems experienced by users of unsealed
switches are caused by the contamination of the contacts during soldering
and cleaning. Contact contamination may be recognized by an increase in
contact resistance and possible intermittent operation of the switch,
especially in low power applications. Care must be taken not to submerge
the switch in the solder bath or spray the switch during cleaning. The switch
must be protected at all times to prevent contamination by flux or cleaning
fluids.
Soldering and Cleaning MULTIMEC
MULTIMEC switches are fully sealed to IP-67M specifications to prevent
solder flux and aqueous or solvent cleaning solutions from entering the
switch and contaminating the contacts. The switches can be placed on the
PC board with other components and wave soldered. No special handling of
MULTIMEC switches is required, but notice the guidelines mentioned under
鈥渢emperature鈥?
Soldering Multimec
Through hole versions
Hand soldering: Max 350擄C for max. 3 s., this applies for both low tempera-
ture and high temp. versions.
Wave soldering: Heat built up in the switch during pre-heating and soldering
must not exceed the maximum operating temperature of the switch. If, for
some reason, a high pre-heating temperature is required, Mec strongly re-
commend using high temperature switches. In any cases peak temperature
must not exceed 260擄C, and soldering time is max. 10 s.
Surface Mount versions
For all methods - Infrared, convection and vapour phase - the upper limit
260擄C/30 s. must be observed. The soldering temperature profile must have
moderate temperature gradients T/t.
General Temperature limitations
Low temperature
65擄C
High temperature
160擄C
LED鈥檚
85/100擄C
Accessories
65擄C
Mec recommend that accessories are mounted after soldering, unless the
process allows the heat exposure to be kept within the limits of 65擄C.
Combinations of high temperature switches with LED鈥檚 will be limited by the
temperature capability of the LED.
Packaging
UNIMEC and MULTIMEC switches are packed in rigid tubes of 50 pieces
each.
How to Assemble
Examples
unimec
15___ + 16300 + 16310
unimec
15___ + 16270 + 16300 + 16324
multimec
廬
3AT + 1A/H + 2A/B
multimec
廬
3AT + 1B/C + 2A/B
MEC
路 Industriparken 23 路 P.O. BOX 26 路 DK-2750 Ballerup 路 Denmark
Tel.: +45 44 97 33 66 路 Fax: +45 44 68 15 14 路 Web: http://www.mec.dk 路 E-mail: danmec@vip.cybercity.dk
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