How to get the best results with MEC switches
These guidelines are offered to users of MEC switches as an aid to ensure successful and reliable
Both Unimec and Multimec 3 series switches are produced in standard and high temperature versions. Multimec 5 series switches are available only in high temperature version.
Please see the technical specifications for details on operating and storage temperatures and soldering guidelines to make sure you select the best switch for your application. When wave soldering is taking place, mec strongly recommend that the temperature profile is analyzed and compared with the temperature rating of the switch. In case of doubt always select the high temperature versions 154XX and 3XXHX or Multimec 5 series. It is also important to monitor the accumulated heat build up from both the pre-heat zones and the solder zone.
Most standard accessories for both Unimec™ and Multimec switches are made from ABS plastic with a maximum operating temperature of 65°C. It is strongly recommended that accessories are mounted after soldering of the switch. If this is not possible care must be taken not to overheat the accessories during the soldering process. Varimec™ caps are, however, made of high temperature materials and will meet the same temperature specifications as the high temperature switches. For accessories made from other plastic materials please see Multimec and Unimec™ technical specifications.
LEDs have their own temperature specifications. When fitted in a high temperature switch the LED will determine the max. operating temperature, i.e. 5GTH922 has an upper temperature limit of 85°C - not 160°C! This also applies to the 3A, 3F and 4F switches.
Mounting and Dismounting
If switches are to be mounted in rows it is essential that the recommendations regarding spacing are followed.
PC board thickness should be 1.2 to 1.6mm and terminal hole diameter 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. The same applies to the 3E with Varimec caps. Once these caps are installed they are not designed to be removed. To do so may cause damage to the switch and the PC board if not done very carefully. 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 position. To correct the fault, the LED must be raised slightly and centered in the actuator to assure unrestricted movement of the actuator. A mounting tool is available for Multimec switches.
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 liquids.
For Unimec™ alternate versions we recommend to leave the actuator in the released upper position during soldering. This makes the switch less heat sensitive.
Soldering and Cleaning Multimec
Multimec switches are fully sealed to IP-67 specifications to prevent solder flux and aqueous based 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. Multimec offers a high level of sealing, however, with aqueous solvent solutions care must be taken to avoid the worst case situation with water jets, complete immersion into a liquid with a temperature below the board and surface tension reducing additives.
Recommended cleaning methods are demineralized water. Any surface tensions reducing agents, such as soap, must not be used as they risk causing a potential leakage of the switch.
Soldering - Through Hole Versions
Hand soldering: Max 350°C for max. 3 sec., this applies for both low temperature and high temperature 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 recommend the high temperature switches. In any case peak temperature must not exceed 260°C, and soldering time is max. 10 sec.
Soldering - Surface Mount Versions
For all methods - infrared, convection and vapour phase. The upper limit 260°C/30 sec. must be observed. The soldering temperature profile must have moderate temperature gradients ∆ T/t.
As of 1 July 2006 mec has completed the conversion to RoHS compliance. A separate part number system assures that there will not be any risk for mixing products in the supply chain.
General Temperature Limits:
Low Temperature 115°C
High Temperature 160°C
Unimec™ and Multimec switches are packed in rigid tubes of 50 pieces each. A box contains 1.000 pcs. The surface mount versions of Multimec switches with a height up to 12.5 mm can also be delivered on tape/reel. Each reel contains 250/500 pcs.