Technical FAQs

Materials
Electrical specifications and lifetime
Actuation force and travel
LED
Unimec

 

Multimec switches and caps

 

Materials

Q: Are MEC components available RoHS compatible?
A: All switches and accessories from MEC are RoHS compatible today.

Q: What has been changed to make the switch RoHS compatible?
A: The terminal plating has been changed from SnPb10 to 100% Sn

Q: Why do you have blue and black switches?
A: The blue switch is made in low temperature material and can take an operating temperature at -40/+115C. The black switch is in high temperature material and can take an ambient operating temperature at -40/+160C.

Q: Do MEC switches and caps resist solvent ink?
A: The resistance depends on what kind of solvent ink and what type of caps and switches. The plastic material varies between the different switches and caps in our product range and therefore each behave differently towards solvents. Please contact MEC if specific information is needed.

Q: Do MEC switches and caps resist UV light?
A: All our switches and caps are resistant to UV light.

Q: Are Multimec switches dry nitrogen resistant?
A: The melting point of nitrogen is -210C. If the switches are directly exposed to the nitrogen they will not be able to resist this temperature. The working temperature of the Multimec is min -40C and max +115C for the low temperature version and min. -40C and max +160C for the high temperature version.

Q: Can the multimec 3F withstand methanol as cleaning solvent after soldering?
A: The MEC switches are made of quality plastic, however we do not guarantee for the future function of the switch by using organic solvents as a cleaning liquid. We only recommend demineralised water with the same temperature as the switch or slightly higher.

Q: What is meant by solid colour?
A: By solid colours we mean not transparent colours.

Q: What is the temperature range of caps?
A: The polycarbonate caps can be used in ambient temperature of -40/+85C.
The ABS caps - -40/+65C.
The PPS caps - -40/+160C.
Polyamide - -40/+160C.
See more information in the Technical Information area on the website or in the latest Product Catalogue.

Q: Do you have specifications about the lifetime of negative printing (number of operations)?
A: The lifetime of the negative print depends on the external environment in which it is going to operate (where the button is placed, what is it exposed to e.g. heat, dust, moist ect.). Also, it is important how the button is activated: Does the person who presses the button wear gloves; are his fingers dirty, is he using a pen or something to activate the switch? For your information, the print complies with the ISO class: 1/ASTM class: 4b

 

Electrical specifications and lifetime

Q: What is the electrical lifetime of the switches?
A: The electrical lifetime is 10 mill operations, provided that the electrical specifications are not exceeded. Product specifications can be found on MEC website or in the latest Product Catalogue.

Q: Under what operating conditions is this lifetime stated?
A: The 10.000.000 cycles are under the conditions shown in the technical specifications: 2.0N, 3.5N or 6.5N activation force depending on the switch, maximum 100N for 10 seconds. Load 0.5-50 mA and 24 VDC, ambient temperature -40C to +115C for low temperature material and +160C for high temperature material.

Q: Which of the 4 pins in the non-illuminated Multimec switch are the 2 pins that have the contact-function?

A: The pins are connected 2 by 2. This means that you can choose what 2 pins you want to make the connection with. Pin 1 is connected to pin 2, and pin 3 is connected to pin 4. The pin numbers can be found on the bottom of the actual switch.


Q: What are the minimum criteria for the Multimec switch regarding voltage and current?
A: The minimum current is 0.5mA for switches with silver terminals and 0.5 μA for switches with gold terminals. There are no min. limits for the voltage.

Q: What is the maximum current that can be interrupted on a Multimec switch?
A: The maximum current that can be interrupted on a Multimec switch under 24Vac is 50 mA.

Q: What happens if the switch is exposed to 32V and 100mA?
A: We have conducted a test where the Multimec was exposed to a constant current and voltage of 100mA and 50V. The initial contact resistance was 17 mΩ. After 2.5 mill operations the contact resistance went up to 85 mΩ.

Q: What is the thermal electromotive force (emf) for golden plated switches?
A: For gold plated switches we recommend the following min. values: 10mV and 0,5 mikroAmp above the contact point (meaning where the gold plated metal dome hits the gold plated contact point inside the switch).

Q: MEC specify the contact resistance on the switch to be <30 milli Ohm. Will this low contact resistance also be the case after long life test?
A: Yes if the maximum resistive load does not exceed 50mA/24VDC.

Q: What is the insulation resistance?
A: <10 Mohm (3 Kvolt 30 seconds).

Q: Due to our design we will have to load the switch 6mA at 24VDC, using silver contacts. Will that cause any problems with the functionality and lifetime?
A: 6 mA will work without any problems; the life time will not be affected.

Q: Is it possible to apply 80mA at 12VDC (instead of the 50mA at 24VDC stated in the catalogue)?
A: We have tested the Multimec up to 500 mA / 24 VDC. The lifetime will be reduced due to burnings in the contact points. The contact resistance ends up in 100mΩ.
Be aware that the load is pure resistive (ohms), so no inductive/capacitive load.


Actuation force and travel

Q: What is the MEC standard actuation force?
A: 3.5N for Multimec 3 series and 2.0N, 3.5N and 6.5N for Multimec 5 series.

Q: What are the minimum activations on the switch?
A: MEC guarantees minimum 10.000.000 cycles.

Q: Can MEC build other actuation force than the standard actuation forces?
A: We can provide switches with custom force from 2.0N up to 10N.

Q: Is there a possibility to have a higher operating force than the normal 3.5N (3 series) and 2.0N (5 series) for a quiet switch?
A: It will be possible to produce a quiet Multimec switch with an operation force higher than the normal 2.0N. Minimum order quantity is as standard 20K for this kind of special switches. Please consult MEC with your request.

Q: Can I have the switch with 1N actuation force?
A: If we reduce the operation force too much we risk it is the friction which takes control and not the metal dome. For this reason the lowest actuation force we can offer is 2N ±0,2N.

Q: What is the actuator travel distance?
A: We guarantee that the contact is established after 1 mm, however due to tolerances in the alloy for the metal dome it cannot be specified 100%. In practice the contact will be established before the 1 mm.

Q: Can contact be established before 1 mm travel?
A: Yes in practice the contact will be established before 1 mm travel, but MEC guarantee contact is established on 1 mm travel.

Q: What is the tolerance for the 1 mm travel?
A: The tolerance on the travel will be 1,1 mm ± 0,1 mm.

Q: If a mechanical stop is built on the switch, where on the travel distance should the stop be placed?
A: The mechanical stop shall be placed after 1 mm travel.

 

LED 

Q: What is the LED lifetime in 4F/5G?
A: In general 100,000 hours (10 years)

Q: What is the recommended current for LEDs? Are they same for green and red?
A: Please see the Technical Specifications for the recommended current for LEDs on the website or in the latest Product Catalogue.

Q: The red LED seems to be substantially brighter than others. Is this generally the case?
A: In general, the red, blue and white LEDs are the brightest.

Q: Is it possible for green and blue LEDs to have the same brightness?
A: Yes, it is possible to obtain the same brightness. For some customers we use a special green LED with higher light intensity than the standard green LED. Please contact MEC for more information.

Q: Will the luminous intensity decrease with time?
A: Yes, all LEDs will decrease with time.

Q: What is the killing/destroying current on standard 4F/5G red LED? And influence on life time?
A: The current we specify is the maximum current @ ambient temperature on 70C. On this current the lifetime is 100.000 hours.
The max pulse can be up to 100 mA at a duty cycle on D= tp/t ≈ 0,02 (tp is active time. t is active time + pause time).
No one specific “killing/destroying” power.

Q: What happens with standard 4F/5G red LED specifications if LED is pulsed?
A: The lifetime is 100.000 hours and will not be affected. But you can achieve a higher light Output if you decide to pulse LED. According to specifications is normal current forward 25mA for e.g. the RED chip LED, but forward peak current can be increased to 100mA if pulsed.

Q: Your switches are IP67, will the LED on 4 and 5 series switch still illuminate if water comes into the LED?
A: Our IP67 tests are done by demineralised water; by this the conductive is very low.
This test will not affect the illumination which use approx. 20mA and 2—3VDC.

 

UNIMEC 

Q: I need your recommendations on cleaning after soldering:
A: Most assembly and field problems experienced by users of unsealed switches are caused by the contamination of the contact during the 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 soldering bath or spray the switch during the cleaning. The switch must be protected at all times to prevent contamination by flux or cleaning fluid.
We recommend only using demineralised water as cleaning liquid; at a maximum temperature up to 50 degrease Celsius.
It is also important to ensure that the actuator on the switches is not activated during the soldering process.

Q: What changes can be made regarding travel and operating force?
A: On a Unimec switch it will not be possible to change either the travel distance or the operating force.



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MEC Switches A/S • Industriparken 23 • DK-2750 Ballerup • Denmark • Phone: +45 44 97 33 66 • E-mail: danmec@mec.dk