Top 7 Tips for High Quality Membrane Switches
1. Don't Risk It!
Membrane switches are one product where getting the cheapest price may be false economy and this can have disastrous implications for your product reputation, product liability and servicing costs.
The price is a function of the following:
- Tooling investment
- Materials used
- Manufacturing techniques used
2. Beware cheap materials
When you actuate a switch you flex the material. The appropriate materials used for membrane overlays are designed to withstand millions of actuations without damage. Initially it is difficult to tell a specialty switch material from a substitute that is one fifth the cost. However in a very short period of time these cheap materials can result in cracked and broken switches that may cause your switch to fail, not to mention the switch appearance.
3. Avoid short circuits from silver migration
Membrane switch inks are made by suspending silver inks in a carrier. Silver tracks have a natural tendency to grow conductive dendrites, which migrate towards the opposing pole of the switch. The result is a low level short circuit and intermittent performance issues.
This risk is overcome through careful design and material selection and a process that does involved additional prints and their associated cost. If your product operates exclusively in a dry and low humidity environment the risks are reduced. Conversely the risk of silver migration is dramatically increased by some common electrical and environmental conditions.
4. Avoid Crossovers
Crossovers occur when a circuit must cross over the top of another circuit. The risk is a short circuit between these tracks. As this can occur over time the switch may pass initial quality testing but fail in the field. Again the solution is in good design and additional processes to counteract this issue.
5. Make sure it sticks
The cheapest way of applying adhesive is to print it. This is fine for many applications and very cost effective. The issue is that the deposit is not thick enough for many situations and environments.
6. Consider the Mounting design
Membrane switches need to be mounted on a fixed surface. In many situations we have seen failure that is due to the inadequate consideration of the mounting surface and the adhesive used to attach the mounting. We often see where rivets and studs have been fixed into the mounting surface below where the domes are located. This will cause premature failure.
7. Use experienced designers
The design of tracks, tolerances and construction layers within the switch impacts heavily on the risk of Electrostatic discharge (ESD), inverting domes, ingression of water and dust into the switch. This knowledge can only come with a high level of technical and manufacturing experience. Anyone can cut corners to get you a product at a price. Not everyone can design you a product that will meet your lifecycle , performance and quality expectations.
When you work with MG Electronic you get the benefit of over 17 years of leading edge technical experience. We are at the forefront of membrane switch technology through our participation in the ASTM committee, the international body responsible for ongoing research to understand and develop testing standards for membrane switches, globally.
If you receive a cheaper price elsewhere you need to ensure that you are comparing like products, where cheap substitutes do not end up costing you more later down the track.
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