Table of Contents
What is FPC in switch?
Flexible circuit options include polyester (PET) that uses silver ink as the circuit element, and flexible PCB (FPC) that uses copper as the conductive element. To understand the impact of using the two circuit designs, it is first necessary to analyze the construction of a typical membrane switch.
How does a membrane switch work?
In general, how a membrane switch works involves a continuous open circuit running through the bottom circuitry’s conductive inks. When pressed by an operator, the top circuit contacts and momentarily shorts the bottom open circuit. The short signals the desired action to the machine.
Can a membrane switch be repaired?
There is a repair kit for membrane switches. It comes with a pen using silver based paint. The problem with this repair is that it will fail again at some point. Replacing the membrane switches with push buttons is your other option.
How are flexible circuits made?
A flexible printed circuit consists of a metallic layer of traces, usually copper, bonded to a dielectric layer, usually polyimide. Often an adhesive is used to bond the metal to the substrate, but other types of bonding such as vapor deposition can be used to attach the metal.
What is FPC and PIC Juniper?
Flexible PIC Concentrators (FPCs) and Physical Interface Cards (PICs) function similarly to MICs and MPCs. PICs provide physical interfaces for the router and install into FPCs which provide packet forwarding services. Each FPC supports up to two Physical Interface Cards (PICs).
What is a network FPC?
The FPC is a component of the Packet Forwarding Engine. FPCs house the various PICs used in the router. The FPCs installed in the router depend on the platform and the PICs needed. Figure 1 shows the location and numbering of the FPCs in each router platform.
What is FPC material?
FPC stands for Flexible Printed Circuit, also known as flexible circuit boards or soft boards. It is a highly reliable flexible printed circuit made by polyimide or polyester film.
How is FPC made?
FPC is made of polyimide material and etched copper conductors. Single-sided flexible circuits have a single conductor layer made of either a metal or conductive (metal filled) polymer on a flexible dielectric film. Double-sided flex circuits are flex circuits having two conductor layers.
What is FPC in Juniper switch?
Why do I need an FPC circuit for my membrane switch?
If a 0.5mm pitch ZIF tail is a requirement on your membrane switch, PET circuits trace width is too large and can’t support ultra-fine pitch ZIF connections so an FPC circuit must be used. Most people are aware of how excellent copper is as a conductor of electricity.
What is the function of the circuit layer in a membrane switch?
The circuit layers primary responsibility is to carry the switches electrical signals and provides the most critical functionality of the membrane switch. Discrete components such as LEDs, resistors, capacitators and some ICs can be affixed directly to the circuit layer, depending on the circuit design.
What is the difference between FPC and FPC polyimide?
As expected the FPC polyimide version was able to be constructed with a considerably smaller trace width. Since the FPC polyimide version can be built with finer circuit trace widths, more traces are able to be fit within the membrane switch footprint.
What is the cost impact of a membrane switch?
A reasonable rule of thumb is that the smaller the membrane switch (in terms of surface area), the lesser the cost impact. Some recent examples to note: A 2 in2 membrane switch experienced a ~20-30\% cost increase between PET and FPC. A 25 in2 membrane switch experienced a ~200-250\% cost increase between PET and FPC.