Stiffeners

What is stiffener?

Stiffener is certain of material that adds to flex circuit board in order to rigidize or structurally support discrete area of the flex circuit. Many flex circuit designs require selectively bonded stiffeners because they are too flexible to achieve some functions.

Material of stiffener

The most common material used for stiffeners in flex PCB designs is FR4 and Polyimide with thicknesses varying from 0.020”, 0.031”, 0.039” to 0.059”
In some flexible circuit designs, alternate materials, such as stainless steel or aluminum are available. These are typically used for applications requiring heat sinking or added rigidity but will significantly increase the cost of the parts and should only be used when required.

Why add stiffener?

When you need a rigid area in your flex circuit, to protect components or connectors that are attached there, you can add a stiffener. This will stop the circuit from bending and protect the integrity of the part’s solder joint.
That is to say the PCB stiffener is not an integrated part of the electrical circuit board design — it exists to offer mechanical support. A stiffener is called for when you need:
Greater thickness in your flex circuit in certain areas
To constrain bend areas to specific predefined locations
To meet ZIF connector specifications
To strengthen specific areas of the board
To support other components or connectors

Methods to add stiffener

Usually we use below two methods to add stiffener to boards:
1, We use laser cutting when stiffener thickness is 0.1 to 0.3mm.  the min stiffener size we can do for laser cutting is 1mm*1mm.
2, We use milling cutter to cut first and then paste it to board when stiffener thickness exceed 0.3mm.   The min stiffener size we can do for milling cutter is 5mm*5mm.

Goldphoenixpcb can make more complicated stiffener designs such as serpentines, pillars, thin channels etc. it depends on your design and requirement. Pls create an separately layer to show the stiffener positions, material and thickness etc.