Technologically, a distinction exists here between symmetric and asymmetric designs, where as the asymmetric solution is more cost-effective.
Rigid-flex printed circuit boards
The advantages of asymmetrical Rigid-Flex printed circuit boards:
- Reliable connection between flexible and rigid areas
- High dynamic and mechanical strength
- Cost savings in the assembly and installation
- No hand soldering since connectors and cables are omitted
- Simple layout design
- Reduced weight
In the rigid area all standard FR4 materials (TG135, TG150, TG180) can be used. In the flexible area single or double sided Polyimide films are preferably used.
The Flex materials differ by the Polyimide thickness, the adhesive systems and the copper thickness.
The copper thicknesses are to be distinguished between either ED or RA copper.
The advantages of symmetric rigid-flex circuit boards are equal to the asymmetric but with additional:
- Increased flatness
- Greater flexibility and resilience
- Higher number of layers in the flex area
Flexible base material
- Polyimide with acrylic adhesive for dynamic applications
- Polyimide with epoxy resin for static applications
- Polyimide without adhesive for high dynamic applications
- 15 μ, 25 μ, 50 μ and 75 μ plus. Adhesive and copper thickness (Total)
Composite adhesive layer
- -20 μ per side
Copper thickness, single and double sided in 12 μ, 18 μ, 35 μ, 70 μ
- ED copper for static applications with limited bending
- RA copper for dynamic applications
- Acrylic adhesive system
- Epoxy Resin system
- NoFlow prepregs
Protective films and coatings
- -Coverlays acrylic
- Coverlays of epoxy
- Photoimageable flexible solder mask