Foldable Device FPCB Segmentation and Bending Guide
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Solution Overview
Problem
Foldable electronic devices face challenges in maintaining the RF characteristics of signals due to the deterioration of flexible circuit boards when repeatedly folded and unfolded, leading to potential damage and reduced service life.
Innovation Solution
The implementation of a foldable electronic device design that includes a flexible display, rigid printed circuit boards, and flexible printed circuit boards with rigid portions affixed to the hinge structure, along with a bending-guide member to maintain the shape of the flexible portions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If flexible circuit boards are used in foldable electronic devices to enable folding functionality, then the device can be folded and unfolded, but the flexible circuit boards deteriorate after repeated folding causing damage and reduced service life
Solution Approach 1:
The flexible circuit board is divided into multiple rigid portions and flexible portions, where rigid portions are fixed to housing structures and flexible portions are positioned in the hinge structure. This segmentation allows different parts to serve different functions - rigid parts provide stability while flexible parts accommodate folding motion, resolving the contradiction between folding capability and reliability.
Solution Approach 2:
Different portions of the flexible circuit board have different physical properties - rigid portions are fixed to provide stable electrical connections, while flexible portions are positioned in the hinge structure to accommodate folding. This local differentiation of properties allows the circuit board to maintain reliability while enabling folding functionality.
2Reliability
If flexible circuit boards are used to connect circuit boards in foldable devices, then electrical connection can be maintained during folding, but RF characteristics of signals deteriorate due to high frequency characteristics
Solution Approach 1:
The flexible circuit board is segmented into rigid and flexible portions, with rigid portions fixed to housing structures to provide stable reference planes for RF signals, and flexible portions positioned in the hinge structure to accommodate folding motion. This segmentation maintains RF characteristics while enabling folding functionality.
3Adaptability or versatility
If the flexible portion of the FPCB is allowed to move freely in the hinge structure, then the device can be folded, but the shape of the flexible portion changes causing damage and reduced service life
Solution Approach 1:
A bending-guide member is introduced as an intermediary component between the flexible circuit board and the hinge structure. This bending-guide member guides the flexible portion along a predetermined bending path, maintaining its shape during folding while still allowing folding motion. This resolves the contradiction between folding adaptability and shape stability.
4Reliability
If rigid portions are affixed to the hinge structure, then the flexible circuit board maintains electrical connection during folding, but the device complexity increases
Solution Approach 1:
The flexible circuit board is segmented into rigid and flexible portions, with rigid portions affixed to housing structures to provide stable electrical connections and flexible portions positioned in the hinge structure to accommodate folding motion. This segmentation maintains electrical connection reliability while managing structural complexity through functional differentiation.
Data Source
AI summary
A foldable electronic device is provided. The foldable electronic device includes a foldable housing including a first housing portion, a second housing portion, and a hinge structure connected with the first housing portion and the second housing portion, the foldable housing configured to be folded about a folding axis; a flexible display accommodated in the first housing portion and the second housing portion; a plurality of rigid printed circuit boards (RPCBs) including a first RPCB accommodated in the first housing portion and a second RPCB accommodated in the second housing portion; a first flexible printed circuit board (FPCB) configured to electronically connect with the first RPCB and the second RPCB, the first FPCB including a first flexible portion located through a designated area of the hinge structure, the first FPCB including a first rigid portion and a second rigid portion affixed to a part of the hinge structure; a second FPCB configured to electronically connect with the first RPCB and the second RPCB, the second FPCB including a second flexible portion located through the designated area of the hinge structure, the second FPCB including a third rigid portion and a fourth rigid portion affixed to a part of the hinge structure, wherein the second flexible portion of the second FPCB is spaced apart and substantially parallel from the first flexible portion of the first FPCB; and a bending-guide member attached to the first FPCB between the first rigid portion and the second rigid portion, and attached to the second FPCB between the third rigid portion and the fourth rigid portion such that the first flexible portion and the second flexible portion are held together.