Membrane Switch Contact Pad Segmentation for Reliable Connection
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Solution Overview
Problem
Membrane switch devices experience poor electrical connections due to stress-induced detachment of metal patterns from connecting ends and the formation of air gaps between covering layers and connecting terminals, leading to signal failures or incorrect signal transmission.
Innovation Solution
The membrane switch device design includes a first and second membrane layer with conductive wires forming contact pads, a spacing layer, and a flexible printed circuit board with protection layers that are not overlapped with the contact pads, ensuring proper electrical connections and reducing the overall thickness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the metal pattern and the upper covering layer are partially overlapped to form a step structure, then the connection between the flexible printed circuit board and the membrane switch is established, but the stress generated on the covering layer causes the metal pattern to detach from the connecting end, forming air gaps and poor electrical connection
Solution Approach 1:
The patent divides the outlet area into a wire area and a no-wire area, and divides the covering layer into corresponding covering areas and non-covering areas. The metal pattern is positioned only in the wire area where it contacts the connecting terminal, while the covering layer is positioned only in the covering area that does not overlap with the metal pattern. This segmentation eliminates the step structure and prevents stress-induced detachment, ensuring reliable electrical connection.
2Reliability
If the membrane switch device uses traditional overlapping structure with steps, then the components can be connected, but the overall thickness of the device increases
Solution Approach 1:
The patent transitions from a three-dimensional stepped structure to a two-dimensional planar structure by positioning the metal pattern and covering layer in different spatial zones on the same plane. The wire area contains the metal pattern while the covering area contains the covering layer, with both areas adjacent to each other rather than overlapping vertically. This dimensional rearrangement eliminates the need for steps and reduces device thickness while maintaining connection reliability.
Data Source
AI summary
A membrane switch device includes first and second membrane layers, a spacing layer between the membrane layers, and a flexible printed circuit board. The first membrane layer includes a first surface and first conductive wires on the first surface and extending to a first wire area to form first contact pads. The second membrane layer includes a second surface and second conductive wires on the second surface and extending to a second wire area to form second contact pads. A wire-connecting end of the flexible printed circuit board is between the first membrane layer and the second membrane layer. A first protection layer of the flexible printed circuit board and the first contact pads are not overlapped with each other, and a second protection layer of the flexible printed circuit board and the second contact pads are not overlapped with each other.