Composite Button Membrane Assembly for Watertight Housing Sealing
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Solution Overview
Problem
The challenge lies in cost-effectively and reliably molding a button membrane onto complex or inaccessible housing geometries, particularly due to suboptimal adhesion compatibility between elastomeric materials and hard plastics used in conventional button assemblies.
Innovation Solution
A method involving the preformation of a composite button component with an elastically flexible membrane mounted on a rigid frame, followed by molding the housing over the button insert, which includes a co-molding operation to create a watertight connection and integrate the button frame with the housing, using a hard island or cap platform for resilient deformation and user interaction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an elastomeric button membrane is directly molded onto a hard plastic housing, then sealing closure is achieved, but adhesion compatibility is suboptimal
Solution Approach 1:
The patent employs a composite material structure where an elastomeric button membrane is bonded to a rigid frame made of hard plastic. This composite construction allows the elastomer to provide sealing and resilient return while the rigid frame provides structural support and geometric definition. The frame acts as an intermediary that improves adhesion compatibility between the elastomer and the housing, resolving the contradiction between achieving reliable sealing and maintaining ease of manufacture.
2Reliability
If conventional direct molding of button membrane onto housing is used, then sealing is achieved, but manufacturing complexity increases for complex geometries
Solution Approach 1:
The button assembly is segmented into distinct components: an elastomeric membrane, a rigid frame, and a housing. The rigid frame is pre-formed with the complex geometry required for sealing engagement, separate from the housing. This segmentation allows the complex geometric features to be molded into the rigid frame independently, then the elastomer is bonded to the frame, and finally the assembly is integrated with the housing. This approach reduces molding complexity compared to directly molding the elastomer onto complex housing geometries.
Solution Approach 2:
The rigid frame is pre-formed with the complex sealing geometries before the elastomer is attached. This preliminary action allows the complex features to be created in a controlled manufacturing process for the rigid frame, rather than attempting to mold the elastomer directly onto complex housing surfaces. The pre-formed frame serves as a template that simplifies subsequent assembly steps.
3Stability of the object's composition
If elastomeric material is used for button membrane, then resilient return is achieved, but adhesion compatibility with hard plastics deteriorates
Solution Approach 1:
The rigid frame serves as an intermediary component between the elastomeric membrane and the hard plastic housing. The elastomer is bonded to the rigid frame, and the frame is integrated with the housing. This intermediary structure allows the elastomer to maintain its resilient properties without requiring direct adhesion to the housing, thereby resolving the adhesion compatibility issue while preserving the elastomer's ability to provide resilient return.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach enhances adhesion compatibility, ensures a watertight seal, improves manufacturing ease, and allows for a wider range of material selection, while minimizing the assembly's size and simplifying mold tooling, thus overcoming the limitations of direct elastomer molding on enclosures.
Implementation Method 1
resilient return of the push button subsequent to pressing is effected by a resilient membrane or elastomer gasket that is deformed when the button is pressed
Data Source
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AI summary
A method of manufacturing a button-enabled housing assembly (200) includes preforming a composite button component or insert (645) having an elastically flexible button membrane (404) that is mounted on a rigid frame (303), and thereafter molding a housing (206) over the button insert. The composite button insert is formed in a co- molding operation and can include a rigid island (423) in the flexible button membrane for supporting a cosmetic keycap (251).