Membrane Switch Adhesive Layer Design
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Solution Overview
Problem
Existing membrane switches face issues with uneven adhesive, poor close adaptation, low defect-free rate, and poor waterproof and sealing performance due to challenges in screen printing and double-sided adhesive tape deformation, leading to instability and quality problems.
Innovation Solution
A membrane switch design featuring an upper membrane, a lower membrane, and an isolation layer with conductive dots and traces, where hot melt glue is applied to the surfaces of the isolation layer to bond the membranes, preventing defects like bubbles and bulges, and enhancing automation and product quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If screen printing with Self-adhesive sticker or double-sided adhesive tape is used for the middle pad layer, then the membrane switch can be manufactured with basic structure, but the adhesive becomes uneven, close adaptation is poor, and product defect-free rate is low
Solution Approach 1:
The patent extracts the adhesive function from the middle pad layer by introducing a separate adhesive layer below the lower circuit layer. This allows the middle pad layer to focus on electrical isolation while the dedicated adhesive layer provides uniform adhesion, resolving the contradiction between ease of manufacture and manufacturing precision.
Solution Approach 2:
The patent segments the adhesive function into a separate layer rather than combining it with the middle pad layer. This segmentation allows independent optimization of each layer's function, enabling uniform adhesive application without compromising the isolation performance of the middle pad layer.
2Ease of manufacture
If double-sided adhesive tape is used for bonding, then bonding can be achieved, but the tape is easily deformed after punching, wrinkles during bonding operation, and bonding is difficult
Solution Approach 1:
The patent extracts the adhesive material from the middle pad layer and places it in a separate adhesive layer. This allows the use of hot melt adhesive materials that are applied in liquid form and then cured, avoiding the deformation and wrinkling issues of pre-formed double-sided adhesive tapes during punching and bonding operations.
3Ease of manufacture
If screen printing or double-sided adhesive tape is used, then the membrane switch can be assembled, but waterproof and sealing performance is poor and oxidation and corrosion occur, leading to instability
Solution Approach 1:
The patent introduces a dedicated adhesive layer as an intermediary between the lower circuit layer and the lower membrane, creating a complete sealing structure. This adhesive layer fills gaps and provides continuous sealing, preventing water penetration and oxidation that would otherwise occur with traditional assembly methods.
4Ease of manufacture
If glue is printed on the UV pad layer to bond upper membrane to lower substrate, then bonding can be achieved, but glue is apt to print on conductive layers affecting contact between upper and lower conductive layers
Solution Approach 1:
The patent extracts the adhesive function from the UV pad layer and places it in a separate adhesive layer below the lower circuit layer. This spatial separation eliminates the risk of glue contamination on the conductive layers, ensuring reliable electrical contact while maintaining the bonding function.
Solution Approach 2:
The patent segments the bonding function into a separate adhesive layer, allowing the UV pad layer to focus solely on electrical isolation. This segmentation prevents the glue printing process from affecting the conductive layers, as the adhesive is applied to a different layer at a different location.
5Ease of manufacture
If glue printing is used for bonding, then layers can be bonded, but defects such as bubbles and hollows occur resulting in quality problems
Solution Approach 1:
The patent introduces a dedicated adhesive layer as an intermediary that provides uniform adhesive distribution. This separate adhesive layer acts as a buffer between the circuit layers and membranes, preventing direct contact that would cause bubbles and hollows, while ensuring complete wetting and bonding.
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
The solution effectively prevents defects caused by conventional printing, improves sealing performance, and simplifies the production process, reducing human costs and enhancing the membrane switch's reliability and durability.
Implementation Method 1
the glue being coated on the upper and/or lower surface is hot melt glue
Implementation Method 2
the isolation layer is bonded with the upper membrane and the lower membrane respectively via glue coated on the upper surface and the lower surface thereof
Data Source
AI summary
A membrane switch and a method of manufacturing the same, includes upper and lower membranes printed with upper and lower conductive dots and an isolation layer between them, holes being opened in the isolation layer corresponding to the dots, the isolation layer is bonded with the upper and lower membranes respectively via the glue coated on the upper surface and the lower surface thereof; and the glue may employ hot melt glue. This method of manufacturing the membrane switch includes a coating the upper surface and/or lower surface of the isolation layer exclusive of the positions of the holes with glue; bonding and adhering the sides of the upper membrane and the lower membrane printed with the conductive dots and respectively to the upper surface and the lower surface of the isolation layer via glue, making the positions of the conductive dots and the holes corresponding to each other.