Waterproof Keyboard Sealing Layer Adhesive Bonding
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Solution Overview
Problem
Conventional waterproof keyboards experience distortion due to different thermal expansion coefficients of materials used for the bottom board and sealing layer, leading to incomplete bonding and potential liquid leakage to the motherboard, causing damage.
Innovation Solution
The use of adhesives formed by a printing technique on the sealing layer, corresponding to the apertures on the bottom board, ensures a firmer union between the sealing layer and the bottom board, preventing distortion and liquid leakage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the sealing layer and bottom board are made of different materials to achieve waterproofing and structural strength, then waterproof performance and structural integrity are improved, but thermal expansion distortion occurs during heating process causing incomplete bonding
Solution Approach 1:
The patent changes the bonding parameters by using a two-stage heating process: first heating to melt the adhesive for initial bonding, then heating again to melt the sealing layer material for complete sealing. This parameter change resolves the thermal expansion distortion issue by controlling the sequence and temperature of different materials during the heating process.
Solution Approach 2:
The patent employs composite materials structure where the sealing layer is made of thermoplastic material that can be melted and re-bonded, combined with the bottom board made of different material having different thermal expansion coefficient. This composite approach allows each material to contribute its advantages while the controlled heating process compensates for the thermal expansion differences.
2Strength
If adhesive is applied to bond the sealing layer and bottom board, then bonding strength is improved, but adhesive may not cover the entire bonding area uniformly leading to potential leakage paths
Solution Approach 1:
The patent applies adhesive specifically at the peripheral portion of the bonding area rather than uniformly across the entire surface. This local quality approach concentrates the adhesive where it is most needed for structural bonding while the thermoplastic sealing layer material provides the uniform sealing across the entire surface when melted during heating.
3Reliability
If the keyboard is heated to solidify the adhesive, then bonding is achieved, but thermal expansion causes distortion and creates clefts between the sealing layer and bottom board
Solution Approach 1:
The patent performs preliminary bonding action first by heating to melt the adhesive and bond the sealing layer to the bottom board. Then a second heating action is applied to melt the thermoplastic sealing layer material for complete sealing. This preliminary action sequence allows the structure to set before final sealing, reducing distortion.
Solution Approach 2:
The patent changes the heating parameters by applying heat in two distinct stages with different temperature profiles and durations. The first heating stage is optimized for adhesive bonding, while the second stage is optimized for melting the sealing layer material. This parameter change resolves the thermal expansion distortion by controlling when and how strongly each material is heated.
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 solution effectively prevents liquid from reaching the motherboard, ensuring normal operation by ensuring a complete and secure bond between the sealing layer and the bottom board, overcoming the issue of thermal expansion-induced distortion.
Implementation Method 1
an adhesive layer formed of a thermosetting adhesive or a thermoplastic adhesive disposed between the bottom board and the sealing layer
Implementation Method 2
The keyboard 30, to which the sealing layer 38 adheres, then needs to go through a heating process so that the glue is solidified to unite the sealing layer 38 and the bottom board 35
Implementation Method 3
Since the substances of the sealing layer 38 and of the bottom board 35 have different thermal expansion coefficients, distortion resulting from thermal expansion may occur after the heating process
Data Source
AI summary
A waterproof keyboard comprises: keys, an elastic rubber layer, a circuit board layer, a bottom board, and a sealing layer. The keys are mounted on the bottom board on which a plurality of apertures are disposed, and the sealing layer is disposed under the bottom surface of the bottom board. Corresponding to the apertures on the bottom board, respective adhesives are formed on the sealing layer so as to firmly adhere the sealing layer to the bottom surface of the bottom board.