Captive Screw Washer Structure for Conductive Chassis Assembly
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Solution Overview
Problem
Existing electronic apparatuses, such as laptop PCs, face issues with screws and washers falling off during assembly or disassembly, and lack effective electrical conduction between chassis members, leading to increased manufacturing costs and poor assembly workability.
Innovation Solution
A screw and washer configuration where the screw has a head portion with a larger diameter than the attachment hole and a male screw portion with a smaller diameter columnar portion, and a washer with a flange portion and second female screw portion, ensuring secure fixation and electrical conduction through a conductive sponge.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a small screw (M2 or M3) is used to fix chassis members, then manufacturing cost is reduced, but the screw and washer may fall off during assembly or disassembly
Solution Approach 1:
The washer is nested within the screw structure by forming it as a hollow cylindrical portion inside the screw shaft. This integration ensures the washer cannot separate from the screw, eliminating the problem of lost components while maintaining the use of small screws for cost-effectiveness.
Solution Approach 2:
The washer and screw are merged into a single integrated component. The washer is formed as an integral part of the screw, combining two previously separate fastening elements into one unified structure that functions as both a fastening and a protective element.
2Ease of operation
If a plastic washer is used to prevent looseness, then assembly workability is improved, but electrical conduction between chassis members is lost
Solution Approach 1:
The screw is made of conductive material (metal) while incorporating a hollow cylindrical portion that can accommodate conductive elements. This composite structure maintains both the ease of assembly and the electrical conduction function by using conductive materials throughout the fastening system.
Solution Approach 2:
The hollow cylindrical portion of the screw acts as an intermediary structure that can contain conductive putty or other conductive materials. This intermediary element ensures electrical conduction between chassis members while the screw itself provides the mechanical fastening function.
3Reliability
If a metal washer (C-ring or E-ring) is used to ensure conduction, then electrical conduction is maintained, but the washer may fall off and requires higher assembly skill
Solution Approach 1:
The washer is nested within the screw structure as a hollow cylindrical portion formed inside the screw shaft. This integration eliminates the problem of the washer falling off during assembly or disassembly, while the hollow structure can still accommodate conductive elements for maintaining electrical conduction.
Solution Approach 2:
The washer and screw are merged into a single integrated component, eliminating the need for separate washer installation steps. This integration significantly improves assembly workability by reducing the number of components and steps, while the conductive material ensures electrical conduction is maintained.
4Reliability
If conductive sponge is used to ensure conduction, then electrical conduction is achieved, but assembly workability deteriorates due to compression requirements
Solution Approach 1:
The hollow cylindrical portion of the screw acts as an intermediary structure that contains the conductive putty. This configuration allows the conductive material to be easily applied and positioned without requiring compression during assembly, significantly improving assembly workability while ensuring reliable electrical conduction.
Solution Approach 2:
The invention changes the physical state and application method of the conductive material from compressed sponge to putty that can be easily molded and positioned. This parameter change eliminates the need for compression during assembly, making the process much more workable while maintaining effective electrical conduction.
Data Source
AI summary
An electronic apparatus includes a bottom cover, a main board provided with a stud, a screw, a washer, and a sponge. The screw has a head portion having a diameter larger than that of an attachment hole, a male screw portion configured to be screwed into a first female screw portion, and a columnar portion having a diameter smaller than a root diameter of the male screw portion. The washer has a flange portion having a diameter larger than that of the attachment hole, a cylindrical portion having a diameter smaller than that of the attachment hole, and a second female screw portion which the male screw portion is screwable into and passable through. The head portion abuts on the bottom cover to fix the bottom cover by the male screw portion. The flange portion is between the stud and the bottom cover.