Disk Retaining Element Captive Screw PCB Mounting
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Solution Overview
Problem
Existing methods for captively mounting screws on workpieces, such as printed circuit boards, are either costly due to high installation height or risk damaging the workpiece with high pressure loads, especially when using deformable materials and deformation components.
Innovation Solution
A disk-like retaining element with a recess having radially inward lugs allows any commercially available screw to be pre-assembled, engaging the screw thread without exerting significant force, enabling automatic assembly and reducing installation costs while minimizing risk of workpiece damage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a deformation component is pressed into the workpiece to secure the screw, then the screw is firmly retained, but high pressure load acts on the workpiece causing deformation or damage
Solution Approach 1:
The patent introduces a holding element as an intermediary component between the screw and the workpiece. This holding element features a recess with radially inward pointing lugs that engage with the screw thread, allowing the screw to be securely retained without directly pressing deformation components into the workpiece. The holding element absorbs the retention function while minimizing harmful pressure effects on the workpiece.
Solution Approach 2:
The invention segments the retention function into two separate components: the holding element with lugs that engage the screw thread, and the workpiece opening that receives the holding element. This segmentation allows the screw to be retained through the lug engagement mechanism rather than through high-pressure deformation of the workpiece material.
2Reliability
If a deformation component is pressed into the workpiece, then the screw is securely retained, but conductor tracks cannot be routed in the immediate vicinity due to workpiece deformation
Solution Approach 1:
The holding element serves as a mediator that provides screw retention without requiring workpiece deformation. By engaging the screw thread through its lugs and being received in a simple opening in the workpiece, it eliminates the need for deformed zones that would interfere with conductor track routing on printed circuit boards.
3Reliability
If a captive screw with large installation height is used, then the screw is firmly connected, but large installation volume is required and costs increase
Solution Approach 1:
The holding element is designed to be received in a simple opening in the workpiece without requiring additional fastening operations or large installation space. The radially inward pointing lugs engage the screw thread to provide firm connection, while the compact design minimizes installation volume requirements.
Data Source
Figure 1a~4
Figure 5
AI summary
The holding element (1) i.e. holding bracket, has an opening (14) including an inner contour (21), where the holding element is designed as disk shaped and soldered in a surrounding area of a drill hole of a workpiece. The inner contour includes projections (10) that are arranged in a radial direction. The inner contour is connected to a thread of a bolt. A bore (7) is formed between the projections and the inner contour, where one of the projections is larger than a core diameter of the bolt. Thickness of the holding element is smaller than a slop of the bolt thread.