Standoff Assembly With Polymer Liner For Circuit Boards
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Solution Overview
Problem
Existing standoff components in circuit card assemblies can cause damage to components and reduce part life due to uneven torque application during assembly and disassembly, leading to loosening, friction, and potential electrical short circuits.
Innovation Solution
A standoff assembly with a support body having a threaded portion, an internal bore, a sleeve, and a support shelf, along with washers to prevent direct contact between the circuit boards and the standoff, reducing friction and wear during assembly and disassembly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If standoffs are used to secure circuit boards with fasteners, then boards are securely mounted with separation gap, but uneven torque application causes fastener loosening and standoff failure during disassembly
Solution Approach 1:
A polymer liner is introduced as an intermediary layer between the metallic standoff and the circuit board aperture. This liner acts as a mediator that distributes the clamping force more uniformly across the aperture edges, preventing stress concentration and fastener loosening while maintaining secure mounting strength
Solution Approach 2:
The polymer liner serves as a pre-installed cushioning element that absorbs and distributes mechanical stresses before they can cause damage to the circuit board or standoff. This protective layer prevents friction-induced loosening during assembly and disassembly operations
2Ease of operation
If fasteners are rotated during assembly and disassembly, then boards can be installed and removed, but friction generation peels copper layers or causes electrical short circuits
Solution Approach 1:
The polymer liner acts as a low-friction intermediary surface between the fastener and the circuit board aperture. This mediator reduces the coefficient of friction during rotation, allowing smooth assembly and disassembly operations without generating enough friction to peel copper layers or cause electrical short circuits
Solution Approach 2:
The polymer liner changes the friction parameter at the interface between the fastener and circuit board. By selecting polymer materials with inherently low friction coefficients, the assembly process enables easier rotation with significantly reduced frictional forces that could otherwise damage sensitive copper traces
3Stability of the object's composition
If standoffs provide support between circuit boards, then boards are held at separation distance, but uneven support causes board bending and stress damage
Solution Approach 1:
The polymer liner modifies the mechanical parameters of the standoff-board interface by providing a compliant, stress-distributing surface. This changes the pressure distribution from concentrated point loads to distributed line loads, preventing board bending and structural damage while maintaining stable positioning
Solution Approach 2:
The polymer liner provides pre-positioned cushioning at the support interface between the standoff and circuit board. This cushioning layer compensates for minor misalignments and unevenness, distributing support forces uniformly to prevent board bending and stress concentration that could lead to structural failure
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 proposed standoff assembly reduces the risk of damage to circuit boards, enhances part life, and improves ease of installation and disassembly by minimizing friction and wear.
Implementation Method 1
a threaded portion extending from the first end and passing through an aperture of the first circuit board
Implementation Method 2
the standoffs may be made of aluminum material to dissipate heat from the CCA via one or more copper layers
Data Source
AI summary
Circuit card assemblies may include an enclosure, first and second circuit boards installed, and a standoff for mounting the first and second circuit boards within the enclosure. The standoff includes a support body extending between the first and second circuit boards and has a first end and a second end. The first end is proximate the first circuit board and the second end is proximate the second circuit board. A threaded portion extends from the first end and passes through an aperture of the first circuit board. An internal bore is defined within the support body and includes an opening at the second end of the support body. A sleeve extends from the second end of the support body and has an opening aligned with the opening of the internal bore. The sleeve extends into an aperture of the second circuit board with a support shelf defined around the sleeve.