Press-fit Contact Pin with Dumbbell Cross-section for PCB
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Solution Overview
Problem
Conventional contact pins for printed circuit boards have a long compression zone that results in an overhang, which prevents close stacking of boards, can act as an antenna at high frequencies, and may damage the circuit board due to point loading, while also having limited current-carrying capacity and requiring thicker materials for deformation.
Innovation Solution
A contact pin with a dumbbell-shaped cross-section featuring a central web area and wing areas with ear regions that deform inwardly, allowing for a larger current-carrying capacity and reduced overhang, manufactured from standard strip material with a geometry that minimizes deformation of the web area and maximizes deformation of the ear areas for a secure frictional fit.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If the compression zone is made long to provide sufficient spring force, then the holding force is improved, but the overhang increases preventing close stacking of boards
Solution Approach 1:
The compression zone is segmented into distinct functional areas: a first compression area with material flowing toward a central bead to form resilient ear portions, and a second compression area with material flowing away from the bead to form a rigid web portion. This segmentation allows different parts of the compression zone to serve different functions - the ear portions provide spring force while the web portion provides structural rigidity, enabling sufficient holding force with reduced overall length.
Solution Approach 2:
Different regions of the compression zone are given different local properties through the bead geometry. The ear portions are made resilient through controlled material flow and deformation, while the web portion is made rigid. This local differentiation of mechanical properties allows the contact pin to achieve both high holding force and minimal overhang by concentrating deformation in specific localized areas rather than requiring a uniformly long compression zone.
2Force
If the compression zone is made long to provide sufficient spring force, then the holding force is improved, but the contact pin can act as an antenna at high frequencies
Solution Approach 1:
The compression zone is divided into resilient ear portions and a rigid web portion through bead segmentation. This creates a compact structure where the functional compression elements are concentrated in specific segments rather than extending over a long continuous zone, reducing the overall length that could act as an antenna while maintaining sufficient spring force capacity.
Solution Approach 2:
By creating localized resilient areas (ear portions) and rigid areas (web portion) within a compact compression zone, the invention confines the elastic deformation to small localized regions. This reduces the effective electrical length of the contact pin, minimizing antenna effects at high frequencies while still providing adequate spring force for reliable electrical connection.
3Force
If the compression zone is made long to provide sufficient spring force, then the holding force is improved, but point loading may damage the circuit board
Solution Approach 1:
The compression zone is segmented to create multiple contact points through the ear portions that deform and conform to the hole wall. This segmentation distributes the contact force across multiple localized areas rather than concentrating it at a single point, reducing the risk of circuit board damage while maintaining sufficient holding force.
Solution Approach 2:
The invention creates localized resilient ear portions that can deform independently to conform to the hole wall geometry. This local deformation capability allows the contact pin to distribute loading more evenly across the contact interface, preventing excessive point loads on the circuit board while still achieving high holding force through the cumulative effect of multiple contact areas.
4Quantity of substance
If thicker material is used to increase current-carrying capacity, then the electrical performance is improved, but the deformation required for press-fit becomes more difficult
Solution Approach 1:
The contact pin cross-section is segmented into a central bead region and peripheral ear portions. During compression, material flows preferentially toward the bead, concentrating deformation in this central region while the peripheral ear portions maintain sufficient thickness for current conduction. This segmentation allows the use of thicker starting material for improved current capacity while deformation is localized to specific regions that do not compromise overall electrical performance.
Solution Approach 2:
Different regions of the contact pin are given different local properties: the ear portions maintain greater thickness for current conduction, while the central bead region undergoes concentrated deformation to create the press-fit mechanism. This local differentiation of material properties and deformation zones enables the use of thicker materials for improved electrical performance without making the press-fit process excessively difficult.
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 design enhances current-carrying capacity, reduces the risk of circuit board damage, allows for closer board stacking, and maintains a high holding force with minimal overhang, using standard materials and optimizing packing density.
Implementation Method 1
the mutually opposite sections of the widened area represent elastically resilient areas. These sections then counteract the inward deformation (towards each other) that takes place during pressing in, by means of which the contact pin is held in a second state (press-in state), e.g. frictionally or non-positively in the through-opening.
Implementation Method 2
the contact pin is held in a second state (press-in state), e.g. frictionally or non-positively in the through-opening
Data Source
Figure 1
Figure 2
Figure 3a~3b
AI summary
The invention relates to an electrically conductive contact pin (100) for pressing into a through-opening (300) of a printed circuit board (302). For the contact pin (100), a press-in direction is defined as a Z direction. An X direction is defined perpendicular to the Z direction. A Y direction is defined perpendicular to the Z direction and the X direction. The contact pin (100) has a pressing zone (104), which, in a cross-sectional area (200) of the contact pin spanned in the X direction and in the Y direction, has a central web region (202) and two wing regions (204), which adjoin the web region (202) in the positive X direction and the negative X direction, each wing region (204) having two ear regions (206). The web region (202) is bounded by a web rectangle, and the ear regions (206) are bounded by ear rectangles (210). Corners of the ear rectangles (210) that are nearest to a centroid (212) of the cross-sectional area (200) correspond with corners of the web rectangle (214). The web rectangle (214) has, in the X direction, a web width (BS) of between 9% and 29% of a starting material thickness (108) of the contact pin (100) and, in the Y direction, a web thickness (DS) of between 35% and 55% of the starting material thickness (108). The ear rectangles (210) have, in the X direction, an ear width (BO) of between 40% and 60% of the starting material thickness (108) and, in the Y direction, an ear thickness (DO) of between 15% and 35% of the starting material thickness (108).