Probe Pin Groove Orientation for Breakage Prevention
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Probe pins made of metal wires, particularly those with tungsten or rhenium-tungsten alloys, are prone to breakage during the bending process due to stress concentrations at the thin needle-shaped tip end, leading to low production yield and short lifespan when used in semiconductor wafer testing.
Innovation Solution
A probe pin with a tapered tip end formed by machine-working, where the angle between the grinding grooves and the longitudinal direction of the metal wire is 45 degrees or less, and a surface roughness of 5 μm or less, is manufactured using a grinding process with a rotary grinding wheel, reducing stress concentrations and notch effects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the tip end portion of the probe pin is machine-worked to create a needle shape, then the probe pin can be used for electrical contact, but stress concentrations and notch effects are generated causing breakage during bending
Solution Approach 1:
The invention applies different surface characteristics to different regions of the probe pin. The tip end portion is machine-worked to create grooves that are substantially parallel to the longitudinal axis, while the body portion maintains its original surface characteristics. This local differentiation allows the tip to be optimized for electrical contact while the body provides structural strength and bendability.
Solution Approach 2:
The invention changes the surface geometry parameter by controlling the groove formation process. By adjusting the grinding wheel rotation direction and other parameters, the grooves are formed at a specific orientation (substantially parallel to the longitudinal axis) rather than radially or tangentially. This parameter change fundamentally alters the stress distribution during bending.
2Measurement precision
If the probe pin is made with a thin needle-shaped tip end portion, then electrical contact precision is improved, but the probe pin becomes more susceptible to breakage during bending and usage
Solution Approach 1:
The groove formation is performed as a preliminary action during the machine-working process. By pre-forming the grooves in a specific orientation before the bending process, the stress concentrations are predetermined and controlled. This preliminary action prevents harmful stress concentrations from developing during subsequent bending operations.
3Ease of manufacture
If conventional bending processes are applied to the probe pin, then the probe pin can be formed into the required shape, but breakage occurs at the needle-shaped tip end portion
Solution Approach 1:
The invention converts the potentially harmful effect of stress concentrations into a beneficial outcome. By controlling the groove orientation to be parallel to the longitudinal axis, the stress concentrations that would normally cause breakage are instead aligned with the bending direction, allowing the bending process to proceed without fracture. This transforms a harmful stress distribution pattern into a beneficial one that enables successful bending.
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 solution effectively suppresses breakage during bending and improves production yield, quality, and durability of the probe pins, making them suitable for use in probe cards.
Implementation Method 1
machine-working a tip end portion of a metal wire... formed with a tapered portion which is formed by machine-working a tip end portion of a metal wire... grinding process with a rotary grinding wheel
Data Source
AI summary
A probe pin having a bent portion at its tip end portion is used for a probe card, the probe pin is configured such that an angle constituted by a direction of work groove generated at a time of machine-working of a tip end portion of the probe pin and a longitudinal direction of a metal wire is set to 45 degree or less, or both directions are set to be almost parallel to each other. Due to above configuration, even if the tip end portion of the probe pin is subjected to a bending work and a worked surface is formed with recessed portion, a breakage of the probe pin caused by the recessed portion existing on the worked surface and functioning as a starting point of the breakage can be effectively prevented whereby a lowering of a production yield of the probe pin can be greatly suppressed.