Composite Vertical Probe Card Pin Structure for Stress Absorption
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Solution Overview
Problem
Conventional vertical probe cards experience short circuits due to elastic deformation of pins, poor conductivity, and damage to contact pads during chip testing, leading to decreased production yield and inefficient electrical performance.
Innovation Solution
A composite pin structure using conductive metal for low resistivity and structural metal for rigidity and oxidation resistance, with a die assembly design that allows longitudinal deformation perpendicular to the contact pad surface, reducing the risk of horizontal contact and surface damage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If pins are made elastic to absorb stress during testing, then reliability is improved, but short circuits occur between adjacent pins
Solution Approach 1:
The pin is divided into multiple segments: a rigid upper portion for electrical contact and a flexible lower portion for stress absorption. This segmentation allows different parts of the pin to perform different functions - the upper part maintains structural integrity to prevent short circuits while the lower part provides elasticity for stress absorption during chip testing
Solution Approach 2:
Different portions of the pin have different mechanical properties - the upper portion near the contact pad is made rigid with high structural integrity to prevent short circuits, while the lower portion is made flexible to absorb stress. This local quality variation resolves the contradiction between needing elasticity for reliability and rigidity to prevent short circuits
2Ease of operation
If pre-bent cobra needles are used to create probe overdrive, then ease of operation is improved, but transmission path length increases and conductivity deteriorates
Solution Approach 1:
Instead of pre-bending the pin to create probe overdrive (which increases transmission path length and reduces conductivity), the invention inverts the approach by using a straight pin configuration with probe overdrive generated through the vertical insertion mechanism and elastic deformation of the lower portion, thereby shortening the transmission path and improving conductivity while maintaining ease of operation
3Strength
If MEMS needles with metal alloy are used to improve physical characteristics, then strength is improved, but resistivity increases and electrical conductivity decreases
Solution Approach 1:
The pin is constructed as a composite structure combining materials with different properties - the upper portion uses highly conductive material for optimal electrical contact, while the lower portion uses materials providing the necessary mechanical strength and flexibility. This composite approach allows the pin to achieve both high strength and low resistivity simultaneously
4Reliability
If pins are tilted to form elastic structure, then reliability is improved, but horizontal force is generated that damages contact pads
Solution Approach 1:
Instead of tilting the pin to create elasticity (which generates harmful horizontal forces), the invention inverts the approach by using a vertically aligned pin configuration where elasticity is achieved through controlled bending of the lower portion during vertical insertion. This eliminates horizontal forces that damage contact pads while maintaining the necessary elastic properties for stress absorption
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 enhances electrical conductivity, reduces production costs, and minimizes contact pad damage, enabling more accurate and efficient chip testing with improved production yield.
Implementation Method 1
The inner conductive metal provides a low resistivity when signals are transmitted
Implementation Method 2
the at least one pin assembly generates a deformation in a longitudinal direction, which is perpendicular to a surface of the at least one contact pad
Data Source
AI summary
A probe device of a vertical probe card is provided and includes a die assembly and at least one pin assembly. The die assembly includes a first die, a second die, and a middle die disposed between the first die and the second die. The at least one pin assembly has a first pin, a second pin, and at least one electrical connector. The at least one electrical connector is connected to the first pin and the second pin. The at least one pin assembly is electrically contacted with at least one contact pad of a device under test. The at least one contact pad leans against the at least one pin assembly, so that the at least one pin assembly generates a deformation in a longitudinal direction.