Dual-Layer Probe Pin for IC Socket Sticking Prevention
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Solution Overview
Problem
Conventional probe pins in IC sockets experience sticking issues with IC package terminals during continuity tests, especially at high temperatures, leading to durability problems and damage to the probe pins.
Innovation Solution
A socket design with a dual-layer structure on the probe pins, where a Pd layer allows rapid Sn diffusion to form an alloy, preventing sticking while ensuring electrical connection, and an Ag layer controls the diffusion rate to prevent excessive alloy formation and oxidation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a single-layer surface structure is used on the probe pin, then the structure is simple and manufacturing is easy, but sticking occurs between the IC package terminal and probe pin at high temperature
Solution Approach 1:
The surface layer of the probe pin is divided into two distinct layers: a first surface layer with high Sn diffusion rate and a second surface layer with low Sn diffusion rate. This segmentation allows each layer to perform its specific function - the first layer prevents sticking through controlled alloy formation, while the second layer prevents oxidation and maintains electrical connection, thereby resolving the sticking problem without requiring overly complex structures.
Solution Approach 2:
The probe pin surface employs a composite layered structure combining materials with different Sn diffusion characteristics. The first surface layer uses a material that allows rapid Sn diffusion to form protective alloys, while the second surface layer uses a material that restricts Sn diffusion to prevent excessive alloy formation. This composite approach enables the probe pin to simultaneously achieve sticking prevention and oxidation resistance.
2Reliability
If tin diffusion into the electric contact is allowed to prevent sticking, then sticking is prevented, but excessive alloy formation may occur causing damage
Solution Approach 1:
The surface layer is segmented into two functional zones: the first surface layer that permits controlled Sn diffusion to prevent sticking, and the second surface layer that acts as a barrier to limit excessive alloy formation. This segmentation ensures that Sn diffusion occurs to the extent needed for sticking prevention but is restrained from causing excessive alloy formation that would damage the probe pin.
Solution Approach 2:
The second surface layer serves as an intermediary barrier between the Sn-rich terminal and the base material of the probe pin. It allows limited Sn diffusion to occur at the interface with the first surface layer while preventing excessive Sn penetration into the probe pin body, thus mediating between the need for alloy formation and the need to preserve probe pin strength.
3Stability of the object's composition
If tin does not diffuse into the electric contact, then alloy formation is controlled, but tin oxidation occurs forming insulators that impede electrical connection
Solution Approach 1:
The surface structure is divided into two layers with different functional properties: the first surface layer that promotes Sn diffusion to prevent oxidation by forming alloys, and the second surface layer that controls the overall diffusion rate. This segmentation ensures that sufficient Sn diffusion occurs to maintain electrical connection through alloy formation, while the second layer prevents excessive diffusion that would compromise structural integrity.
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
Prevents sticking between the IC package terminals and probe pins, enhancing the durability of the socket and probe pins by allowing controlled Sn diffusion and alloy formation, maintaining electrical connection and reducing damage from high-temperature tests.
Implementation Method 1
a first layer (33) into which Sn melts and diffuses upon application of heat
Implementation Method 2
when heat is applied with a terminal of an electric part and an electric contact placed in contact with each other in a continuity test, tin which is the material of the terminals of the electric part melts and diffuses into the material of the electric contact to form an alloy
Implementation Method 3
a second layer (34) formed on the outer side of the first layer (33) and lower in the rate at which Sn melts and diffuses upon application of heat than the first layer
Data Source
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AI summary
[Problem to be Solved] An electric contact for preventing a terminal of an electric part and the electric contact from sticking to each other after a continuity test to improve the durability of the electric contact; and a socket for electric parts using the electric contact. [Solution] The electric contact of this invention includes a first layer made from a material into which Sn melts and diffuses upon application of heat; and a second layer formed on the outer side of the first layer and made from a material lower in the rate at which Sn melts and diffuses upon application of heat than the first layer.