Contact Probe Spring Buckling Prevention via Plunger Stem Design
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Solution Overview
Problem
Contact probes used for testing semiconductor chips face spring deterioration due to high-current test signals, leading to buckling and a short lifespan.
Innovation Solution
A contact probe design where the stem of the first plunger moves within the opening of the second plunger, preventing the spring from buckling by ensuring it does not contact the barrel's inner wall during compression, and optionally using an insulating film or tube to further prevent deformation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If a thin spring is used in the contact probe, then the contact probe can be made compact and suitable for testing fine-patterned semiconductor terminals, but the spring deteriorates quickly and has a short lifespan when high current flows through it
Solution Approach 1:
The patent introduces a current bypass path as an intermediary solution. When the spring buckles and contacts the conductive barrel, the current can flow through the barrel instead of being forced through the spring. This mediator (barrel) provides an alternative current path that protects the spring from excessive current damage while maintaining the compact structure.
Solution Approach 2:
The patent changes the electrical parameter distribution by allowing current to switch paths. Normally current flows through the spring, but when buckling occurs, the current path parameter changes to flow through the conductive barrel instead, protecting the spring from current-induced deterioration while maintaining mechanical functionality.
2Ease of operation
If the spring is allowed to buckle during compression, then the contact probe can accommodate the movement of the upper plunger, but the spring contacts the inner wall of the barrel and deteriorates due to high current flow
Solution Approach 1:
The conductive barrel acts as an intermediary that receives both the mechanical contact from the buckled spring and the electrical current. This dual-function mediator allows the spring to buckle for plunger movement accommodation while the barrel intercepts the current, preventing spring deterioration.
Solution Approach 2:
The conductive barrel serves multiple functions: it provides structural containment for the spring, conducts electrical current during normal operation, and acts as a current bypass path when the spring buckles. This multi-functionality resolves the contradiction by making the barrel a versatile component that addresses both mechanical and electrical requirements.
3Power
If high current is forced through the thin spring during testing, then the test signal can be transmitted, but the spring generates heat and deteriorates rapidly
Solution Approach 1:
The conductive barrel serves as a thermal and electrical intermediary with higher current capacity. When high current flows through the system, the barrel provides an alternative low-resistance path that bypasses the thin spring, preventing excessive heat generation in the spring while maintaining test signal transmission capability.
Solution Approach 2:
The patent effectively substitutes the electrical current path mechanically by allowing the buckled spring to contact the barrel, creating a parallel electrical circuit where the barrel carries the high current load instead of the spring. This mechanical substitution of the current path protects the spring from thermal deterioration.
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
This design extends the lifespan of the spring by preventing buckling and maintaining its structural integrity under high-current test conditions, thereby enhancing the reliability and durability of the contact probe.
Implementation Method 1
a spring interposed between the upper plunger and the lower plunger and providing elasticity against compression of the upper plunger at the test
Implementation Method 2
the spring begins to buckle, i.e. contact an inner wall of the barrel as the spring becomes out of balance under increasing compression and is laterally deformed
Data Source
Figure 1~3
AI summary
Disclosed is a contact probe for a high current, which electrically connect a contact point of an object to be tested and a contact point of a test circuit. The contact probe comprises a first plunger configured to be in contact with the contact point of the object to be tested, a second plunger configured to be in contact with the contact point of the test circuit, a barrel configured to support at least one of the first plunger and the second plunger to slide therein, and a spring configured to be interposed between the first plunger and the second plunger within the barrel, wherein one of the first plunger and the second plunger comprises an opening hole to accommodate one end of the spring, the other one of the first plunger and the second plunger includes a stem to be accommodated in the opening hole, and a free end of the stem is disposed at least within the opening hole after the spring is restored due to completion of the test.