Composite Contact Probe with Filling Material for High Frequency Testing
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Solution Overview
Problem
Short contact probes with lengths less than 5000 μm used in high frequency applications face increased stiffness and risk of breaking due to reduced length, which can lead to irreparable damage to the device under test and the probes themselves.
Innovation Solution
Incorporating pass-through openings in the contact probe bodies filled with a suitable filling material, such as polymeric materials like Parylene or alumina, to reduce stiffness and enhance elasticity, along with auxiliary guides to manage bending stresses and prevent breakage, and using stoppers to prevent undesired movements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the contact probe length is reduced to less than 5000 μm for high frequency applications, then the self-inductance is reduced improving high frequency performance, but the stiffness increases and the risk of breaking increases
Solution Approach 1:
The contact probe is constructed as a composite structure with a metallic core providing electrical conductivity and a polymer coating providing mechanical flexibility and stress distribution. This composite design allows the probe to maintain low self-inductance through its short length while the polymer layer prevents breaking by distributing mechanical stresses and providing elasticity.
Solution Approach 2:
A polymer coating or shell is applied over the metallic contact probe body. This flexible polymer layer acts as a protective shell that allows the short, stiff metallic core to bend without breaking, thereby maintaining high frequency performance while preventing probe failure due to increased stiffness.
2Speed
If the contact probe length is reduced to less than 5000 μm, then the self-inductance is reduced improving high frequency performance, but the force exerted on contact pads increases which can damage the device under test
Solution Approach 1:
The polymer coating acts as a compliant layer that reduces the contact force exerted on the device under test. When the probe contacts the pad, the polymer deforms first, absorbing some of the force, while the short metallic core maintains electrical connectivity with low inductance for high frequency applications.
Solution Approach 2:
The composite structure combines the low inductance benefit of the short metallic probe with the force-distributing properties of the polymer material. This allows high frequency performance to be maintained while the contact force is reduced to prevent damage to the device under test.
3Speed
If the contact probe body is made shorter, then high frequency characteristics are improved, but the elasticity decreases and the risk of breaking during operation increases
Solution Approach 1:
The polymer shell provides the elasticity that the short metallic core lacks. This flexible coating allows the probe to undergo bending and deformation during operation without breaking, thereby improving reliability while maintaining the short length necessary for high frequency characteristics.
Solution Approach 2:
The composite design combines the electrical advantages of the short metallic probe with the mechanical advantages of the polymer material. The metallic core ensures low self-inductance for high frequency operation, while the polymer matrix provides elasticity and fracture resistance, together improving both high frequency performance and operational reliability.
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 reduces the likelihood of breaking the contact probes and minimizes the force exerted on contact pads, ensuring reliable operation in high frequency applications while maintaining the probes' integrity and extending their useful life.
Implementation Method 1
reduce the stiffness of the probes and consequently the pressure exerted by the probes on the contact pads, at the same time guaranteeing enough elasticity to the body of those probes
Data Source
AI summary
It is described a contact probe for a testing head for a testing apparatus of electronic devices, the probe comprising a probe body extended in a longitudinal direction between respective end portions adapted to contact respective contact pads, the second end being a contact tip adapted to abut onto a contact pad of the device under test, the body of each contact probe having a length of less than 5000 μm, and including at least one pass-through opening extending along its longitudinal dimension. Conveniently, the at least one pass-through opening is filled by a filling material, in order to define at least one first and one second lateral portions in the body, being parallel and joined to each other by a connecting central portion realized by the filling material at the pass-through opening, the connecting central portion made of the filling material acting as a strengthening element.