High-Planarity Probe Card Stiffener Design
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Solution Overview
Problem
Existing probe card technologies face limitations in achieving high planarity, particularly with ceramic base technology, which results in defects and compromised operation due to the thinness and flexibility of intermediate plates, leading to issues with maintaining optimal contact between probes and devices under test.
Innovation Solution
A probe card design that incorporates a support element made of a nickel-iron alloy, such as a metal plug, joined with an intermediate plate to provide local micro-rectifications and improved stiffness, along with a regulation system using adjustment screws to apply forces and ensure proper planarity and contact, overcoming the limitations of existing technologies.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If an intermediate plate is used to support the testing head, then the device can be assembled with flexible positioning, but the plate bows under load compromising contact quality
Solution Approach 1:
The support structure is divided into multiple segments: the intermediate plate is segmented from the stiffener, and the stiffener itself is segmented into multiple support elements distributed across the plate. This segmentation allows each component to perform its specialized function - the plate provides positioning flexibility while the distributed stiffener segments provide localized support to prevent bowing under load.
Solution Approach 2:
The support structure combines two different materials with complementary properties: an intermediate plate made of a flexible material (such as aluminum or copper) and a stiffener made of a rigid material (such as stainless steel or titanium). This composite construction allows the flexible plate to accommodate positioning adjustments while the rigid stiffener prevents excessive deformation under probe card load, maintaining contact planarity.
2Volume of moving object
If the intermediate plate is made thinner to reduce size, then the device becomes more compact, but planarity defects increase
Solution Approach 1:
Instead of using a single thick plate, the support structure is segmented into a thin intermediate plate and separate stiffener elements. This segmentation allows the plate to remain thin for compactness while the distributed stiffener segments provide localized rigidity to maintain planarity, eliminating the need for a uniformly thick plate.
Solution Approach 2:
The stiffener is designed with varying thickness and is positioned strategically at locations where maximum support is needed under the probe card assembly. This local quality approach provides enhanced rigidity precisely where required to maintain planarity, while allowing the rest of the intermediate plate to remain thin for compactness.
3Manufacturing precision
If a rigid stiffener is added to improve planarity, then contact quality improves, but the assembly becomes more complex
Solution Approach 1:
The stiffener is segmented into multiple discrete support elements rather than a single monolithic structure. These segmented stiffener elements can be independently positioned and attached to the intermediate plate, simplifying the assembly process while providing distributed support to maintain planarity across the entire probe card contact area.
Solution Approach 2:
The stiffener elements are designed to be attached to the intermediate plate in a way that allows for self-alignment and self-adjustment during assembly. The rigid material properties of the stiffener enable it to naturally assume its support function once attached, reducing the need for complex adjustment mechanisms or precision alignment procedures.
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 achieves high-planarity and robust contact between probes and devices, enabling reliable testing without bowing of the interposer under load, and accommodates thermal expansion, thus enhancing the operational reliability and flexibility of the probe card.
Implementation Method 1
a support element being joined with an intermediate plate or interposer realized with PCB technology, in such a way as to provide local micro rectifications of the interposer itself, thereby improving the planarity thereof, the assembly of the support element and the interposer also being rigid enough
Implementation Method 2
accommodates thermal expansion, thus enhancing the operational reliability and flexibility of the probe card
Data Source
AI summary
A probe card for a testing apparatus of electronic devices comprises at least one testing head which houses a plurality of contact probes, each contact probe having at least one contact tip suitable to abut onto contact pads of a device under test, and a support plate of the testing head associated with a stiffener and an intermediate support, connected to the support plate and suitable to provide a spatial transformation of the distances between contact pads made on the opposite sides thereof. Conveniently, the probe card comprises a support element which is joined to the intermediate support, this support element being made by means of a material having a greater stiffness than the intermediate support, thereby being able to provide local micro rectifications of the intermediate support.