Etched Probe Pin Tips for IC Die Testing
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
E-testing of unpackaged IC die is challenging due to their small dimensions and numerous testable points, requiring precise electrical probe pin dimensions and alignment to avoid damage during testing.
Innovation Solution
The use of composite probe pins with a hydrophobic monolayer coating and a porous solid medium for etching, where the pins are recessed to expose only the core metal at the tip, ensuring accurate contact and reducing capillary forces, and a method involving submerging the pins in a thiol solution and exposing them to a wet chemical etchant through a porous medium.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional probe pins with exposed peripheral metals are used, then the pins can be easily manufactured, but the etchant wicks along the pin surfaces causing imprecise etching and potential damage to the die
Solution Approach 1:
The probe pin is designed with different properties at different locations: the peripheral metals are recessed while the core metal remains exposed at the tip. This local differentiation ensures that etchant only contacts the core metal at the very tip, providing precise etching control exactly where needed for making contact with the die, while the rest of the pin structure maintains its original manufacturing simplicity.
Solution Approach 2:
The probe pin is segmented into distinct functional zones: peripheral metals that are recessed to prevent etchant wicking, and a core metal tip that remains exposed for precise etching and contact. This segmentation isolates the etching function to only the necessary location, preventing harmful capillary action along the pin surfaces.
2Ease of operation
If probe pins with larger dimensions are used, then alignment is easier, but the pins may damage the small-dimensional unpackaged die
Solution Approach 1:
The probe pin structure concentrates the functional contact area to only the core metal tip, which can be precisely controlled in size and position. This localized contact point provides sufficient alignment tolerance for ease of operation while minimizing the contact area to prevent damage to the delicate unpackaged die.
3Reliability
If peripheral metals are exposed at the pin tip, then electrical contact is ensured, but capillary forces cause etchant to wick and compromise testing accuracy
Solution Approach 1:
The probe pin design ensures that only the core metal is exposed at the tip, creating a localized electrical contact point. This eliminates capillary wicking along the pin surfaces while maintaining reliable electrical contact through the exposed core metal, thereby improving both test point accuracy and contact reliability.
Solution Approach 2:
The design converts the potential harm of exposed metals (which cause etchant wicking) into a benefit by selectively recessing the peripheral metals while leaving the core metal exposed. This transforms the structure to prevent capillary action while ensuring the exposed core metal provides the necessary electrical contact function.
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 solution allows for precise and accurate electrical testing of unpackaged IC die without damaging them, by ensuring the core metal makes direct contact while the peripheral metals are recessed, enhancing the contact angle and reducing wicking of the etchant, thus facilitating effective etching and improving the reliability of the testing process.
Implementation Method 1
at least a partial length of each of the pins is coated with a hydrophobic monolayer
Implementation Method 2
reducing capillary forces
Implementation Method 3
contacting a first end of the structural members to a first surface of a porous solid medium, wet chemical processing the first end of the structural members with a fluidic chemical agent conveyed through the medium
Data Source
AI summary
A prober head to interface an E-testing apparatus to a device under test, which may be an unpackaged die, for example. In some embodiments, the prober head includes an array of conductive pins, each of the pins extending outwardly from a first pin end anchored to a substrate. At least a partial length of each of the pins is coated with a hydrophobic monolayer. The conductive pins may be composite metal wires including a core metal encased by one or more peripheral metal. At a tip of the pins, opposite the first pin end anchored to the substrate, the peripheral metals are recessed from the core metal. In further embodiments, the hydrophobic monolayer is disposed on an outer surface of the peripheral metals, but is substantially absent from a surface of the core metal exposed at the tip.