Conductive Elastomer Interposer for Semiconductor Testing
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Solution Overview
Problem
Conventional probe card interposers face issues such as thermal expansion mismatches, distortion, and planarity errors due to solder area array and vertical compliant interposers, making them unreliable and difficult to disassemble or repair, especially for large area or high pin count applications.
Innovation Solution
A novel interposer design using conductive elastomers with piercing structures or adhesives that allow for zero or near-zero nascent force connections, enabling precise alignment and easy separation for rework, and utilizing conductive elastomers that can be adjusted in X, Y, and Z directions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If solder area array technology is used to electrically connect the interposer to the PCB and probe contactor substrate, then reliable electrical connections are achieved, but thermal expansion mismatches cause distortion and planarity errors, and the connections become difficult to disassemble or repair
Solution Approach 1:
The patent divides the interconnection system into separable modules: the interposer with probe contactors can be detached from the PCB assembly. This segmentation allows the probe card to be replaced or repaired independently without damaging the PCB, directly addressing the repair difficulty issue while maintaining reliable electrical connections through the interposer's contact pads
Solution Approach 2:
The interposer serves as an intermediary component between the PCB and probe contactors. It provides a detachable connection interface that mediates the electrical connection, allowing reliable signal transmission while enabling easy separation for repair. The interposer's contact pads on one side connect to the PCB, while the other side connects to probe contactors, facilitating modular replacement
2Adaptability or versatility
If solder area array technology is used to connect large area probe cards with high pin count, then comprehensive electrical interconnects are achieved, but yield becomes unacceptable due to shear forces and mismatch-related distortion
Solution Approach 1:
The patent introduces compliance elements that provide dynamic adjustment capability to the rigid solder joint system. The compliant interposer structure can flex and adapt to thermal expansion differences and assembly variations, reducing shear forces on solder joints and improving yield for large area, high pin count applications where rigid connections would fail
3Adaptability or versatility
If vertically compliant interposers with vertical springs are used to provide vertical compliance, then displacement accommodation is improved, but nascent force creates distortion and planarity errors on the probe contactor substrate
Solution Approach 1:
The patent uses a compliant interposer structure that acts as a flexible element between the rigid PCB and probe contactor substrate. This flexible interposer accommodates vertical displacement and thermal expansion without transmitting excessive force to the probe substrate, maintaining planarity while providing necessary compliance through its material properties and结构设计
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 minimizes planarity errors, reduces stress on the probe contactor substrate and PCB, and allows for efficient rework and repair, maintaining reliable electrical connections with improved yield and flexibility.
Implementation Method 1
an interposer that has at least one electrical via made of a conductive elastomer. When the PCB piercing structure and the substrate piercing structure pierce the elastomer, the PCB becomes electrically connected to the probe contactor
Implementation Method 2
vertically compliant interposers. These interposers provide an array of vertical springs with a degree of vertical compliance, such that a vertical displacement of a contact or array of contacts results in some vertical reaction force
Data Source
AI summary
A novel device for testing semiconductor chips is disclosed. A benefit with all the embodiments described herein is that the device may experience zero (or near zero) nascent force. The device may be comprised of a printed circuit board (PCB) that has at least one PCB piercing structure, a probe contactor substrate that has at least one substrate piercing structure, wherein the substrate piercing structure is electrically connected to a probe contactor, and an interposer that has at least one electrical via made of a conductive elastomer. When the PCB piercing structure and the substrate piercing structure pierce the elastomer, the PCB becomes electrically connected to the probe contactor. Instead of the piercing structure, the PCB or the probe contractor substrate may be adhered to the elastomer by an adhesive, such that the PCB becomes electrically connected to the probe contactor. The PCB piercing structure and the substrate piercing structure may include a flying lead wire, soldered pins or pressed pins. The adhesives may include, but are not limited to, screenable conductive surface mount adhesives. Finally, a diagnostic computer may be electrically connected to the PCB to assist in testing the semiconductor chips.