Probe Card Space Transformer Segmentation for Alignment Precision
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Solution Overview
Problem
Conventional probe cards for testing large area wafers face challenges in minimizing process defects, thermal deformation, flatness, and alignment precision, particularly with the increasing complexity and size of ceramic substrates, which are difficult to fabricate and align accurately.
Innovation Solution
A probe card design featuring a space transformer with vertically conductive media, where unit probe modules of varying sizes (corresponding to semiconductor chips or 20-1000% of chip size) are mounted on a large area space transformer, utilizing a combination of a circuit board, interposers, and stiffener plates for improved alignment and electrical connectivity, along with a method for fabricating these components to enhance assembly and testing efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a ceramic substrate is used for the space transformer to provide stable probe alignment, then alignment precision is improved, but manufacturing complexity and cost increase significantly
Solution Approach 1:
The probe card is divided into multiple probe blocks, each containing a subset of probes. These blocks are independently manufactured and then assembled onto the space transformer. This segmentation allows each block to be fabricated with high precision using standard processes, while the overall system achieves the required alignment precision through controlled assembly of the modular blocks.
2Productivity
If the area of the space transformer is increased to accommodate more probes for large area wafers, then productivity is improved, but thermal deformation and flatness control become more difficult
Solution Approach 1:
The probe card is divided into multiple probe blocks that are independently manufactured and then assembled onto the space transformer. This segmentation allows each block to be fabricated with controlled thermal deformation and flatness, while the overall large area structure achieves the required precision through modular assembly with precise alignment features.
Solution Approach 2:
A carrier substrate is introduced as an intermediary component during the assembly process. The carrier substrate provides a stable platform for mounting the probe blocks and maintaining their relative positions. This intermediary structure enables the assembly of multiple blocks while controlling thermal deformation and ensuring flatness across the large area probe card.
3Manufacturing precision
If multiple probe blocks are precisely aligned on a block fixing frame, then alignment precision is improved, but assembly time increases significantly
Solution Approach 1:
Alignment marks are pre-formed on both the probe blocks and the space transformer before assembly. This preliminary preparation of alignment features enables rapid and precise alignment during the assembly process, significantly reducing the time required to position multiple probe blocks accurately on the block fixing frame.
Data Source
AI summary
A probe card for testing semiconductor chips on a semiconductor wafer, includes a circuit board receiving electrical signals from outside, a plurality of unit probe modules contacting the semiconductor chips on the wafer to transfer the electrical signals, a space transformer having the plurality of probe modules seated on the upper portion thereof and electrically connected to the circuit board, wherein the respective probe modules are arranged at intervals from each other on the space transformer and the space transformer has vertical apertures penetrating through it up and down, and at least one vertical conductive medium electrically connecting the respective unit probe modules and the circuit board, wherein the vertical conductive medium is arranged in the vertical apertures provided in the space transformer and the respective unit probe modules are arranged at positions spaced from the vertical conductive medium.