Probe Card Elastic Contact Bump for Pad Alignment
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Solution Overview
Problem
The increasing number of electrode pads on semiconductor chips with decreasing pitch poses challenges in accurately contacting probe needles during electrical testing, as existing contact projections may not match the size and shape of the pads due to the aspect ratio of the passivation film openings.
Innovation Solution
A probe card design featuring a substrate with through electrodes and elastic bodies, where contact bumps are formed on the elastic bodies to match the shape and size of the electrode pads, allowing for precise and adaptable contact even with varying pad sizes and shapes, and accommodating the expansion and contraction of the elastic material to maintain contact during testing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If contact projections are molded from resin to be pyramidal or semispherical, then the probe structure is simplified, but the contact projections may not be able to contact the electrode pads accurately depending on the aspect ratio of the openings
Solution Approach 1:
The contact bump changes its physical parameters (shape, size, elasticity) to match the electrode pad characteristics. The elastic body allows the contact bump to deform and adapt its geometry to the specific opening dimensions and pad shape, ensuring accurate contact regardless of aspect ratio variations.
Solution Approach 2:
The contact bump is designed with non-uniform properties - the elastic body provides localized compliance only where needed for contact, while the substrate body maintains structural rigidity. This local differentiation allows the contact interface to adapt to varying pad geometries without compromising overall probe stability.
2Adaptability or versatility
If the number of electrode pads is increased with decreasing pitch, then the functionality and integration of the semiconductor chip is improved, but it becomes difficult to accurately contact each electrode pad with the probe needle
Solution Approach 1:
The contact bump's elastic properties allow it to change its contact characteristics dynamically. The elastic body enables the contact bump to deform to match the decreasing pitch between pads, maintaining accurate contact even as pad spacing reduces and contact difficulty increases.
Solution Approach 2:
The contact bump transitions from a rigid structure to a dynamic, adaptable structure through the elastic body. This allows the contact interface to adjust its geometry and position in response to variations in pad location and dimensions, maintaining precision despite increased pad density.
3Ease of manufacture
If contact projections are made with fixed geometry, then the manufacturing process is simplified, but they cannot adapt to varying pad sizes and shapes
Solution Approach 1:
The contact bump incorporates an elastic body that allows its geometric parameters (shape, volume, contact surface area) to change dynamically. This enables adaptation to various pad sizes and shapes while maintaining a relatively simple manufacturing process where the elastic body is formed as an integral part of the contact bump structure.
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 probe card ensures reliable electrical connection to multiple semiconductor chips in parallel, reducing testing time and maintaining contact accuracy despite variations in pad size and shape, as well as thermal expansion differences between the probe card and the test subject.
Implementation Method 1
maintaining contact accuracy despite variations in pad size and shape, as well as thermal expansion differences between the probe card and the test subject
Implementation Method 2
An elastic body is filled in an accommodating portion. The contact bump is formed on the elastic body
Data Source
AI summary
A probe card for conducting an electrical test on a test subject includes a substrate body including a first surface, which faces toward the test subject, and a second surface, which is opposite to the first surface. A through electrode extends through the substrate body between the first surface and the second surface. A contact bump is formed in correspondence with the electrode pad and electrically connected to the through electrode. An elastic body is filled in an accommodating portion, which is formed in the substrate body extending from the first surface toward the second surface. The contact bump is formed on the elastic body.