Variable-Angle Electron-Beam Testing for Complex Packaging Substrates
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Solution Overview
Problem
Existing methods for testing complex packaging substrates, such as panel-level and advanced packaging substrates, face challenges due to miniaturization and increasing complexity, leading to difficulties in reliable and efficient detection of defects like shorts, opens, and leakages, as conventional electrical-mechanical probing and other methods struggle with reduced contact sizes and topography issues.
Innovation Solution
A contactless testing method using electron beams with variable beam diameters and angles is employed to inspect packaging substrates, allowing for the detection of defects by directing electron beams at specific surface contact points and analyzing signal electrons emitted, thereby avoiding physical contact and potential damage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If contact probes are used to test contact pads, then electrical connections can be tested, but the risk of damaging the device under test increases and contacting reliability decreases due to miniaturization
Solution Approach 1:
The patent replaces mechanical contact probes with a non-contact testing method using electromagnetic fields. The testing system generates an electromagnetic field that couples with the interconnect paths under test, allowing electrical connection testing without physical contact. This eliminates the mechanical wear and damage risks associated with traditional probe-based testing while maintaining testing capability for miniaturized contact pads.
2Reliability
If the number of test points increases to cover complex packaging substrates, then more defects can be detected, but throughput decreases
Solution Approach 1:
The patent implements a multi-functional testing system that can simultaneously perform multiple testing functions using a single electromagnetic field generation approach. The system can test multiple interconnect paths and different defect types (opens, shorts, leakage) concurrently by adjusting field parameters, thereby maintaining high throughput while comprehensively detecting defects across complex packaging substrates with numerous test points.
3Ease of operation
If capacitive detectors or electrical field detectors are used, then testing can be performed without contact, but the topography of packaging substrates creates difficulties due to required small mechanical spacing
Solution Approach 1:
The patent employs parameter changes in the electromagnetic field characteristics to overcome topography interference. By adjusting field frequency, amplitude, and spatial distribution parameters, the system can penetrate and account for substrate topography variations, enabling accurate non-contact testing despite complex surface geometries. This allows the electromagnetic field to effectively couple with contact pads regardless of their three-dimensional positioning.
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 method enables reliable and rapid detection of defects in packaging substrates, ensuring high throughput and accuracy without damaging the substrate, even for small contact pads and complex geometries, while overcoming topography challenges.
Implementation Method 1
directing an electron beam of the at least one electron beam column with a landing energy Upe, a first beam diameter BD1 and a first impact angle θ1 on one or more first surface contact points on the packaging substrate
Implementation Method 2
detecting signal electrons emitted upon impingement of the electron beam
Data Source
AI summary
A method of testing a substrate, particularly a packaging substrate, with at least one electron beam column is described. The packaging substrate can be a panel level packaging substrate or an advanced packaging substrate. The method includes: placing the substrate on a stage in a vacuum chamber; directing the electron beam of the at least one electron beam column with a landing energy Upe, a first beam diameter BD1 and a first impact angle θ1 on one or more first surface contact points on the substrate; directing the electron beam with at least one of a second beam diameter BD2 and a second impact angle θ2 on one or more second surface contact points different from the one or more first surface contact points, wherein at least one of the following applies: i) the first impact angle θ1 is different from the second impact angle θ2, and ii) the second beam diameter BD2 is different from the first beam diameter BD1; and detecting signal electrons emitted upon impingement of the electron beam for testing at least a first device-to-device electrical interconnect path of the substrate.