Laser Optical Path Detection in IC Packages
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Solution Overview
Problem
As integrated circuit (IC) packages decrease in size, the probability of forming inadvertent optical paths through glass particles in the epoxy compound increases, leading to potential damage during laser marking, and existing non-destructive detection methods are inadequate, making it difficult to assess susceptibility to laser identification marking damage.
Innovation Solution
A method using a laser scanning microscope in Optical Beam Induced Current (OBIC) or Thermally Induced Voltage Alteration (TIVA) mode to detect optical paths through IC packages by scanning the package surface with a laser and monitoring current changes, identifying underlying glass sphere structures that may cause optical pathways.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If IC packages decrease in size, then productivity and miniaturization are improved, but the probability of forming inadvertent optical paths through glass particles increases, leading to potential laser damage
Solution Approach 1:
The patent performs preliminary detection of optical paths using a laser scanning microscope with OBIC or TIVA mode before laser marking is performed. This advance detection identifies potential optical pathways through glass beads in the epoxy compound, allowing operators to avoid or modify laser marking parameters in affected areas, thereby preventing damage while maintaining miniaturization benefits
Solution Approach 2:
The patent introduces an intermediary detection system (laser scanning microscope with OBIC/TIVA mode) that acts as a mediator between the packaging process and laser marking process. This intermediary device detects optical paths without destroying the package, providing critical information that bridges the gap between miniaturization requirements and laser safety
2Measurement precision
If metallurgical cross-sectioning is used to detect optical pathways, then detection capability is improved, but the process becomes tedious and labor intensive
Solution Approach 1:
The patent replaces the mechanical metallurgical cross-sectioning process with an optical detection method using laser scanning microscopy in OBIC or TIVA mode. This substitution eliminates the need for physical sectioning, polishing, and microscopic examination of cross-sections, reducing detection time from hours or days to minutes while maintaining high precision in optical pathway identification
Solution Approach 2:
The patent enables the IC package itself to serve as the detection target without requiring external preparation. The laser scanning microscope directly scans the packaged device, and the package's own electrical characteristics (current changes in OBIC mode or voltage alterations in TIVA mode) provide the detection signal, eliminating the need for destructive cross-sectioning preparation
3Reliability
If x-ray or acoustic microscopy is used for non-destructive investigation, then non-destructive detection is achieved, but these methods cannot detect optical pathways
Solution Approach 1:
The patent changes the detection parameter from physical/structural properties (detected by x-ray or acoustic microscopy) to electrical/optical interaction properties. By using OBIC mode (detecting laser-induced current) or TIVA mode (detecting thermally induced voltage alterations), the method detects optical pathways through their effect on electrical parameters, providing both non-destructive detection and optical pathway specificity
Solution Approach 2:
The patent makes the laser scanning microscope multi-functional by operating in different modes (OBIC and TIVA) to detect various phenomena. The same instrument can detect optical pathways through current induction or thermal voltage alterations, providing universal non-destructive detection capability that neither x-ray nor acoustic microscopy can achieve for optical path detection
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
Enables non-destructive detection of optical pathways, improving the reliability and quality of IC packages by identifying potential damage risks from laser marking, without requiring the removal of glass beads from epoxy compounds, thus maintaining industry standards and reducing requalification needs.
Implementation Method 1
Optical beam induced current (OBIC) is a semiconductor analysis technique performed using laser signal injection. The technique induces current flow in the semiconductor sample through the use of a laser light source.
Implementation Method 2
A laser scanning microscope is configured in the Optical Beam Induced Current (OBIC) mode, or Thermally Induced Voltage Alteration (TIVA) mode.
Data Source
AI summary
A method is provided for detecting laser optical paths in integrated circuit (IC) packages. The method provides an IC die encapsulated as a package in a compound of glass spheres and epoxy. Power is supplied to the IC. The IC is scanned with a laser. Typically, a laser wavelength is used that is minimally absorbed by the glass spheres in the epoxy compound of the IC package, and changes in current to the IC are detected. A detected current change is cross-referenced against a scanned IC package surface region. This process identifies an optical pathway underlying the scanned IC package surface region. In some aspects, this process leads to the identification of a glass sphere-collecting package structure underlying the optical pathway. Examples of a glass sphere-collecting structure might include an inner lead wire, lead frame edge, or die edge.