Laser Via Drilling Control Using Plasma Feedback
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Solution Overview
Problem
Existing laser processing methods struggle to accurately control the formation of openings in insulating layers of wiring substrates, often causing damage to conductor layers due to abrupt changes in irradiation sites during the drilling process.
Innovation Solution
A laser processing device and method that utilizes a sensor to detect plasma light emitted from the substrate, allowing the control device to adjust the laser beam's irradiation conditions based on the detected changes, thereby reducing processing capability and continuing the irradiation to achieve a desired opening state.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the laser beam irradiation is continued with high processing capability after the irradiation site changes, then the opening formation is accelerated, but damage to the conductor layer occurs
Solution Approach 1:
The control device monitors plasma light emission characteristics in real-time during laser irradiation. When the irradiation site transitions from insulating layer to conductor layer, the plasma light characteristics change, providing feedback to the control device. This triggers automatic adjustment of laser processing capability to prevent conductor layer damage while maintaining opening formation efficiency
Solution Approach 2:
The laser processing capability is dynamically adjusted based on the detected irradiation site conditions. The system transitions from high processing capability during insulating layer drilling to reduced processing capability when conductor layer exposure is detected, optimizing both productivity and damage prevention throughout the processing sequence
2Object-affected harmful factors
If the laser processing capability is reduced early to prevent damage, then the conductor layer is protected, but the opening formation efficiency decreases
Solution Approach 1:
The system performs preliminary high-capability laser irradiation to efficiently form the opening through the insulating layer before the conductor layer is exposed. Only after detecting the transition to conductor layer material does the system reduce processing capability, maximizing overall efficiency while preventing damage
3Device complexity
If the irradiation site change is not detected, then the processing is simple, but the opening size and shape deviate from desired specifications
Solution Approach 1:
The control device uses plasma light emission as a feedback signal to detect irradiation site changes. By monitoring characteristics of the emitted plasma light, the system automatically identifies when the laser transitions from insulating layer to conductor layer, enabling precise control of opening dimensions and shape without excessive system complexity
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 the formation of openings closer to the desired size and shape while minimizing damage to the conductor layers by dynamically adjusting the laser beam parameters in response to changes in the irradiation site.
Implementation Method 1
a sensor that outputs to the control device a sensor output based on plasma light emitted from the wiring substrate due to irradiation of the laser beam
Data Source
AI summary
A laser processing device for forming an opening in an insulating layer of a wiring substrate includes a light source that emits a laser beam, an objective lens that focuses the laser beam onto a surface of a wiring substrate, a control device including circuitry that controls an irradiation condition of the laser beam, and a sensor that outputs to the control device a sensor output based on plasma light emitted from the wiring substrate due to irradiation of the laser beam. The circuitry of the control device recognizes a change in an irradiation site of the laser beam based on the sensor output, reduces processing capability of the laser beam and continues the irradiation upon.