Plated-Through Hole Defect Detection via Airflow and Capillary Measurement
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Solution Overview
Problem
Current methods for detecting defects in plated-through holes on printed circuit boards are often destructive, time-consuming, and inadequate for identifying weak connectivity issues, which can lead to premature failures due to thermal stress and localized stress concentrations.
Innovation Solution
A non-destructive method involving airflow measurement through sealed plated-through holes using an orifice plate and anemometer to determine airflow initial and exit measurements, and a probe system with air nozzles to measure back pressure, allowing for the calculation of hole diameter and defect detection, as well as a fluid bath capillary height measurement to assess plating quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If destructive testing methods are used to detect defects in plated-through holes, then defect detection capability is improved, but manufacturing time and productivity are reduced
Solution Approach 1:
The patent replaces destructive mechanical testing methods with non-destructive airflow measurement and optical inspection methods. Air is passed through the plated-through hole and measurements are taken of pressure differential, flow rate, or velocity to detect defects such as cracks, voids, or discontinuities in the plating without physically damaging the component.
Solution Approach 2:
The patent uses pneumatic principles by passing air through the plated-through hole and measuring various airflow parameters (pressure differential, flow rate, velocity) to detect defects. This non-contact method allows for rapid inspection without destroying the component, thereby improving both defect detection capability and manufacturing productivity.
2Measurement precision
If conventional inspection methods are used, then manufacturing simplicity is maintained, but defect detection accuracy is insufficient
Solution Approach 1:
The patent introduces air as an intermediary medium to detect defects in plated-through holes. By passing air through the hole and measuring airflow characteristics, the system can detect internal defects such as cracks and voids that are not visible through conventional visual inspection, thereby improving detection accuracy without requiring overly complex equipment.
Solution Approach 2:
The patent replaces complex destructive testing equipment with simpler pneumatic measurement devices such as flow meters, pressure sensors, or anemometers. These devices provide accurate defect detection while maintaining relative simplicity in the inspection system architecture.
3Productivity
If non-destructive testing methods are implemented, then productivity is improved, but measurement precision for certain defects may be reduced
Solution Approach 1:
The patent transitions from single-point visual inspection to multi-point airflow measurement along the length of the plated-through hole. By measuring pressure differential, flow rate, or velocity at multiple positions, the system can characterize defects more accurately while maintaining high inspection speed through non-destructive methodology.
Solution Approach 2:
The patent uses feedback from airflow measurement data to identify and characterize defects. Measurements of pressure differential, flow rate, or velocity are analyzed to detect anomalies in the plating, allowing for accurate defect identification while maintaining the speed advantages of non-destructive testing.
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 accurate, non-destructive detection of defects along sidewalls, preventing electrical failures and reducing waste by identifying potential issues before thermal cycling, ensuring reliable printed circuit board performance.
Implementation Method 1
measuring a pressure differential across the orifice plate
Implementation Method 2
measuring the velocity of the airflow as it passes through the plated-through hole
Implementation Method 3
measuring a capillary height difference within a plated-through hole and the surrounding fluid bath
Data Source
AI summary
A method and a system for detecting defects in plated-through hole by partially submerging a printed circuit board in a fluid bath. The method includes partially submerging a printed circuit board on a first side and measuring a capillary height difference within a plated-through hole and the surrounding fluid bath. The method further includes partially submerging the printed circuit board on a second side and measuring a second capillary height difference within the plated-through hole and the surrounding fluid bath. The method also includes comparing the measured values with predetermined values to determine the quality of the plated-through hole.