BGA IC Height Measurement Using Inclined Laser Inspection
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Solution Overview
Problem
Automated inspection of BGA-mounted integrated circuits is limited by conventional methods, which struggle to accurately measure the integrity of solder joints due to their position on the underside of the IC package, leading to potential faults and revenue loss in manufacturing.
Innovation Solution
A method and apparatus using a horizontally offset and tilted laser measurement device to measure the height of BGA-mounted ICs by projecting a laser line onto the component and substrate, calculating the height through trigonometric calculations, and comparing it with reference data to determine correct mounting.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If Automated Optical Inspection (AOI) is used to inspect PCB-mounted ICs, then placement errors and missing components can be detected, but the integrity of solder joints cannot be measured due to their position on the underside of the IC package
Solution Approach 1:
The patent transitions from conventional top-down optical inspection to a dimensional approach that measures the height/position of the IC package relative to the PCB substrate. By measuring in the vertical dimension (Z-axis) rather than only in the horizontal plane, the system can indirectly assess solder joint integrity through package positioning, overcoming the limitation of not being able to directly observe underside solder joints.
Solution Approach 2:
The patent uses the IC package itself as an intermediary object. Instead of directly measuring the solder joints, the system measures the package's position and orientation, which are affected by the solder joint quality. The package serves as a mediator that translates solder joint conditions into measurable positional parameters.
2Device complexity
If conventional laser measurement devices are used positioned directly overhead, then the measurement setup is simple, but the accuracy is limited by the inability to capture height information of the package above the substrate
Solution Approach 1:
The patent repositions the laser measurement device from a vertical overhead position to a lateral position, and changes the measurement from a single point to an inclined plane measurement. This dimensional change allows the system to capture height information by measuring the position where the laser plane intersects the package, thereby achieving accurate height measurement while maintaining relatively simple device configuration.
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
This approach significantly increases accuracy in detecting improperly soldered components, enabling quick, cost-effective, and reliable automated inspection of solder reflow processes, surpassing the theoretical capabilities of conventional equipment.
Implementation Method 1
measuring the distance of each of a plurality of points on the electronic component from the laser measurement device by detection of backscattered light from said points
Data Source
AI summary
A method and apparatus for testing the mounting of an integrated circuit on a printed circuit board using a ball grid array comprises directing an inclined laser beam from a line scan laser sensor at the integrated circuit, detecting the position of the lower edge of the integrated circuit from laser light backscattered from the integrated circuit and printed circuit board, determining through a trigonometric calculation the height of the integrated circuit above the printed circuit board following soldering of the ball grid array and comparing the height with reference data. The integrated circuit is deemed to have been successfully mounted to the printed circuit board if the height falls within a predetermined range.