In the field of electronics manufacturing, FPGAs (Field-Programmable Gate Arrays) are highly integrated circuit components, and the quality of their solder joints directly affects product performance and reliability. Among these factors, the precise measurement of solder joint height is one of the key indicators for evaluating soldering quality.

Testing Protocol

The solution employs a line laser profile scanning sensor to capture 3D profile data of FPGA solder joints using a non-contact measurement method. To minimize the impact of environmental noise on measurement results, the camera must be tilted approximately 10° during sensor installation. This design ingeniously leverages optical principles to effectively filter out some interference signals, thereby improving measurement accuracy.

Testing Process

1. Data Acquisition: A line laser profilometer rapidly scans the surface of the FPGA to generate high-precision 3D point cloud data.

2. Image Processing: Using specialized inspection software, the 3D point cloud data is converted into grayscale images for subsequent analysis and processing. By identifying the intersection coordinates of the lines connecting the centers of the circles in regions 1 and 4 with those in regions 2 and 3, the product is precisely positioned, ensuring a consistent reference plane for each measurement.

3. Height Calculation: In the 3D model of the positioned product, key points are selected from four square regions (1, 2, 3, and 4) to fit a reference plane. Subsequently, by calculating the height difference of each solder joint relative to this reference plane, precise height data for the solder joints is obtained.

Results

Advantages of the Solution

• High Precision: Non-contact measurement eliminates errors caused by physical contact, and the tilted camera design further enhances measurement accuracy.
• High Efficiency: Automated processes significantly reduce inspection time and improve production efficiency.
• High Stability: Through precise positioning and reference plane fitting, errors caused by uneven product placement are effectively compensated for, ensuring the stability and reliability of the data.

Addressing Testing Challenges

To meet the requirement that products remain flat during measurement, this solution optimizes the design of the measurement platform and employs high-precision positioning fixtures to ensure the stability of the FPGA throughout the measurement process. Additionally, the software’s automatic calibration feature compensates to some extent for minor surface irregularities in the product, further enhancing measurement accuracy.

Validation Testing

To verify the reliability of the solution, multiple solder joints on the FPGA were selected for 10 round-trip tests. The results showed minimal fluctuation in the height data for each solder joint, demonstrating the solution’s exceptional performance in terms of data stability.