3D Solder Ball Coplanarity Measurement Solution for Advanced Semiconductor Packaging

Project Background

In semiconductor packaging, solder balls are the core elements for electrical connectivity between the chip and substrate. The consistency of their height—specifically, coplanarity—directly dictates final product yield.

A prominent semiconductor assembly and test manufacturer encountered severe process bottlenecks on their advanced production line. Dealing with DUTs characterized by microscopic sizes and ultra-fine pitch, the client needed a robust solution to measure the solder ball apex height relative to the reference plane, requiring error control within minimal limits.

Core Challenges

Extremely Microscopic Targets:

Diameter: 200μm

Height: 230μm

Pitch:400 μm

Strict Tolerance Requirements:

The height difference of all solder ball apexes relative to the reference plane must be controlled within ≤20μm

High Stability Demands:

The system must maintain exceptional consistency during continuous, high-frequency measurements to avoid misjudgments caused by equipment jitter or algorithmic errors.

Raw Image

The Solution

We implemented an advanced, high-precision 3D vision measurement system combined with a customized plane-fitting algorithm to provide a one-stop inspection solution for the client.

• High-Resolution Imaging:Targeting the microscopic solder ball structure, we configured high-resolution industrial cameras (supporting up to 20MP). This ensures the capture of clear edges and morphological details even within a microscopic field of view.

• Intelligent Plane Fitting Algorithm:Within the testing area (a single grid of 78 solder balls), the system employs a method of randomly selecting multiple grid groups for reference plane fitting. This approach effectively filters out interference caused by substrate warpage, accurately calculating the height of each solder ball relative to the "true reference plane."

• Robust Testing Process:The solution established a mechanism for 100 continuous height measurements to verify the system's stability over long-term operation.

SQ081017 (81 Mega pixel) 

SQ162053( 16.2 Mega pixel) 

Measurement Results & Effectiveness

Field testing demonstrated that the solution delivered superior performance, fully meeting and exceeding the client's expectations:

Zero Data Loss: Under complex reflection conditions, point cloud completeness reached 100%, with no blind spots or data defects.

Extreme Repeatability: Across 100 continuous tests, area repeatability precision stabilized within $\le 2\,\mu m$, far surpassing industry standards.

Perfect Morphology Reconstruction: Solder ball integrity was rated as "High," enabling precise identification of defective parts with height anomalies.

Full Compliance: Measurement results completely satisfied the process tolerance requirements, ensuring the reliability of the client's shipped products.