Characterization of Solder Defects in Package on Package
This paper is part of series of studies on X-Ray inspection technology to quantify solder defects in BGA balls.
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Authored By:
Zhen (Jane) Feng, Ph. D., David Geiger, Weifeng Liu, Ph.D., Anwar Mohammed, Murad Kurwa
AEG, FLEXTRONICS International Inc.
Milpitas, CA, USA
George Tint, Ph. D.
Saki America
Santa Clara, CA, USA
Summary
As a part of series of studies on X-Ray inspection technology to quantify solder defects in BGA balls, we have conducted inspection of 3 level POP package by using a new AXI that capable of 3D-CT imaging. The new results are compared with the results of earlier AXI measurements. It is found that 3D measurements offer better defect inspection quality, lower false call and escapes.
Conclusions
As an extended study of earlier reported projects, we have conducted inspection of solder defects on the top layer of mounted POP devices by an AXI system capable of high speed CT imaging, AXI 5.
AXI 5 produced better testing results with the top layer of POP as shown in Table 5. The interesting facts are that pCT pass/fail calls generated by AXI 5 are independent from operator judgments, and they can be automatically saved to a server to be reviewed by the engineers.
The attribute Gage RR results are in progress.
This project is still ongoing to develop a process for AXI with pCT algorithms and parameter optimization.
For POP applications, 3D imaging offer less ambiguous decisions for solder bridges, open defects while 2D or 2.5D images sometimes encounter confusion from the shadow of neighbors.
This study on POP with AXI 5 is just a start, while more packages evaluation like connectors ongoing to utilize the machine's 3D imaging capability in a wider range of applications.
Initially Published in the IPC Proceedings
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