OCT versus x-ray imaging in the inspection of ball grid arrays (BGAs)

Sorina Coroban; Corina Anca Mnerie; Virgil-Florin Duma

doi:10.1117/12.2673194

15 August 2023 OCT versus x-ray imaging in the inspection of ball grid arrays (BGAs)

Sorina Coroban, Corina Anca Mnerie, Virgil-Florin Duma

Proceedings Volume 12618, Optical Measurement Systems for Industrial Inspection XIII; 1261825 (2023) https://doi.org/10.1117/12.2673194
Event: SPIE Optical Metrology, 2023, Munich, Germany

Conference Poster

Abstract

In the automotive industry it is necessary to automatically inspect Ball Grid Arrays (BGAs) components. As BGAs are surface-mounted devices that are soldered on a Printed Circuit Board (PCB), they have soldered balls fixed on their bottom. In order for such a device to work properly, it is important that these balls do not create „bridges” between them when they are soldered to the PCB. In order to verify this aspect in the industry, X-ray imaging is utilized for the inspection of BGA components. The aim of this work is to assess the capability of Optical Coherence Tomography (OCT) to perform the inspection of solder bridges, as well as to try to image the integrated circuits located inside a BGA component. A second aim is to compare the performances of OCT and X-ray imaging for such purposes. We utilized an industrial X-ray system and an in-house developed SS-OCT system working at 1310 nm, the latter characterized by an axial resolution of 15 μm. Five BGA components were inspected and the obtained images were utilized to perform the proposed comparison. While using OCT one cannot penetrate the upper layers of the BGAs, proof-of-concept 3D OCT images were obtained from the bottom of the investigated components. Therefore, X-ray imaging remains to be utilized for the inspection of components after they are soldered on the PCB, whereas OCT is only able to inspect smaller unsoldered components. However, OCT proves to be a viable method to cover the existing gap in the process because it can inspect the surface of the solder balls before entering the production area. While the industrial X-ray imaging used for this research is not able to inspect individual BGA components, OCT can perform this task. Therefore, using OCT could prevent supplying defect components to be soldered on the PCB.

Citation Download Citation

Sorina Coroban, Corina Anca Mnerie, and Virgil-Florin Duma "OCT versus x-ray imaging in the inspection of ball grid arrays (BGAs)", Proc. SPIE 12618, Optical Measurement Systems for Industrial Inspection XIII, 1261825 (15 August 2023); https://doi.org/10.1117/12.2673194

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