Three-dimensional inline inspection for substrate warpage and ball grid array coplanarity using stereo vision

Takeshi Nakazawa, Ayman Samara

Research output: Contribution to journalArticle

6 Citations (Scopus)


We present a method for full-field 3D measurement of substrate warpage and ball grid array coplanarity, which is suitable for inline back-end inspection and process monitoring. For evaluating the performance of the proposed system, the linearity between our system and a reference confocal microscope is studied by repeating measurements 35 times with a particular substrate sample (38 mm × 28.5 mm). The point-to-point correlation coefficient with 1σ between two methods is 0.968 ± 0.002, and the 2σ difference is 25.15 ± 0.20 μm for warpage measurement. 1σ repeatability of the substrate warpage is 4.2 μm. For BGA coplanarity inspection the bump level correlation coefficient is 0.957 ± 0.001 and the 2σ difference is 28.79 ± 0.14 μm. 1σ repeatability of BGA coplanarity is 3.7 μm. Data acquisition takes about 0.2 s for full field measurements.

Original languageEnglish
Pages (from-to)3101-3109
Number of pages9
JournalApplied Optics
Issue number14
Publication statusPublished - 10 May 2014
Externally publishedYes


ASJC Scopus subject areas

  • Atomic and Molecular Physics, and Optics

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