Abstract
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 language | English |
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| Pages (from-to) | 3101-3109 |
| Number of pages | 9 |
| Journal | Applied Optics |
| Issue number | 14 |
| DOIs | |
| Publication status | Published - 10 May 2014 |
| Externally published | Yes |