The manufacturing lines are huge. Building 20 has two floors with 11 SMD lines each on south wing and two floors with 12 SMD lines on north wing, for a total of 46 SMD lines.

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Figure 11: Some of the 46 SMD lines from ECSM.
The manual insertion area is a little bit smaller, with two floors with four lines each, for a total of eight manual insertion lines. These lines are very long, as you can see on Figure 12.

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Figure 12: One of the eight manual insertion lines on Building 20.

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Figure 13: Detail of the manual insertion line.
The third main step on a motherboard manufacturing process is testing. Build 20 has two floors with four testing lines each on south wing and two floors with two testing lines each on north wing, so this factory has total of 12 testing lines.
All motherboards are individually tested. The tests are performed in two steps. On first step the manufacturer simply tests if the motherboard turns on. On second step all motherboard features are tested. It is important to notice that all motherboards are tested.

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Figure 14: First testing step.

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Figure 15: One of the testing lines (second step).