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4.2.4 Heatsinks ............................................................................................................ 44
4.2.5 Shielded components ......................................................................................... 44
4.3 Power Supply .............................................................................................................. 45
4.3.1 Mains .................................................................................................................. 45
4.3.2 Voltage regulators .............................................................................................. 45
4.3.3 Switching mode power supplies ......................................................................... 46
4.4 Routing ....................................................................................................................... 47
4.4.1 Clock distribution ................................................................................................ 47
4.4.2 Guarding ............................................................................................................. 48
4.4.3 Stubs ................................................................................................................... 49
4.5 System design ............................................................................................................. 49
4.5.1 Chassis grounding ............................................................................................... 49
4.5.2 Cables ................................................................................................................. 50
4.5.3 Connectors ......................................................................................................... 51
4.6 ESD & Safety ............................................................................................................... 52
4.6.1 Connectors ......................................................................................................... 52
4.6.2 Sensitive pins .......................................................................................................... 54
4.6.3 High Voltage ........................................................................................................... 54
5. Design for Test ............................................................................................................... 55
5.1 Test Points .................................................................................................................. 55
5.2 Tooling Pins ................................................................................................................ 55
5.3 Push fingers ................................................................................................................ 56
5.4 Sealing ........................................................................................................................ 56
5.5 AOI .............................................................................................................................. 56
6. Design for Manufacture ................................................................................................. 57
6.1 Stackup ....................................................................................................................... 57
6.1.1 Symmetry ........................................................................................................... 57
6.1.2 Drill pairs ............................................................................................................. 57
6.1.3 Copper balance ................................................................................................... 58
6.2 Design Rules Check ..................................................................................................... 59
6.2.1 Clearance ............................................................................................................ 59
6.2.2 Width .................................................................................................................. 60
6.2.3 Annular Ring ....................................................................................................... 60
6.2.4 Slivers .................................................................................................................. 60
6.2.5 Acid Traps ........................................................................................................... 61
6.2.6 Silkscreen Over Pads ........................................................................................... 62
6.3 Mechanical ................................................................................................................. 62
6.3.1 Mechanical Drawings ......................................................................................... 62
6.3.2 Drill Drawings ..................................................................................................... 63
6.3.3 Slots .................................................................................................................... 63
6.3.4 Mounting holes .................................................................................................. 64
6.3.5 Panelization ........................................................................................................ 64
6.3.6 PCB manufacturing specifications ...................................................................... 65
6.4 Assembly Considerations ........................................................................................... 66
6.4.1 Assembly Flow .................................................................................................... 66
6.4.2 Stencils ................................................................................................................ 66
6.4.3 Panelized Assembly ............................................................................................ 67
6.4.4 Decals ................................................................................................................. 67
6.4.5 Fiducials .............................................................................................................. 68
