Nvidia GB200 NVSwitch Tray Redesign Issue
The reason why GB200 production delays...
Nvidia GB200 as the ODM for NVSwitch trays (Foxconn) provided feedback to NVIDIA, stating that once the overpass in the tray is fully packed, it becomes difficult to arrange the liquid cooling pipes. Additionally, if a cable inside the overpass is damaged, it is impossible to identify which specific cable is faulty, so the entire bundle of cables has to be replaced. Moreover, replacing the overpass is much more expensive than replacing the PCB.
New Solution:
The NVSwitch tray overpass has two types of cables: copper color and blue. The copper color cables connect to the compute trays within the same rack, while the blue cables (red box) connect to the NVSwitch trays in adjacent cabinets. The blue cables will be removed, leaving only the cooper color cables. After upgrading the PCB material and reducing the number of jump wires by half, the liquid cooling pipes can be smoothly placed, solving the heat dissipation issue.
NVSwitch tray PCB has been changed from a 24-layer M7 HDI board to a 22-layer M8 PTH(Plating Through Hole) PCB board. Originally, the HDI board was mainly supplied by Unimicron (60%) with Wus (40%) as the secondary supplier. The new PTH PCB board will be primarily supplied by Wus (60%) and TTM as the secondary supplier (40%).
What is Plating Through Hole (PTH)?
PTH refers to a type of circuit board connection where components are inserted into holes drilled in the board and then soldered onto the copper pads on the other side. These connections are called PTH connections because the component pins go all the way through the board instead of being surface-mounted like they would be with SMD (surface-mount device) technology. PTH connections are often used for larger or higher-power components, as well as for components that need more physical support or durability than can be achieved with SMD connections.
Why change PCB suppliers?
Unimicron, the original primary supplier, has experience with HDI boards but lacks experience with multilayer PTH PCB boards.
Wus and TTM are already the primary and secondary suppliers for NVIDIA's switch PCBs, and the new NVSwitch tray board is very similar to the switch board, so NVIDIA is continuing with the existing switch suppliers.
Timeline:
-> NVIDIA started discussing the revision in July
-> The 1st version of the new board sample was released in early September
-> Validation of the new PCB is expected to be completed by the end of October
-> ODM will need 2 months to assemble the system, so the earliest the system can be delivered to customers for validation is by the end of December
-> If everything goes smoothly, mass production of the GB200 can begin by the early Feb.
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