VR2-0367
① SA Source
- Source: 開啟完整 SA 文章
- Section:
PCB Materials Upgrade and Area Growth - Line hint:
469
Context Before
Copper foil content in Rubin is upgraded from HVLP2 to HVLP4 grade copper foil for the signal layers. As discussed earlier, due to the skin effect, smoother copper foil equals to lower insertion loss. HVLP is the classification of copper foil standing for Ultra-Low Profile Copper Foil. The higher the HVLP grade equals to lower surface roughness.
For the power layers, the additional layers in Strata compared to Blackwell are mostly power layers to accommodate more power going into the GPU. By adding more dedicated power layers, cross talk is reduced as power layers and signal layers are separated. Power layer copper foils are much thicker to insulate the current travelling through it.
Evidence
Beside glass fiber cloth, resin is also a key factor contributing to dielectric constant
Context After
Quartz cloth is the next generation material that replaces the glass fiber cloth materials as the reinforcing layer, pushing dielectric constant even lower. Besides lower dielectric constant, quartz cloth also has the benefits of being stronger, more temperature resistance, and having a lower CTE. On the other hand, the cost is multiples higher than that of the highest-grade glass fiber cloth and is much harder to process at the PCB manufacturing level, leading to worse yield.
Within VR NVL72, Quartz is initially adopted for the Orchid board and the midplane to allow the longest distance PCIe Gen 6 signal traveling through these two boards with as little insertion loss as possible. However, given the cost of the Quartz cloth and the difficulty in Q cloth processing, Nvidia is currently exploring the option of downgrading back to glass fiber cloth. The final decision is pending on the signal performance with the downgraded glass fiber cloth.
② Atomic Claim
除了 glass fiber cloth，resin 也是影響 dielectric constant 的關鍵因素。
- Epistemic Mode:
ASSERTED - Mapping Status:
PARTIAL
③ Semantic Frame
{
"attribute": "UNSPECIFIED_ATTRIBUTE",
"context_nodes": [],
"entity": {
"id": "04_knowledge_base/高階玻纖布",
"label": "glass fiber cloth"
},
"frame_type": "ATTRIBUTE",
"qualifiers": {
"condition_text": null,
"numeric_mentions": [],
"temporal_mentions": []
},
"value": {
"numeric_mentions": [],
"value_text": "除了 glass fiber cloth，resin 也是影響 dielectric constant 的關鍵因素。"
}
}④ Canonical Entity Mapping
| Role | Surface Label | Canonical Target |
|---|---|---|
| entity | glass fiber cloth | 04_knowledge_base/高階玻纖布 |
⑤ Human Review
請在 Properties 逐項確認：
- 原文 → Atomic Claim 是否忠實
- Atomic Claim → Semantic Frame 是否忠實
- Canonical Entity mapping 是否正確
- Epistemic mode 是否保留原文語氣
- 最後選擇
review_action
Review state
Markdown 內文不是正式 approval。只有 Apply bridge 寫入的 Decision Ledger event 才是正式決策。