VR2-0327
① SA Source
- Source: 開啟完整 SA 文章
- Section:
PCB vs Flyover Cables - Line hint:
433
Context Before
Source: DesignCon, Circuit Foil Luxembourg
Conductor loss is driven by copper surface roughness. As signals travel down the copper traces in the PCB, energy is lost due to the resistance in copper. At higher frequencies, the signal traveling through the copper crowds toward the surface of the trace, which is known as the skin effect. On top of the natural resistance of copper, if the surface is rough, the current will not travel along a uniform path incurring more resistance and loss.
Evidence
Dielectric loss scales with frequency, hence dielectric loss is a dominant limiter of signal performance of long reach PCB traces
Context After
Geometry loss describes the insertion loss incurred from abrupt structures of the PCB traces. Real PCB channels include many abrupt structures, such as vias and layer swaps. These are like bumps in a highway, and signals could reflect backward and be interrupted increasing insertion loss.
Another factor that affects signal performance is cross-talk. Given the increase in the number of I/Os per GPU, lane density in the PCB also increases. Cross-talk describes the scenario where the copper traces are too close to each other and the signal from one lane affects the signal in a neighboring lane. Some copper traces are designed for power as well. When the power lanes are too close to the signal lanes, noise from the power lanes can also modulate the signal as well.
② Atomic Claim
Dielectric loss 會隨頻率提高，因此是 long-reach PCB traces signal performance 的主要限制之一。
- Epistemic Mode:
ASSERTED - Mapping Status:
PARTIAL
③ Semantic Frame
{
"attribute": "UNSPECIFIED_ATTRIBUTE",
"context_nodes": [],
"entity": {
"id": "04_knowledge_base/PCB",
"label": "PCB"
},
"frame_type": "ATTRIBUTE",
"qualifiers": {
"condition_text": null,
"numeric_mentions": [],
"temporal_mentions": []
},
"value": {
"numeric_mentions": [],
"value_text": "Dielectric loss 會隨頻率提高，因此是 long-reach PCB traces signal performance 的主要限制之一。"
}
}④ Canonical Entity Mapping
| Role | Surface Label | Canonical Target |
|---|---|---|
| entity | PCB | PCB |
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。