叠层设置中的Shield一项是做什么用的啊！拜托了~

布线参考层，计算阻抗用的。

不是吧，shield是屏蔽的意思吧，我查的资料上说地层和电源层这样设置好像是和电流回路有关，是不是和保证地层和电源层的完整性相关?

或者是屏蔽那一层的走线，但这样设置就管用吗

同样问shield选项是怎么用的

请高手们指教一下?

By using the Setup > Cross-section form you can define how the
board stackup will be built. The board must have at least one internal plane that is defined
as ‘Shielded’. This is necessary for simulating correctly in Allegro SI. Inside the Allegro
SI tool is a calculator tool that helps the engineer decide the width of the trace to route to
achieve the required impedance。
标注为屏蔽层，就是用来计算阻抗的（参考平面）。