Composite Layers A Love or Hate Situation

haidaowang

Composite Layers A Love or Hate Situation
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" w( W" E) E% oSo Rich says, "Hey John. I just got that 4 layer CAM job from
Curkits-R-US and after CAM350 loaded them, I got 25 layers!
What the frapp is going on?"

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) s- y9 d7 I  |/ Z3 t5 E4 n% `And John says, "Doesn't Curkits-R-US use Allgro? It probably
% R- w" y$ F6 t6 C2 C4 ^contains one or more composite layers."
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& C* I8 I4 Z- G! Q! ^5 nAnd Rich responds, "I don't care if they designed it with an Etch-
% i/ z4 r4 f! a, l6 [0 j0 sO-Sketch. I don't know how to edit the stuff, or export it, or check
it, or plot it and I feel if we took the time for you to show me, we'd
/ W% b5 c4 o, F9 N) ~( |' W  Dno longer be friends."
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" @, Q" `0 L- o- t( xDoes this sound familiar? Does the word c-o-m-p-o-s-it-e cause your stomach to start twitching? This document is supposed to answer all your questions. Think of this as Rolaids for the PCB CAM.
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: I/ g6 Q: W3 B6 m9 e* What is a composite?
- Why do we have composites?
% h' I8 s! D) j+ l6 D/ H! u) E# o- How it's done in the Gerber file
: - Good things about them
6 K. U" }- K& ~  @1 c4 n5 Q% H- Bad things about them
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* A, P* R, I4 f: z* Working with composites
, L7 A5 Z0 ^; F" z! ]- How to create a composite
- How to view them
. X5 G- b  u. j- How to edit them
-HowtodoaDRC
- How to export them

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* Cautions when working with composites
- Netlist extraction and DRC
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$ [+ l+ W. b4 K; Y1 w6 c/ J) a* How to convert a multilayer composite to a single layer.
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WHAT IS A COMPOSITE


/ }# |5 f5 X1 z' {$ `***** A composite is a single layer that is made up from multiple layers. ***** **
Usually each layer has a different polarity (dark vs clear, NOT voltage!) A dark layer adds data to the plot and a clear layer removes data. This is often called paint and scratch too.

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Why do we have composites?
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8 p7 ~/ c9 }9 Z; c% b5 {8 V( }- N( j& RWhat's the easiest way to place a connecting trace on an intermal power plane? Ever try to do it? In the old days before laser plotters, you would create three different layers. One was the original plane information. Another opened up a channel or space where the trace from the third
layer was placed. Then you would leave the film in the plotter and plot each layer on top of the previous. Or, how do you shield a trace on an outside layer that begins as a solid copper area?



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CCxiaom

哎呦喂，还是英文的