PCB各層含義（eagle和protel）

1 Signal layer(信號(hào)層)
信號(hào)層主要用于布置電路板上的導(dǎo)線.Protel 99 SE提供了32個(gè)信號(hào)層,包括Top layer(頂層),Bottom layer(底層)和30個(gè)MidLayer(中間層).
2 Internal plane layer(內(nèi)部電源/接地層)
Protel 99 SE提供了16個(gè)內(nèi)部電源層/接地層.該類型的層僅用于多層板,主要用于布置電源線和接地線.我們稱雙層板,四層板,六層板,一般指信號(hào)層和內(nèi)部電源/接 地層的數(shù)目.

3 Mechanical layer(機(jī)械層)
Protel 99 SE提供了16個(gè)機(jī)械層,它一般用于設(shè)置電路板的外形尺寸,數(shù)據(jù)標(biāo)記,對(duì)齊標(biāo)記,裝配說明以及其它的機(jī)械信息.這些信息因設(shè)計(jì)公司或PCB制造廠家的要求 而有所不同.執(zhí)行菜單命令Design|Mechanical Layer能為電路板設(shè)置更多的機(jī)械層.另外,機(jī)械層可以附加在其它層上一起輸出顯示.
4 Solder mask layer(阻焊層)
在焊盤以外的各部位涂覆一層涂料,如防焊漆,用于阻止這些部位上錫.阻焊層用于在設(shè)計(jì)過程中匹配焊盤,是自動(dòng)產(chǎn)生的.Protel 99 SE提供了Top Solder(頂層)和Bottom Solder(底層)兩個(gè)阻焊層.
5 Paste mask layer(錫膏防護(hù)層)
它和阻焊層的作用相似,不同的是在機(jī)器焊接時(shí)對(duì)應(yīng)的表面粘貼式元件的焊盤.Protel 99 SE提供了Top Paste(頂層)和Bottom Paste(底層)兩個(gè)錫膏防護(hù)層.
6 Keep out layer(禁止布線層)
用于定義在電路板上能夠有效放置元件和布線的區(qū)域.在該層繪制一個(gè)封閉區(qū)域作為布線有效區(qū),在該區(qū)域外是不能自動(dòng)布局和布線的.
7 Silkscreen layer(絲印層)
絲印層主要用于放置印制信息,如元件的輪廓和標(biāo)注,各種注釋字符等.Protel 99 SE提供了Top Overlay和Bottom Overlay兩個(gè)絲印層.一般,各種標(biāo)注字符都在頂層絲印層,底層絲印層可關(guān)閉.
8 Multi layer(多層)
電路板上焊盤和穿透式過孔要穿透整個(gè)電路板,與不同的導(dǎo)電圖形層建立電氣連接關(guān)系,因此系統(tǒng)專門設(shè)置了一個(gè)抽象的層,多層.一般,焊盤與過孔都要設(shè)置在多 層上,如果關(guān)閉此層,焊盤與過孔就無法顯示出來.
9 Drill layer(鉆孔層)
鉆孔層提供電路板制造過程中的鉆孔信息(如焊盤,過孔就需要鉆孔).Protel 99 SE提供了Drill gride(鉆孔指示圖)和Drill drawing(鉆孔圖)兩個(gè)鉆孔層.
相應(yīng)的在eagle中也有很多的層（常用的用綠色標(biāo)記）
In Layout and Package Editor
1 Top Tracks, top side
2 Route2 Inner layer (signal or supply)
3 Route3 Inner layer (signal or supply)
4 Route4 Inner layer (signal or supply)
5 Route5 Inner layer (signal or supply)
6 Route6 Inner layer (signal or supply)
7 Route7 Inner layer (signal or supply)
8 Route8 Inner layer (signal or supply)
9 Route9 Inner layer (signal or supply)
10 Route10 Inner layer (signal or supply)
11 Route11 Inner layer (signal or supply)
12 Route12 Inner layer (signal or supply)
13 Route13 Inner layer (signal or supply)
14 Route14 Inner layer (signal or supply)
15 Route15 Inner layer (signal or supply)
16 Bottom Tracks, bottom side
17 Pads Pads (through-hole)元件的引腳（過孔型，貼片引腳算在頂層和底層上）
18 Vias Vias (through all layers)過孔
19 Unrouted Airlines (rubber bands)
20 Dimension Board outlines (circles for holes) *)板子外形，相當(dāng)于機(jī)械層
21 tPlace Silk screen, top side絲印層
22 bPlace Silk screen, bottom side絲印層
23 tOrigins Origins, top side (generated autom.)元件中間有個(gè)十字叉，代表元件位置
24 bOrigins Origins, bottom side (generated autom.)
25 tNames Service print, top side (component NAME)
26 bNames Service print, bottom s. (component NAME)
27 tValues Component VALUE, top side
28 bValues Component VALUE, bottom side
21~28制版時(shí)可全部放在絲印層
29 tStop Solder stop mask, top side (gen. autom.)
30 bStop Solder stop mask, bottom side (gen. Autom.)
31 tCream Solder cream, top side
32 bCream Solder cream, bottom side
33 tFinish Finish, top side
34 bFinish Finish, bottom side
35 tGlue Glue mask, top side
36 bGlue Glue mask, bottom side
37 tTest Test and adjustment information, top side
38 bTest Test and adjustment inf., bottom side
39 tKeepout Restricted areas for components, top side
40 bKeepout Restricted areas for components, bottom s.
41 tRestrict Restricted areas for copper, top side
42 bRestrict Restricted areas for copper, bottom side
43 vRestrict Restricted areas for vias
44 Drills Conducting through-holes
45 Holes Non-conducting holes
46 Milling Milling
47 Measures Measures
48 Document Documentation
49 Reference Reference marks
51 tDocu Detailed top screen print
52 bDocu Detailed bottom screen print