1. PCB LAYERS
IN LAYOUT
Prepared by:
Anum Mairaj

2. TYPE OF LAYERS IN
PCB LAYOUT
GLOBAL LAYER
1.GLOBAL LAYER
“The boundary or outline around
a component on PCB, where any
other component is not enter, this
layer is known as global layer.”
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3
2
1
6
5
4
7 8
11
10
9
14
13
12

3. 2. TOP LAYER
“In solder mount assembly, the layer which
are at the top of PCB where are mounted,
called TOP layer. This layer is normally
green in colour.”
3. BOT (BOTTOM) LAYER
“In through hole, where the components
are soldered, this layer is called BOT
(BOTTOM) layer.”

4. 5. SMT (Solder Mask Top)
“On the top of PCB Solder mask is a thin layer of polymer that
is usually applied to the copper traces of a printed circuit
board (PCB) for protection against oxidation.”
6. SMB (Solder Mask Bottom)
“The green layer which is on the bottom of PCB, coated with
solder mask, called SMB (Solder Mask Bottom).”
With Solder Mask Without Solder Mask

5. 7. SPT (Solder Paste Top)
“The layer which is on the top of PCB, use to define the area
of solder paste on the pad of any component, this is called
SPT (Solder Paste Top).”
8. SPB (Solder Paste Bottom)
“On the bottom of PCB, the layer is use to define the area of
solder paste on pad of any component, called SPB (Solder
Paste Bottom).”
PAD OF COMPONENT
SOLDER PASTE LAYER

6. 9. SST (Silk Screen Top)
“Line, art and text may be printed onto the top surface of PCB
usually by screen printing epoxy ink, the layer use to represent
the area of the text is known as SST (Silk Screen Top).”
10. SSB (Silk Screen Bottom)
“Line art and text may be printed onto the bottom surface
of PCB usually by screen printing epoxy ink, the layer use
to represent the area of the text is known as SSB (Silk Screen
Bottom).”

7. 11. AST (ASSEMBLY TOP)
“The size or shape of any component is
define on the top of PCB, through layer
called AST (Assembly Top).”
Assembly layer
12. ASB (ASSEMBLY BOTTOM) layer
“The size or shape of any component
is define on the bottom of PCB, through
layer called ASB (Assembly BOTTOM).”

8. 4. INNER LAYER
“In multilayer PCB, the central
or mid Layer is present between
top and bottom layer, called
INNER layer of PCB.”
13. DRL (DRILL LAYER)
“The layer which is use to define the diameter
or size of drill on pad of any component, is
known as DRL (DRILL LAYER).”
DRILL LAYER
PAD OF COMPONENT