+44 (0)1992 510000 Manufacturing Processes for a 4 Layer Multi-layer PCB The following presentation covers the main processes during the production of a 4 layer.
Download ReportTranscript +44 (0)1992 510000 Manufacturing Processes for a 4 Layer Multi-layer PCB The following presentation covers the main processes during the production of a 4 layer.
Slide 1
Slide 2
+44 (0)1992 510000
Manufacturing Processes for a 4 Layer Multi-layer PCB
The following presentation
covers the main processes
during the production of
a 4 layer or a multi-layer PCB.
Tracks under solder mask
Via hole
The diagrams which follow
represent a section through
a PCB, as indicated
in red.
SMD Pad
Section through PCB
Slide 3
+44 (0)1992 510000
Typical Layer Construction - 4 Layer PCB
Copper
Layer 1 (Outer)
Laminate
COPPER FOIL
PRE-PREG
Layer 2 (Inner)
Layer 3 (Inner)
INNER LAYER (CORE)
4 Layer PCB’s
PRE-PREG
Layer 4 (Outer)
COPPER FOIL
1.
Multilayer PCB’s have
inner tracking layers which
are individually processed
layer pairs which require
bonding and connecting to
form the finished PCB.
Slide 4
+44 (0)1992 510000
Inner Layer Processing
Copper
Laminate (Dielectric)
Layer 2 (Inner)
Core
Layer 3 (Inner)
• For Multilayer PCB’s Inner
layer Core materials are
usually processed as “Layer
pairs”
• Core materials can be
typically 0.2mm thick which
come pre coated with a ½ oz
copper foil.
Slide 5
+44 (0)1992 510000
Laminating and Imaging of Internal Layers
UV sensitive film is laminated over top and bottom
surfaces of the Core
Areas of the Core where no copper is required are
left exposed
Inner Layer Imaging
Layer 2 (Inner)
Core
Layer 3 (Inner)
• The addition of the inner layer
track patterns to layers 2 and
3.
Slide 6
+44 (0)1992 510000
Etch Process - Remove Exposed Copper
Copper Removed
Inner Layer Etching
Layer 2 (Inner)
Core
Layer 3 (Inner)
• The etch process produces
an ‘etch back’ or undercut of
the tracks. This can be
specified by the W / W1
parameters
• This means that tracks will
end up approximately
0,025 mm (0.001”) thinner
than the original design.
Slide 7
+44 (0)1992 510000
Remove Laminating Film
Film Strip
Layer 2 (Inner)
Core
Layer 3 (Inner)
• The laminated film is
removed prior to AOI
inspection.
Slide 8
+44 (0)1992 510000
Completed Inner Layer Core
All inner layer Core materials are processed as
“Layer Pairs” prior to Bonding
At this stage the Cores are inspected visually
(AOI) and defective Cores rejected
Sometimes a surface treatment is applied to the
Cores to aid with the Bonding process
AOI Inspection
Layer 2 (Inner)
Core
Layer 3 (Inner)
• Automatic Optical Inspection
(AOI).
• Inner layers are scanned and
compared to Gerber data for
errors.
Slide 9
+44 (0)1992 510000
Layer stackup
Layer 1 (Outer)
FOIL
PRE-PREG
Layer 2 (Inner)
Layer 3 (Inner)
INNER LAYER
PRE-PREG
Layer 4 (Outer)
FOIL
Layer Stackup
•
•
Layer 1 (Outer)
FOIL
Layer 2 (Inner)
PRE-PREG
Layer 3 (Inner)
INNER LAYER
Layer 4 (Outer)
PRE-PREG
FOIL
The order in which the
layers are to be bonded
together.
The outer layer copper
foils, layers 1 and 4 are
purchased in sheet form.
For a 1 oz finished copper
weight typically a ½ oz foil
would be used during
bonding process to form
the outer layers.
Slide 10
+44 (0)1992 510000
Layer stackup
Layer 1 (Outer)
FOIL
PRE-PREG
Layer 2 (Inner)
Layer 3 (Inner)
INNER LAYER
PRE-PREG
Layer 4 (Outer)
FOIL
Layer 1 (Outer)
FOIL
Layer 2 (Inner)
PRE-PREG
Layer 3 (Inner)
INNER LAYER
Layer 4 (Outer)
PRE-PREG
FOIL
Slide 11
+44 (0)1992 510000
Layer stackup
Layer 1 (Outer)
FOIL
PRE-PREG
Layer 2 (Inner)
Layer 3 (Inner)
INNER LAYER
PRE-PREG
Layer 4 (Outer)
FOIL
Layer 1 (Outer)
FOIL
Layer 2 (Inner)
PRE-PREG
Layer 3 (Inner)
INNER LAYER
Layer 4 (Outer)
PRE-PREG
FOIL
Slide 12
+44 (0)1992 510000
Layer stackup
Layer 1 (Outer)
FOIL
PRE-PREG
Layer 2 (Inner)
Layer 3 (Inner)
INNER LAYER
PRE-PREG
Layer 4 (Outer)
FOIL
Layer 1 (Outer)
FOIL
Layer 2 (Inner)
PRE-PREG
Layer 3 (Inner)
INNER LAYER
Layer 4 (Outer)
PRE-PREG
FOIL
Slide 13
+44 (0)1992 510000
Layer stackup
Layer 1 (Outer)
FOIL
PRE-PREG
Layer 2 (Inner)
Layer 3 (Inner)
INNER LAYER
PRE-PREG
Layer 4 (Outer)
FOIL
Layer 1 (Outer)
FOIL
Layer 2 (Inner)
PRE-PREG
Layer 3 (Inner)
INNER LAYER
Layer 4 (Outer)
PRE-PREG
FOIL
Slide 14
+44 (0)1992 510000
Layer stackup
Layer 1 (Outer)
FOIL
PRE-PREG
Layer 2 (Inner)
Layer 3 (Inner)
PRE-PREG
Layer 4 (Outer)
FOIL
Layer 1 (Outer)
FOIL
Layer 2 (Inner)
PRE-PREG
Layer 3 (Inner)
INNER LAYER
Layer 4 (Outer)
PRE-PREG
FOIL
Slide 15
+44 (0)1992 510000
Layer stackup
Layer 1 (Outer)
FOIL
PRE-PREG
Layer 2 (Inner)
Layer 3 (Inner)
PRE-PREG
Layer 4 (Outer)
FOIL
Layer 1 (Outer)
FOIL
Layer 2 (Inner)
PRE-PREG
Layer 3 (Inner)
INNER LAYER
Layer 4 (Outer)
PRE-PREG
FOIL
Slide 16
+44 (0)1992 510000
Layer stackup
Layer 1 (Outer)
FOIL
PRE-PREG
Layer 2 (Inner)
Layer 3 (Inner)
PRE-PREG
Layer 4 (Outer)
FOIL
Layer 1 (Outer)
FOIL
Layer 2 (Inner)
PRE-PREG
Layer 3 (Inner)
INNER LAYER
Layer 4 (Outer)
PRE-PREG
FOIL
Slide 17
+44 (0)1992 510000
Bonding – Heat
Layer 1 (Outer)
FOIL
PRE-PREG
Layer 2 (Inner)
Layer 3 (Inner)
PRE-PREG
Layer 4 (Outer)
FOIL
Bonding
Layer 1 (Outer)
FOIL
Layer 2 (Inner)
PRE-PREG
Layer 3 (Inner)
INNER LAYER
Layer 4 (Outer)
PRE-PREG
FOIL
• Once the layers are built up
heat is applied over a period
of time, this is to allow the
Pre-Preg material time to
melt and flow evenly between
the layers, this is in effect the
material that sticks the layers
together.
Slide 18
+44 (0)1992 510000
Bonding – Multilayer Press
Layer 1 (Outer)
FOIL
PRE-PREG
Layer 2 (Inner)
Layer 3 (Inner)
PRE-PREG
Layer 4 (Outer)
FOIL
Bonding
• Layers are pressed together
over a set period of time
typically a bonding cycle will
last for approx. 4 hours.
• Bonding capacity would
depend on the number of
openings and size of press.
Slide 19
+44 (0)1992 510000
Drilling of a Panel
Copper
Laminate
Drilled Hole
Layer 1
Drilling
Layer 4
• The holes are drilled for both
thru-hole components and via
connections. Once plated this
will form the connection from
1 side of the PCB to the
other, at the same time
connecting the inner layers
where required.
Slide 20
+44 (0)1992 510000
Electroless Copper Process
Addition of Copper to all Exposed Surfaces
Copper
Drilled Hole
Layer 1
Layer 2
Plating
Layer 3
Layer 4
• Plating is the same process
for 2 or 4 Layer.
• The aim is plate down the
barrel of the hole to make the
connection from 1 side of the
PCB to the other.
Slide 21
+44 (0)1992 510000
Laminating and Imaging of External Layers
UV sensitive film is laminated over top and bottom
surfaces of PCB
It is then exposed and developed, leaving an
exposed image of the PCB pattern
Layer 1
Imaging
Layer 2
• The outer layer track patterns
are photo-imaged onto the
panels using UV sensitive
film.
Layer 3
Layer 4
Copper
Slide 22
+44 (0)1992 510000
Electro-plating Process 1
Additional Copper to all Exposed Surfaces
Laminated Film
Plate Additional Copper
Layer 1
Layer 2
Layer 3
Layer 4
Plating
• Electro-plating increases the
copper thickness on the outer
layers and through the barrel of
the hole. The copper foils for a 4
layer or the starting copper
weight on 2 layer boards is most
commonly ½ oz the plating then
increases the finished copper
weight to the desired 1oz each
side.
Slide 23
+44 (0)1992 510000
Electro-plating Process 2
Add Tin over Exposed Copper Areas
Laminated Film
Additional Copper
Tin Plating
Layer 1
Layer 2
Layer 3
Layer 4
Tin Plating
• A tin plate is added to all
exposed copper areas, this
act as a mask during the
etching process.
Slide 24
+44 (0)1992 510000
Electro-plating Process 3
Remove Laminated Film
Laminated Film Removed
Tin Plating
Layer 1
Film Strip
Layer 2
Layer 3
Layer 4
• The laminated film is
removed to expose copper
areas ready for the etching
process.
Slide 25
+44 (0)1992 510000
Etch Process - Remove Exposed Copper
Copper Removed
Tin Plating
Layer 1
Etching Process
Layer 2
Layer 3
Layer 4
• The etching process removes
unwanted areas of copper.
• The etch process produces
an ‘etch back’ or undercut of
the tracks.
• This means that tracks will
end up approximately
0,025 mm (0.001”) thinner
than the original design.
Slide 26
+44 (0)1992 510000
Tin Strip - Remove Tin Plating
Tin Plating Removed
Layer 1
Tin Strip
Layer 2
Layer 3
Layer 4
• The Removal of Tin will very
slightly reduce the copper
thickness (T) on the outer
layers
Slide 27
+44 (0)1992 510000
PCB is now complete except for
surface finishes and panel routing/punching
Tracks
Via Hole
SMD Pad
Layer 1
Layer 4
Tracks
Slide 28
+44 (0)1992 510000
Solder Mask Application
Image, Develop and Cure
UV Image, Develop and Cure
Layer 1
Solder Mask
Layer 4
• The image is semi cured and
then UV image exposed.
• Any areas that are not
exposed to the UV light are
then dissolved in the
developer, exposing the
areas where the final surface
finish is required.
Slide 29
+44 (0)1992 510000
Surface Finish Process
Apply Solder to Exposed Copper Areas
Layer 1
Surface Finish
Layer 4
• Surface Finish (Tin / Lead,
Gold, Silver, OSP, Tin) is
usually only added to pads.
The solder mask prevents
coating of any other areas.
Slide 30
+44 (0)1992 510000
Component Ident
SCL2 9624
R 34
Ident / Silk Screen
• An optional component Ident
or Silk Screen is printed onto
the PCB.
IC 3
Slide 31
+44 (0)1992 510000
Routing or Punching
Routing or Punching
• The circuit profile is then
punched or routed.
Slide 32
+44 (0)1992 510000
Testing and Inspection
All PCB’s are 100% Electrically tested
All PCB’s are 100% Visually Inspected
Slide 2
+44 (0)1992 510000
Manufacturing Processes for a 4 Layer Multi-layer PCB
The following presentation
covers the main processes
during the production of
a 4 layer or a multi-layer PCB.
Tracks under solder mask
Via hole
The diagrams which follow
represent a section through
a PCB, as indicated
in red.
SMD Pad
Section through PCB
Slide 3
+44 (0)1992 510000
Typical Layer Construction - 4 Layer PCB
Copper
Layer 1 (Outer)
Laminate
COPPER FOIL
PRE-PREG
Layer 2 (Inner)
Layer 3 (Inner)
INNER LAYER (CORE)
4 Layer PCB’s
PRE-PREG
Layer 4 (Outer)
COPPER FOIL
1.
Multilayer PCB’s have
inner tracking layers which
are individually processed
layer pairs which require
bonding and connecting to
form the finished PCB.
Slide 4
+44 (0)1992 510000
Inner Layer Processing
Copper
Laminate (Dielectric)
Layer 2 (Inner)
Core
Layer 3 (Inner)
• For Multilayer PCB’s Inner
layer Core materials are
usually processed as “Layer
pairs”
• Core materials can be
typically 0.2mm thick which
come pre coated with a ½ oz
copper foil.
Slide 5
+44 (0)1992 510000
Laminating and Imaging of Internal Layers
UV sensitive film is laminated over top and bottom
surfaces of the Core
Areas of the Core where no copper is required are
left exposed
Inner Layer Imaging
Layer 2 (Inner)
Core
Layer 3 (Inner)
• The addition of the inner layer
track patterns to layers 2 and
3.
Slide 6
+44 (0)1992 510000
Etch Process - Remove Exposed Copper
Copper Removed
Inner Layer Etching
Layer 2 (Inner)
Core
Layer 3 (Inner)
• The etch process produces
an ‘etch back’ or undercut of
the tracks. This can be
specified by the W / W1
parameters
• This means that tracks will
end up approximately
0,025 mm (0.001”) thinner
than the original design.
Slide 7
+44 (0)1992 510000
Remove Laminating Film
Film Strip
Layer 2 (Inner)
Core
Layer 3 (Inner)
• The laminated film is
removed prior to AOI
inspection.
Slide 8
+44 (0)1992 510000
Completed Inner Layer Core
All inner layer Core materials are processed as
“Layer Pairs” prior to Bonding
At this stage the Cores are inspected visually
(AOI) and defective Cores rejected
Sometimes a surface treatment is applied to the
Cores to aid with the Bonding process
AOI Inspection
Layer 2 (Inner)
Core
Layer 3 (Inner)
• Automatic Optical Inspection
(AOI).
• Inner layers are scanned and
compared to Gerber data for
errors.
Slide 9
+44 (0)1992 510000
Layer stackup
Layer 1 (Outer)
FOIL
PRE-PREG
Layer 2 (Inner)
Layer 3 (Inner)
INNER LAYER
PRE-PREG
Layer 4 (Outer)
FOIL
Layer Stackup
•
•
Layer 1 (Outer)
FOIL
Layer 2 (Inner)
PRE-PREG
Layer 3 (Inner)
INNER LAYER
Layer 4 (Outer)
PRE-PREG
FOIL
The order in which the
layers are to be bonded
together.
The outer layer copper
foils, layers 1 and 4 are
purchased in sheet form.
For a 1 oz finished copper
weight typically a ½ oz foil
would be used during
bonding process to form
the outer layers.
Slide 10
+44 (0)1992 510000
Layer stackup
Layer 1 (Outer)
FOIL
PRE-PREG
Layer 2 (Inner)
Layer 3 (Inner)
INNER LAYER
PRE-PREG
Layer 4 (Outer)
FOIL
Layer 1 (Outer)
FOIL
Layer 2 (Inner)
PRE-PREG
Layer 3 (Inner)
INNER LAYER
Layer 4 (Outer)
PRE-PREG
FOIL
Slide 11
+44 (0)1992 510000
Layer stackup
Layer 1 (Outer)
FOIL
PRE-PREG
Layer 2 (Inner)
Layer 3 (Inner)
INNER LAYER
PRE-PREG
Layer 4 (Outer)
FOIL
Layer 1 (Outer)
FOIL
Layer 2 (Inner)
PRE-PREG
Layer 3 (Inner)
INNER LAYER
Layer 4 (Outer)
PRE-PREG
FOIL
Slide 12
+44 (0)1992 510000
Layer stackup
Layer 1 (Outer)
FOIL
PRE-PREG
Layer 2 (Inner)
Layer 3 (Inner)
INNER LAYER
PRE-PREG
Layer 4 (Outer)
FOIL
Layer 1 (Outer)
FOIL
Layer 2 (Inner)
PRE-PREG
Layer 3 (Inner)
INNER LAYER
Layer 4 (Outer)
PRE-PREG
FOIL
Slide 13
+44 (0)1992 510000
Layer stackup
Layer 1 (Outer)
FOIL
PRE-PREG
Layer 2 (Inner)
Layer 3 (Inner)
INNER LAYER
PRE-PREG
Layer 4 (Outer)
FOIL
Layer 1 (Outer)
FOIL
Layer 2 (Inner)
PRE-PREG
Layer 3 (Inner)
INNER LAYER
Layer 4 (Outer)
PRE-PREG
FOIL
Slide 14
+44 (0)1992 510000
Layer stackup
Layer 1 (Outer)
FOIL
PRE-PREG
Layer 2 (Inner)
Layer 3 (Inner)
PRE-PREG
Layer 4 (Outer)
FOIL
Layer 1 (Outer)
FOIL
Layer 2 (Inner)
PRE-PREG
Layer 3 (Inner)
INNER LAYER
Layer 4 (Outer)
PRE-PREG
FOIL
Slide 15
+44 (0)1992 510000
Layer stackup
Layer 1 (Outer)
FOIL
PRE-PREG
Layer 2 (Inner)
Layer 3 (Inner)
PRE-PREG
Layer 4 (Outer)
FOIL
Layer 1 (Outer)
FOIL
Layer 2 (Inner)
PRE-PREG
Layer 3 (Inner)
INNER LAYER
Layer 4 (Outer)
PRE-PREG
FOIL
Slide 16
+44 (0)1992 510000
Layer stackup
Layer 1 (Outer)
FOIL
PRE-PREG
Layer 2 (Inner)
Layer 3 (Inner)
PRE-PREG
Layer 4 (Outer)
FOIL
Layer 1 (Outer)
FOIL
Layer 2 (Inner)
PRE-PREG
Layer 3 (Inner)
INNER LAYER
Layer 4 (Outer)
PRE-PREG
FOIL
Slide 17
+44 (0)1992 510000
Bonding – Heat
Layer 1 (Outer)
FOIL
PRE-PREG
Layer 2 (Inner)
Layer 3 (Inner)
PRE-PREG
Layer 4 (Outer)
FOIL
Bonding
Layer 1 (Outer)
FOIL
Layer 2 (Inner)
PRE-PREG
Layer 3 (Inner)
INNER LAYER
Layer 4 (Outer)
PRE-PREG
FOIL
• Once the layers are built up
heat is applied over a period
of time, this is to allow the
Pre-Preg material time to
melt and flow evenly between
the layers, this is in effect the
material that sticks the layers
together.
Slide 18
+44 (0)1992 510000
Bonding – Multilayer Press
Layer 1 (Outer)
FOIL
PRE-PREG
Layer 2 (Inner)
Layer 3 (Inner)
PRE-PREG
Layer 4 (Outer)
FOIL
Bonding
• Layers are pressed together
over a set period of time
typically a bonding cycle will
last for approx. 4 hours.
• Bonding capacity would
depend on the number of
openings and size of press.
Slide 19
+44 (0)1992 510000
Drilling of a Panel
Copper
Laminate
Drilled Hole
Layer 1
Drilling
Layer 4
• The holes are drilled for both
thru-hole components and via
connections. Once plated this
will form the connection from
1 side of the PCB to the
other, at the same time
connecting the inner layers
where required.
Slide 20
+44 (0)1992 510000
Electroless Copper Process
Addition of Copper to all Exposed Surfaces
Copper
Drilled Hole
Layer 1
Layer 2
Plating
Layer 3
Layer 4
• Plating is the same process
for 2 or 4 Layer.
• The aim is plate down the
barrel of the hole to make the
connection from 1 side of the
PCB to the other.
Slide 21
+44 (0)1992 510000
Laminating and Imaging of External Layers
UV sensitive film is laminated over top and bottom
surfaces of PCB
It is then exposed and developed, leaving an
exposed image of the PCB pattern
Layer 1
Imaging
Layer 2
• The outer layer track patterns
are photo-imaged onto the
panels using UV sensitive
film.
Layer 3
Layer 4
Copper
Slide 22
+44 (0)1992 510000
Electro-plating Process 1
Additional Copper to all Exposed Surfaces
Laminated Film
Plate Additional Copper
Layer 1
Layer 2
Layer 3
Layer 4
Plating
• Electro-plating increases the
copper thickness on the outer
layers and through the barrel of
the hole. The copper foils for a 4
layer or the starting copper
weight on 2 layer boards is most
commonly ½ oz the plating then
increases the finished copper
weight to the desired 1oz each
side.
Slide 23
+44 (0)1992 510000
Electro-plating Process 2
Add Tin over Exposed Copper Areas
Laminated Film
Additional Copper
Tin Plating
Layer 1
Layer 2
Layer 3
Layer 4
Tin Plating
• A tin plate is added to all
exposed copper areas, this
act as a mask during the
etching process.
Slide 24
+44 (0)1992 510000
Electro-plating Process 3
Remove Laminated Film
Laminated Film Removed
Tin Plating
Layer 1
Film Strip
Layer 2
Layer 3
Layer 4
• The laminated film is
removed to expose copper
areas ready for the etching
process.
Slide 25
+44 (0)1992 510000
Etch Process - Remove Exposed Copper
Copper Removed
Tin Plating
Layer 1
Etching Process
Layer 2
Layer 3
Layer 4
• The etching process removes
unwanted areas of copper.
• The etch process produces
an ‘etch back’ or undercut of
the tracks.
• This means that tracks will
end up approximately
0,025 mm (0.001”) thinner
than the original design.
Slide 26
+44 (0)1992 510000
Tin Strip - Remove Tin Plating
Tin Plating Removed
Layer 1
Tin Strip
Layer 2
Layer 3
Layer 4
• The Removal of Tin will very
slightly reduce the copper
thickness (T) on the outer
layers
Slide 27
+44 (0)1992 510000
PCB is now complete except for
surface finishes and panel routing/punching
Tracks
Via Hole
SMD Pad
Layer 1
Layer 4
Tracks
Slide 28
+44 (0)1992 510000
Solder Mask Application
Image, Develop and Cure
UV Image, Develop and Cure
Layer 1
Solder Mask
Layer 4
• The image is semi cured and
then UV image exposed.
• Any areas that are not
exposed to the UV light are
then dissolved in the
developer, exposing the
areas where the final surface
finish is required.
Slide 29
+44 (0)1992 510000
Surface Finish Process
Apply Solder to Exposed Copper Areas
Layer 1
Surface Finish
Layer 4
• Surface Finish (Tin / Lead,
Gold, Silver, OSP, Tin) is
usually only added to pads.
The solder mask prevents
coating of any other areas.
Slide 30
+44 (0)1992 510000
Component Ident
SCL2 9624
R 34
Ident / Silk Screen
• An optional component Ident
or Silk Screen is printed onto
the PCB.
IC 3
Slide 31
+44 (0)1992 510000
Routing or Punching
Routing or Punching
• The circuit profile is then
punched or routed.
Slide 32
+44 (0)1992 510000
Testing and Inspection
All PCB’s are 100% Electrically tested
All PCB’s are 100% Visually Inspected