Transcript One Way Circuits Limited Printed Circuit Board Manufacturer A Guide To Manufacturing Multilayer PCBs Use Left and Right Cursor keys to navigate ESC to.

One Way Circuits Limited
Printed Circuit Board Manufacturer
A Guide To Manufacturing
Multilayer PCBs
Use Left and Right Cursor keys to navigate ESC to quit presentation
A Guide to Manufacturing Multilayer
PCBs
 Presentation Title:
A Guide to Manufacturer Multilayer PCBs.
 Created / Modified:
15th September 2009.
 Compiled By:
One Way Circuits Limited.
 Description:
The following is a guide only.
Inner layer material is supplied in
cut panels.
• Inner Layer material is thin pieces of
rigid epoxy glass material. Handling
precautions are important.
• The panels are cleaned ready for the
application of an etching Resist film on
which the circuit pattern will be printed.
INNER LAYERPREPARATION
A light-sensitive etching Resist film
is applied.
•A Positive inner layer image is printed using a negative artwork.
•The light-hardened areas remain intact after developing
protecting the base Copper.
•The developed resist exposes the base copper which is then is
etched.
•The etching resist is then removed to reveal the copper image of
the inner layer.
ETCHING RESIST
Layers Are Exposed to UV Light –
Photo Shows Panel after Exposure to Light.
The Layer is Developed Leaving the
Circuit Image.
The Layer is Etched Leaving the Circuit
Image – the resist protects the Circuit from
etching.
The Layer is Stripped of Resist –
Leaving the Circuit Image in Copper.
The Copper is chemically treated to ensure
good adhesion to the pre-preg that
separates the layers.
• An Oxide process (or similar) is used to
increase the surface roughness of the
Copper to aid adhesion.
ADHESION PROMOTION
The Copper is chemically treated to ensure
good adhesion during bonding.
Inner Layers and Copper foil are
interleaved with pre-preg.
• Inner Layers are interleaved with prepreg and copper foil is placed on the
outside before bonding together.
LAY - UP (4 Layer)
Multi-layer P.C.B’s
• Higher complexity requirements have forced
the circuit route (tracking) to be passed
between several layers of circuitry. Several
layers of circuitry have to be bonded together
and inter-connected to each other via plated
through holes.
Buried Via Layer
The layers and foil are then bonded
together under heat and pressure.
• As the heat is applied the semi - cured resin
contained within the pre-preg melts.
• Combined with the pressure applied during the
bonding process, the resin flows within the layers
before finally becoming hard, sealing all materials
together as one board.
BONDING
Tooling holes are drilled locating off internal
targets to ensure accurate drill hole to
Innerlayer registration.
• The bonded panels are drilled, making
sure that the inner layer circuit features
are drilled centrally.
DRILLING
Electroless copper plating provides the
electrical connection between the layers.
A thin deposit of Copper on internal walls of holes
provides the conductivity for the electroplating
processes.
ELECTROLESS COPPER
Plating Resist is applied to the
panels ready for electroplating.
A light-sensitive Resist is
applied, to mask parts of the
base Copper from being plated.
RESIST LAMINATION
Plating Resist is applied to the
panels ready for electroplating.
• A film-work which has the circuit image in
black is applied to the board ready for printing.
•High intensity ultra-violet light passes through
the clear areas of the film-work this hardens the
Resist.
PRINTING
A Plating Resist is applied, this is mask that
protects areas that do not require plating.
U/v light
Non hardened
Has hardened
areas of photo
the Resist
Resist Remain
through
Soft and are
the clear
dissolved Into
parts of the
the developer
solution.
Film-work.
PLATING RESIST
A plating Resist is applied as a mask to prevent
unwanted Copper from becoming plated.
The panels are Electroplated with Copper
to form the circuit features.
• The drilled holes, already made conductive
with Electroless Copper, are plated up to a
thickness Suitable for carrying current through
the finished board.
PATTERN PLATING
Electroplate Tin as an etch Resist.
• The Tin plating will protect the Copper
plated circuit features against the
etching chemicals which will be used to
dissolve the unwanted surplus base
copper.
TIN PLATING
Panels After Copper and Tin Plating.
The Photo resist is chemically stripped
after plating.
• The plating Resist is removed to reveal
the now “surplus” base Copper which is
removed during the etching process,
leaving only the Tin plated circuit
features.
STRIP PLATING RESIST
Panel After Resist Stripping – Tin Plate
acts as an etch Resist.
The exposed Copper is now etched.
• The unwanted Copper is now etched
away leaving only the circuit features
which were protected with Tin.
ETCHING
After Etching the Copper Remains
under the tin plate.
Remove Tin Etch Resist leaving the
circuit features in Copper.
• Tin plating is stripped from the circuit
features.
• You can see how the Copper plating
through the holes is used to connect the
layers together and so form the circuit
networks.
STRIP TIN
Circuit after Tin Strip now ready for
Soldermask Application.
Solder Resist or Solder Mask.
• A photo - imageable coating is applied
to the circuit.
• This inhibits metal finishing or soldering
of the covered areas.
SOLDER RESIST
Solder Resist or Solder Mask.
Finishing.
• A solderable finish is applied to the
exposed Copper, followed by:
Component identification, Routing,
Testing, Final Inspection, Despatch to
customer:
FINISHING PROCESSES
Board now has Solderable finish and
Ident and is ready to cut to size.
Board is Profiled to size – picture
shows 2 boards in biscuit frame.
Testing.
 Board is then electronically tested to
customers data.