Electronics Manufacturing Processes

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Electronics Manufacturing Processes
Manufacture of Electronics Components
Manufacture of Printed Circuit Boards (PCBs)
Assembly of components on PCBs
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Electronics Manufacturing Processes
Manufacture of Electronics Components
Manufacture of Printed Circuit Boards (PCBs)
Assembly of components on PCBs
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Electronics Component Manufacture
Electronics Components Mechanical and
Electro-mechanical PCB mounted DIP switches,
mains switches, disc drives Passive Solid State
Devices Resistors, Capacitors Active Solid
State Devices Transistors, Diodes, Thermionic
valves, FETs and MOSFETs
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Passive devices resistors
Carbon Composite Resistor Slug ? leads ? mold ?
bake ? seal - cheap, poor tolerance, rugged
Wire-wound resistor wind wire ? leads ? mold ?
seal - high power, low resistance, high frequency
apps
Film resistor Film is cut by laser ? high
precision - low frequency applications
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Passive devices capacitors
Tabbed tubular paper capacitor
Tubular ceramic capacitors
Disk-ceramic capacitor
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Active devices Silicon wafer production
Quartzite (SiO2) Carbon (C) Heat catalysts
? Si CO2
Raw Si
Si HCl ? SiCl4 Hydrogen ? Fractional
distillation ? SiCl4 H2 catalysts ? Si HCl
Pure Si
Pure Monocrystalline Si
Melt pure Si, Seed crystal drawn out slowly
Typical Single Crystal Ingot sizes 1-2m long,
8cm / 15cm / 30 cm diameter
? Ingot sliced (Diamond saw)
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Active Devices Doping pure silicon
Doping processes Diffusion (heat wafer in
atmosphere with atoms of dopant) Ion
implantation (ions of dopant are accelerated,
bombard surface)
Diode (showing doping)
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Active components Transistors
NPN transistor
MOSFET Metal-Oxide Silicon Field Effect Transistor
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Active components Integrated Circuits
Monolithic IC Entire circuit made on a single
crystal wafer
Hybrid IC Monolithic IC other components
directly assembled into it
Hybrid micro-circuit film components
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Active components ICs..
Depositing films of materials on substrate to
make circuits
Thin Film Processes Form components on circuits
by vacuum evaporation, sputtering, or
anodization Film thickness is 5 mm
Thick Film Processes (silk-screening) Print
liquid or paste through a screen (mask) onto
substrate ? firing (baking) Film thickness is
10 mm
Silk-screening
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vacuum deposition
ICs Resistive elements deposition
Subtractive process
Additive process
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Diffused Junction Process
- Photolithography is the most commonly used
process - Photoresists positive more
soluble when exposed negative less soluble
when exposed - Feature size f(wavelength) ?
small features need low l radiation - Mask
Artwork - Projection - Direct mask scale is
11 - Reducing mask scale is 101
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Packaging of components
- Packaging puts the chip (silicon) into a
protective case - Package provides external
connections that are spaced conveniently (at
distance, arranged in array) for soldering
Exploded view of TO package
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Packaging of components
Structure of a Surface mount component
SOIC package Small Outline IC

Avoiding possible heat damage to IC during
soldering - Solder a chip carrier to the PCB
- Insert chip into carrier
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Integrated Circuit (IC) Manufacture
- Slicing the Silicon ingot - Fabrication of ICs
(Lithography, Sputtering, diffused junction, ) -
Testing each IC on the slice
- Dicing (cutting each chip out with a diamond
saw) - Packaging
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Packaging
- Make leadframe
- Die attachment (chip bonded to leadframe using
epoxy) - Wire bonding (ultrasonic welding) -
Encapsulation (moisture resistant coating) -
Molding (plastic package)
- Marking (chip number, co. name, marked on
package laser, silkscreen) - DTFS deflash,
trim the leadframe, form the leads, singulate
(cut dambars) - Leadfinishing electroplating the
leads
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Electronics Manufacturing Processes
Manufacture of Electronics Components
Manufacture of Printed Circuit Boards (PCBs)
Assembly of components on PCBs
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PCB Manufacture
Types of PCB's single-side, double-side and
multi-layer Which type to use ? (a) Circuit
complexity (b) Available space (c) Cost
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Manufacturing glass reinforced epoxy resin
copper-clad boards
Boards are produced in "clean-rooms" Manufacturing
process hot-pressing Place copper sheet on
the lower plate Place few layers of glass cloth
impregnated with epoxy on top IF two-sided
PCB's Place copper sheet on above Press
between steel plates in a steam-heated hydraulic
press (7,000,000 Pa) Water cooling to 25º C
Trim to clean out extruded epoxy
Punch/Drill holes for alignment Make circuit
on PCB (lithography) Drill through holes (for
component leads)
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Multi-layer PCBs
Similar process as single layer, but takes
several steps
Schematics and features on Multi-layer PCBs
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Electronics Manufacturing Processes
Manufacture of Electronics Components
Manufacture of Printed Circuit Boards (PCBs)
Assembly of components on PCBs
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PCB Assembly
- Insert leaded component into holes on PCB -
Solder - Protective coating
Manual electronics assembly
Automated electronics assembly
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Automated PCB Assembly
Component inputs
Leaded Component
ICs, components with no wire leads
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PCB Manufacture
Surface mount chip assembly - Silk-screening
to apply solder paste on the board - Automated
assembly of components (gt30,000 components per
hour) - IR or Wave soldering
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Automatic soldering
Step 1. Application of the solder resist Cover
PCB with solder resist except Lands
Step 2. Flux application
Spray fluxing
Foam fluxing
Ultrasonic Spray fluxing
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Automatic soldering..
Step 3. Solder Application
Dual wave solder bath
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Automatic soldering..
Step 4. Automatic removal of solder bridges Hot
air-jet knives
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Types of circuit boards
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Special considerations for SMT boards