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Electronics Manufacturing Processes
Manufacture of Electronics Components
Manufacture of Printed Circuit Boards (PCB’s)
Assembly of components on PCB’s
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Electronics Manufacturing Processes
Manufacture of Electronics Components
Manufacture of Printed Circuit Boards (PCB’s)
Assembly of components on PCB’s
![Page 3: Electronics Manufacturing Processes Manufacture of Electronics Components Manufacture of Printed Circuit Boards (PCB’s) Assembly of components on PCB’s](https://reader036.vdocuments.us/reader036/viewer/2022062407/56649d495503460f94a2513e/html5/thumbnails/3.jpg)
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 ResistorSlug leads mold bake seal- cheap, poor tolerance, rugged
Wire-wound resistorwind wire leads mold seal- high power, low resistance, high frequency apps
Film resistorFilm is cut by laser high precision- low frequency applications
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Passive devices: capacitors
Tabbed tubular paper capacitor
Disk-ceramic capacitor Tubular ceramic capacitors
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Active devices: Silicon wafer production
Quartzite (SiO2) + Carbon (C) + Heat + catalysts Si + CO2Raw 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
Silicon Dopant: Phosphorus, N-type Dopant: Aluminum, P-type
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
MOSFETMetal-Oxide SiliconField 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: IC’s..
Depositing films of materials on substrate to make circuits
Thin Film Processes:
Form components on circuits by vacuum evaporation, sputtering, or anodizationFilm thickness is ≤ 5 m
Thick Film Processes (silk-screening)
Print liquid or paste through a screen (mask) onto substrate firing (baking) Film thickness is ~ 10 m
Silk-screening
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IC’s: Resistive elements depositionvacuum deposition
Subtractiveprocess
Additiveprocess
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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 radiation- Mask = = Artwork- Projection: - Direct: mask scale is 1:1 - Reducing: mask scale is 10:1
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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 componentsStructure of a Surface mount component
SOIC packageSmall Outline IC
Avoiding possible heat damage to IC during soldering:
- Solder a chip carrier to the PCB - Insert chip into carrier
IC
Chip carrier
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Integrated Circuit (IC) Manufacture
- Slicing the Silicon ingot- Fabrication of IC’s (Lithography, Sputtering, diffused junction, …)- Testing each IC on the slice
[source: www.towajapan.co.jp]
- Dicing (cutting each chip out with a diamond saw)- Packaging
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Packaging
Dual Inline Package and its lead-frame
Steps in Lead Frame Manufacture:
(1) Cut copper strips(2) Clean in a chemical bath(3) laminate a layer of photoresist(4) Expose photoresist through mask(5) Develop and etch(6) Remove lamination(7) Plate internal regions with gold/silver
Dual Inline Package and its lead-frame
Steps in Lead Frame Manufacture:
(1) Cut copper strips(2) Clean in a chemical bath(3) laminate a layer of photoresist(4) Expose photoresist through mask(5) Develop and etch(6) Remove lamination(7) Plate internal regions with gold/silver
- 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 (PCB’s)
Assembly of components on PCB’s
![Page 18: Electronics Manufacturing Processes Manufacture of Electronics Components Manufacture of Printed Circuit Boards (PCB’s) Assembly of components on PCB’s](https://reader036.vdocuments.us/reader036/viewer/2022062407/56649d495503460f94a2513e/html5/thumbnails/18.jpg)
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
Typical PCB
insulated substrate
copper connections
protective covering
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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 onMulti-layer PCB’s
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Electronics Manufacturing Processes
Manufacture of Electronics Components
Manufacture of Printed Circuit Boards (PCB’s)
Assembly of components on PCB’s
![Page 22: Electronics Manufacturing Processes Manufacture of Electronics Components Manufacture of Printed Circuit Boards (PCB’s) Assembly of components on PCB’s](https://reader036.vdocuments.us/reader036/viewer/2022062407/56649d495503460f94a2513e/html5/thumbnails/22.jpg)
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 IC’s, 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 (>30,000 components per hour) - IR or Wave soldering
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Automatic soldering
Step 1. Application of the solder resistCover PCB with solder resist except Lands
Land
Step 2. Flux application
Foam fluxing Spray fluxing Ultrasonic Spray fluxing
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Automatic soldering..
Step 3. Solder Application
Dip solderingDip soldering
Dual wave solder bath
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Automatic soldering..
Step 4. Automatic removal of solder bridges: Hot air-jet knives
air-jet
Hot air jet knifeSOLDER
WAVE
air-jet
Hot air jet knifeSOLDER
WAVE
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Types of circuit boards
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Special considerationsfor SMT boards