Mohit Final
Transcript of Mohit Final
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Recap Printed circuit boards(PCBs) Designing of PCB Through Hole Technology and
its limitations. Surface mount technology Common SMT packages SMT Components SMT Techniques Summary of SMT techniques Advantages of SMT Disadvantages of SMT Applications
Refrences
TABLE OF CONTENTS
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Printed circuit board(PCB).
Integrated circuits
which are soldered on PCBs
using through-hole technology.
RECAP
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Basic component.
Before PCBs point to point or wire wrap was
used.
Provide mechanical support and electrically
connect electronic components.
Use conductive pathways, or traces.
PRINTED CIRCUIT BOARD
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DESIGNING OF PCB
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Components are inserted on PCB by making
holes.
Loaded on one side and soldered on other.
Soldered through the leads of the components.
THROUGH-HOLETECHNOLOGY
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THROUGH-HOLE PCB
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Method for constructing electronic circuits.
Components are mounted directly onto the
surface.
Electronic devices so made are calledsurface-
mount devices orSMDs.
Largely replaced the through-hole technology
SURFACE MOUNTTECHNOLOGY
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Replaced the leads by castellation.
An SMT component is usually smaller than its
through-hole.
Components on both sides of board.
SURFACE MOUNTTECHNOLOGY
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Unwanted effects are more.
Drilling may damage the PCB.
Electric connections are weak.
Single side usage.
Large in size.
DISADVANTAGESOFHT-TECHNOLOGY
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DISADVANTAGESOFHT-
TECHNOLOGY
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COMMON SMT PACKAGES Three popular package:-0603(60 thou long,30 thou wide)
0805(80 thou long,05 thou wide)
1206(120 thou long,60 thou wide)
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SMT COMPONENTS
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SMT PCB
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Fine tip soldering
Uses conventional soldering techniques on a
much smaller scaleHot air reflow
Uses soldering paste and hot air to reflow the
soldering paste with components presetOven reflow
Uses soldering paste and reflows entire board
HOW TO SMT (TECHNIQUES)
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Conventional equipment
Causes eye strain
Requires a steady hand
FINE TIP SOLDERING
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Hot-Air Rework Station
Fine tip solder tools
Desoldering tools
Hot tweezers
Hot air gun
HOT AIR REFLOW
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Typical Reflow oven
Large and bulky
Expensive $$$
OVEN REFLOW
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After applying solder paste and
setting components, the board is
inserted to be cooked
End result is a perfectly
soldered board for a
fraction of the cost
(no eye strain either).
OVEN REFLOW OVERVIEW
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Apply soldering paste
Set ICs and components
Cook!
Touch up using soldering wick to
remove excess solder.
OVEN REFLOW STEPS
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Fine tip soldering is hard, but essential
sometimes
Hot air reflow is more convenient for
reworking of components
Oven reflow is great for creating a whole board
at once.
SUMMARY OF TECHNIQUES
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Faster for automatic machine to place.
Smaller physical size.
Less parasitic effects.
Cheaper.
Components can be fitted to both sides of the
circuit board.
ADVANTAGES OF SMT
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Soldering and de-soldering is easy.
Reusability.
Modern components are available in SMT
form.
Less loaded.
Failure is minimum.
ADVANTAGES OF SMT
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The initial cost and time of setting up for
production is high.
Mechanically weak.
The manufacturing processes for SMT are
much more sophisticated than through-hole
boards.
DISADVANTAGES OF SMT
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Most aims towards the future in SMT is
geared towards:
To evolve solder, to create a newer, better
alloy composition to improve
performance.
The capability to create PCBs smaller and
lighter (eventually to the nano scale). Nanotechnology .
Bright spot in the world of PCB.
FUTURE
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http://books.google.co.in/books?id=IcxDPA2U6esC&dq=su
rface+mount+technology+principles&printsec=frontcover
&source=bl&ots=r5hvHGF12s&sig=eSO_N60CRWxaFMybEr
kog_3SKAE&hl=en&ei=qxyYSoqKFMONkQXJwMGxBQ&sa=X
&oi=book_result&ct=result&resnum=4#v=onepage&q=&f=
false
www.geocities.com/vk3em/smtguide/SMT-GuideV1-3.PDF
www.intel.com/Assets/PDF/pkginfo/ch_07.pdf
http://en.wikipedia.org/wiki/Surface-mount_technology
www.emeraldinsight.com/ssmt www.geocities.com/vk3em/smtguide/SMT-GuideV1-3.PDF
http://en.wikipedia.org/wiki/Printed_circuit_board
REFRENCES
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TIME FOR-
Queries
?
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THANK YOU