Mohit Final

8/14/2019 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

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Mohit Final