A

PRESENTATION

ON

“SURFACE MOUNT TECHNOLOGY”

Submitted in partial fulfillment of Bachelor in TechnologyRajasthan Technical University, Kota

(Session:-2010-2011) Guided By: Presented By: Dr. S. K. Bhatnagar Shivani Gosain (EC07110) Professor of Electronics ECE And Head 8th SEM R&D Center for Engg. & Sc.

Department of Electronics & CommunicationJaipur Engineering College,

Kukas, Jaipur-303101

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CONTENTS What is SMT??? Characterisitics of SMT Types of SMT SMC(Surface Mount

Components) & Their Placement Soldering Surface Mount Design Advantages Conclusion

WHAT IS SMT ?? A method for constructing electronic

circuits in which the components (SMC, or Surface Mounted Components) are mounted directly onto the surface of printed circuit boards (PCBs).

Electronic devices made for this purpose are called surface-mount devices or SMDs. And this technique is known as Surface Mount Technology.

CHARACTERISTICS OF SMT Allows production of more reliable

assemblies Higher I/O Increased board density Reduced weight, volume, and cost.

TYPES OF SURFACE MOUNT TECHNOLOGYSMT replaces DIPs(Dual in

package) with surface mount components.

When attached to PBs, both active and passive SMCs form three major types of SMT assemblies.

1. TYPE I2. TYPE II3. TYPE III

SURFACE MOUNT COMPONENTS & THEIR PLACEMENTS There are various types of surface

mount components available. For eg. Tape and Reel are comman.

PLACEMENT OFCOMPONENTS

Requirements for accuracy make it necessary to use auto-placement machines for placing surface mount components on the PCB.

The selection of appropriate auto -placement machine is depends on the type of component which have to be placed.

There are different types of auto-placement machines available on the market today:

(A) In-line

(B) Sequential

(A)In- line:

It employs a series of fixed-position placement stations.

(A)Sequential:

Components are individually placed on the PC board in succession.

SOLDERING

A Process of joining metallic surfaces with solder, without melting the base material.

Type of soldering depends upon the component which have to be solder.

1. Wave soldering2. Reflow soldering

WAVE SOLDERING

•Wave soldering is a large-scale soldering

process, used to solder the electronic

components on PCB.

• The name is derived from the use of waves of

molten solder.

• The process uses a tank to hold a quantityof molten solder; the components are inserted into or placed on the PCB and the loaded PCB is passed across a pumped wave or waterfall of solder.

• Used for both through-hole printed circuit assemblies, and surface mount.

ADVANTAGES

• Ease in automation results in higher production throughput and better yields.

• Closer spacing of components coupled with the ability to use both sides of the PCB for component mounting results in significant savings in board real estate.

• Board rework costs and time are significantly reduced.

• The components are glued by the placement equipment onto the printed circuit board surface before being run through the molten solder wave.

Solder Types:• Many different types of solder that can be used in wave soldering, tin/lead-based solders are the most common.

• But these are replaced by Lead free solder pastes, Because of highly toxic in nature.

• The next best metals to use are nickel, brass, aluminum, tungsten, and lastly steel.

A coil of Lead – free solder

A coil of pure tin solder wire

REFLOW SOLDERING:

Reflow soldering contains the steps as same as wave soldering.But the soldering plate source is different.It can be done by 2heating sources those are

• Vapour Phase• Infrared

Steps Included In ReflowSoldering:

1. Pre Heating2. Soldering3. Cooling

Pre Heating→→ Soldering→→ Cooling

SURFACE MOUNT DESIGN

1.Design for manufacturability:

Includes the considerations of land pattern, placement, soldering, cleaning, repair, and test are important issues.

2.Land Pattern Design:

•The surface mount land patterns, also called footprints or pads, define the sites where components are to be soldered to the PC board.• The design of land patterns is very critical, because it determines solder joint strength and thus the reliability of solder joints, and also impacts solder defects, cleanability, testability, and repair or rework.

3.Design for Testability:

In SMT boards, designing for testability requires that test nodes be accessible to automated test equipment (ATE).

CONCLUSION

At last we conclude that this technologywill be very useful & effective in thefabrication of electronics circuits on PCB.

• Throuh hole component technique has been replaced by SMT, with higher I/O capacity, and high efficiency.• Weight and volume reduced.

THANK YOU

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