Docstoc

Study of SMD PCB Circuit Assembly

Document Sample
Study of SMD PCB Circuit Assembly Powered By Docstoc
					  GTBKIET Chhapianwali
     Malout Muktsar

Study of SMD PCB Circuit Assembly
Internal Guide: -             External Guide: -




           Project Work (2011 – 2012)
                    Prepared By: -
                   Index
1. What is “surface mount”?
2. Difference between SMT & PTH Tech.
3. Advantages of SMT
4. Disadvantages of SMT
5. Common SMT Components
6. Various Steps Involved in PCB Circuit Assembly
   Via SMT
7. Paste and printing
8. Pick & Place
9. Reflow Process
10.Products
        What is “surface mount”?

 A way of attaching electronic
  components to a printed
  circuit board
 The solder joint forms the
  mechanical and electrical
  connection
 Bonding of the solder joint is
  to the surface of a conductive
  land pattern
 Connection does not use
  through holes or terminals
    Difference between SMT & PTH Tech.
         Surface mount                   Through-Hole Technology
       technology (SMT)                         Through-hole       technology,
Surface mount technology (SMT) is a     also spelled "thru-hole", refers to the
method for constructing                 mounting scheme used for electronic
electronic circuits in which the        components that involves the use
components (surface-mounted             of leads on the components that are
components/SMCs) are mounted            inserted into holes (PTH - Plated
directly onto the surface of printed    Through-Hole) drilled in printed circuit
circuit boards (PCBs).r by the use of   boards (PCB) and soldered to pads on
automated insertion mount machines.     the opposite side either by manual
                                        assembly by hand placement o
    Advantages of SMT
• Smaller parts
• Denser layout
• Cheaper pcbs (no holes to drill)
• Improved shock and vibration
  Characteristics
• Improved frequency response
• Easier to shield from EMI / RFI
• Easier to automate manufacturing
  Disadvantages of SMT
• More heat generated
• Small clearance makes cleaning
  Difficult
• Visual inspection difficult
• Good joint formation important for
  mechanical reliability of assembly
• Harder to hand assemble
• Greater number of different
  materials to match CTE’s
Common SMT Components
Various Steps Involved in PCB
 Circuit Assembly Via SMT

   a. Printing
   b. Pick & Place
   c. Reflow Pasting
           Paste and printing
 Solder paste has tiny
  metal spheres of the alloy
  mixed with flux, solvents,
  and thixotropic materials
 Methods of applying
  solder paste:
   Stencil printing
   Syringe dispensing
 Most influential step
  affecting yield
               Pick & Place
            Siemens Siplace HS-50
Type of Placement head: 12-
 nozzle Collect and Place
Number of Gantries: 4
Placement Rate: 50,000cph
Placement
 Accuracy: +90microm 4
 sigma
PCB Dimensions Single
 Lane: 50mm x 50mm up to
 368mm x 460mm / 2' x 2' up
 to 14.5' x 18'
                  Pick & Place
              Siemens Siplace HS-50
Optional Flexible Dual Lane: 2 x 50mm x 50mm up to 368mm x 216mm
 / 2' x 2' up to 14.5' x 8.5' or
 50mm x 50mm up to 369mm x 380mm / 2' x 2' up to 14.5' x 15'
Feeding Capacity: 144 with 3x8mm, 96 with 2x8mm
Component Table: Quick changeover table with integrated wheels, reel
 holder and scrap bin
Types of Feeder Modules: 3x8mm, 2x8mm, 12/16mm, 24/32mm tape
 feeders, Bulk case feeders
                  Pick & Place
              Siemens Siplace HS-50
Power Requirements: 4KW, 230/400V
 or 110/208V
Compressed Air Requirement: min
 6.5bar, 950l/min
Machine Dimensions: 385mm L x
 3160mm W x 1699mm H
Range of Components: 0402 to
 PLCC44 incl. DRAM, BGA, CSP, micro
 BGA, optional: 0201
Component Height: max 6mm
Options: Automatic Nozzle Changers,
 Component barcode readers
 Please call for more information - +44
 (0)20 7284 4074
Reflow Process
Sample Reflow Profile Development
            Products
1. Electronic Fan Regulator
2. Electronic Light Dimmer
3. Electronic ballasts
4. CFL
5. Call Bell Indicator
6. DVR (Digital Video Recorder)

				
DOCUMENT INFO
Shared By:
Categories:
Tags:
Stats:
views:145
posted:11/8/2012
language:English
pages:16
Description: Study of SMD PCB Circuit Assembly | More at http://www.final-yearproject.com/