SMT Process : Reflow Oven

Reflow Oven :

A machine that acts as oven to complete the soldering process of components on surface of PCB by passing it through various hot zones reach 10 which are controllable

 Points Of Management :

Making temperature profile according to the standard showing in picture to assure a high quality soldering process

Defects :

Cold Solder  Due To Sufficient Temperature 

Solder Balls Due to Wrong temperature profile

Video :

SMT Process: M-AOI

Mounting Automatic Optical Inspection:

Inspection Stage after adding components to the PCB that inspect the location and condition of each component by taking picture of it and compare it to a reference using a CCD camera

 Defects to inspect:

• Missing Component
• Wrong polarity
• Tombstone 
• twisted component
• wrong part number

Video:

Mounter Machine:

Flexible Chip Mounter:

A Machine that fix big SMT components such as (SOP,QFP,BGA)

Points Of Management:

• Components mount position (X,Y)
• Component Pick up Position
• Components drop rate
• Nozzles cleaning
• Feeder accuracy

Defects & Errors:

• Wrong Polarity
• Shifted
• Up-Side-Down
• Wrong component

Mounter Machine

Mounter Machines:

Standard Chip Mounter:

A machine that fix chip components on PCB surface such as ( Resistors, Coils, Diodes, Capacitors)

Management Points:

• PCB Fiducial  (X,Y)
• Pick-Up Position (X,Y)
• Mount Position (X,Y)
• Drop Components
• Nozzles Cleaning
• Feeder Cleaning and calibration

Defects & Errors:

 Up-Side-Down

Lifted

On Side

 Shifted

Twisted

Wrong Polarity

Wrong Component

Video:

SMT Process: SPI (Solder Paste Inspection)

SMT Basic Process:

SMT Line Logic:

Production is very important but quality comes first that's exactly why after each stage that add value in SMT we must apply inspection stage it's simply a desired waste to insure SMT line quality

What is AOI ?

The term AOI stands for Automatic optical inspection in which an inspection machine take pictures or measure height , volume and area (using laser beam) of SMT material and compare it to reference (image frame or value) and decide if it's defect or good product

SPI (Solder Paste Inspection):

An inspection machine that generate a 3D image of solder paste print using laser beam 

to perform a 3D inspection by calculating and visualizing of Volume, height and area of solder paste on the PCB and view it in analytic way (Graphs, histograms and Pareto charts)

Defects:

Video:

SMT Process: Screen Printer

SMT Process: Screen Printer

It's a Machine that print solder paste on Copper pads of PCB (printed circuit board) 

using metal mask and squeegee 

Metal Mask

Solder Paste

Metal Mask and Squeegee

Screen Printer Process

Management Points:

• PCB Size (L,W,T) , PCB fiducial marks (X,Y) .
• Screen Printer Parameters like: Squeegee Speed (print speed), Print pressure (Squeegee force), Separation speed, Metal mask Cleaning Cycle.
• Solder paste should be ready (mixed for 2 min on 1000 RPM in mixer) and on room temperature.

Defects & Errors:

• Short Circuit ( Bridge)
• Excessive Solder Volume 
• Insufficient solder volume or area
• shifted print

Video Contents :

1. Homing machine
2. Load job file
3. Adjust conveyor
4. Insert magnetic block support 
5. Insert Metal mask
6. Add solder paste
7. Run production

  

Basic Process of SMT: Vacuum Loader

Basic Process of SMT:

• Vacuum Loader:

Its a Machine that transfer PCB to the 1st step on SMT line using vacuum pins as shown in picture

Management Points:

PCB Positioning, Air Pressure of vacuum pins, Dust control, PCBs alignment, Distributions of vacuum pins, Conveyor width 

Defects & Errors:

PCB falling, PCB no Pick up due to bad distribution of Vacuum pins, pcb warpage due to wrong Conveyor width

What is SMT?

What is SMT?

SMT Stands for Surface Mount Technology
it's a process of assembling and testing electronics device (board)

History : THT

Before SMT we had older Technology called THT Through Hole Technology
This is where we make this holes on PCB ( Printed Circuit board) and attach those electronics components into this holes and solder it


THT now almost a history rare to use unless we need to fix big component or we assembling a power board ( the bigger the component is the more we likely use THT)

SMT

SMT is process of mounting small electronics components on PCB surface in specific sequential process that i will describe in details later 

Let's Start

Introduction:

My name is Ahmed Abd El Nasser Seddik i'm SMT Engineer At Heesung electronics LG Group
i have worked for Samsung electronics before and studied electronics and communications engineering

In this Blog i will be publishing some basics and important information about electronics manufacturing

i hope you will all enjoy it !!