Chapter 1
Photolithography in Printed Wiring Board Fabrication
1.1     Introduction
1.2     Scope
1.3     Overview of Circuit Board Design, Fabrication and Assembly
1.4     The Function of Photopolymeric Materials in the Fabrication of Printed Wiring Boards (PWBs)
1.4.1     Consumable Photopolymeric Materials
1.4.2     Permanent Photopolymeric Materials
1.5     Application of Photoresists as Liquids or Dry Film
1.6     Photoresist Composition and Functionality
1.6.1     Reaction Mechanisms of Negative and Positive Working Resists
1.6.2     Dry Film Resist Components and Their Function
1.7     Liquid Photoresists: Methods of Application, Drying and Imaging
1.8     Dry Film Photoresists
1.8.1     Dry Film Structures

Chapter 2
Comparison of Circuitising Processes

Chapter 3
Conductor Via (Through-hole) Formation
3.1     Mechanical Drilling and Deburr 3.2     Microvia Formation

Chapter 4
Initial Through-hole Metallisation
4.1     Principle
4.2     Critical Process Variables
4.3     Direct Metallisation and Non formaldehyde Processes
4.3.1     Palladium Based Systems
4.3.2     Carbon/Graphite Based Systems
4.3.3     Conductive Polymers
4.3.4     Non-formaldehyde Based Electroless Processes
4.4     Avoiding Metallisation Hole Voids
4.4.1     Hole Void Defects Associated with Processing Steps prior to Metallisation
4.4.1.1     Drilling
4.4.1.2     Desmear/Etch Back
4.4.1.3     Pre-electroless Catalysis Sequence
4.4.2     Hole Void Defects Associated with the Electroless Metallisation
4.4.3     Hole Void Defects Associated with Resist Application Steps
4.4.3.1     'Rim Voids'
4.4.3.1.1     Defect Description
4.4.3.1.2     Defect Mechanism
4.4.3.1.3     Eliminating Rim Voids
4.4.3.2     Hole Voids associated with the Tenting Process
4.4.4     Direct Metallisations
4.4.5     Hole Voids Associated with Copper, Tin/Lead and Tin Electroplating
4.4.6     Hole Voids due to Copper Removal
4.4.7     Summary and Conclusions

Chapter 5
Copper Surfaces and Base Material Construction
5.1     Construction of Dielectric Layers
5.2     Copper Surfaces
5.2.1     Vendor Copper Foil (Innerlayers) 5.2.2     Electroless Copper
5.2.3     Reverse Treated Foil (RTF)
5.2.4     Double Treated (DT) Copper
5.2.5     Fine Grain/Low Profile Foils
5.2.6     Very Thin Foils
5.2.7     Electroplated Copper
5.2.8     Antitarnished Copper Surfaces
5.2.9     Direct Metallisation Surfaces

Chapter 6
Prelamination Surface Preparation
6.1     Principle
6.2     Critical Variables
6.3     Introduction
6.4     Scope
6.5     General Adhesion and Surface Preparation Considerations
6.6     Copper Topography and Contact Area
6.7     Topography Modifying Processes
6.8     Surface Preparation Process Selection Criteria
6.9     The Chemical Composition of Copper Surfaces
6.9.1     Analysis of Chemical Surface Composition and Yield Correlation Studies
6.9.2     Hold Time Considerations
6.9.2.1     Prelamination Hold Time
6.9.2.2     Post-lamination Hold Times
6.10     Quality Assurance (QA) Specifications
6.11     Features, Benefits and Controls of Surface Preparation Processes
6.11.1     Brushing
6.11.2     Pumice, Aluminium Oxide, Quartz (Hand Applied, Jet Applied, Brushed)
6.11.3     Chemical Processes (Cleaners, Microetchants, Electrochemical Cleaning)
6.11.4     Processes for Particulate Removal
6.12     Preferred Surface Preparation Processes
6.12.1     Preferred Surface Preparation Processes for Vendor Copper
6.12.2     Preferred Surface Preparation Processes for Electroless Copper
6.12.3     Preferred Surface Preparation Processes for Electroplated Copper
6.13     Critical Surface Preparation Variables and Process Features

Chapter 7
Lamination
7.1     Principle
7.2     Critical Variables
7.3     The Lamination Process
7.3.1     Achieving Contact through Air Removal
7.3.2     Making the Photopolymer Flow
7.3.3     Lamination Pressure
7.3.4     Lamination Temperature
7.3.5     Selected Other Laminator Features
7.3.6     Wet Lamination of Dry Film Photoresist
7.4     Lamination Defects
7.4.1     Effects of Lamination Parameters on Wrinkling and Dimensional Properties of Dry Film
7.4.1.1     The Trend to Thinner Dry Film Resist Architecture
7.4.1.2     Nip-generated Wrinkles in Cut sheet Laminators
7.4.1.2     Post-lamination Wrinkles
7.5     Critical Lamination Parameters and System Features

Chapter 8
Tenting
8.1     Principle
8.2     Variables
8.3     Economics and Regional Differences
8.4     Tent & Etch Processing
8.4.1     Surface Preparation
8.4.2     Lamination and Post-lamination Hold Time
8.4.3     Resist and Coversheet Thickness
8.4.4     Exposure and Development
8.5     Tent Failure Modes
8.6     End-use Tests and Test Simulations
8.6.1     End-use Tests
8.6.2     Testing Significant Physical Resist Parameters

Chapter 9
Phototools
9.1     Principle
9.2     Critical Variables
9.3     Artwork Generation and Phototool Use
9.3.1     Artwork Generation
9.3.2     Phototool Generation
9.4     Film Types and Properties
9.5     Film Structures and Photochemistry
9.5.1     Silver Halide Films
9.5.2     Diazo Films
9.6     Phototool Quality Characteristics
9.7     Proper Handling and Use of Phototools
9.8     Size Holding

Chapter 10
Exposure
10.1     Principle
10.2     Critical Variables
10.3     Spectral Sensitivity of Photoresists
10.3.1     Step Tablets (Grey Scales; Step Wedges)
10.3.2     Energy Absorption and Photopolymerisation
10.4     Exposure Equipment
10.5     Contact Printing Problems 10.5.1     Radiation in Non-exposure Areas
10.5.1.1     Fundamental Considerations
10.5.1.2     Off-contact
10.5.2     Imaging of Dirt, Defects and Matte Surface Particles
10.6     Imaging in a Cleanroom Environment
10.7     Outlook on Laser Direct Imaging (LDI)
10.7.1     Cost/Benefits of LDI
10.7.2     The Fundamentals of LDI
10.7.3     LDI and Image Resolution
10.7.4     Imaging Speed
10.8     Other Alternatives to Contact Printing
10.9     Critical Imaging Variables and System Features

Chapter 11
Development
11.1     Principle
11.2     Critical Variables
11.3     Pre-development (Post-exposure) Hold Time and Hold Conditions
11.3.1     Enhancing Chemical Contrast between Exposed and Unexposed Areas
11.4     Fundamental Shortcomings in Aqueous Development of Negative Working Resists
11.4.1     Danger of Over-development
11.4.2     Resolution Limitation due to Resist Swelling
11.5     The Chemistry of Aqueous Development
11.6     The Function of Sprays in the Development Chamber
11.7     The Function and Effects of Rinsing
11.8     Drying the Developed Resist
11.9     Practical Operation of Aqueous Development
11.9.1     A Closer Look at Developer Chemistry
11.9.2     Chemistry Control
11.9.2.1     Resist Loading
11.9.2.2     Feed-and-Bleed Controls
11.9.2.3     Use of Hydroxide to Regenerate Carbonate
11.9.3     Breakpoint Determination and Control
11.9.3.1     The Significance of 'Post-Break Point Residence Time'
11.9.3.2     Breakpoint Tests
11.9.4     Temperature
11.9.5     Rinsing Variables and Controls
11.9.6     Miscellaneous Equipment Features
11.9.6.1     Developer Solution Filtration
11.9.6.2     Automatic Replenishment of Developer Chemistry
11.9.6.3     Developer Cleaning
11.10     Critical Development Variables and System Features

Chapter 12
Electroplating
12.1     Principle
12.2     Critical Process Variables
12.3     Structural Outline of the Plating Section
12.4     Acid Copper Plating
12.4.1     Pre-plate Cleaning
12.4.2     The Copper Bath
12.5     Solder Plating
12.6     Bright Acid Tin
12.7     Nickel Plating
12.8     Gold Plating
12.9     Improved Surface Copper Thickness Uniformity: What are the Options?
12.10     A Closer Look at the Function of Organic Additives in Copper Plating Baths
12.10.1     Brighteners, Carriers and Levellers
12.10.2     Control of Organic Additives
12.11     Plating Problems and Troubleshooting
12.11.1     Plating Pits
12.11.2     Organic Interferences with Plating Additive Systems
12.11.3     Ragged Pattern Plated Circuit Lines
12.11.4     Plating Nodules
12.11.5     Step Plating
12.11.6     Barrel or Corner Cracks
12.11.7     Over-plating
12.12     Critical Plating Variables and System Features

Chapter 13
Etching
13.1     Principle
13.2     Critical Variables and Features
13.3     Dry Film Selection
13.4     Acid Etch Uniformity - A Key Performance Consideration
13.5     Fighting the Etch Factor
13.5.1     Thin Copper Foil Options
13.5.2     Improved Copper Thickness Uniformity
13.6     Etchant Chemistries Overview
13.6.1     Acid Cupric Chloride
13.6.2     Alkaline Cupric Chloride
13.6.3     Hydrogen Peroxide
13.7     The Etch Process and Equipment
13.7.1     Cupric Chloride Etch Chemistry and Process Control
13.7.2     Alkaline Cupric Chloride Etch Chemistry and Process Control
13.7.3     Hydrogen Peroxide Etch Chemistry and Process Control
13.8     Problems with Residual, Excess Copper in Print/ Etch and Tent/ Etch Processes
13.9     Critical Etch Variables and System Features

Chapter 14
Stripping of Aqueous Resist
14.1     Principle
14.2     Critical Process Variables
14.3     The Stripping Process and Chemistries
14.3.1     Time-to-Strip, Break-point, and Dwell Time
14.3.2     Loading
14.3.3     Strip Speed
14.3.4     'Cleanliness' of Stripping
14.3.5     Feed-and-Bleed Replenishment
14.3.6     Reworking Panels by Stripping
14.3.7     Tank Stripping
14.4     The Cost Elements of Stripping
14.4.1     Thinking Outside the Box
14.4.2     Choosing Stripper Disposal Routes
Based on Cost and Environmental Considerations
14.4.3     Filtration Choices
14.4.4     Cleaning the Stripper Equipment
14.4.5     Combining Cost Elements in a Model
14.5     Critical Stripping Variables and System Features

Chapter 15
Safety and Health
15.1     Health Effects of Acrylate Exposure
15.2     Incidence of Health Effects

Chapter 16
Waste Treatment and Disposal
16.1     Aqueous Effluent
16.2     Solid Wastes
16.3     Specific Resist Waste Streams
16.4     Waste Treatment
16.4.1     Waste Treatment to Remove Metals
16.5     Resist Process Solution Pretreatment
16.6     Environmental Compatibility Aspects

Chapter 17
Water Quality in PWB Fabrication

Chapter 18
Recycling PWB Scrap