1 Design and Process Considerations.- 1.1 Overview.- 1.2 Assembly Packaging.- 1.2.1 Throughhole Mounted Technology.- 1.2.2 Surface Mounted Technology.- 1.3 Component Packaging.- 1.3.1 Materials.- 1.3.2 Package and Mounting Configuration.- 1.4 The Printed Wiring Assembly.- 1.4.1 Substrate and Solder Mask.- 1.4.2 Component Placement.- 1.5 Assembly and Solder Process.- 1.5.1 Assembly Aids.- 1.5.2 Component Mounting Adhesives.- 1.5.3 Soldering Cycles and Fluxes.- 1.5.4 Conformal Coating.- 1.6 Cleaning Operation.- 1.6.1 Cleaning Solution Properties.- 1.6.2 Process Enhancements.- 1.7 Summary.- References.- 2 Flux Considerations with Emphasis on Low Solids.- 2.1 Introduction.- 2.1.1 Purpose and Chapter Description.- 2.1.2 Definition of Soldering Flux.- 2.2 Specifications.- 2.2.1 Test Methods.- 2.2.2 IPC.- 2.2.3 U. S. Military.- 2.2.4 Telecommunications.- 2.2.5 Summary.- 2.3 Flux Materials.- 2.3.1 Rosin.- 2.3.2 Water Soluble.- 2.3.3 Synthetic Activated.- 2.3.4 Low Solids (No-Clean).- 2.3.5 Controlled Atmosphere Soldering.- 2.4 Application Methods.- 2.4.1 Wave.- 2.4.2 Foam.- 2.4.3 Spray.- 2.4.4 Application Issues for LSFs.- 2.5 Monitoring Techniques.- 2.5.1 Specific Gravity.- 2.5.2 Acid Number (Titration).- 2.5.3 Weight Measurements.- 2.5.4 Monitoring for LSFs.- 2.6 Process Issues.- 2.6.1 Flux Residue.- 2.6.2 Solder Ball Formation.- 2.6.3 Top Side Fillet Formation.- 2.6.4 Conformal Coating Compatibility.- 2.7 Nonliquid Fluxes.- 2.7.1 Core Solder Material.- 2.7.2 Solder Paste Material.- 2.7.3 Specifics for LSFs.- 2.8 Importance of Soldering Parameters.- 2.8.1 Wave Soldering.- 2.8.2 Hand Soldering.- 2.8.3 Reflow Soldering.- 2.8.4 Specifics for LSFs.- 2.9 Summary and Trends.- 2.9.1 Summary.- 2.9.2 Trends.- References.- 3 Solvent Defluxing of Printed Wiring Board Assemblies and Surface Mount Assemblies: Materials, Processes, and Equipment.- 3.1 The Need for Cleaning.- 3.1.1 The Bare Board and Assembly Process—An Overview.- 3.1.2 Types of Contaminants.- 3.1.3 Results of Different Types of Contaminants on Printing Wiring/.- 3.2 The Cleaning Process.- 3.2.1 Solvents for Cleaning.- 3.2.2 Bipolar Solvent Cleaning.- 3.2.3 Equipment for Cleaning.- 3.2.4 The Defluxing Process.- 3.2.5 Solvent Conservation and Reclamation.- 3.3 Testing for Cleanliness.- 3.3.1 Overview of Contamination Testing.- 3.3.2 Testing for Ionics.- 3.3.3 Testing for Nonionics.- 3.3.4 Surface Insulation Resistance (SIR) Test.- 3.3.5 Electromigration (EM) Test.- 3.4 Environmental Concerns of Solvents.- 3.4.1 The Ozone Depletion Problem.- 3.4.2 The Benchmark/Phase 2 Test.- 3.4.3 Alternative Defluxing Solvents.- 3.5 Conclusion.- References.- 4 Aqueous Defluxing: Materials, Processes, and Equipment.- 4.1 Introduction.- 4.1.1 Why Aqueous?.- 4.1.2 Plusses and Minuses.- 4.2 Design Considerations.- 4.2.1 Layout.- 4.2.2 Component Choice.- 4.2.3 Surface Mount versus Throughhole.- 4.2.4 Process/Materials Considerations.- 4.2.5 Summary.- 4.3 Process Considerations.- 4.3.1 Cleaning Materials.- 4.3.2 Equipment.- 4.4 Process Qualification and Control.- 4.4.1 Qualification Strategies.- 4.4.2 Cleanliness Evaluation Techniques.- 4.5 Environmental Concerns.- 4.5.1 Heavy Metals.- 4.5.2 pH.- 4.5.3 BOD.- 4.5.4 Summary.- References.- 5 Alternative Defluxing: Materials, Processes, and Equipment.- 5.1 Introduction.- 5.2 Methods and Equipment.- 5.2.1 Acoustical (Ultrasonic) Cleaning.- 5.2.2 Spray Equipment.- 5.2.3 Centrifugal Cleaning Equipment.- 5.3 Materials.- 5.3.1 Performance.- 5.3.2 Environmental Acceptability and Safety Considerations.- 5.3.3 Economics.- 5.3.4 Specific Material Descriptions.- 5.3.5 Use of Semi-Aqueous Materials in Military Electronics.- References.- 6 Defluxing for High Reliability Applications and General Environmental Issues.- 6.1 Introduction.- 6.2 Background.- 6.3 Cleanliness Requirements.- 6.3.1 Necessity for Cleanliness.- 6.3.2 Military Requirements.- 6.4 Cleaning Materials.- 6.4.1 Solvents.- 6.4.2 Aqueous.- 6.4.3 New Alternatives.- 6.4.4 Acceptance of Alternatives.- 6.5 Cleaning Equipment.- 6.5.1 Batch Cleaners.- 6.5.2 Inline Cleaners.- 6.6 Cleanliness Verification.- 6.6.1 Ionic Test Methods.- 6.6.2 Organic Residue Test Methods.- 6.7 Environmental Issues.- 6.7.1 Atmospheric Impact.- 6.7.2 Montreal Protocol.- 6.7.3 CFC Solvent Availability.- 6.8 The Future of Cleaning.- 6.8.1 Unilateral CFC Reductions.- 6.8.2 Alternative CFC Cleaning Materials.- 6.9 Conclusions.- References.
