Design Guidelines for Surface Mount Technology

1st Edition - January 28, 1990
Author: John Traister
Language: English
eBook ISBN:
9 7 8 - 0 - 3 2 3 - 1 4 1 6 5 - 9

Design Guidelines for Surface Mount Technology covers the basics and the mechanics of surface mounted design technology. Surface mount technology (SMT) embodies an automated… Read more

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Design Guidelines for Surface Mount Technology covers the basics and the mechanics of surface mounted design technology. Surface mount technology (SMT) embodies an automated circuit assembly process, using a generation of electronic components called surface mounted devices (SMDs). Organized into eight chapters, the book discusses the component selection, space planning, materials and processes, and total concept needed to ensure a manufacturable design. The opening chapters of the book examine the significant requirements and variables affecting SMT and SMDs. The book then deals with the substrate materials specifications, including fabrication and material planning, assembly, design rules, layout guidelines, package outlines, and bar code labeling. The next chapters describe the manufacturing and assembly processes in SMDs and process-proven footprint patterns for each of the component types used, as well as guidelines for creating a suitable pattern on future products. Other chapters discuss the component spacing requirements for SMT and the generation of footprint patterns for passive and active components of SMDs. The concluding chapter describes the design criteria for maximizing machine insertion of leaded electronic components into printed circuit boards (PCBs). These criteria aid the PCB designer by detailing the considerations and some of the trade-offs that will provide reliable insertion in a production environment. Supplementary texts on surface mount equipment, supplies, and services are also provided. Design engineers and researchers will find this book invaluable.

Preface Chapter 1 SMD Essentials Designing with SMD Substrate Configurations Mixed Prints Automated SMD Placement Machines Soldering Techniques Footprint Definition Footprints for Wave Soldering The "Shadow Effect" Footprint Orientation Solder Thieves Placement Inaccuracy Dummy Tracks for Adhesive Application Footprints for Reflow Soldering Solder Cream Applications Screen Printing Floating Footprint Dimensions Layout Considerations Component Pitch Solder Land/Via Hole Relationship Solder Land/Component Lead Relationship Placemant Machine Restrictions Substrate Population Test Points CAD Systems for SMD Substrate Layout CAE/CAD/CAM Interaction Chapter 2 Space Planning and Interface Standards for SMT Components Component Packaging Options Component Selection Guidelines Passive Devices: Monolithic Capacitors Tantalum Capacitors Resistors for SMT Resistor Networks Potentiometer for SMT Active Devices ICs for SMT Small Outline (SO) ICs Plastic Chip Carriers and Quad Packages Ceramic ICs Connectors and Interface for SMT Assembly Heat Seal Compression Assembly Considerations Estimating Total Component Area Optimizing Component Placement Component Orientation Utilizing Both Sides of Substrate Thermal Considerations Power Dissipation Thermal Resistance Junction Temperature (Tj) Factors Affecting θJA Package Considerations Thermal Resistance Measurements Test Method TSP Calibration Thermal Resistance Measurement Test Ambient θJC Tests Data Presentation Thermal Calculations System Considerations Using Leaded Devices (SO, SOL, & PLCC) Compliant Layer Matching TCE Substrate Types Conclusion Chapter 3 Specifying Materials for Substrates Common Substrate Materials Fabrication and Material Planning Providing for Assembly Automation Design Rules and Layout Guidelines Plated through-Holes Multilayer and Fine Line Construction Surface Mount and Via Holes Computer Aided Design and Via Holes Solder Mask on PC Boards Using SMT Plating Process for SMT High Tech Materials for Military Applications Specifying Copper Clad Invar Materials for Copper Clad Invar/Polyamide Commercial SMD Packages Military Packages Special Package Outlines Bar Code Labeling Footprints Chapter 4 SMD Assembly Process Solders for SMD Applications Fluxing and Cleaning Types of Flux Flux Types Solder Applications Curing Solder Paste The Reflow Process Cleaning after Reflow Soldering Assembly Methods Assembly Options for SMDs Adhesive Applications and Curing Physical Characteristics Adhesive Application Pin-Transfer Screen-Printing Pressure Syringe Adhesive Dot Height Criteria Dummy Tracks Solder Land Contamination MELF Component Placement Adhesive Curing Curing by Heat/Time Plus Catalyst Curing by Catalytic Action Alone Anaerobic and UV Assisted Curing Fluxing and Cleaning Fluxes Types of Flux Organic Soluble Fluxes Non-Activated Rosin (R) Flux Rosin, Mildly Activated (RMS) Flux Rosin, Activated (RA) Flux Water Soluble Fluxes Water Soluble Fluxes with Inorganic Salts Water Soluble Fluxes with Organic Salts Water Soluble Fluxes with Organic Acids Solder Creams Flux Selection Application of Flux Foam Fluxing Wave Fluxing Spray Fluxing Flux Density Pre-Heating Post-Soldering Cleaning Polar Contaminants Non-Polar Contaminants Solvents Solvent Cleaning Aqueous Cleaning Conformal Coatings Conclusions Solder Joint Criteria Inspection Defect Classification Soldering Defects Drawbridging Adhesive Contamination Blow Holes General Solder Joint Criteria Good Wetting Sound Smooth Surface Correct Amount of Solder SMD Joint Assessment Leadless SMDs SMDs with Few Short Leads SO IC Packages VSO IC Packages PLCC with J-Leads Chip Carriers with Metallized Castellation Inspection Systems Component and Substrate Solderability Aspects of Solderability Protective Coatings Fusible Coatings: Electro-Plated Tin/Lead Solder Coating Solder Land Contamination Chapter 5 Contact (Footprint) Design Designing for Producibility Component Spacing Discrete Component Contact Design Preferred Component Orientation Commercial IC Footprint Planning: SOIC, PCC, and QUAD Lead Packages Ceramic IC Packages Contact Design for Other SMT Products: DIP and SIP Module Design Chip Carrier Design Building Contact (Footprint) Libraries for SMT Contact Geometry for Chip Components Optional Wave Solder Contact Geometry for Chip Components Tantalum Capacitor Contact Geometry MELF Component Contact Geometry SOT-23 Contact ACT Geometry SOT-89 Contact Geometry Plastic Chip Carrier (PCC) Contact Geometry Small Outline Contact Geometry Chapter 6 Component Spacing for SMT Basic Considerations Placement Accuracy Requirements Placement Techniques Trace-to-Trace Guidelines Contact (Footprint) to Via Pad Solder Mask for Solder Control Automatic Assembly and Testing Mixed Technology, Through-hole and Surface Mounted Component-to-Board Edge Requirement Chapter 7 Artwork Generation Footprint (Contact) Pattern for Passive Devices Footprint Planning for Active (IC) Components Hand-Taped Artmaster Preparation Tape and Reel Computer-Aided Design Autorouting SMT Preparing for Future Assembly Methods CAD Applications Chapter 8 PCB Design Considerations Printed Circuit Board Design Board Considerations Component Location Objectives Component Selection Lead Diameter Considerations Board Holder Design Workboard Holder Considerations Rotary Workboard Holder Design Automatic Board Handling Workboard Holders Programming Considerations Insertion Machine Pattern Program Format Board Error Correction Axial Lead Component Insertion Component Input Taping Considerations Axial Lead Sequencing Insertion Center Considerations Lead Form and Tooling Printed Circuit Board Thickness Versus Body Diameter Hole Diameter Requirements Component Body Configuration Location Considerations Clinch Patterns Pattern Program Considerations Radial Lead Component Insertion Taping Considerations Tape Splicing Specification Hole Diameter Requirements Hole Span Considerations Board Sizing Considerations Location Considerations Uninsertable Area Cut and Clinch Patterns Pattern Program Considerations Insertion Reference Point Optimum Pattern Programming Special Programming Considerations Appendix I Surface Mount Equipment, Supplies, and Services Appendix II Surface Mount Device Bibliography Index