BS 6221-23:1991

Committees responsible
Foreword
Guide
1. Scope
2. Definitions
3. Design for surface mounting components
3.1 General
3.2 Design considerations
4. Substrates and mounting of chip carriers
4.1 Introduction
4.2 Resin and fabric substrates
4.4 Leadless ceramic chip carriers (LCCCs)
     considerations
4.5 Plastic leaded chip carriers (PLCCs)
4.6 Mounting considerations
5. Soldering process considerations
5.1 Introduction
5.2 Designing for soldering
5.3 Wave soldering
5.4 The infra-red (IR) reflow soldering process
5.5 The condensation reflow soldering process (vapour
     phase)
5.6 Onsertion machine to pattern alignment
5.7 Artwork
5.8 Solder resist
5.9 Solder paste
5.10 Design for adhesive application
5.11 Process and assembly parameters
5.12 Conductor geometries
5.13 Guidelines for wave-soldered layout
5.14 Guidelines for reflow-soldered layout
5.15 Metallic finishes
5.16 Solder resistive coatings
6. Land design for SMDs
6.1 Two terminal SMD
6.2 Land dimension calculations
6.3 Multiple terminal SMDs
6.4 Solder mask considerations
6.5 Additional considerations
7. Recommended component layouts
7.1 Component separation
7.2 Auto placement clearances (ACPs)
7.3 Mixed components
8. Testability of surface mounted assemblies (SMAs)
8.1 Introduction
8.2 Fixturing. General information for designers
8.3 Test probes
8.4 Design consideration
8.5 Recommended code of practice
8.6 Methods for providing open nodes
8.7 Recommendations for vacuum fixturing on a 2.54 mm
     (0.100 in) pitch
Tables
1. Mounting of ceramic devices
2. Process and assembly parameters
3. Physical dimensions of rectangular chip components
Figures
1. Possible board configurations
2. Wave soldering
3. Design for adhesive application
4. Orientation of component to solder wave direction
5. Layout and terminology for chip component lands
6. The effect of component rotation
7. Rectangular chip components dimensions and
     terminology
8. Recommended design land pattern parameters for
     surface mounted assembly 1206 resistor
9. Recommended design land pattern parameters for
     surface mounted assembly capacitors
10. Recommended design land pattern parameters for
     surface mounted assembly SO-123
11. Recommended design land pattern parameters for
     surface mounted assembly SO-197
12. Recommended deisng land pattern parameters for
     surface mounted assembly SO1C (SO-193A, SO-193B,
     SO-193C)
13. Recommended design land pattern parameters for
     surface mounted assembly SO1C (SO-192A, SO-192B,
     SO-192C, SO-192D)
14. Recommended design land pattern parameters for
     surface mounted assembly SO-200
15. Recommended design footprint parameters for surface
     mounted assembly plastic 'J' leaded chip carriers
16. Recommended design footprint parameters for surface
     mounted assembly leadless chip carriers (square)
17. Recommended design footprint parameters for surface
     mounted assembly leadless chip carriers
     (rectangular)
18. Recommended design footprint parameters for surface
     mounted assembly tantalum chip capacitors
19. Recommended design footprint parameters for surface
     mounted assembly tantalum rectangular chip
     capacitors
20. Preferred distance between chip components
21. Chip components: clearance dimensions for ACP
22. Traditional fixtures with protective carriage plate
23. SMA fixture without protective carriage plate
24. Test probes and modules
25. Module test probe access to a matrix of SMDs
26. Test lands for surface mounted components
27. Provision of test lands

Gives guidance on the design of printed wiring boards for surface mounted components. Addresses substrates and mounting of surface mounting device carriers, soldering process, land design, component layouts, and testability. Contains several figures.