اخوانى واخوتى فى الله معى اليوم كتاب
SMT Soldering Handbook
Rudolf Strauss, Dr.Ing., FIM
اتمنى ان ينال اعجابكم
Contents
Preface to the first edition xii
Preface to the second edition xiv
Glossary xvi
1 Why SMDs? 1
References 5
2 The SMD family 6
2.1 Shapes, sizes and construction 6
2.1.1 Melfs and chips 6
2.1.2 LCCCs 8
2.1.3 SOs and PLCCs 9
2.2 High-pincount components 9
2.2.1 TABs 10
2.2.2 Flip-chips and BGAs 11
2.3 Multichip modules 13
2.4 The solderable surfaces of SMDs 14
2.4.1 Melfs and chips 14
2.4.2 Components with legs 15
2.5 SMD shapes and wavesoldering behaviour 16
2.6 The popcorn effect 16
2.7 References 18
3 Soldering 20
3.1 The nature of soldering and of the soldered joint 20
3.1.1 The roles of solder, flux and heat 203.1.2 Soldering methods 21
3.1.3 Soldering success 24
3.2 The solder 24
3.2.1 Constituents, melting behaviour and
mechanical properties 24
3.2.2 Composition of solders for use in electronics 27
3.2.3 Lead-free solders 29
3.2.4 Solder impurities 31
3.3 The soldered joint 36
3.3.1 Soldering as a surface reaction between a
molten and a solid metal 36
3.3.2 Structure and characteristics of the soldered
joint 37
3.3.3 Mechanical properties of soldered joints 40
3.3.4 Soldering on surfaces other than copper 41
3.3.5 Long-term behaviour of soldered joints 43
3.3.6 Long-term reliability of soldered joints 44
3.4 The flux 45
3.4.1 Tasks and action of the soldering flux 45
3.4.2 Wetting and interfacial tension 47
3.4.3 Properties required in a flux 48
3.4.4 Rosin fluxes 50
3.4.5 Low-solids and no-clean fluxes 52
3.4.6 Watersoluble fluxes 53
3.4.7 Solvents used in fluxes 54
3.4.8 Flux standards 54
3.4.9 Testing soldering fluxes 57
3.5 Soldering heat 60
3.5.1 Heat requirements and heat flow 60
3.5.2 Heating options 61
3.6 Solderability 63
3.6.1 Wetting and dewetting 63
3.6.2 Capillarity and its effects 65
3.6.3 Capillarity and joint configuration 65
3.6.4 The importance of solderability 69
3.6.5 Oxide layers 69
3.6.6 Solderability-enhancing surface coatings 71
3.6.7 Leaching effect of molten solder 73
3.6.8 Measuring solderability 74
3.7 References 81
4 Wavesoldering 84
4.1 The wave concept 84
4.1.1 Wavesoldering before SMDs 84
4.1.2 Wavesoldering after SMDs 85
4.2 Applying the flux 87
4.2.1 Types of fluxer 87
4.2.2 Monitoring and controlling flux quality 96
4.3 Preheating the board 98
4.3.1 Heat requirements 98
4.3.2 Heat emitters and their characteristics 100
4.3.3 Temperature control 102
4.4 The solderwave 103
4.4.1 Construction of the soldering unit 103
4.4.2 Thermal role of the solderwave 104
4.4.3 Interaction between molten solder and the
circuit board 105
4.4.4 Chipwaves 110
4.4.5 Formation and control of dross 114
4.5 Wavesoldering in an oxygen-free atmosphere 118
4.5.1 Origins and development 118
4.5.2 Wavesoldering in nitrogen 119
4.6 Board conveyor systems 126
4.6.1 Functional requirements 126
4.6.2 Board-handling systems 126
4.7 Wavesoldering practice 130
4.7.1 Operating parameters and their role 130
4.7.2 Choosing and monitoring operating parameters 131
4.7.3 Optimizing machine parameters 136
4.7.4 Machine maintenance 137
4.7.5 Check-analysis of the solderbath 138
4.7.6 Dealing with dross 138
4.7.7 Hygiene and safety 139
4.8 The role of adhesives in wavesoldering 141
4.8.1 Demands on the adhesive and the glued joint 141
4.8.2 Storage and handling behaviour of adhesives 141
4.8.3 Applying the adhesive 143
4.8.4 Curing the adhesive joint 145
4.8.5 The glass transition temperature 146
4.9 References 147
5 Reflowsoldering 148
5.1 The reflow concept 148
5.1.1 SMDs and reflowsoldering 148
5.1.2 Reflowsoldering versus wavesoldering 154
5.2 Solder paste 158
5.2.1 Operational requirements 158
5.2.2 Standard specifications 159
5.2.3 Solderpowder 160
5.2.4 The flux and its residue 164
5.2.5 Printing and dispensing properties 165
5.2.6 The solderball test 167
5.3 Putting the solder paste on the board 169
5.3.1 Single-spot dispensing 169
5.3.2 Stencilling and screen printing 171
5.3.3 Depots of solid solder 178
5.4 Vapourphase soldering 179
5.4.1 The basic concept 179
5.4.2 Vapourphase working fluids 180
5.4.3 The physics of vapourphase soldering 180
5.4.4 Vapourphase soldering equipment 184
5.4.5 ‘New-generation’ vapourphase soldering
systems 186
5.5 Infrared soldering 189
5.5.1 Working principle 189
5.5.2 The physics of heat transfer by radiation 191
5.5.3 The physics of heat transfer by convection 200
5.5.4 Operation of infrared ovens 201
5.5.5 Oven design 203
5.5.6 Infrared soldering in a controlled atmosphere 208
5.6 Reflowsoldering with hot air or gas 209
5.6.1 Convection versus radiation 209
5.6.2 The physics of convection reflowsoldering 210
5.6.3 Convection reflow ovens 210
5.6.4 Development potential of convection
reflowsoldering 212
5.6.5 Convection soldering of single components 214
5.7 Laser soldering 217
5.7.1 How a laser works 218
5.7.2 Nd:YAG and CO
lasers 218
5.7.3 Laser soldering in practice 220
5.7.4 Laser-soldering equipment 221
5.8 Impulse soldering 223
5.8.1 Operating principle 223
5.8.2 The solder depot 2245.8.3 The thermode and its heating cycle 225
5.8.4 Impulse-soldering equipment 227
5.9 SMD soldering methods – A survey 228
5.10 References 232
6 The circuit board 234
6.1 The beginnings 234
6.2 SMD-specific demands on a circuit board 234
6.3 Thermal management 236
6.3.1 Thermal expansion mismatch 237
6.3.2 Effects of temperature differences between
components and board 237
6.4 Solderable surfaces 238
6.4.1 Galvanic coatings 239
6.4.2 Hot tinning 239
6.4.3 Organic coatings 241
6.4.4 Flat solder depots 242
6.5 The soldermask 244
6.6 Layout 244
6.6.1 Layout for wavesoldering 244
6.6.2 Layout for reflowsoldering 247
6.7 References 249
7 Component placement 250
7.1 The task 250
7.2 Reliability of placement 251
7.3 Placement options 253
7.3.1 Fully manual placement 253
7.3.2 Semi-automatic placement 255
7.3.3 Fully automatic sequential systems 256
7.3.4 Simultaneous placement systems 257
7.4 The practice of automatic component placement 258
7.4.1 The range of choice 258
7.4.2 Classes of placement machines 259
7.5 Reference 260
8 Cleaning after soldering 261
8.1 Basic considerations 261
8.1.1 Reasons for cleaning 263
8.1.2 Designing for cleanability 266
8.1.3 What must be removed? 267
8.2 The theory of cleaning 269
8.2.1 The physics of cleaning 269
8.2.2 The chemistry of cleaning 274
8.3 The practice of solvent cleaning 276
8.3.1 Organic solvents 277
8.3.2 Solvent-cleaning installations 282
8.3.3 In-line cleaning plants 288
8.3.4 Halogenated solvents: safety and health 291
8.3.5 The three environmental threats 293
8.3.6 Restrictions on solvent usage 297
8.3.7 Non-flammable organic solvents with reduced
environmental risks 298
8.3.8 Flammable solvents 299
8.4 Cleaning with water 302
8.4.1 Chemical and physical aspects 302
8.4.2 Water quality 303
8.4.3 Water recycling and effluent problems 305
8.4.4 Removal of residue from watersoluble fluxes 306
8.4.5 Removal of residue from resinous fluxes 306
8.4.6 Water washing installations 307
8.5 Semi-aqueous cleaning 310
8.5.1 The concept 310
8.5.2 The cleaning solvents 311
8.5.3 Semi-aqueous washing installations for
water-immiscible solvents 313
8.5.4 Semi-aqueous washing installations for
water-miscible solvents 315
8.6 Testing for cleanliness 318
8.6.1 The meaning of cleanliness 318
8.6.2 Measuring ionic contamination (MIL test) 319
8.6.3 Measuring surface insulation resistance (SIR) 321
8.7 The future of cleaning and of fluxing 322
8.8 References 323
9 Quality control and inspection 325
9.1 The meaning of ‘quality’ 325
9.1.1 Product quality and product reliability 325
9.1.2 Classification according to reliability
requirements 326
9.2 Soldering success and soldering perfection 327
9.2.1 Soldering success and soldering faults 327
9.2.2 Soldering perfection and soldering imperfections 330
9.3 Practical examples of soldering faults 332
9.4 The ideal and the imperfect joint 3329.5 Inspection 332
9.5.1 When to inspect 335
9.5.2 Visual inspection 337
9.5.3 Automated opto-electronic inspection 338
9.5.4 X-ray inspection 338
9.5.5 Electronic inspection 340
9.5.6 Thermographic inspection 340
9.6 References 340
10 Rework 342
10.1 The unavoidability of rework 342
10.1.1 Rework in the production process 342
10.1.2 Desoldering and resoldering 343
10.2 Basic considerations 343
10.2.1 Metallurgical and mechanical consequences of
rework 343
10.2.2 The cost of rework 344
10.2.3 Lessons to be learned 344
10.3 Rework equipment 345
10.3.1 Heat sources 345
10.3.2 Rework stations 347
10.4 Rework tasks and procedures 348
10.4.1 Removing bridges and solderballs 348
10.4.2 Desoldering SMDs 348
10.4.3 Filling empty joints 353
10.4.4 Resoldering SMDs 356
10.4.5 Cleaning after rework 358
10.4.6 Semi-mechanized work stations 359
10.5 Integrating rework into the production process 360
10.5.1 Rework personnel 360
10.5.2 Closed-loop soldering 361
10.6 References 361
Index 363
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