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PCB Design Guide to Via and Trace Currents and Temperatures Unabridged edition [Kõva köide]

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  • Formaat: Hardback, 246 pages
  • Ilmumisaeg: 28-Feb-2021
  • Kirjastus: Artech House Publishers
  • ISBN-10: 1630818607
  • ISBN-13: 9781630818609
Teised raamatud teemal:
PCB Design Guide to Via and Trace Currents and Temperatures Unabridged editionSuurem pilt
  • Formaat: Hardback, 246 pages
  • Ilmumisaeg: 28-Feb-2021
  • Kirjastus: Artech House Publishers
  • ISBN-10: 1630818607
  • ISBN-13: 9781630818609
Teised raamatud teemal:
Püsilink: https://www.kriso.ee/db/9781630818609.html
Märksõnad:
A very important part of printed circuit board (PCB) design involves sizing traces and vias to carry the required current. This exciting new book will explore how hot traces and vias should be and what board, circuit, design, and environmental parameters are the most important. PCB materials (copper and dielectrics) and the role they play in the heating and cooling of traces are covered. The IPC curves found in IPC 2152, the equations that fit those curves and computer simulations that fit those curves and equations are detailed.





Sensitivity analyses that show what happens when environments are varied, including adjacent traces and planes, changing trace lengths, and thermal gradients are presented. Via temperatures and what determines them are explored, along with fusing issues and what happens when traces are overloaded. Voltage drops across traces and vias, the thermal effects going around right-angle corners, and frequency effects are covered. Readers learn how to measure the thermal conductivity of dielectrics and how to measure the resistivity of copper traces and why many prior attempts to do so have been doomed to failure. Industrial CT Scanning, and whether or not they might replace microsections for measuring trace parameters are also considered.
Preface xiii
Technical Note: TRM xvii
Acknowledgments xix
1 Introduction and Historical Background
1(6)
1.1 Bottom Line
1(1)
1.2 Historical Background
1(4)
1.3 A Note about Consistency
5(2)
End Notes
6(1)
2 Materials Used in PCBs
7(10)
2.1 Bottom Line
7(1)
2.2 Background
7(1)
2.3 Copper Used in PCBs
8(5)
2.3.1 Copper-clad laminates
8(2)
2.3.2 Copper Plating Manufacturing Step
10(2)
2.3.3 Copper Resistivity
12(1)
2.3.4 Summary
12(1)
2.4 Dielectrics Used in PCBs
13(4)
2.4.1 Thermal Conductivity (Tcon or k)
13(1)
2.4.2 Glass Transition Temperature (Tg)
13(1)
2.4.3 Decomposition Temperature (Td)
14(1)
2.4.4 Time to Delamination (T260/T288)
14(1)
2.4.5 Summary
15(1)
End Notes
15(2)
3 Resistivity and Resistance
17(10)
3.1 Bottom Line
17(1)
3.2 Resistivity
17(3)
3.3 Resistance
20(1)
3.4 Thermal Coefficient of Resistivity (a)
21(1)
3.5 Measuring Resistivity
22(5)
3.5.1 Resistivity Investigation
25(1)
3.5.2 Nondestructive Measurements
25(1)
End Notes
25(2)
4 Trace Heating and Cooling
27(14)
4.1 Bottom Line
27(1)
4.2 Overview
27(1)
4.3 Trace Heating
28(1)
4.3.1 Power and Energy
28(1)
4.3.2 Trace Heating
29(1)
4.4 Trace Cooling
29(3)
4.4.1 Conductive Cooling
30(2)
4.5 Mathematical Model of Trace Heating and Cooling
32(1)
4.6 Role of Current Density
32(1)
4.7 Measuring Trace Temperature
33(3)
4.7.1 IPC Procedure
33(1)
4.7.2 Infrared Measurement
34(1)
4.7.3 Thermocouple Measurement
35(1)
4.7.4 Point versus Average Measurements
36(1)
4.8 Trace Temperature Curves
36(5)
4.8.1 Typical Curve
37(1)
4.8.2 Heavy Overload
37(1)
4.8.3 Marginal Overload
37(2)
End Notes
39(2)
5 KV IPC Curves
41(10)
5.1 Bottom Line
41(1)
5.2 IPC-2152
41(1)
5.3 Measuring the Temperature
41(3)
5.4 IPC Curves
44(7)
5.4.1 External Results
44(1)
5.4.2 External IPC Data Equations
45(2)
5.4.3 Internal IPC Data Equations
47(1)
5.4.4 IPC Vacuum Data
48(2)
End Notes
50(1)
6 Thermal Simulations
51(12)
6.1 Bottom Line
51(1)
6.2 Background
51(1)
6.3 Modeling Traces
51(3)
6.4 The Modeling Process
54(9)
End Notes
62(1)
7 Thermal Simulations
63(26)
7.1 Bottom Line
63(1)
7.2 Sensitivities: Layout Parameters
63(12)
7.2.1 Small Trace Widths
64(2)
7.2.2 Transient Response
66(1)
7.2.3 Thermal Gradients
66(1)
7.2.4 Changing Trace Length
67(1)
7.2.5 Dimensional Uncertainties
68(1)
7.2.6 Presence of Planes
69(1)
7.2.7 Adjacent Trace
69(2)
7.2.8 Adjacent Trace with Underlying Plane
71(1)
7.2.9 Parallel Power Traces
71(1)
7.2.10 Stacked Power Traces
72(1)
7.2.11 Air Flow
73(1)
7.2.12 Summary
73(2)
7.3 Sensitivities: Material Parameters
75(7)
7.3.1 Board Thickness and Ptanes
75(2)
7.3.2 Effect of Resistivity
77(1)
7.3.3 Effect of Heat Transfer Coefficient
78(1)
7.3.4 Effects of Thermal Conductivity Coefficient
79(1)
7.3.5 Effect of Trace Thickness
80(1)
7.3.6 Summary
80(2)
7.4 Sensitivities: Trace Depth
82(4)
7.5 Conclusions
86(3)
7.5.1 Call to Action
87(1)
End Notes
87(2)
8 Via Temperatures
89(20)
8.1 Bottom Line
89(1)
8.2 Background Information
89(2)
8.3 Thermal Simulation
91(7)
8.3.1 Simulation Strategy
91(1)
8.3.2 Board Model
92(1)
8.3.3 First Simulation
92(1)
8.3.4 Additional Simulations
93(3)
8.3.5 Two Vias
96(2)
8.3.6 Conclusion
98(1)
8.4 Experimental Verification
98(2)
8.4.1 Simulation
98(1)
8.4.2 Simulation Results
99(1)
8.5 Experimental Results
100(2)
8.5.1 Measured Results
100(1)
8.5.2 Conclusion
101(1)
8.6 Voltage Drop Across Trace and Via
102(2)
8.6.1 Summary
103(1)
8.7 Thermal Vias
104(5)
8.7.1 Special Via
107(1)
8.7.2 Conclusion
107(1)
End Notes
107(2)
9 Current Densities in Vias
109(8)
9.1 Bottom Line
109(1)
9.2 Background
109(1)
9.3 Single Via
110(3)
9.4 Multiple Vias
113(1)
9.5 Multiple Vias and Turn
114(1)
9.6 Conclusions
115(2)
End Notes
116(1)
10 Thinking Outside the Box
117(8)
10.1 Bottom Line
117(1)
10.2 Start Thinking Outside Our Boxes
117(1)
10.3 Test Board
118(1)
10.4 Copper Under the Trace
118(2)
10.4.1 Discussion
119(1)
10.5 Adding Additional Copper to Traces
120(1)
10.5.1 Discussion
121(1)
10.6 Dealing with Connecting Links
121(3)
10.6.1 Discussion
123(1)
10.7 Conclusions
124(1)
End Notes
124(1)
11 Fusing Currents: Background
125(8)
11.1 Bottom Line
125(1)
11.2 Background
125(1)
11.3 W. H. Preece
126(1)
11.4 I. M. Onderdonk
127(6)
11.4.1 Cautions
129(1)
End Notes
130(3)
12 Fusing Currents: Analyses
133(20)
12.1 Bottom Line
133(1)
12.2 Background
133(1)
12.3 Fusing Time and Temperature
134(1)
12.4 Assumptions and Cautions
134(1)
12.5 Simulation Models
135(7)
12.5.1 Simulation Results, TRM Fuse
136(1)
12.5.2 Simulation Results, TRM Trace
137(1)
12.5.3 Short-time Effects
138(4)
12.5.4 Final Conclusions
142(1)
12.6 Experimental Results
142(2)
12.6.1 Heating Uncertainties
143(1)
12.6.2 Cooling Uncertainties
143(1)
12.7 The Fusing Process
144(1)
12.7.1 Strong Overload
145(1)
12.7.2 Slight Overload
145(1)
12.8 Experimental Results
145(4)
12.8.1 Case A: Fast Fusing
146(1)
12.8.2 Case B: Slow Fusing
147(2)
12.8.3 Other Cases
149(1)
12.9 Summary
149(4)
End Notes
151(2)
13 Do Traces Heat Uniformly?
153(12)
13.1 Bottom Line
153(1)
13.2 Background
153(1)
13.3 Thermal Gradients on Traces
154(4)
13.3.1 Thermal Gradients on Narrow Traces
156(1)
13.3.2 Does Trace Thickness Matter?
156(1)
13.3.3 Is Trace Thickness Uniform?
156(1)
13.3.4 What Causes Thermal Nonuniformity?
157(1)
13.3.5 Conclusion
158(1)
13.4 Thermal Gradients Around Corners
158(7)
13.4.1 Software Simulation
159(3)
13.4.2 Experimental Verification
162(1)
13.4.3 Conclusions
163(1)
End Notes
164(1)
14 Stop Thinking about Current Density
165(6)
14.1 Bottom Line
165(1)
14.2 Background
165(1)
14.3 Current Density Is Not an Independent Variable
166(1)
14.4 IPC Curves
166(1)
14.5 Copper Type
166(1)
14.6 Dielectric Type
167(1)
14.7 Right-Angle Corners
167(1)
14.8 Trace Form Factor
168(1)
14.9 Via Current Densities
168(2)
14.10 Conclusion
170(1)
15 AC Currents
171(16)
15.1 Bottom Line
171(1)
15.2 Digital Simulation Models
171(6)
15.2.1 Preliminary Results
176(1)
15.3 Experimental Verification
177(4)
15.3.1 Conclusions
179(2)
15.4 Analog AC Currents
181(6)
15.4.1 Test Circuit
181(1)
15.4.2 RMS Signal Levels
182(1)
15.4.3 Nonline arities
183(1)
15.4.4 Results
184(1)
15.4.5 Conclusion
185(1)
End Notes
185(2)
16 Industrial CT (X-Ray) Scanning
187(12)
16.1 Bottom Line
187(1)
16.2 Background
187(1)
16.3 The Promise
188(1)
16.4 The Microsectioning Process
189(1)
16.5 Industrial CT Scanning
190(5)
16.5.1 Results
193(2)
16.6 Comparison of the Processes
195(1)
16.7 Conclusion
196(3)
End Notes
196(3)
Appendix A Measuring Thermal Conductivity
199(4)
A.1 Measurement
199(4)
End Notes
201(2)
Appendix B Measuring Resistivity
203(10)
B.1 Resistance versus Resistivity
203(1)
B.2 How to Measure PCB Trace Resistivity
204(2)
B.3 Problem with Ohmmeter Measurement
206(1)
B.4 Sources of Measurement Error
207(2)
B.4.1 Trace Width
207(1)
B.4.2 Trace Length
208(1)
B.4.3 Trace Thickness
208(1)
B.4.4 Roughness
208(1)
B.5 An Experimental Study
209(2)
B.5.1 What Is Expected Resistivity?
211(1)
B.6 Summary
211(2)
End Notes
211(2)
Appendix C IPC Internal and Vacuum Curves Fitted with Equations
213(6)
Appendix D Detailed Set of Equations for the Curves
219(2)
Appendix E Current/Temperature Curves, 0.25 to 5.0 oz
221(10)
Appendix F Current Density in Vias
231(12)
F.1 Interpretations
231(2)
F.1.1 Caution
232(1)
F.1.2 Symmetry
233(1)
F.2 Single Via Model
233(1)
F.3 Single Via Model with Core 1 Broken into Three Cores, the First Two with 15-μm Thicknesses
233(4)
F.4 Simulation of Four Vias, Proceeding Straight Ahead
237(1)
F.5 Simulation of Four Vias, Traces at Right Angles
237(6)
Appendix G Derivation of Onderdonk's Equation
243(10)
G.1 Onderdonk's Equation
243(1)
G.2 Background
243(6)
G.2.1 Basic Equation
244(1)
G.2.2 Solving the Equation
245(4)
G.3 Proof that αT2 *ρT2 = ρT1 *αT1
249(4)
End Notes
251(2)
Appendix H Results of All Six Fusing Configuration Simulations
253(4)
Appendix I Nonuniform Heating Patterns
257(4)
About the Authors 261(2)
Index 263