Modification of Signal Propagation Velocity Through Printed Circuit Boards Using High Dielectric Constant Materials

Size: px

Start display at page:

Download "Modification of Signal Propagation Velocity Through Printed Circuit Boards Using High Dielectric Constant Materials"

Brianne Hunter
5 years ago
Views:

1 Modification of Signal Propagation Velocity Through Printed Circuit Boards Using High Dielectric Constant Materials RICHARD JIANG, BROWN UNIVERSITY DOUGLAS JACKSON, UNIVERSITY OF LOUISVILLE JOHN NABER, UNIVERSITY OF LOUISVILLE

2 Motivation

3 Motivation

4 Motivation

5 Motivation

6 Motivation

7 Motivation

8 Motivation

9 Background

10 Background Copper Routing W T FR4 Substrate H Power/Ground Planes

11 Background Copper Routing FR4 Substrate W T H V " = c sqrt dk +,, Power/Ground Planes

12 Background Copper Routing FR4 Substrate W T H V " = c sqrt dk +,, Power/Ground Planes Signal Velocity for Stripline vs Microstrip for W/H = 2 Signal Velocity (m/s) 3.50E E E E E E E E Dielectric Constant of Substrate Stripline Microstrip

13 Methods

14 Methods Recall: Can we modify speeds of signals through PCBs?

15 Methods Recall: Can we modify speeds of signals through PCBs? c V " = sqrt dk +,,

16 Methods Recall: Can we modify speeds of signals through PCBs? c V " = sqrt dk +,, V "- = dk 1 dk 2 c sqrt dk +,,- V ". = c sqrt dk +,,.

17 Methods Control/Reference Trace Variable/Modified Trace

18 Methods Control/Reference Trace Variable/Modified Trace

19 Methods Control/Reference Trace Variable/Modified Trace

20 Methods Copper 120 mils (3.048 mm) FR4 Substrate Void (Air) 10 mils (0.254 mm) 240 mils (6.096 mm) 50 mils (1.270 mm)

21 Methods Tested Materials Considerations: Range Ease of Application Safety Mechanical Integrity

22 Methods Material Reported dk Tested Materials Considerations: Range Ease of Application Safety Mechanical Integrity FR4 4.2 Air 1 PVDF (Polyvinylidene Fluoride) 8.4 Barium Titanate 2000 Water* 80.4 Silicon Nitride 7 Titanium Dioxide 10 Mica 7

23 Methods

Methods Material Capacitance (pf) Reported k Notes / k FR4 20.7 / 4.17 4.2 Reference material Air 7.9 / 1.59 1 Lowest dielectric PVDF (polyvinylidene 26.6 / 5.36 8.

24 Methods Material Capacitance (pf) Reported k Notes / k FR / Reference material Air 7.9 / Lowest dielectric PVDF (polyvinylidene 26.6 / layers of film difluoride) Barium Titanate 48.5 / Dried but not sintered Water* 63.0 / Water & cornstarch mixture Silicon Nitride 15.3 / Research grade Titanium Dioxide 19.0 / Consumer grade Mica 11.5 / Consumer grade

25 Experimentation

26 Experimentation Material FR4 Air PVDF (Polyvinylidene Fluoride) Barium Titanate Water* Silicon Nitride Titanium Dioxide Mica

27 Experimentation Material FR4 Air PVDF (Polyvinylidene Fluoride) Barium Titanate Water* Silicon Nitride Titanium Dioxide Mica

28 Experimentation Control/Reference Trace Variable/Modified Trace

29 Experimentation Control/Reference Trace Control/Reference Trace Variable/Modified Trace Variable/Modified Trace

30 Experimentation Control/Reference Trace Variable/Modified Trace

31 Experimentation Control/Reference Trace Variable/Modified Trace

32 Experimentation O_Scope Ch1 Control/Reference Trace O_Scope Ch2 Variable/Modified Trace

33 Experimentation O_Scope Ch1 Control/Reference Trace O_Scope Ch2 Variable/Modified Trace

34 Experimentation O_Scope Ch1 Control/Reference Trace 0E- 01 0E- 01 0E- 01 0E- 01 0E- 02 0E+00 0E- 02 0E- 01 0E- 01 0E- 01 0E- 01 0E- 01-6E- 09-4E- 09-2E- 09 Time 0E+00 (s) 2E- 09 4E- 09 6E- 09 Voltage (V) O_Scope Ch2 Variable/Modified Trace

35 Results

36 Results Measured Tp Calculated Tp % Error Measured Td Calculated Td % Error (ns) (ns) (ns) (ns) FR Air PVDF Heated BaTiO3 Water* Silicon Nitride TiO Mica

37 Results VNA Delay (ns) Oscope Delay (ns) % Error FR Air PVDF Heated BaTiO Water* Silicon Nitride TiO Mica

38 Results Measured Velocity Calculated Velocity % Error (10^8m/s) (10^8m/s) FR Air PVDF Heated BaTiO Water* Silicon Nitride TiO Mica

39 Conclusion

40 Conclusion The propagation speeds of signals through printed circuit board traces were successfully varied by modifying the surrounding material.

41 Conclusion The propagation speeds of signals through printed circuit board traces were successfully varied by modifying the surrounding material. The amount by which the speeds varied followed the trend dictated by the equation V s = c/sqrt(dk eff ).

42 Conclusion The propagation speeds of signals through printed circuit board traces were successfully varied by modifying the surrounding material. The amount by which the speeds varied followed the trend dictated by the equation V s = c/sqrt(dk eff ). Not all measured dielectric constants matched with their reported values, indicating a need for further work in measurement techniques. Measured results agree with calculations with the exception of PVDF.

43 Conclusion The propagation speeds of signals through printed circuit board traces were successfully varied by modifying the surrounding material. The amount by which the speeds varied followed the trend dictated by the equation V s = c/sqrt(dk eff ). Not all measured dielectric constants matched with their reported values, indicating a need for further work in measurement techniques. Measured results agree with calculations with the exception of PVDF. Results show that signal velocities between 4.45 and in/ns (11.31 and cm/ns) can be obtained.

Conclusion The propagation speeds of signals through printed circuit board traces were successfully varied by modifying the surrounding material.

44 Conclusion The propagation speeds of signals through printed circuit board traces were successfully varied by modifying the surrounding material. The amount by which the speeds varied followed the trend dictated by the equation V s = c/sqrt(dk eff ). Not all measured dielectric constants matched with their reported values, indicating a need for further work in measurement techniques. Measured results agree with calculations with the exception of PVDF. Results show that signal velocities between 4.45 and in/ns (11.31 and cm/ns) can be obtained. These numbers are promising for increasing the efficiency of PCB area utilization and with further work, this research may find itself within standard PCB processingsteps.

AN B. Basic PCB traces transmission line effects causing signal integrity degradation simulation using Altium DXP version 6.

AN B. Basic PCB traces transmission line effects causing signal integrity degradation simulation using Altium DXP version 6. AN200805-01B Basic PCB traces transmission line effects causing signal integrity degradation simulation using Altium DXP version 6.9 By Denis Lachapelle eng. and Anne Marie Coutu. May 2008 The objective