1 / 23

How VPS* helps find ground plane shorts (*Vector plane stimulus)

How VPS* helps find ground plane shorts (*Vector plane stimulus). PolarInstruments.com. Toneohm help locate shorts - After ATE or flying probe test has isolated a faulty net. Short circuit and bus fault location - Simple trace to trace or - Multilayer plane / trace or plane / plane.

uta
Télécharger la présentation

How VPS* helps find ground plane shorts (*Vector plane stimulus)

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript


  1. How VPS* helps find ground plane shorts(*Vector plane stimulus) PolarInstruments.com

  2. Toneohm help locate shorts - After ATE or flying probe test has isolateda faulty net. Short circuit and bus fault location- Simple trace to trace or- Multilayer plane / trace or plane / plane Overview

  3. How do you deal with an ATE printout that lists 50 components on one node all short to 50 components on another? E.G. a Vcc +5V short to Gnd? Or a Trace to plane short? Tools for post ATE faultfinding

  4. Milliohm measurement For bus leakage non invasive track current measurement... Contact Or non contact For simple track shorts û

  5. Present a new set of challenges The short (or bus fault) has to be located in two dimensions So what how can a VPS equipped Toneohm help? Plane to plane shorts...

  6. Surprisingly most plane shorts occur during assembly.... Without a 950 they can be difficult to find they are assumed to be “internal” However 90% are assembly related and Easy to repair Are plane shorts worth repairing?

  7. From a quality standpoint it is important to know why the plane short has occurred... Is it a thermal cause? a layout problem? a latent defect with the PCB? Why not throw away boards with plane shorts?

  8. How? – The next slides tell you how VPS works

  9. First imagine a track to ground short Ground Plane

  10. VPS also works for plane to plane shorts Track Ground Plane

  11. The unknown short circuit is a position û Track û Ground Plane Short

  12. VPS Injects a current across the plane I+ Track û Ground Plane Short I-

  13. This sets up a potential gradient across the PCB I+ Track +3 û Ground Plane +2 Short I- +1 0 -1 -2

  14. Measure voltage between short and plane position.The track simply acts as an extension of the meter lead I+ Track +3 û Ground Plane +2 Short I- V1 +1 0 -1 -2

  15. The short is somewhere along the line where V=0. I+ Track +3 û Ground Plane +2 Short I- V1 +1 0 -1 -2

  16. Inject the current at right angles to locate the second dimension. This has isolated the short in one dimension.

  17. By injecting at right angles.. I+ Track +3 Ground Plane û +2 Short I- V2 +1 0 -1 -2

  18. Now find where V2 = 0 I+ Track +3 Ground Plane û +2 Short I- V2 +1 0 -1 -2

  19. The short is located where V1 + V2 = 0 I+ Track +3 Ground Plane û +2 Short I- V +1 0 -1 -2

  20. By looking at the polarity of V1 and V2 the 950 can display directional arrows on the front panel that guide you to the area of the short I+ + + Track +3 + - Ground Plane - + û +2 Short - - I- V +1 0 -1 -2

  21. The 950 Plane shorts mode uses this VPS technique to helpyou rapidly locate plane to plane shorts, A 950 givesa continuous display of short direction while you probe and the current injection is switched automatically I+ + + Track +3 + - Ground Plane - + û +2 Short - - I- V -2 +1 0 -1

  22. Your Toneohms pay for your investment very quickly

  23. USA / Canada - Polar Instruments Inc(800) 328 0817 - Richard Smith UK Polar Instruments (UK) Ltd023 9226 9113 - Paul Norrington Asia / Pacific Polar (Singapore)+65 873 7470 - Amit Bhardwaj R.O.W. - Polar Instruments LtdTel: +44 1481 253081- Martyn GaudionEmail all offices: mail@polarinstruments.com Toneohm short and bus fault locators Ó Polar Instruments 2001 All trademarks recognized

More Related