Probe. Placement P Primer P. Copyright 2011, Circuit Check, Inc.

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Alberta Bell
6 years ago
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1 Probe Placement P Primer P

2 What's Involved? Control Design ICT Friendly UUT Location Location Location Increase your odds in the manufacturing process Good contact Small targets Agilent Bead Probes Suggested Probes Questions 2

Design ICT Friendly UUT Even distribution of test pads to mitigate stress Tooling holes P0.125 on a diagonal, non plated Design ICT Friendly UUT 3 PCB tooling to pad: +/- 0.002 Tooling hole size:+ 0.

3 Design ICT Friendly UUT Even distribution of test pads to mitigate stress Tooling holes P0.125 on a diagonal, non plated Design ICT Friendly UUT 3 PCB tooling to pad: +/ Tooling hole size: Total PCB tolerances +/ Probing gold-plated fingers may cause blemishes from probes Check company quality acceptance practices Add test point location Test pads located away from edge of board, and or away from edge of rails. Test pad minimum spacing from component edge to test pad center 0.018" plus half solder pad width (component can be off solder pad by as much as 50% of solder pad width) per IPC-9850 placement guidelines IPC-A-610D Class 3 High Performance Electronic Products.

Location Location Location Half the solder pad width plus probe clearance equals total test pad clearance required. X75.038 X50.0312 X39.0264 X31.024 X75.080 X50.073 X39.0684 X31.

4 Location Location Location Half the solder pad width plus probe clearance equals total test pad clearance required. X X X X X X X X Half the solder pad width plus probe clearance equals total test pad clearance required. X X X X X X X X Test Pad Location to Component 4

5 Location Location Location Are here to stay! X-Probe Technology.039 Spacing Standard Technology.050 Spacing.075 Spacing.100 Spacing Spacing 100 mil probe.050 Spacing 75 mil probe.039 Spacing 50 mil probe.030 Spacing 39 mil probe Probe Probe Plate Spacer Plate Termination Plate Termination Probe Spacing Choices 5

50-Mil Probe 39-Mil Probe 100-Mil Probe.085.075.064.

6 Location Location Location Relative to Each other Minimum Recommended Probe / Receptacle Spacing 100-Mil Probe 75-Mil Probe 50-Mil Probe 39-Mil Probe 100-Mil Probe Mil Probe Mil Probe Mil Probe.039 Test Pad MINIMUM Spacing 6

7 Location Location Location Relative to Each other Minimum Recommended Probe / Receptacle Spacing X75 Probe X50 Probe X39 Probe X31 Probe X75 Probe X50 Probe X39 Probe X31 Probe.030" Test Pad MINIMUM Spacing 7

Increase Your Odds 8 PCB Manufacturing Solder mask clearance from edge of pad P.2mm Solder mask aperture 0.

8 Increase Your Odds 8 PCB Manufacturing Solder mask clearance from edge of pad P.2mm Solder mask aperture larger than test target Filled/Plugged vias: Plan on probing only IPC 4761 Type VII Filled and Capped vias Copper plated vias and pads can be more difficult due to oxidation and OSP other plating options to consider: ENIG Electroless Nickel Immersion Gold IAg Immersion Silver or ISn Immersion Tin SAC Tin Silver Copper ENEPIG Electroless Nickel, Electroless Palladium, Immersion Gold Carefully select probable fluxes Keep lead lengths to 0.050" for mil probes Probing leads with < 75mil probes is not recommended Increase Your Odds

9 Good Contact 9

10 Small Targets 10 Guide Plate" added for Top Side probing Guide Plate Options "Quick Plate " is cut out of the Top Plate

11 Small Targets 0.020" Test Pad Test Pad Probe contacting inner 2/3 rds of test pad. Probe contacting edge of test pad. Probe/Socket tilted in mounting hole, UUT pushed to maximum tolerance extreme. Top plate "funnel" drilled slightly larger than probe shaft. Probe/Socket tilted in mounting hole, UUT pushed to maximum tolerance extreme. Receptacle mounting and fit are less of a concern when probes are guided. Smaller Test pads w/guided Probe 11

12 Agilent Bead Probe Is it any different than a test pad? It is a round or oblong pad of solder on the surface of a trace or test pad. Typically no wider than the trace and length is < Height < Agilent Bead Probe 12 Photographs courtesy of Agilent

13 Agilent Bead Probe Now Probing small bead with a large probe 5 mil wide trace with Bead Probe How do we contact that little bump mil diameter test probe

14 Agilent Bead Probe ABP Probe Selection 14

15 Agilent Bead Probe Good design recommendations: Keep ABPT spacing at 75 mil or greater Guide topside probes when possible to prevent probe drag Precise registration of topside probes Make sure that ABPT locations are clearly identified in your fixture files Make sure that you have notified your fixture vendor that your board has ABPT If you are an OEM and outsource notify your vendors that ABPT probe locations are present If experiencing consistent opens brush test probes with a stiff bristle brush Monitor flux contamination on UUT ABPT correct stencil aperture and orientation Agilent Bead Probe Wrap Up 15

16 Suggested Probes PTH Probe Selection 16

17 Suggested Probes Connector Probe Selection 17

18 Suggested Probes Filled Vias Probe Selection 18

19 Suggested Probes Unfilled Vias Probe Selection 19

20 Suggested Probes Test Pads Probe Selection 20

What the Designer needs to know

White Paper on soldering QFN packages to electronic assemblies. Brian J. Leach VP of Sales and Marketing AccuSpec Electronics, LLC Defect free QFN Assembly What the Designer needs to know QFN Description: