Solving Today s Test Challenges: Razor Sharp Probes

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Dustin Griffin
7 years ago
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1 Solving Today s Test Challenges: Razor Sharp Probes

2 Test Challenges Variety targets, materials, finishes, processes Organic Solderability Preservatives (OSP) lead-free (Pb-free) air vs. nitrogen (N2) atmosphere unpasted (unfilled) via variety of solder pastes pasted (filled) via select wave soldering Failed ENIG Immersion Au (gold) wave soldering variety of solder fluxes Immersion Ag (silver) single reflow thru-hole leads higher melting point small via holes Immersion Sn (tin) test pads double sided reflow decreased solder flow rate pin-testable solder paste no-clean large via holes

3 Effects of Test Challenges Increased Cost Of Test False Failures Unreliable Contact Slower Throughput Reduced Probe Life $ Fewer Probes Higher Spring Forces Increase Board Flex Reduced Coverage NDF No Defects Found Missed Defects Bad Boards Pass The Test

4 Variety of Difficult Test Targets OSP Copper Via, Unpasted OSP, Lead-Free Solder Pasted Via Lead-Free Solder Pasted Test Pad Lead-Free Dome of Solder

5 New Probe Design Challenge To significantly improve probe contact reliability on even the most difficult to probe test targets.

6 Internal Test Vehicles (pcbs) Board Mfg. & Provided by Major OEM Processed at Multiple CM s to OEM Spec s OSP Copper, Lead-Free, Pasted Vias (no-clean) All Paste Stencils Were 6 mils Thick Rows 1-16 =.010 hole,.030 dia. Rows =.012 hole,.035 dia. Boards Processed in Both Air and Nitrogen (N2) Typical Alpha Metals OM338-PT Pin-Testable Extreme Difficult Alpha Metals OM338

7 Internal PCB Testing Vacuum Test Fixture PCB Indexing Capability Captures Resistance Test Measurements Failure was defined as resistance > 500 milliohms Single Hit Per Target (First Pass) 32 Targets per Row, 691 Rows 2 second cycle time 22,112 Total Points / board = 20 min.

8 The Solution RAZOR SHARP PROBE TIPS designed to contact Vias and Test Pads on boards manufactured with difficult to contact processes. 8R-S 150 6R-S 90 9R-S 40

blocked by a pool of flux in the center.

9 8R-S Razor Sharp Tip Style Primarily designed to contact VIAS. The 8R-S, 150 angle contacts the face of a via, and reduces the chance of being blocked by a pool of flux in the center. Also works well on flat test pads, but not solder domes. 150º Extremely sharp cutting edge. Front View primary angle. Side view with 60º secondary angle.

10 Witness Marks 8R-S Razor Sharp Tip Style Witness mark of an 8R-S Razor sharp tip on lead-free pasted via, no-clean process Witness mark of an 8R-S Razor sharp tip on lead-free pasted test pad, no-clean process

11 8R-S Razor on Solder Dome

12 6R-S Razor Sharp Tip Style Primarily designed to contact VIAS & TEST PADS. The 6R-S, 90 angle improves electrical contact on filled, unfilled vias & flat test pads. Having a steeper angle than 8R-S, they may not work quite as well on filled vias. 90º Extremely sharp cutting edge. Front view primary angle. Side view with 45º secondary angle.

13 Witness Marks 6R-S Razor Sharp Tip Style Witness mark of a 6R-S Razor on a lead-free pasted via, no-clean process. Witness mark of a 6R-S Razor on a lead-free pasted test pad, no-clean process. Witness mark of a 6R-S Razor on an OSP via, unpasted, no-clean process.

14 9R-S Razor Sharp Tip Style Primarily designed to contact TEST PADS & DOMES of SOLDER. The steep 9R-S, 40 angle creates a sharp center point that works well on test pads & solder domes. 40º angle Extremely sharp cutting edge. Front view primary angle. Side view with 23º secondary angle.

15 Witness Marks 9R-S Razor Sharp Tip Style Witness mark of a 9R-S Razor on a lead-free pasted solder dome, no-clean process Witness mark of a 9R-S Razor on a flat lead-free soldered test pad, no-clean process

16 SEM Photos of Razor Tips 8R-S Razor Face View 8R-S Razor Side View 61-S Typical Blade Side View 6R-S Razor Side View

17 First Pass Yield <500Millohms Performance Testing FPY Typical Case - Test Vehicles Identically Processed in Air 100mil Conventional - Pin-Testable Solder Paste 100% 90% 80% "02" Alpha OM338-PT, DSDR % 60% 50% 40% 30% 20% 10% 0% 3.5 (99) "L" Spring 5.5 (156) "S" Spring 6.5 (184) "H" Spring 8.1 (230)"Y" Spring 61-S Blade 6R-S Razor 8R-S Razor "Spring force is in ounces (gms) at 2/3 stroke"

First Pass Yield <500milliohms Performance Testing FPY Extreme Case Test Vehicles Identically Processed in Air 100mil Conventional - Difficult To Probe Solder Paste "0S" Alpha OM338, DSDR 100% 90% 97.

18 First Pass Yield <500milliohms Performance Testing FPY Extreme Case Test Vehicles Identically Processed in Air 100mil Conventional - Difficult To Probe Solder Paste "0S" Alpha OM338, DSDR 100% 90% % % 60% 50% % 30% % 10% 0% 3.5 (99) "L" Spring 5.5 (156) "S" Spring 6.5 (184) "H" Spring 8.1 (230)"Y" Spring 61-S Blade 6R-S Razor 8R-S Razor "Spring force is in ounces (gms) at 2/3 stroke."

19 Beta Site Test Results In three independent studies performed at two different CMs in China, the Razor sharp tip style outperformed conventional probes with consistent and reliable contact. Lead-Free Pasted Vias with No-Clean Process Beta Site 1 Beta Site 2 (Reduced Spring Forces) Beta Site 3 (Reduced Spring Forces) Conventional Blade 8.1oz Razor 8.1oz Conventional Blade 8.1oz Razor 6.5oz Conventional Blade 8.1oz Razor 6.5oz 1st Pass 55% 96% 82% 100% 11% 96% 2nd Pass 30% 4% 12% 17% 4% 3rd Pass 10% 0% 4% 4th Pass 0% 6% 0% 5th Pass 0% 4% Total Success Rate 95% 100% 100% 100% 36% 100% Increased First Pass Yields, Faster Throughput, Lower Spring Forces

20 Internal Life Cycle Testing Condition of probes after 58k cycles on OSP, lead-free pasted, no-clean processed boards still performing with single actuation. Longer Probe Life results in lower board test costs Fixture Actuations Cycle Life Boards Tested Standard Steel Blade 5 60,000 12,000 Steel Razor 2 60,000 30,000

95% 90% 85% 80% First Pass Yield <500milliohms100% Total

21 Life Testing 100mil 6R-S Razor Probe Life Test Using TV's with Alpha OM338 and OM338-PT solder paste and various processes. 95% 90% 85% 80% First Pass Yield <500milliohms100% Total Cycles New Probe Same Probe after 67,900 cycles (flux has been cleaned)

22 Customer Feedback 1. Large CM in Mexico FPY: Start 40%, Razor Probes 88%. Comments: It is the best probe for any OSP process, pasted or non-pasted. It will be our standard probe for all OSP assemblies tested at ICT. Board throughput: Increased 68 to 93 boards per hour. 2. Mid Size CM in Mexico FPY: Start 85%, Razor Probes 92%. Comments: It improves the test contact on boards tested. 3. OEM in the USA FPY: Start 50%, Razor Probes 80%. Comments: I am extremely impressed with the Razor Probes. 4. OEM in Mexico FPY: Start 65%, Razor Probes 70%. QA Technology has shipped Razors to over 130 customers.

23 Via Damage Testing Conventional Blade Tip vs. Razor Tip Style 8R-S Razor 61R-S Blade 1 Hit 6R-S Razor 1 Hit 8R-S Razor 1 Hit 61H-S Blade 20 Hits 6R-S Razor 20 Hits 8R-S Razor 20 Hits

24 Reduce Board Flex Use of lower spring forces reduce stress (shown in red) on board

Goal Achieved Significantly Improved Probe Contact Reliability on Even the Most Difficult to Probe Test Targets New Razor Tip Design Results:

s) Achieves higher board throughput rate (reduces test time & retest rate) Extends probe life significantly Reduces Board Flex Enables the use of

25 Goal Achieved Significantly Improved Probe Contact Reliability on Even the Most Difficult to Probe Test Targets New Razor Tip Design Results: Fewer number of Fixture Actuations Required = Lower Board Test Costs Significantly reduces false failures (NDFs) Increases first pass yields (FPY s) Achieves higher board throughput rate (reduces test time & retest rate) Extends probe life significantly Reduces Board Flex Enables the use of lower spring forces under dense areas. Improves Test Results Allows for tighter tolerances on component measurements Guarantees more stable digital tests

26 Care and Installation Use of a plastic probe installation tool or other plastic pusher reduces the risk of tip and/or probe damage when installing the Razor tip probes.

27 Availability

28 Thank you.

How to Build a Printed Circuit Board. Advanced Circuits Inc 2004

How to Build a Printed Circuit Board 1 This presentation is a work in progress. As methods and processes change it will be updated accordingly. It is intended only as an introduction to the production