Reliability of Solder Joint Quality on J-Lead Oscillators Using HALT with Lead and Lead Free Compositions

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Reliability of Solder Joint Quality on J-Lead
Oscillators Using HALT with Lead and Lead Free
Compositions

• Steve Laya
• Elite Electronic Engineering
• Todd Treichel
• Precision Devices, Inc.

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Presentation Overview

• Primary Objective Evaluation of Lead vs. Lead
  Free
• Use of HALT Vibration (and Thermal Shock)
• Initial Findings
• Sometimes things dont go as planned
• Understanding HALT Stresses
• Resonance Dwell To Determine Lead vs. Lead Free
• Post Test Analysis

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Lead vs. Lead-Free

• Conversion from Lead to Lead-Free
• European Union
• Automotive Electronics
• Industrial and Commercial Electronics
• Assure reliability of Lead-Free

4
Published Research

• Follow up on
• PDI Testing
• Joint Council on Ageing Aircraft (JCAA)

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J-Lead Ceramic Package Under Test
JL4
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Test Vehicle PCB

• 10 parts Lead
• 10 parts Lead-Free
• J-Leaded Oscillators
• Hand Soldered To Fiberglass Epoxy PCB

Lead Free
Lead
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Termination Diagram
Electro Au, 1.00 µm Min. Kovar, 0.25
Min. Dia.
Electro Ni, 1.78 µm Min.
Cu
FR4 Substrate
Alloys Under Test
Tin/Lead SAC 305 Solder
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Solder Joint Inspection
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HALT Table Location

• Placed in the center of the HALT vibration table
  with Air Flow evenly distributed
• Instrumentation to measure open circuit on PCB
  component interface.

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Instrumentation
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Elites HALT System

• HALT Testing
• 60C/m Temp Shock
• 6-Axis Vibration
• Repetitive Shock
• Power Spectral Density Characteristics
• HALT Test Purpose

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6-Axis RS Vibration Table
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Test Results

• Thermal Shock
• Step Vibe
• Sustained Vibration at 50gs
• No failures after 35 hours of vibration testing.
• How come???

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Perform a Vibration Survey
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Perform a Vibration Survey
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Perform a Vibration Survey
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Measure PCB Resonance
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Lead-Free
3
Lead
2
4
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Resonance Search Run 1
3
4
2
Gs
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Multiple Searches Location 3
Gs
Multiple Searches Location 4
Gs
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Measure resonance of the Oscillator
Gs
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Overlay resonance on plot of PSD Location 4
G2/Hz
4
G2/Hz
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Overlay resonance on plot of PSD Location 3
G2/Hz
3
G2/Hz
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Overlay resonance on plot of PSD Location 2
G2/Hz
2
G2/Hz
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What is the Board Acceleration

• _at_ 718Hz Location 4 was at 23.3 g2/Hz
• RMS Acceleration at 718 (location 4) is
• Accel (23.3 x 3.13)1/2 8.6g
• _at_ 1371Hz Location 3, 9.37 g2/Hz
• Accel (9.37 x 3.13)½ 5.4g
• _at_784 Hz Location 2, 15.15 g2/Hz
• Accel (15.15 x 3.13)½ 6.8

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Perform Resonance Dwell

• Pick a resonance
• Test to failure
• Determine time to failure

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Lead-Free
3
Lead
2
4
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Lead Free Resonance Dwell at 748Hz
An still no pop-off failures!
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Solder Joint Inspection
63Sn/37Pb
96.5Sn/3.0Ag/0.5Cu
Worst Case
40 of Joints Fractured
22 of Joints Fractured
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Conclusions Lessons Learned

• Both constructions are durable
• HALT
• Suitable for generating high vibration on PCB
  components
• Good fixturing is important
• Resonance Dwell
• Concentrates enormous energy at one frequency
• Selection of resonance frequency could skew
  results.
• Test Uniformity Repeatability
• Difficult to achieve
• Board Resonances
• Locations

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• Any questions
• Thank you!
• Enjoy the remainder of the conference.