Coupon Evaluation for GSFC Flight PWBs

1
Coupon Evaluation for GSFC Flight PWBs

• presented by
• Diane Kolos
• Materials Engineering Branch
• NASA Goddard Space Flight Center
• November 14, 2007

2
Introduction

• Coupon as an Indicator of Board Quality
• A coupon is representative sample of the printed
  circuit board (PCB) designed for destructive
  analysis. It is produced on the same
  manufacturing panel with the PCB and has
  experienced all of the production processes with
  the board it represents.
• The coupon is our best tool for determining the
  acceptability of flight PCBs.
• Failure rate as a function of coupon analysis
• 26 in 1992 11-15 today
• These rejections are after vendor coupon
  screening

3
Significant Trigger Events

• Instrument failure at launch site
• On-orbit failure of device
• 1992 - 4 million replacement of 148 boards on
  one S/C
• Alert against major independent coupon laboratory

4
Coupon Testing Basics

• Cross-sectioning technique
• GSFC uses 5 grinding steps and 3 polishing
  slurries to prepare coupons
• Sample preparation is critical to identification
  of defects
• Trace to barrel joints are copper and easily
  smeared
• Thermal Stress Testing
• 550F for 10 seconds

5
GSFC Policies for PCB Procurement

• Require coupon evaluation for every flight board
• Includes double sided product
• Applicable Specifications
• Rigid boards 6012B Class 3/A
• Uses Performance Specification Sheet for Space
  Military Avionics
• Flex boards 6013B
• Must be done at GSFC or a GSFC-approved lab

6

• Coupon Failures

7
Missing Plating in Through Hole
8
Missing Annular Rings at Buried Via
9
Gross Plating Folds in Through Hole
10
Missing External Annular Ring
11
Inadequate Internal Annular Rings
12
Missing Cap Plating
13
Trace to Barrel Separations
14
Laminate Defect
15
Laminate Defect
16
Contact Information

• Diane Kolos [phone]
• e-mail Diane.M.Kolos_at_nasa.gov
• Rita Rozenbaum [phone]
• e-mail Rita.Rozenbaum-1_at_nasa.gov