Root Cause Failure Analysis of Printed Circuit Board ... - SMTA

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Component Pad - Thermal Imbalance • Small Passive Component Pad Design – Mixed Solder Mask Defined • Multiple/Large Trace • Exposed Plane – Smaller Component Package, The Greater The Impact
Thick Copper Design A A CTE CTE Mismatch Mismatch Between Between Copper Copper And And FR FR-4 FR 4 Exists Exists • Copper = 18ppm • FR-4 = 15-16ppm • As Copper Gets Thicker, It Has Greater And Greater Influence Over Post Lamination Dimensions Of The Resulting Substrate Rolled Rolled , , Annealed Annealed Copper Copper Reacts Reacts Differently Differently Differently Than Than ED ED ED Copper Copper • Design Influences On Net Shrinkage Become Far More Significant Standard Scaling Factors (That Compensate Net Shrinkage Effects) Do Not Apply! More More More Resin Resin Is Is Required Required To To “Fill” “Fill” “Fill” Etched Etched Out Out Areas Areas • “In-plane” CTE Increases With % Resin Content • “Another Complication To Net Shrinkage Prediction” • Resin Rich Package = Higher Z-axis CTE = Greater Sensitivity To Thermal Excursions, Assembly In Particular. • Heavy Copper Substrates Generally Require More Heat Input To Assemble • Reliability!
Page 1 and 2: Root Root Root Cause Cause Failure
Page 3 and 4: Today’s Electronic Designs • Co
Page 5 and 6: Component Issues - Warpage • High
Page 7 and 8: Component Issues - Decreasing Pitch
Page 9 and 10: LGA Pad Design Solder Solder Mask M
Page 11 and 12: % PAD SIZE INCREASE 60 50 40 30 20
Page 13: Component Pad - Thermal Imbalance
Page 17 and 18: Thick Copper Design Lack Lack Of Of
Page 19 and 20: Copper Etch Process • H H = = = H
Page 21 and 22: Pad Size Reduction Current Procedur
Page 23 and 24: • Voids in Solder Joints - Unfill
Page 25 and 26: Stencil Tolerances Artwork Artwork
Page 27 and 28: Offset Paste - Normal Placement Pho
Page 29 and 30: Match Placement To Paste • Slight
Page 31 and 32: Solder Paste Printing Volume Air Bu
Page 33 and 34: Internal PCB Impacts Number Of Laye
Page 35 and 36: Wave Solder & Rework Issues 0.005
Page 37 and 38: PCB Finish Vs Solder Spread - OSP -
Page 39 and 40: Defects Caused By Improper Thermal
Page 41 and 42: Through Hole Pad Design • Square
Page 43 and 44: Effect of Board Thickness On Topsid
Page 45 and 46: Solder Mask Selection Matte Finish
Page 47 and 48: Cleaning Chemistry Compatibility
Page 49 and 50: Inspectability - AOI, AXI, HVI •
Page 51 and 52: Cracked Cap Issue • PCA Is Assemb
Page 53 and 54: Source Of Contamination What is Sou
Page 55 and 56: DFX Software Flexibility • Concur
Page 57 and 58: DFX PCA-PCB Software Systems Mentor
Page 59 and 60: DFX Mechanical Software Systems Ana
Page 61 and 62: Closing Thought “We can’t solve

Root Cause Failure Analysis of Printed Circuit Board ... - SMTA

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