Design for Reliability: PCBs - DfR Solutions

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Surface Finishes - Post Pb-FreeooMultiple Pb-Free Surface Finish Options Now Exists.oNo clear winner, no ideal solution.2003Each PCB surface has different advantages and disadvantagesthat affects fabrication, solderability, testability, reliability, orshelf life.Surface Finishes,WorldwideoooThe 5 most popular Pb-Free Surface Finishes are:oooooElectroless nickel/immersion gold (ENIG)oAnd ENEPIG (electroless Pd added)Immersion silver (ImAg)Immersion tin (ImSn)Organic solderability preservative (OSP)Pb-free HASL.2007These finishes (except for Pb-free HASL)have been in use for several years.Newer finishes are currently being developed (direct Pd,PTFE-like coatings, etc.18%Ref: J. BeersGold Circuits© 2004 - 2007 2010
Surface Finish Selection ApproachoooooComponent Procurement: Select the cheapest one and let theengineers figure out how to use it.PCB Engineer: Select the finish that is easiest for the suppliers toprovide (their sweet spot); let the assembler figure out how touse it.Assembly Engineer: Select the finish that provides the largestprocess window for assembly and test.Sustaining Engineer: Select the finish that minimizes field failures.CEO: Select the finish that minimizes the overall cost (includingreliability risk).© 2004 - 2007 2010
Page 1 and 2:
Design for Reliability: PCBsNorth T
Page 3 and 4:
Course OutlineINTRODUCTIONSooIntro
Page 5 and 6:
Why Design for Reliability (DfR)?o
Page 7 and 8:
Physics of Failure DefinitionsoFail
Page 9 and 10:
A Word on Quality, Reliability & Cl
Page 11 and 12:
PCB Materials / Laminate Selectiono
Page 13 and 14:
Laminate DatasheetsooOut-of-plane C
Page 15 and 16:
Glass StyleoooPCB laminates (and pr
Page 17 and 18:
Laminate Properties (cont.)oMore re
Page 19 and 20:
Thermal Parameters and IPC Slash Sh
Page 21 and 22:
PTV Degradation due to Assembly© 2
Page 23 and 24:
PCB Materials: StackupoMaximum stre
Page 25 and 26:
PCB ViasPlated Through Holes© 2004
Page 27 and 28:
How to Design a Reliable PTV?PTH Ar
Page 29 and 30:
PCB Industry PTV Capability95% of I
Page 31 and 32:
IPC TR-579oRound Robin Reliability
Page 33 and 34: IPC TR-579 (cont.)oDetermine strain
Page 35 and 36: IPC TR-579 (cont.)o Iteratively cal
Page 37 and 38: The Effect of Design Parameters (He
Page 39 and 40: Effect of Design Parameters (cont.)
Page 41 and 42: Plating (Thickness and Material Pro
Page 43 and 44: Case Study: Microvia Fill and PTV R
Page 45 and 46: Plating Mechanical PropertiesoIndus
Page 47 and 48: Cycles to FailureThe Reality of PTV
Page 49 and 50: Post-Plating MeasurementsoHardness
Page 51 and 52: Other Platings (cont.)oS. Neumann,
Page 53 and 54: Test / Qualify PTVoQualifying PTV i
Page 55 and 56: Simulation and ModelingoSecond step
Page 57 and 58: Initial Qualification (PCQR2)oQuali
Page 59 and 60: Lot QualificationoInterconnect stre
Page 61 and 62: ConclusionoThe base knowledge and u
Page 63 and 64: CAF: ExamplesInfluenced by electric
Page 65 and 66: Strain Flexure Issues & Pad Crateri
Page 67 and 68: Strain & Flexure: Pad CrateringoCra
Page 69 and 70: Potential Mitigations to Pad Crater
Page 71 and 72: Pad Geometry• Pad design influenc
Page 73 and 74: Future of Contamination / Cleanline
Page 75 and 76: Failure ModeoWhy do you care about
Page 77 and 78: ECM MechanismsoooSome ECM Mechanism
Page 79 and 80: Nominal Ionic LevelsooooBare printe
Page 81 and 82: Process Material Qualification - SI
Page 83: Importance of Surface FinishooooThe
Page 87 and 88: Surface Finish Selection GuidelineA
Page 89 and 90: OSP Issues: Plated Through-Hole Fil
Page 91 and 92: Surface Finish Selection GuidelineP
Page 93 and 94: ImAg Trace EtchingSolder maskGalvan
Page 95 and 96: Typical Creep Corrosion• Corrosio
Page 97 and 98: Wetting Force ( mN/mm)Impact of Tar
Page 99 and 100: Immersion Sn (ImSn)• A single mat
Page 103 and 104: ENIG - Ni Interface Issues w/ SACBr
Page 105 and 106: Unreliability, F(t)ENIG: Mechanical
Page 109 and 110: Pb-Free HASL: Ni-modified SnCuoAllo
Page 111 and 112: Newer Finishes to the MarketProduct
Page 113 and 114: Newer Finishes to the MarketProduct
Page 115 and 116: Examples of Best Application Fitsoo
Page 117 and 118: What to do if there is no SF fit?oo
Page 119 and 120: SummaryoooooThe surface finish you
Page 121 and 122: ConclusionsoooDesign for Reliabilit
Page 123: Contact Information• Questions?
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