IPC-D-279 EN.pdf - 第5页

Table of Contents 1.0 SCOPE ...................................................................... 1 1.1 Purpose ................................................................. 1 1.2 Design Philosophy .................…

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Acknowledgment
Any Standard involving a complex
technology draws material from a
vast number of sources. While the
principal members of the SMT
Design Reliability Task Group of the
Product Reliability Committee are
shown below, it is not possible to
include all of those who assisted in the
evolution of this standard. To each of
them, the members of the IPC extend
their gratitude.
Product Reliability
Committee
SMT Design Reliability
Task Group
Technical Liaison of the
IPC Board of Directors
Chair
Werner Engelmaier
Engelmaier Assoc., Inc.
Chairs
Nick Virmani
Unisys-NASA/Goddard
Space Flight Center
and Ed Aoki
Hewlett-Packard Company
Stephen Wohlgemuth
Photocircuits
SMT Design Reliability Task Group
Amick, Patricia, McDonnell Douglas
Aerospace
Aoki, Edward Masami, Hewlett
Packard Laboratories
Barela, Phillip, Jet Propulsion
Laboratory
Bevan, Matthew, Johns Hopkins
University
Branch, Howard, Smiths Industries
Bright, Burton, Adtran Inc.
Burg, John, 3M Company
Burt, Ronald, Jet Propulsion Laboratory
Carroll, Thomas, Hughes Aircraft Co.
Clifton, Lori, Hewlett Packard Co.
Collins, Henry, Amp Inc.
Colokathis, Elaine, Exotic Plating Lab
Inc.
Croce, Samuel, Litton Aero Products
Division
Currier, Charles, Ambitech Inc.
Currier, Dal, Ambitech Inc.
DiFranza, Michele, The Mitre Corp.
Dunn, Barrie, European Space Agency
Dunn, Linda, Compaq Computer
Corporation
Engelmaier, Werner, Engelmaier
Associates Inc.
Gandhi, Mahendra, Hughes Aircraft Co.
Gonzalez, Constantino, ACME Assembly
Contract Manufacturing Engineering
Gray, Foster, Texas Instruments Inc.
Grosskopf, Curtis, IBM Corp.
Harford, Lyle, Texas Instruments Inc.
Hawken, David, IBM Corp./Endicott
Electronic Packaging
Hersey, Ralph, Lawrence Livermore
National Lab
Hinton, Phillip, Hinton PWB
Engineering
Hymes, Les, Les Hymes Associates
Johnson, Kathryn, Hexacon Electric
Company
Kotecki, George, Northrop Grumman
Corporation
Long, Andrea, Lucent Technologies Inc.
Maguire, James, Boeing Defense &
Space Group
McCluskey, Patrick, University of
Maryland
Moffitt, James, EMPF
Nelson, David, Adtran Inc.
Nicewarner, Earl, Orbital Sciences
Corporation
Officer, R. Bruce, Sanders, A Lockheed
Martin Co.
Olsen, Richard, Continental Circuits
Corp.
Payne, Ron, Olin Aerospace Company
Pepersack, Cindy, NASA/Goddard
Space Flight Center
Reddy, Srirama, AT&T Interconnect
Center of Excellence
Redinger, Vicki, EFW Inc.
Rietdorf, Bruce, Hughes Defense
Communications
Robb, Jeff, Lockheed Martin
Astronautics
Rosser, Jerald, Hughes Missile Systems
Co.
Rumps, Don, Lucent Technologies Inc.
Samples, Wesley, EFW Inc.
Saunders, Penny, NASA Johnson Space
Center
Savage, Robert, The Bergquist
Company
Smith, E. Lon, Lucent Technologies
Inc.
Solberg, Vern, Tessera Inc.
Virmani, Nick, NASA/Goddard Space
Flight Center
Wasler, David, Jet Propulsion
Laboratory
Witzman, Sorin, NORTEL
Special Note of Appreciation
A special note of appreciation goes to the following principle members of the committee who initiated and contributed
significantly to make this document possible.
Vern Solberg, Tessera
Werner Engelmaier, Engelmaier Associates
IPC-D-279 July 1996
ii
Table of Contents
1.0 SCOPE...................................................................... 1
1.1 Purpose................................................................. 1
1.2 Design Philosophy............................................... 1
1.2.1 Establishing the Design Team............................. 1
1.2.2 Defining Reliability Requirements...................... 1
1.2.3 Understanding the Product Life Cycle................ 1
1.2.4 Defining the Product Environment...................... 2
1.3 Document Organization....................................... 2
1.3.1 Applicable Documents......................................... 2
1.3.2 Design for Reliability of SM Assemblies........... 2
1.3.3 Substrates ............................................................. 2
1.3.4 Components.......................................................... 2
1.3.5 Attachment Materials and Coatings.................... 2
1.3.6 Assembly Processes and DfM............................. 2
1.3.7 Testing.................................................................. 3
1.4 Terms and Definitions.......................................... 3
2.0 APPLICABLE DOCUMENTS .................................. 5
2.1 Institute for Interconnecting and Packaging
Electronic Circuits (IPC)..................................... 5
2.2 Electronic Industries Association ....................... 5
2.3 Joint Industry Standards...................................... 5
3.0 DESIGN FOR RELIABILITY FOR SURFACE
MOUNT ASSEMBLIES
............................................. 5
3.1 Life Cycle Environment...................................... 5
3.1.1 Manufacturing Processes..................................... 5
3.1.2 Processing Temperature Excursions.................... 5
3.1.3 Burn-In and Environmental Stress Screening
(ESS).................................................................... 6
3.1.4
Transport .............................................................. 6
3.1.5
Storage.................................................................. 6
3.1.6
Use Environments................................................ 6
3.1.7
Environmental Stresses........................................ 7
3.1.8
Temperature/Thermal........................................... 7
3.1.9
Cyclic Temperature Swings................................. 7
3.1.10
Thermal Shock..................................................... 7
3.1.11
Electrical ............................................................. 8
3.1.12
EMC/EMI............................................................. 8
3.1.13
Mechanical Shock and Vibration ........................ 8
3.1.14
Insulation Resistance .......................................... 9
3.1.15
Solvent Compatibility........................................ 10
3.1.16
Corrosion............................................................ 10
3.1.17
External Radiation ............................................. 10
3.1.18
Space Environment............................................ 10
3.2
Thermal Design.................................................. 10
3.3 Printed Board Design and Layout..................... 10
3.3.1 Thermal Design and Layout.............................. 11
3.3.2 Thermal Design and Conformal Coating.......... 11
3.3.3 Land Patterns ..................................................... 11
3.3.4 Balance About Neutral Axis.............................. 11
3.3.5 Vias..................................................................... 11
3.3.6 Printed Board Trace Widths and Spaces........... 11
3.3.7 PTH and PTV Thermal Isolation/Relief ........... 12
3.3.8 Test Pads ............................................................ 12
3.3.9 Spacing Between Parts...................................... 12
3.3.10 ‘‘Pads-Only’’ Design.......................................... 12
3.3.11 Components with Reduced Clearances
(Traces Under) ................................................... 13
3.3.12 Components with Reduced Clearance and
Open Vias........................................................... 13
3.4 Coefficient of Thermal Expansion (CTE)
and CTE-Mismatch............................................ 13
3.5 Solder Joint Reliability...................................... 14
3.5.1 Primary Design Parameters............................... 14
3.5.2 Secondary Design Parameters........................... 15
3.6 Plated-Through Hole and Via Reliability ......... 16
3.7 DfR of SM Solder Attachments........................ 16
3.8
DfR of Insulation Resistance ............................ 16
4.0 SUBSTRATES ........................................................ 16
4.1
General Substrate Categories ............................ 16
4.2
Substrates and Their Functions:........................ 16
4.3 Moisture and its Effects on Polymer
Substrates ........................................................... 17
4.4 Coefficient of Thermal Expansion (CTE) of
Polymer Systems................................................ 17
4.5
Constraining Cores in Substrates...................... 17
4.5.1
Printed Board Stiffness and Damping............... 19
4.6 Flexible Printed Board with Metal
Support Plane..................................................... 19
4.7 Discrete Wire Structures with Metal Support
Plane................................................................... 19
4.8
Outgassing of Polymer Substrates .................... 19
4.9 Assembly Process Effects on Polymer
Substrates ........................................................... 19
4.10
Printed Board Solderability............................... 19
4.11 Design for Reliability of Plated-Through-Hole
Vias (PTVs)........................................................ 19
5.0 GENERAL COMPONENT SELECTION
CONSIDERATIONS
................................................ 19
5.1
Component Selection Strategy.......................... 20
5.2
Package Leadframe and Local Materials.......... 20
July 1996 IPC-D-279
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5.3 Package Lead Configuration Selection ............ 20
5.3.1 Gull Wing Components..................................... 20
5.3.2 J-Lead Components ........................................... 20
5.3.3 Pin Grid Arrays.................................................. 20
5.3.4 Fine Pitch Components...................................... 20
5.3.5 Plastic Surface Mount Components
(PSMC) .............................................................. 21
5.3.6 Component Termination Coplanarity and
Configuration...................................................... 21
5.3.7 Component Lead Configuration........................ 21
5.4 Component Termination Finishes...................... 21
5.4.1 Nickel Barrier Layer.......................................... 21
5.4.2 Tin and Tin-Lead Solder Termination
Finishes .............................................................. 21
5.4.3 Termination Recommendations When Using
Electrically Conductive Adhesives.................... 22
5.4.4 Gold, Palladium, Silver Termination Finishes.. 22
5.5 Solderability of Termination Finishes............... 22
5.6 Soldering Considerations................................... 22
5.7 CTE Mismatch Considerations.......................... 22
5.8 ESD Packaging Requirements........................... 23
5.9 Specials or Custom Devices Use Precaution.... 23
5.10 Components to Avoid or to Use with
Caution .............................................................. 23
5.11 Component Selection Considerations for
Military and Space Applications....................... 23
6.0 SOLDER MASK AND CONFORMAL COATING
CONSIDERATION
.................................................. 23
6.1 Solder Mask Considerations for SM................. 23
6.1.1 Solder Mask Selection....................................... 24
6.1.2 Solder Mask Thickness Issues........................... 24
6.2 Temporary Solder Mask and Tapes................... 24
6.3 Conformal Coatings........................................... 24
7.0 ASSEMBLY PROCESSES AND DESIGN FOR
MANUFACTURABILITY
......................................... 24
7.1
Solder Paste Application.................................... 26
7.2
Adhesive Application......................................... 26
7.3
Component Placement....................................... 26
7.4
Soldering............................................................ 27
7.4.1
Solder Paste Reflow........................................... 27
7.4.2
Wave Soldering.................................................. 27
7.5
Cleaning ............................................................. 27
7.6
Rework/Repair ................................................... 27
7.7
Depaneling ......................................................... 28
7.8
Design for Manufacturability ........................... 28
7.8.1
Components........................................................ 28
8.0 TESTING................................................................. 28
8.1
Design for Testability (DfT).............................. 29
8.2 Testing Philosophy............................................. 29
9.0 REFERENCE DOCUMENTS ................................ 29
9.1 General Books on SMT Process and Design .. 29
9.2 SMT Soldering Process Technical Details........ 30
9.3
SMT Solder Paste.............................................. 30
9.4
SMT Cleaning.................................................... 30
9.5
Solder Joint Reliability...................................... 30
9.6 Design of Electronic Packages and
Packaging .......................................................... 30
9.7 EMC, High Speed Transients and Electrical
Overstress........................................................... 31
9.8
ESD.................................................................... 31
9.9
Scanning Acoustic Microscopy ........................ 31
9.10
Plastic Package Cracking .................................. 31
9.11
Solder Joint Metallurgy and Etching................ 31
9.12
PWA Thermal Design........................................ 31
9.13
Substrate Fabrication Information..................... 32
9.14 Component Derating, Applications,
Qualification....................................................... 32
9.15
Testability, Manufacturability............................ 32
9.16
Vibration, Shock ................................................ 32
9.17
Accelerated Life Testing.................................... 33
9.18 Solder, Solderability, Soldered Assembly
Quality................................................................ 33
9.19
Solder Mask and Conformal Coating ............... 33
9.20
General Reliability............................................. 33
Appendix A Design for Reliability (DfR) of Solder
Attachments
A-1.0 SURFACE MOUNT SOLDER ATTACHMENT
RELIABILITY
...................................................... 34
A-2.0 DAMAGE MECHANISMS AND FAILURE......... 34
A-2.1
Solder Joints and Attachment Types................. 34
A-2.2
Global Expansion Mismatch ............................. 36
A-2.3
Local Expansion Mismatch............................... 36
A-2.4
Internal Expansion Mismatch............................ 36
A-2.5
Solder Attachment Failure................................. 36
A-3.0 RELIABILITY PREDICTION MODELING.......... 36
A-3.1
Creep-Fatigue Modeling.................................... 36
A-3.2
Damage Modeling.............................................. 37
A-3.3
CAVEAT 1 — Solder Joint Quality.................. 38
A-3.4 CAVEAT 2 — Large Temperature
Excursions.......................................................... 38
A-3.5 CAVEAT 3 — High-Frequency/
Low-Temperatures ............................................. 39
A-3.6
CAVEAT 4 — Local Expansion Mismatch...... 39
A.3.7 CAVEAT 5 — Very Stiff Leads/Very Large
Expansion Mismatches ..................................... 40
IPC-D-279 July 1996
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