1. Manufacturing Processes
Printed Circuit Board Assembly (PCB): Must specify or account for all components mounted into, onto or attached in some way to a printed circuit board as well as test for same
Electrical Components: Passives, IC’s, Optical, ElecMech, ElecMag, Connectors, Switches, Sensors, Protection Devices, etc
Mechanical Components: Heat Sinks, Thermal Grease, Pullers, Stiffeners, Mounting Hardware, Sensors, Protection Devices, etc
High Level Assembly (HLA): Must specify or account for all elements or parts of an assembly level including testing
Electrical Elements: PCB’s, Cables, Harnesses, Fans, Power Supplies, Sensors, Protection Devices, User Displays, Switches, etc
Mechanical Elements: Enclosures, Feet, Standoffs, Card Guides, Gaskets, Sealants, Fasteners, Hardware, etc

2. Printed Circuit Board Assemblies
Printed Circuit Boards (PCBs):
Convenient form of interconnecting electrical components using industry standard attachment processes
3 Basic Types of PCB-Component Assembly Technology
Thru Hole (TH)
Surface Mount (SMT)
Micro-electronic Multi-Chip-Module (MCM)
3 Basic Types of PCB substrate systems (fabs)
Rigid epoxy including FR4, BT and others
Ceramic, Alumina (Al203), AlNi or other exotics
Flexible Substrate (flex circuit)
Single, Double and Multi-Layered

3. PCB Manufacturing Guide Links

5. Basic Photo-Etch
PCB Mfg Process
Plated Through Hole
PCB Cross Section

6. Cu PCB Trace Width & Depth
IPC Current Capacity Limitations

7. Cu PCB Trace Conductor
IPC* Spacing vs Voltage Summary (*Simplified)

8. The PCB is part of the circuit
Signal Routing is Important!
The PCB is part of the circuit
Good Signal Routing
Equal Lengths, Uniform
Good Power Bus Routing
Bypass Caps Closest to IC Power Pins
Poor Power Routing
Bypass Caps and 1 Conductor too Lengthy
Poor Signal Routing
Un-Equal Lengths, Non-uniform

9. PCB Ionic Cleanliness is Important
Acetate & Formate - These organic acids can be extracted from some solder masks.  High levels can be indicative of an incompletely cured solder mask.  Incomplete cure can allow exposure of the copper traces to the environment resulting in corrosion and board failure.
Bromide:  Brominated compounds are added to laminates as a flame retardant.  Some laminates are employing alternate, non-bromine, flame retardants.  These are usually called specified as containing non-halogen flame retardants.  The surface bromide concentration is a function of the laminate heat history.  Bromide has also been identified as a component in some marking ink formulations and some solder masks.
Chloride - Chloride ions are the single most damaging material that can be on the board.  High levels are usually due to insufficient washing prior to applying the solder mask.  Chloride can also be transferred to the board by handling.
Nitrate and Ammonium - Both of these can be introduced in various plating processes.
Sulfate - Sulfate is rarely a problem.  High levels are usually caused by poor housekeeping:  dirty equipment, unpainted walls or unsealed floors.  
Sodium & Potassium - Sodium can be induced by handling but is also a component of tap water and may be indicative of poor water treatment.  In this case, chloride, calcium and magnesium should also be present. 
Calcium and Magnesium - Calcium and magnesium come from rinse water and are indicative of poor water quality. 
Citrate - Citrate salts and acids are components of some gold plating solutions.  They also are in many environmentally friendly cleaners.
IPC-6012 mandates the total ionic cleanliness prior to solder mask be <10ug/in2 in NaCl equivelants (IPC-TM-650)
Most Low Signal Or High Bias, High Reliability Designs Require Much Lower Levels on Individual Ions

10. Component Packaging

11. Thru-Hole Device Packages
Passives and Discretes
Axial Leaded (2 terminal, lying down)
Resistors, Capacitors, Inductors, Diodes
Radial Leaded (2 terminal, standing up)
Capacitors, Inductors, LEDs, MOVs, Power Resistors, …
T0 – Series (2-N terminals, Most Accommodate Std Heat Sink hardware)
T0-92 Small Signal Transistors, Regulators, References
T0-220 Moderate Power (~1W) Transistors, Regulators, Amplifiers
T0-3 Higher Power (~3W) Transistors, Regulators, Amplifiers

12. Transistor Package Examples

13. Thru-Hole Device Packages
Integrated Circuits, Resistors, Relays
DIP (Dual In-Line Package)
PDIP, CDIP
SIP (Single In-Line Package)
Rectangular

14. P-DIP (plastic) and C-DIP (ceramic) Examples

15. SMT – Surface Mount Technology Generations
20mm
DIP
Small Outline Package
Shrink SO Package
Thin Shrink SOP
Depopulated, Very Thin, Quad Flat Pack, No Leads
3 mm

16. SOT – Small Outline Transistors (SOT-3, SOT-223)

17. QFP – Quad Flat Packs

18. PLCC – Plastic Leaded Chip Carriers

19. BGA – Ball Grid Arrays

20. Typical BGA Pin Layout

21. Electronic Assembly Quality and Standards

22. Simplified Comparison of Thru Hole and SMT PCB Assembly Process
Component
Procure
Setup
Substrate
(Fab)
Fabrication
Fab, Comp
Prep
Bake, Clean
Simplified Comparison of Thru Hole and SMT PCB Assembly Process
Thru Hole
Mechanical
Hand
Operations
SMT
Auto
Component
Insertion
Screen
Solder Paste
Wave Solder
Auto
Component
Placement
Vision System Inspection
Lead
Trim
Reflow
Solder
(Oven)
Stresses and Test Processes
Vision/Xray System Inspection

23. Typical SMT Complex Circuit Board Assembly Processes
Setup
Screen Print
SMT Placement
Reflow
Hand Assembly
Wave Solder
Final Assembly
Wash
In Circuit Test
Stress Screen
Functional Test
Pack / Ship
Typical SMT Complex Circuit Board Assembly Processes

24. Solder Geometry Variability in SMT and THT

25. IPC = Institute of Printed Circuits, WWW. IPC
IPC = Institute of Printed Circuits, Association Connecting Electronics Industries
IPC-A-610 Acceptability of Electronic Assemblies
IPC-6011 Series of Board PCB Performance Standards
IPC/EIA J-STD-001 Requirements for Soldered Electrical and Electronic Assemblies
IPC-7095 Design and Assembly Process Implementation for BGAs
IPC-2221 Generic Std for Printed Board Design
IPC-D-279 Design Guidelines for Reliable Surface Mount Technology Printed Board Assemblies
Quality!

26. IPC Electronic Assembly Classifications
High Reliability Electronic Products:
Continued performance, performance on demand, and extended life is critical and equipment downtime cannot be tolerated. Equipment must function when required with a high level of reliability assurance.
End-use environment is harsh
Includes equipment for commercial, military products, and for such applications as life support or missile systems.
Dedicated Service Electronic Products:
Continued performance, extended life and uninterrupted service is desired but not critical.
Typically the end-use environment would not cause failures
Includes communications equipment, sophisticated business machines, instruments and military equipment
General Electronic Products:
Function of the completed assembly is the major requirement
Cosmetic imperfections are not important
Includes consumer, some computer, peripherals, general military HW
Aerospace, Military
10 Yr Stresses
# of Bds, # of solder joints
# of Mechanical Cycles
4# of Power Cycles
# of Therm Cycles, Excursion
PROCESS CONTROL – PROCESS QUALITY
Ref: IPC-A-610, IPC-JSTD-001, IPC-7095
Telecom & Certain Medical

27. IPC Workmanship Classes: Solder Volume, Shape, Placement Control
High Reliability Electronic Products: Includes the equipment for commercial and military products where continued performance or performance on demand is critical. Equipment downtime cannot be tolerated, and functionality is required for such applications as life support or missile systems. Printed board assemblies in this class are suitable for applications where high levels of assurance are required and service is essential.
Requirement for Aero-Space, Certain Military, Certain Medical
Dedicated Service Electronic Products: Includes communications equipment, sophisticated business machines, instruments and military equipment where high performance and extended life is required, and for which uninterrupted service is desired but is not critical. Typically the end-use environment would NOT cause failures.
Requirement for High Eng Telecom, COTS Military, Medical
General Electronic Products: Includes consumer products, some computer and peripherals, as well as general military hardware suitable for applications where cosmetic imperfections are not important and the major requirement is function of the completed printed board assembly.
100 %
75 %
50 %
25 %
0 %
100 %
75 %
50 %
25 %
0 %
IPC-7095 BGA Std
Class 1
Class 2
Class 3
Max Void Size
60% Dia
36% Area
45% Dia
20.3% Area
30% Dia
9% Area
Max Void Size at Interfaces
50% Dia
25% Area
35% Dia
12.3% Area
20% Dia
4% Area
Min PTH Vertical Fill: Class 2 = 75% Class 3 = 100%
Ref: IPC-A-610, IPC-JSTD-001

28. BGA Void Size and Locations, Uniform Void Position Distributions
Sampling_Grid
Position
Model
Solder_Joint_Radius
Void_Distance
Void_Radius S
Void_Solder Interface Distance
S = Shell
Potential for Early Life Failure (ELFO) if S < D/10 = (solder_joint_radius)/10
S =Shell = solder_joint_radius – (void_distance + void_radius)

29. P(D<10) = 81.11 % P(D<10) = 52.21 % P(D<10) = 27.00 % CLASS 1
Solder Joint_Radius: mm
Void_Radius: mm
Void_Area: 36% of Joint Area
Failure criteria: D/10
P(D<10) = %
CLASS 2
Solder Joint_Radius: mm
Void_Radius: mm
Void_Area: 20% of Joint Area
Failure criteria: D/10
P(D<10) = %
CLASS 3
Solder Joint_Radius: mm
Void_Radius: mm
Void_Area: 9% of Joint Area
Failure criteria: D/10
P(D<10) = %

30. Class vs Shell Size Relative Probabilities ~ 2x more likely to exceed D/10 threshold with Class 2 vs Class 3
S = Shell
Depth

31. Physics of Failure: Accumulated Fatigue Damage (AFD) is related to the number of stress cycles N, and mechanical stress, S, using Miner’s rule
Exponent B comes from the S-N diagram. It is typically ~3 for 63/37 SnPb Solders
Example: Solder Joint
Shear
Force
voids
Effective cross-sectional
Area: D/2
Effective cross-sectional
Area: D F
Applied stress:
Applied stress:
Let  = 10, then
AFD with voids will “age” about
1000x faster than AFD with no voids
Voids in solder joints

32. IPC-A-610 Conditions IPC-A-610 Workmanship Conditions
Target Condition- This is the most desired condition and previously was referred to as preferred. It is not always essential to achieve this condition for reliability considerations.
Acceptable Condition- is a condition that, while not at a Target Condition, will result in a reliable product for the application. Corrective actions shall be directed to move toward the Target Condition.
Nonconforming Process Indicator- Is when a condition exists which does not affect the use of the product, but is not optimum. May result in repair, rework or scrap depending upon the customer’s requirements. Corrective action is necessary to bring the result back toward the Target.
Nonconforming Defect Condition- is when a condition exists that does not meet the reliability or performance in the application. Correction action is mandatory.
All the IPC-A-610 Measurements utilize
Temp (Deg F/C)
Mass (Oz/Kg)
Distance (mils/mm)
There are three key words used in the workmanship standards: Must, Shall and Should.
Must means mandatory for Class 1, 2, & 3
Shall means mandatory for Class 3 only.
Should means recommended only for Class 1,2 & 3.
Quality!

33. Solder Joints
Solder Joints: A solder joint is formed when two metal surfaces are soldered together. The solder fills the void between the surfaces and is the area most important. It provides the majority of “strength of attachment.” A solder fillet is formed after the solder joint is filled, and, is the visible solder verifying the presence of the solder joint.
Blow Hole Defects: Blowholes are solder voids visible from the surface going into the solder joint alongside a through-hole lead. A blowhole is a nonconforming process indicator provided the solder connection meets the minimum circumference and depth requirements.
Dewetting Defects: Solder joints are visually inspected for wetting characteristics. Dewetting occurs because the flux has been burned off and moisture attacks the surfaces. A good indicator of dewetting is solder pooling and pulling back off leads or lands.
Oxidation Defects: When moisture in the air attacks a solder joint, it forms a protective rust-like layer. This is referred to as oxidation, which attacks metal surfaces. Oxidation dramatically reduces the transfer efficiency of thermal energy.
Dimensional Defects: For any of the above in addition to poor placement, screening, reflow and other processes, solder joint geometric defect limits are clearly specified in these Stds (see above)

34. Discrete Component Geometries
NOTES 1. The maximum fillet may overhang the land or extend onto the top of the chip cap metallization; however the solder shall not extend further onto the component body. 2. Properly wetted fillet evident.

35. J-Lead Component Geometries
NOTES 1. The maximum solder fillet shall not touch package body. 2. Properly wetted fillet evident.

36. Gull Wing Component Geometries
NOTES 1. Solder fillet may extend through the top bend. Solder must not touch the package body or end seal, except for low profile SMD devices, e.g., SOICs, SOTs. Solder should not extend under the body of low profile surface mount components whose leads are made of Alloy 42 or similar metals. 2. Must not violate minimum design conductor spacing. 3. Properly wetted fillet evident.

37. Thru-Hole Component Geometries
NOTES 1. Wetted solder refers to solder applied by the solder process. 2. The 25% unfilled volume includes both source and destination side depressions.

38. Advanced Packaging

39. IC Packaging Progression:
Through Hole
Surface Mount
CSP / WLP
TSOP
25 mil pitch
Limited by perimeter leads
CSP/WLP
Area array 0.8 mm to 0.5 mm
Limited by substrate wiring
100 mil pitch
Limited by through hole spacing
IC Packaging Progression:

40. Fujitsu SuperCSP Solder balls on copper posts
Redistribution
Trace (Cu)
SiN
Al Pad
Polyimide Layer
Die
Encapsulant
Barrier Metal
Solder Ball
Metal Post (Cu)
Solder balls on copper posts
Redistribution wiring to posts
Encapsulant is molded onto wafer

41. Wafer Level Packaging Will Become Std
Density
VOLUME
Chip Scale
CSP
Wafer Level
Stacked Die
SiP
Surface Mount
QFP
TSOP
SOJ
BGA
Thru Hole
DIP
Pin Grid
1960
1980
2000
YEAR

42. µProcessor ASICs DRAM SRAM Flash Passives Analog ICs Power ICs
10000
Flip-Chip Underfill+
µProcessor
0.25 mm grid
HDI
PWB
1000
0.5 mm grid
ASICs
DRAM
Pins (#)
100
SRAM
Flash
Passives 10
Analog ICs
Power ICs
Discretes 1 1 10
100
1000
Die Area (mm2)

43. Process Flow: Wafer Level Packaging vs. Conventional Packaging
* From Motorola