Rigid
Most common board style
Solid construction, hard mounted to next assembly
Flex
Flexible circuits, typically used to replace cabling within a system
Showing posts with label PCB. Show all posts
Showing posts with label PCB. Show all posts
PCB Producibility
It is related to the difficulty of the design, and the particular printed board or printed board assembly.
When appropriate this standard will provide three design producibility levels of features, tolerances, measurements, assembly, testing of completion or veriļ¬cation of the manufacturing processes that concerning progressive increases in sophistication of tooling, materials or processing and, accordingly advanced increases in fabrication cost.
Producibility Levels:
Level A – General Design Complexity - Preferred
Level B – Moderate Design Complexity - Standard
Level C – High Design Complexity – Reduced Producibility.
When appropriate this standard will provide three design producibility levels of features, tolerances, measurements, assembly, testing of completion or veriļ¬cation of the manufacturing processes that concerning progressive increases in sophistication of tooling, materials or processing and, accordingly advanced increases in fabrication cost.
PCB Technology
Analog PCB
Typical functions are op-amps, voltage converters - power
supplies
Digital PCB
Typical function is signal processing
RF PCB
Function to produce radio frequencies, usually in the super high
Frequency Ranges:
Low Frequency (LF) = 100 kHz
Medium Frequency (MF) = 300-3000 kHz
High Frequency (HF) = 3-30 MHz
Very High Frequency (VHF) = 30-300 MHz
Ultra High Frequency (UHF) = 300-3000 MHz
Super High Frequency (SHF) = 3-30 GHz
PCB Assembly Classes
Class A – Through-hole mounted components only
Class B – Surface Mount components only
Class C – Simplistic through-hole and surface mount intermixed assembly
Class X – Complex intermixed assembly (Through-hole, surface mount, fine pitch and BGA)
Class Y – Complex intermixed assembly (Through-hole, surface mount, ultrafine pitch and chip scale)
Class Z – Complex intermixed assembly (Through-hole, ultrafine pitch, COB, flip-chip and TAB)
PCB Component Mounting
Automatic Insertion - Through-Hole Components
~ Board changes positions under insertion head
~ Dip Inserter
Tube feeds DIPs into insertion head
~ Axial and Radial Inserter
Components are sequenced and taped, then fed into lead former, then insertion head
Automatic Placement - Surface Mount Components
~ Board remains stationary
~ Chip Shooter
For mounting chip components
~ Vacuum nozzle
Selection and placement of larger components - ICs
Manual Placement
~ Unique and odd-form components formed and mounted by hand
PCB Solder Methods
Wave Soldering
- Through-Hole Assemblies
Fluxing
Preheating
Conveyed over wave of molten solder
Cool Down
- Surface Mount Assemblies
Apply bind paint
Component mounting
Preheating
Conveyed over wave of molten solder
Cool Down
Reflow Soldering - Surface Mount Assemblies
Apply solder paste
Component mounting
Preheating
Solder reflow - Forced convection, Infrared
Cool Down
Hand Soldering
Used for temperature sensitive or odd-form components
PCB Features
Mechanical Outline
Defines overall area for board design
Clearances
Board edge, mating area at next assembly
Mounting Holes
Location, size, hardware used
Tooling Holes
Used throughout fabrication, assembly and testing of boards
Fiducials
Surface feature used for optical alignment of board during assembly
Keep-out Areas
Areas where no components and/or copper can be located
Height Restrictions
Areas where there are potential interference issues at next assembly
Fixed Component Location
Connector locations for mating to next higher assembly
Critical component locations
Additional Mechanical Hardware
Card Guides, stiffeners, sockets
Design, Fabrication and Manufacturing constraints
Board material
Board thickness / Layer stack-up
Via size
Voltage and current used for circuits
Critical circuit routing requirements
Thermal considerations
Fabrication and assembly methods
PCB Materials
FR4 - Flame Retardant 4
– Woven glass reinforcement with epoxy resin binder
– FR indicates it meets UL requirements for flame resistance
PTFE
– Polytetrafluoroethylene (Teflon)
RO4350
– Woven glass reinforcement with ceramic filled thermoset
Polyimide Film
– Epoxy resin system without
Introduction to PCB: Printed Circuit Board
Printed Circuit Boards are primarily an insulating material used as base, into which conductive strips are printed.
The base material is generally fiberglass, and the conductive connections are generally copper and are made through an etching process
The main PCB board is called the motherboard, the smaller attachment PCB boards are called daughter boards or daughter cards
PCB board design defines the electrical pathways between components
It is derived from a schematic representation of the circuit
When it is derived, or imported from a schematic design, it translates the schematic symbols and libraries into physical components and connections.
A PCB design package allows the designer to define and design on multiple layers
The base material is generally fiberglass, and the conductive connections are generally copper and are made through an etching process
The main PCB board is called the motherboard, the smaller attachment PCB boards are called daughter boards or daughter cards
PCB board design defines the electrical pathways between components
It is derived from a schematic representation of the circuit
When it is derived, or imported from a schematic design, it translates the schematic symbols and libraries into physical components and connections.
A PCB design package allows the designer to define and design on multiple layers
Printed Circuit Board Type
Types of PCB:
Type 1 – Single Sided PCB
Type 2 – Double sided PCB
Type 3 – Multilayer without Blind or Buried vias
Type 4 – Multilayer With Blind and/or Buried vias
Type 5 – Multilayer Metal Core board without blind and/or buried vias
Type 6 – MultiLayer Metal Core board with blind and/or buried vias
HASL - Hot Air Solder Level
It is a molten solder immersion and hot air leveling or blasting of surfaces and holes to provide a "retained" coating on exposed copper surfaces.
The advantage of HASL is excellent solderability, because as its name implies "Nothing solders better than solder." One of the less-expensive surfaces finished with a good shelf life.
However, the problem with this finish is its limitation and difficulty. A limited capability on high density boards and a capacity to clear vias holes on a greater than 6:1 aspect ratio. A difficulty to maintain hole size tolerance along plated edges and to process thin material.
The advantage of HASL is excellent solderability, because as its name implies "Nothing solders better than solder." One of the less-expensive surfaces finished with a good shelf life.
However, the problem with this finish is its limitation and difficulty. A limited capability on high density boards and a capacity to clear vias holes on a greater than 6:1 aspect ratio. A difficulty to maintain hole size tolerance along plated edges and to process thin material.
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