part ii: using pcb layout software – custom component libraries
DESCRIPTION
Introduction to Prototyping a LED Driver. Part II: Using PCB Layout Software – Custom Component Libraries. September 24-28, 2012 Carol Lenk. What’s in a Component. Component Connection between pins and pads Values, Component height, Digikey/Mfr part number. Board Symbol - PowerPoint PPT PresentationTRANSCRIPT
Part II: Using PCB Layout Software – Custom Component Libraries
September 24-28, 2012Carol Lenk
Introduction to Prototyping a LED Driver
What’s in a Component
Board SymbolPad Footprint:
copper, maskReference NameSilkscreen, Document
Board SymbolPad Footprint:
copper, maskReference NameSilkscreen, Document
Schematic SymbolSchematic ShapePins
Schematic SymbolSchematic ShapePins
ComponentConnection between pins
and padsValues, Component height,
Digikey/Mfr part number
ComponentConnection between pins
and padsValues, Component height,
Digikey/Mfr part number
HV9910
• Component not in library.• Package is standard.• Schematic symbol is standard.• Need to make a new Component that uses
existing SO-8 PCB symbol and schematic symbol.
• Library Manager• PCB Symbol Tab• Use All Libraries• Find…• Search for “SO” and 8
pads• Click on 8-SOIC
[prolib]
Find SO-8 PCB Symbol
• Library Manager• Schematic Symbol
Tab• Use All Libraries• Find…• Search for “SO” and 8
pads• Click on FCH-SO8
[fairchild1]
Find SO-8 Schematic Symbol
New Component• Library Manager• Components Tab• New Item…
HV9910• Assign pins 1 to 1• Enter Terminal Name• Save to our custom library
Custom Footprint
• Download datasheet from Digikey.• Find component size and recommended land
pattern.
Create custom PCB Symbol library• Library Manger• PCB Symbols Tab: New Lib… : 9910Demo.psl
Custom PCB Symbol
Copy a 2 pad footprint• In prolib.psl, copy
SMD1 to custom library• Name new pcb symbol
DR1050
Edit Custom PCB Symbol• Library Manager, go to 9910Demo.psl, select DR1050, click Edit• Right click on S (symbol origin) : Origins : Set System Origin at Item• Menu: Units: mm• Double click on pad to bring up Properties
• Change position (center of pad)
4.45
3.65
0.8
4.45
X
• Menu: Settings: Grids: Step Size 0.1mm.• Double click on corners to add chamfer.• Move R reference locator to outside of body• Pads underneath part makes it hard to hand solder.
– Increase pad size by 1 mm.
• Library Manager: Component Tab: New Item
Component Editor• Connect Sch
Terminals to PCB Pads
• Save to custom library
• Add Component to schematic.
MOSFET
MOSFET• Add pad numbers• Add description in Properties window.
• Schematic Symbol– Use Diode-2 in diode.ssl
library
• Need to create custom PCB symbol– Copy pcb symbol “1206”
from sm.psl library.– Name new symbol “SMA”
Diode
Diode PCB Symbol• With line selected, hit “L” to change layers.• Purple items are on Top Document layer to show components.
Layer not printed on PCB.• Yellow items are on Top Silkscreen layer. They are printed on
the PCB.• With line selected, hit “s” to change line style thickness.• For closed shape, use Properties and click on Filled.
Footprint Guidelines
• Reduce production errors.– Alignment, solderability, inspectable.
• IPC Standards.• From datasheets for resistors,
capacitors, etc.• Generally ~ 0.005” wider overall,
0.020” longer on each side.• Hand solderable for prototypes.
How is a PCB Made?1 2
3 4
Looking at a PCB
Pin connector
Green Solder Mask
Copper Trace visible under solder mask
White Silkscreen
Reference Designator on Silkscreen Layer
Tinned Pad
Layers
• Hit “c” to bring up colors.
• In Interaction Bar (Menu: View or F9), Layers Tab is at bottom.
Thank You