Part II: Using PCB Layout Software – Custom Component Libraries 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 Board Symbol Schematic Symbol Connection between pins and pads Values, Component height, Digikey/Mfr part number Board Symbol Pad Footprint: copper, mask Reference Name Silkscreen, Document Schematic Symbol Schematic Shape Pins

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.

Find SO-8 PCB Symbol Library Manager PCB Symbol Tab Use All Libraries Search for “SO” and 8 pads Click on 8-SOIC [prolib]

Find SO-8 Schematic Symbol Library Manager Schematic Symbol Tab Use All Libraries Find… Search for “SO” and 8 pads Click on FCH-SO8 [fairchild1]

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.

Custom PCB Symbol Create custom PCB Symbol library Library Manger PCB Symbols Tab: New Lib… : 9910Demo.psl 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) 0.8 4.45 4.45 3.65 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.

Diode Schematic Symbol Need to create custom PCB 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 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. IPC Standards. 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. AVX Technical Information: Solder Pad Geometry Studies for Surface Mount of Chip Capacitors. http://www.avx.com/docs/techinfo/soldpad.pdf

How is a PCB Made? 2 1 3 4

Looking at a PCB White Silkscreen Pin connector Reference Designator on Silkscreen Layer Green Solder Mask Copper Trace visible under solder mask Tinned Pad

Layers In Interaction Bar (Menu: View or F9), Layers Tab is at bottom. Hit “c” to bring up colors.

Thank You