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PCB materials and considerations

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jb8822

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How to go by choosing PCB materials and their considerations.
 

PCB design

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PWB Materials
♦ Dozens of dielectric materials to chose from
- Rogers 20 types
- Taconic 10 types
- Polyclad 25 types
- Park Nelco 30 types
♦ Several dielectric thickness options
♦ Several copper thickness options
♦ Two copper plating options
- Rolled
- Electro-Deposited

---------- Post added at 21:09 ---------- Previous post was at 21:08 ----------

Electrical Considerations in
Selecting Materials
♦ Dielectric Constant (permittivity)
- The more stable, the better
- Lower values may be more suitable for high layer counts
- Higher values may be more suitable for some RF structures
♦ Loss Tangent
- The lower, the better
- Becomes more of an issue at higher frequencies
♦ Moisture Absorption
- The lower, the better
- Can effect dielectric constant and loss tangent
♦ Voltage Breakdown
- The higher, the better
- Typically not an issue, except in high voltage applications
♦ Resistivity
- The higher, the better
- Typically not an issue, except in low leakage applications

---------- Post added at 21:09 ---------- Previous post was at 21:09 ----------

Mechanical Considerations in
Selecting Materials
♦ Peel Strength
- The higher, the better
♦ Flammability
- UL Standards
♦ Glass Transition Temperature (Tg)
♦ Thermal Conductivity
- Typically PWB material is considered an insulator
- Thermal Clad (Bergquist)
- Planes & vias contribute to thermal conductivity
♦ Coefficient of Expansion
- XY matching to components, solder joint stress (LCC)
- Z axis expansion, via stress
♦ Weight (density)
♦ Flexibility
 
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marce

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Use FR4 Tg 150, unless doing high GHz designs. Choose copper weight of copper layers based on feature size, current requirements and thermal considerations.
Look at manufacturers capabilities and they list what feature size they can etch for a given copper weight, and thats its basicly.
Some basic links.
https://pcbtalk.com/data/upload/Designing_Balanced_PCBs.pdf
https://www.pcb3d.com/uploads/PCB_Design_and_Fabrication_Process.pdf
https://www.alternatezone.com/electronics/files/PCBDesignTutorialRevA.pdf
 

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