PCB Materials: Types, Specifications, and Cost Considerations

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What is PCB material ?

PCB material forms the foundation of printed circuit boards, crucial components in modern electronics. The most common PCB material is FR-4, a composite of fiberglass and epoxy resin. It offers excellent electrical insulation and mechanical strength. Other materials include FR-2 (paper-based), aluminum, and ceramic, each suited for specific applications. High-frequency circuits often use specialized materials like PTFE. The choice of PCB material impacts performance, durability, and cost. Factors such as dielectric constant, thermal conductivity, and coefficient of thermal expansion are considered when selecting PCB materials. As electronics evolve, new PCB materials are developed to meet demanding requirements in various industries.

Different applications for printed circuit boards (PCBs) demand the use of various substrate materials to meet specific performance requirements. While the standard FR4 material, including its high Tg variant (offering enhanced thermo-mechanical properties), is suitable for many conventional applications, specialized fields such as high-frequency circuits often require alternative materials.

The following overview provides a concise summary of the available material types and their core properties, helping you select the most appropriate substrate based on your application needs.

1. FR-4 Material

FR4 material standard values

FR-4 is the most widely used material in PCB manufacturing. It consists of a glass-reinforced epoxy laminate that is both flame-retardant and water-resistant. Known for its excellent strength-to-weight ratio, FR-4 offers high tensile strength, making it a reliable choice for a broad range of standard applications. Its versatility and cost-effectiveness have made it the go-to material for many electronic designs.

2. PTFE (Teflon)

PTFE, commonly known as Teflon, is a specialized plastic material ideal for high-speed and high-frequency applications due to its low electrical resistance. Its exceptional flexibility makes it suitable for designs with tight tolerances, while its lightweight nature allows for use across diverse industries. PTFE is flame-resistant, offers high physical strength, maintains temperature stability, and is highly versatile, making it a preferred choice for demanding applications.

Material samples of the Rogers material can directly be requested here: http://rogerscorp.force.com/samples/samples_university

3. Metal Core (IMS)

Multilayer Metal Core PCB

Metal core PCBs, also known as Insulated Metal Substrates (IMS), utilize traditional materials like copper, aluminum, and iron. These materials enable the use of Surface Mount Technology (SMT) for component integration and provide enhanced mechanical durability. As a result, metal core PCBs have a significantly longer product lifespan, making them ideal for applications requiring robust performance and thermal management.

Material for Rigid PCB Circuit boards

Material for rigid PCBsTgCTE-z (T<Tg)εr, Dk-
Permittivity
Dk
Loss Tangent
Electric
Strength
Surface
Resistivity
Tracking
resistance CTI
Td valuePeel strength
°Cppm/°C@1GHz@1GHzKV/mmMOPLC°CN/mm
ISOLA Duraver DE104
Standard FR4
135°704,40,020541,0 x 10^62315°1,6
Shengyi S1141
FR4 alternative
140°654,6*0,015*605,4 x 10^73310°1,8
ISOLA Duraver DE104 KF
FR4 tracking resistant
135°454,6 –
4,9
0,020*391,0 x 10^61315°1,6
ISOLA DE156
FR4 halogen-free
155°454,00,016364,0 x 10^6390°1,4
ISOLA IS400
FR4 MidTg
150°504,0**0,020483,0 x 10^63330°1,4
ITEQ IT-158
FR4 MidTg alternative
155°604,30,016601,0 x 10^10345°1,7
ITEQ IT-180A
FR4 HTg
175°454,40,015453,0 x 10^10345°1,4
Shengyi S1000-2
FR4 HTg alternative
180°454,8*0,013*637,9 x 10^73345°1,4
ISOLA IS410
FR4 HTg, CAF-Enhanced
180°554,00,019448,0 x 10^63350°1,2
ISOLA IS420
FR4 HTg, CAF-Enhanced alt.
170°454,00,016543,0 x 10^63350°1,3

Unless otherwise noted, the CTI (Comparative Tracking Index) which indicates the tracking resistance, is PLC3 (175V – 250V) for rigid PCBs. On request, we are also able to produce PCBs with PLC 2 (> 250V), PLC 1 (> 400V) or PLC 0 (> 600V). 

Materials for flexible PCB circuit boards

Material for flexible PCBsRecommended max.
operating temperature
Copper typeTgεr, Dk-
Permittivity
CTE-z (T<Tg)Electric
Strenght
Surface
Resistivity
Peel strength
 °C*°C@1MHzppm/°CKV/mmN/mm
Polyimide + Adhesive
Shengyi SF305105°RA3,6211 x 10^51,1
Polyimide Adhesiveless
DuPont Pyralux AP180°RA2203,4252561 x 10^101,8
Panasonic RF775130°ED3433,22761 x 10^81,7
Thinflex W-05050105°ED3503,3242161 x 10^50,6
PI Coverlay
Shengyi SF305C105°3 x 10^6
DuPont Pyralux FR180°3,51381 x 10^7
Adhesive tape
3M 9077150°

* RA = Rolled copper, suitable for dynamic, flexible applications; ED = Electrolytically deposited copper , only suited for stable and semi-dynamic applications

Materials for metal core PCB boards

1 layer

Material for metal core boards
1 Layer
Thermal
conductivity
Thermal
resistance
Surface
Resistivity
Dielectric glass
transition (Tg)
Dielectric
Breakdown (AC)*
Tracking
resistance CTI
 W/mKK/W°CkVPLC
TC-Lam 2.02.00.5010^71005.00
HA50 (3)2.20.4110^61204.30
AL-2002.00.3510^83.50
AL-3003.00.3010^83.50
Ventec VT-4B3
Ceramic Filled
3.05 x 10^81308.00
Ventec VT-4B4
Ceramic Filled
4.22 x 10^71208.00
Ventec VT-4B7
Ceramic Filled
7.02 x 10^71008.00

2 layers (plated-through)

Material for metal core boards
2 Layers (plated-through)
Thermal
conductivity
Thermal
resistance
Surface
Resistivity
Dielectric glass
transition (Tg)
Dielectric
Breakdown (AC)*
Tracking
resistance CTI
 W/mKK/W°CkVPLC
Ventec VT-4A22.22 x 10^71307.50
Ventec VT-4B3
Ceramic Filled
3.05 x 10^81308.00

Material for high frequency PCB boards

Material for high frequency boardsOrder Shareεr, Dk-
Permittivity
Dk Loss TangentTgTd ValueThermal
Conductivity
CTE-z (T<TG)Electric
Strength
Surface
Resistivity
Peel
Strength
 @10GHz@10GHz°C°CW/m*Kppm/°CKV/mmN/mm
Rogers 4350B
HF Material
+++3,50,0037280°390°0,6932315,7 x 10^90,9
Rogers 4003C
PTFE HF Material
++3,40,0027280°425°0,7146314,2 x 10^91,1
Panasonic Megtron6
HF Material
+3,60,004185°410°451 x 10^80,8
Rogers RO3003
PTFE ceramic-filled
+3,00,0013500°0,50251 x 10^72,2
Rogers RO3006
PTFE ceramic-filled
o6,20,002500°0,79241 x 10^51,2
Rogers RO3010
PTFE ceramic-filled
o100,0022500°0,95161 x 10^51,6
Taconic RF-35
Ceramic
o3,5**0,0018*315°0,24641,5 x 10^81,8
Taconic TLX
PTFE
o2,50,00190,191351 x 10^72,1
Rogers RO3001
Bonding Film for PTFE
2,30,003160°0,22981 x 10^92,1
Taconic TLC
PTFE
3,20,24701 x 10^72,1

Material for high-Tg circuit boards (selection)

Material for High-Tg boardsTgCTE-z (T<Tg)εr, Dk-
Permittivity
Electric
Strenght
Surface
Resistivity
Tracking
Resistance CTI
Thermal
Conductivity
Td valuePeel
Strength
°Cppm/°C@1GHzKV/mmMOPLCW/m*K°CN/mm
ISOLA IS410
FR4 HTg, CAF-Enhanced
180°554,0448,0 x 10^630,5350°1,2
ISOLA IS420
FR4 HTg, CAF-Enhanced
170°454,0543,0 x 10^630,4350°1,3
ITEQ IT-180A
FR4 HTg
175°454,4453,0 x 10^10345°1,4
Shengyi S1000-2
FR4 HTg
180°454,8*637,9 x 10^73345°1,4
ARLON 85N
Polyimid HTg
250°554,20*571,6 x 10^90,2387°1,2

PCB Material Selections and Design Features Impacting Cost

Rogers RO4500 PCB

The cost of a Printed Circuit Board (PCB) can vary significantly based on the materials used and the specific design features incorporated. Understanding these factors is crucial for engineers and designers aiming to balance performance requirements with budget constraints.

High-Cost Design Features

Several design elements can substantially increase the cost of PCB production:

  1. Gold Tabs: While offering excellent conductivity and corrosion resistance, gold plating is significantly more expensive than standard surface finishes.
  2. Blind and Buried Vias: These specialized vias increase PCB complexity and require additional manufacturing steps, driving up costs.
  3. Via Filling: Filled vias improve reliability and allow for higher component density but require extra processing steps.
  4. Fine Line/Width Spacing: PCBs with line width and spacing below 6 mils typically cost more due to the precision required in manufacturing.

Reasons for Higher Costs

The increased prices associated with these features stem from several factors:

  1. Specialized Processes: Unusual or complex PCB designs often require alternative manufacturing processes, which can be more time-consuming and resource-intensive.
  2. Lower Yield Rates: Designs with very fine lines or inner vias may have lower production success rates, leading to higher prices to offset potential losses.
  3. Equipment Requirements: Advanced features often necessitate specialized, expensive equipment for production.

Extreme Design Considerations

While some fabricators can produce PCBs with line/width measurements as low as 3 mils, this level of precision is generally not recommended unless absolutely necessary. Such extreme designs can lead to:

  1. Significantly higher costs
  2. Reduced manufacturing yield
  3. Potential reliability issues
  4. Limited choice of manufacturers

Material Selection Impact

Beyond design features, the choice of PCB material itself plays a crucial role in determining cost:

  1. Standard FR-4: Generally the most cost-effective option for many applications.
  2. High-Frequency Materials: Specialized materials for RF applications (like Rogers or Taconic laminates) are typically more expensive.
  3. Flex and Rigid-Flex: These materials offer unique benefits but come at a premium compared to standard rigid boards.
  4. High-Temperature Materials: Polyimide and other high-Tg materials cost more but offer better performance in extreme conditions.

Balancing Cost and Performance

When designing PCBs, it’s essential to consider:

  1. The specific requirements of your application
  2. The trade-offs between advanced features and cost
  3. The long-term reliability needs of your product
  4. The volume of production, as some features may become more cost-effective at higher volumes

By carefully evaluating these factors, designers can make informed decisions about PCB materials and features, optimizing both performance and cost-effectiveness for their specific application needs.