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
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)
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 PCBs | Tg | CTE-z (T<Tg) | εr, Dk- Permittivity | Dk Loss Tangent | Electric Strength | Surface Resistivity | Tracking resistance CTI | Td value | Peel strength |
|---|---|---|---|---|---|---|---|---|---|
| °C | ppm/°C | @1GHz | @1GHz | KV/mm | MO | PLC | °C | N/mm | |
| ISOLA Duraver DE104 Standard FR4 | 135° | 70 | 4,4 | 0,020 | 54 | 1,0 x 10^6 | 2 | 315° | 1,6 |
| Shengyi S1141 FR4 alternative | 140° | 65 | 4,6* | 0,015* | 60 | 5,4 x 10^7 | 3 | 310° | 1,8 |
| ISOLA Duraver DE104 KF FR4 tracking resistant | 135° | 45 | 4,6 – 4,9 | 0,020* | 39 | 1,0 x 10^6 | 1 | 315° | 1,6 |
| ISOLA DE156 FR4 halogen-free | 155° | 45 | 4,0 | 0,016 | 36 | 4,0 x 10^6 | – | 390° | 1,4 |
| ISOLA IS400 FR4 MidTg | 150° | 50 | 4,0** | 0,020 | 48 | 3,0 x 10^6 | 3 | 330° | 1,4 |
| ITEQ IT-158 FR4 MidTg alternative | 155° | 60 | 4,3 | 0,016 | 60 | 1,0 x 10^10 | – | 345° | 1,7 |
| ITEQ IT-180A FR4 HTg | 175° | 45 | 4,4 | 0,015 | 45 | 3,0 x 10^10 | – | 345° | 1,4 |
| Shengyi S1000-2 FR4 HTg alternative | 180° | 45 | 4,8* | 0,013* | 63 | 7,9 x 10^7 | 3 | 345° | 1,4 |
| ISOLA IS410 FR4 HTg, CAF-Enhanced | 180° | 55 | 4,0 | 0,019 | 44 | 8,0 x 10^6 | 3 | 350° | 1,2 |
| ISOLA IS420 FR4 HTg, CAF-Enhanced alt. | 170° | 45 | 4,0 | 0,016 | 54 | 3,0 x 10^6 | 3 | 350° | 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 PCBs | Recommended max. operating temperature | Copper type | Tg | εr, Dk- Permittivity | CTE-z (T<Tg) | Electric Strenght | Surface Resistivity | Peel strength |
|---|---|---|---|---|---|---|---|---|
| °C | * | °C | @1MHz | ppm/°C | KV/mm | MΩ | N/mm | |
| Polyimide + Adhesive | ||||||||
| Shengyi SF305 | 105° | RA | – | 3,6 | – | 21 | 1 x 10^5 | 1,1 |
| Polyimide Adhesiveless | ||||||||
| DuPont Pyralux AP | 180° | RA | 220 | 3,4 | 25 | 256 | 1 x 10^10 | 1,8 |
| Panasonic RF775 | 130° | ED | 343 | 3,2 | – | 276 | 1 x 10^8 | 1,7 |
| Thinflex W-05050 | 105° | ED | 350 | 3,3 | 24 | 216 | 1 x 10^5 | 0,6 |
| PI Coverlay | ||||||||
| Shengyi SF305C | 105° | – | – | – | – | – | 3 x 10^6 | – |
| DuPont Pyralux FR | 180° | – | – | 3,5 | – | 138 | 1 x 10^7 | – |
| Adhesive tape | ||||||||
| 3M 9077 | 150° | – | – | – | – | – | – | – |
* 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/mK | K/W | MΩ | °C | kV | PLC | |
| TC-Lam 2.0 | 2.0 | 0.50 | 10^7 | 100 | 5.0 | 0 |
| HA50 (3) | 2.2 | 0.41 | 10^6 | 120 | 4.3 | 0 |
| AL-200 | 2.0 | 0.35 | 10^8 | – | 3.5 | 0 |
| AL-300 | 3.0 | 0.30 | 10^8 | – | 3.5 | 0 |
| Ventec VT-4B3 Ceramic Filled | 3.0 | – | 5 x 10^8 | 130 | 8.0 | 0 |
| Ventec VT-4B4 Ceramic Filled | 4.2 | – | 2 x 10^7 | 120 | 8.0 | 0 |
| Ventec VT-4B7 Ceramic Filled | 7.0 | – | 2 x 10^7 | 100 | 8.0 | 0 |
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/mK | K/W | MΩ | °C | kV | PLC | |
| Ventec VT-4A2 | 2.2 | – | 2 x 10^7 | 130 | 7.5 | 0 |
| Ventec VT-4B3 Ceramic Filled | 3.0 | – | 5 x 10^8 | 130 | 8.0 | 0 |
Material for high frequency PCB boards
| Material for high frequency boards | Order Share | εr, Dk- Permittivity | Dk Loss Tangent | Tg | Td Value | Thermal Conductivity | CTE-z (T<TG) | Electric Strength | Surface Resistivity | Peel Strength |
|---|---|---|---|---|---|---|---|---|---|---|
| @10GHz | @10GHz | °C | °C | W/m*K | ppm/°C | KV/mm | MΩ | N/mm | ||
| Rogers 4350B HF Material | +++ | 3,5 | 0,0037 | 280° | 390° | 0,69 | 32 | 31 | 5,7 x 10^9 | 0,9 |
| Rogers 4003C PTFE HF Material | ++ | 3,4 | 0,0027 | 280° | 425° | 0,71 | 46 | 31 | 4,2 x 10^9 | 1,1 |
| Panasonic Megtron6 HF Material | + | 3,6 | 0,004 | 185° | 410° | – | 45 | – | 1 x 10^8 | 0,8 |
| Rogers RO3003 PTFE ceramic-filled | + | 3,0 | 0,0013 | – | 500° | 0,50 | 25 | – | 1 x 10^7 | 2,2 |
| Rogers RO3006 PTFE ceramic-filled | o | 6,2 | 0,002 | – | 500° | 0,79 | 24 | – | 1 x 10^5 | 1,2 |
| Rogers RO3010 PTFE ceramic-filled | o | 10 | 0,0022 | – | 500° | 0,95 | 16 | – | 1 x 10^5 | 1,6 |
| Taconic RF-35 Ceramic | o | 3,5** | 0,0018* | 315° | – | 0,24 | 64 | – | 1,5 x 10^8 | 1,8 |
| Taconic TLX PTFE | o | 2,5 | 0,0019 | – | – | 0,19 | 135 | – | 1 x 10^7 | 2,1 |
| Rogers RO3001 Bonding Film for PTFE | – | 2,3 | 0,003 | 160° | – | 0,22 | – | 98 | 1 x 10^9 | 2,1 |
| Taconic TLC PTFE | – | 3,2 | – | – | – | 0,24 | 70 | – | 1 x 10^7 | 2,1 |
Material for high-Tg circuit boards (selection)
| Material for High-Tg boards | Tg | CTE-z (T<Tg) | εr, Dk- Permittivity | Electric Strenght | Surface Resistivity | Tracking Resistance CTI | Thermal Conductivity | Td value | Peel Strength |
|---|---|---|---|---|---|---|---|---|---|
| °C | ppm/°C | @1GHz | KV/mm | MO | PLC | W/m*K | °C | N/mm | |
| ISOLA IS410 FR4 HTg, CAF-Enhanced | 180° | 55 | 4,0 | 44 | 8,0 x 10^6 | 3 | 0,5 | 350° | 1,2 |
| ISOLA IS420 FR4 HTg, CAF-Enhanced | 170° | 45 | 4,0 | 54 | 3,0 x 10^6 | 3 | 0,4 | 350° | 1,3 |
| ITEQ IT-180A FR4 HTg | 175° | 45 | 4,4 | 45 | 3,0 x 10^10 | – | – | 345° | 1,4 |
| Shengyi S1000-2 FR4 HTg | 180° | 45 | 4,8* | 63 | 7,9 x 10^7 | 3 | – | 345° | 1,4 |
| ARLON 85N Polyimid HTg | 250° | 55 | 4,20* | 57 | 1,6 x 10^9 | – | 0,2 | 387° | 1,2 |
PCB Material Selections and Design Features Impacting Cost
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:
- Gold Tabs: While offering excellent conductivity and corrosion resistance, gold plating is significantly more expensive than standard surface finishes.
- Blind and Buried Vias: These specialized vias increase PCB complexity and require additional manufacturing steps, driving up costs.
- Via Filling: Filled vias improve reliability and allow for higher component density but require extra processing steps.
- 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:
- Specialized Processes: Unusual or complex PCB designs often require alternative manufacturing processes, which can be more time-consuming and resource-intensive.
- 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.
- 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:
- Significantly higher costs
- Reduced manufacturing yield
- Potential reliability issues
- Limited choice of manufacturers
Material Selection Impact
Beyond design features, the choice of PCB material itself plays a crucial role in determining cost:
- Standard FR-4: Generally the most cost-effective option for many applications.
- High-Frequency Materials: Specialized materials for RF applications (like Rogers or Taconic laminates) are typically more expensive.
- Flex and Rigid-Flex: These materials offer unique benefits but come at a premium compared to standard rigid boards.
- 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:
- The specific requirements of your application
- The trade-offs between advanced features and cost
- The long-term reliability needs of your product
- 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.
