What is the loss tangent of FR4?
0.02
Properties
| Parameter | Value |
|---|---|
| Dielectric Constant (εr) | 3.9 – 4.7, 4.4 @ 1 GHz (Supplier Isola) |
| Loss Tangent (tanδ) | 0.02 – 0.03, 0.030 @ 1 GHz |
| Glass transition temperature | Can vary, but is over 120 °C |
| Young’s modulus – LW | 3.5×106 psi (24 GPa) |
How is PCB loss calculated?
αt = αc + αd + αr + αl The effect of leakage loss can be ignored because PCBs have very high volume resistance. Radiation loss is the energy lost from the circuit due to RF radiation. This loss is dependent on frequency, dielectric constant (Dk), and thickness.
What causes insertion loss in PCB?
Insertion loss will usually occur because the PCB will be receiving multiple frequencies from the sent signals. Due to the different frequencies, differing impedance is present from the material, which can result in some of the signals becoming reflected or to experience phase distortion.
At what temperature does FR4 burn?
Materials for printed circuit boards
| Type | Description | Glass transient temp. Tg |
|---|---|---|
| FR4 halogen free | This laminate type does not contain halogen, antimony, phosphorus, etc., does not emit hazardous substances when burning. | 140°C |
| FR4 High Tg, FR5 | These laminate types have excellent performance in Pb-free soldering. | 170°C |
Which parameter is insertion loss?
S12
Insertion loss is the magnitude of S12 in an S-parameter matrix and expressed in dB, where port 1 is input and port 2 is output. Standard nomenclature is to express insertion loss as a negative number for attenuation and positive for gain.
Why does insertion loss increase with frequency?
Insertion loss characteristics of a link change with the frequency of the signal to be transmitted; e.g. higher frequency signals experience much more resistance. Stated a different way, the links show more insertion loss for higher frequency signals.
What is the difference between insertion loss and attenuation?
A transmission line will attenuate an amount (based on distance) whilst maintaining impedances so, it could be regarded as causing “insertion loss”. Insertion loss, also referred to as attenuation, refers to the loss of signal strength at the far end of a line compared to the signal that was introduced into the line.
Is FR4 anisotropic?
Properties of FR-4 ER=4.7 (has been reported between 4.35 and 4.8, and is slightly frequency dependent and varies by manufacturer and lot-to-lot) When it comes to delectric constant, FR-4 is an example of an anisotropic material. FR-4 is rated to 140C by Underwriter Laboratories.
Is FR4 a PTFE?
Rogers will sell you FR-4 laminates (FR-4 core with copper laminate), they are better known for cores with better high frequency properties, such as PTFE (Teflon). They’re more expensive than fiber glass, but are less lossy at high frequencies. This makes them be good for RF circuit boards.
Why does FR-4 have a higher loss than other materials?
In most passive circuits, such as filters, loss increases as frequency increases. FR-4 has a higher dissipation factor (Df) than laminates engineered for high frequency use, circuits fabricated on FR-4 will suffer higher losses than similar circuits formed on a high frequency circuit.
How does FR4 affect the dispersion of a PCB trace?
Just like any other material, FR4 has dispersion that affects travelling pulses and waves in PCB traces. The physics that describes dispersion is well-known and can be used to develop analytical models for signal behavior in a PCB, but working with a simulation package can make your life much easier.
Can FR4 boards be used for high speed/high frequency applications?
For this reason, FR4 boards used in high speed/high frequency applications should include high speed laminates that reduce loss and compensate for the inherent negative dispersion of FR4. Alternatively, you should use a different material that is specialized for RF applications.
Should I Choose FR-4 or a high frequency laminate?
When trying to decide between FR-4 or a high frequency laminate, the lower cost of FR-4 may be important, but it may not be the only consideration. For example, how critical is signal loss to your design? In most passive circuits, such as filters, loss increases as frequency increases.