As a supplier of PFA insulated electric wire, I am often asked about the shielding effectiveness of our products. In this blog post, I will delve into the concept of shielding effectiveness in PFA insulated wire, exploring what it means, how it is measured, and the factors that influence it.
PFA insulated wire itself is the "anti-interference basic model"
Before discussing the shielding effect, let's first clarify one premise: PFA insulated wire itself has a certain anti-interference potential, which is closely related to its core material. PFA, as a high-performance fluorinated polymer, one of its biggest advantages is its low dielectric constant (about 2.1) and excellent high-frequency stability. This is also the key reason why it can become the mainstream insulation material for high-frequency cables - the lower the dielectric constant, the smaller the signal loss in the insulation layer, and the more solid the anti-interference "foundation".
It is worth mentioning that the PFA insulation layer treated by physical foaming technology will have even better performance. This process uses nitrogen injection extrusion to form uniform closed spherical micropores (with a pore size of only 0.006-0.033mm) inside the insulation layer, which can further reduce the dielectric constant to around 1.4, significantly reduce signal attenuation, and make high-frequency signal transmission more stable. Simply put, PFA insulation layer is like putting an "anti-interference base coat" on the conductor, while the shielding layer is a "protective armor" stacked on top of it.
How effective is the PFA wire after shielding?
The core purpose of adding a shielding layer to PFA wire is to solve two types of problems: one is to block the intrusion of external electromagnetic interference (EMI) and radio frequency interference (RFI), and protect internal signals; The second is to prevent internal signal leakage and avoid interfering with peripheral devices. The strength of the shielding effect mainly depends on three key factors: shielding material, shielding structure, and grounding method. The effect of different configurations varies significantly, and we will explain them one by one based on actual application scenarios.
Shielding material: Different materials have vastly different "protection levels"
The core function of the shielding layer is to "absorb+reflect" electromagnetic waves, and the conductivity and permeability of the material directly determine its "protective ability". At present, there are three main types of shielding materials commonly used for PFA cables, with effects upgrading from basic to high-end:
- Aluminum foil shielding: entry-level protection, suitable for general interference scenarios. The advantages of aluminum foil are low cost, tight packaging, and effective blocking of high-frequency electromagnetic interference. The shielding effectiveness is usually between 60-80dB (the higher the dB value, the better the shielding effect). However, aluminum foil has a brittle texture and weak tensile and bending resistance, making it suitable for scenarios where wiring is fixed and not easily bent, such as fixed lines in computer rooms or internal connections of ordinary instruments.
- Tin plated copper wire braided shielding: the main force at the middle end, balancing protection and toughness. Tin plated copper wire has high conductivity, and its braided structure can form a dense "protective net", which not only blocks high-frequency interference but also has a certain inhibitory effect on low-frequency interference. The shielding efficiency can reach 80-100dB. Moreover, the braided layer has good flexibility and can adapt to frequent bending scenarios, such as industrial robot cables and mobile drive systems, which is currently the most widely used shielding method.
- Conductive fiber shielding: high-end customized, lightweight and efficient. This type of shielding layer is made of polyacrylonitrile based carbon fiber twisted and coated with copper conductive coating, with a deployment area of up to 80% -95% of the supporting network. It can replace traditional metal shielding layers to ensure shielding stability and significantly reduce cable weight. It is suitable for scenarios that require weight and diameter, such as drones and medical minimally invasive surgical equipment, and the shielding efficiency can be stable at over 90dB.
Shielding Structure: Single Shielding vs Double Shielding, with a difference of more than twice
In addition to the material, the design of the shielding structure directly determines the "upper limit" of the shielding effect. At present, the shielding structures of PFA electric wire are mainly divided into two types, which are suitable for scenarios with different interference intensities:
Single shielding (aluminum foil or single-layer weaving): suitable for environments with weak interference, such as ordinary office equipment and small instruments. This type of structure can meet basic anti-interference requirements, such as blocking RF interference from surrounding routers and computers, ensuring signal transmission is not lagging. However, in strong interference environments such as industrial workshops and substations, single shielding protection is insufficient and prone to signal distortion.
Double shielding (aluminum foil+woven mesh): a "standard configuration" for strong interference environments, and also our most recommended high-frequency and high demand scenario configuration. Aluminum foil is responsible for blocking high-frequency interference, while woven mesh is responsible for blocking low-frequency interference and mechanical damage. After dual protection, the shielding effectiveness can reach 100-120dB, effectively resisting strong electromagnetic radiation generated by high-power equipment and frequency converters. For example, in medical imaging equipment, double shielded PFA insulated electric wire can ensure clear and delay free image signals, avoiding diagnostic errors caused by interference; In high-frequency communication scenarios, ultra-low distortion high-speed data transmission can be achieved.
In addition, there is a multi shielding structure (such as double-layer weaving+aluminum foil) mainly used in extreme scenarios such as aerospace, with a shielding efficiency of over 120dB, which can resist various interferences in complex electromagnetic environments. However, the cost is high, and there is no need to excessively pursue it in ordinary industrial scenarios.
Grounding method: If not properly grounded, the shielding layer is equivalent to "virtually non-existent"
Many customers tend to overlook a key factor: the effectiveness of the shielding layer must be achieved through standardized grounding. If the shielding layer is not properly grounded, it not only cannot block interference, but may also become an "interference amplifier" that introduces external interference into the cable through capacitive coupling.
The correct grounding method needs to be adjusted according to the signal frequency: low-frequency signal transmission (such as industrial control signals) is suitable for single point grounding to avoid ground loop interference; High frequency signal transmission (such as RF and image transmission) is suitable for multi-point grounding, reducing grounding impedance and ensuring that interference currents can be smoothly introduced into the ground. And the grounding resistance needs to be controlled within a reasonable range, otherwise it will significantly weaken the shielding effect - this is also one of the core reasons why the same shielding PFA insulated electric wire has a large difference in effectiveness among different customers.
Avoid pitfalls in selection: Don't step on these 3 misconceptions!
After discussing the effectiveness, let's talk about the three most common mistakes customers make when selecting, to help you avoid unnecessary losses:
Misconception 1: The stronger the shielding effect, the better, blindly pursuing high dB values. In fact, the shielding effect needs to match the scene. For example, in ordinary office scenarios, a single shielding aluminum foil is sufficient. Blindly choosing dual shielding or multiple shielding will only increase procurement and installation costs, but also cause waste.
Misconception 2: Only focus on the shielding material and ignore the quality of PFA insulation layer. High quality PFA insulation layer (such as foamed PFA) can better adhere to the shielding layer, reducing signal leakage, while inferior PFA insulation layer is prone to cracking and falling off, which can seriously affect the shielding effect - this is also why the shielding effect of tinned copper wire varies significantly among products from different manufacturers.
Misconception 3: Neglecting installation details and non-standard grounding. Many customers have purchased high-quality shielded PFA wire, but due to non-standard grounding (such as excessive grounding resistance and chaotic multi-point grounding), the shielding effect is greatly reduced, and even inferior to unshielded wires. It is recommended to follow the principle of "single point grounding (low frequency), multi-point grounding (high frequency)" during installation to ensure reliable grounding.
Is shielding PFA insulated wire worth choosing?
Returning to the original question: What is the shielding effectiveness of PFA insulated wire if shielded? The answer is very clear: as long as the material, structure, and grounding method are chosen correctly, its shielding effect can meet the needs of the vast majority of mid to high end scenarios, especially high-frequency, strong interference, and high signal stability requirements. Shielding PFA electric wire is definitely the first choice for cost-effectiveness.
Its core advantage lies in the dual combination of "low loss characteristics of PFA insulation layer+anti-interference ability of shielding layer", which can ensure the integrity of signal transmission, resist interference from complex environments, and also have the characteristics of temperature resistance (-65 ℃~260 ℃), corrosion resistance, and aging resistance, with a service life far exceeding that of ordinary shielded cables.
Finally, a selection suggestion for everyone: If your scene has weak interference (such as ordinary instruments or fixed wiring in computer rooms), choose single shielded (aluminum foil or single-layer braided) PFA electric wire; If it is a scenario with strong industrial interference, medical treatment, high-frequency communication, etc., priority should be given to using foam PFA electric wire with dual shielding (aluminum foil+woven mesh) or conductive fiber shielding, and grounding should be standardized to maximize the shielding effect.
If your application scenario is quite special and you are unsure which shielding configuration to choose, feel free to leave a message about your industry and usage environment. We will help you accurately match the most suitable shielding PFA electric wire solution.
