Cable 101: Shielding and Why it’s Important

Cable 101: Shielding and Why it’s Important

Whether designing a disposable medical device, mass-producing a consumer charging cable or developing a wire harness for a piece of capital equipment, careful detail must be paid to connect the different components. This coming-together is most typically accomplished using some version of wire. Unbeknownst to the majority of the general public, this much design and engineering go into each type of wire. We discussed the conductor and insulation for both carrying the charge and not losing the electrical charge, but now the question is—how do we keep outside influences from interfering with our wire’s signal?

Before we discuss what the “shield” is, let’s review the very basic anatomy of a wire. Within a “simple” wire you have, moving from inside to outside;

  1. Conductor
  2. Insulation
  3. SHIELDING
  4. Jacketing

What is “shielding”?

A shield is most commonly constructed of either foil or a woven mesh braid.

Foil Shielding is a layer of aluminum that is attached to the carrier. The foil layer method is the only shielding option that provides total coverage of the conductors—particularly important with data cables. Foil shielding is thin which can increase the complexity of the production of the wire.

Braid Shielding, also referred to Mesh Shielding is produced using thin wires. This method of shielding provides low resistance path to ground, it is a less complex medium in production but does not provide the total coverage that the foil shielding provides, due to the small gaps resulting from the braiding manufacturing process. Expected coverage for a braided shield is 70%-95%—70% coverage is sufficient for most applications.

When to use Foil over Braid or vice versa?

Positives of Foil:

• Thinner, allowing for a smaller diameter wire
• Less expensive
• Complete coverage—threrefore better protection from electrostatic interference

Positives of Braid:

• A more effective shield than foil
• Additional strength, harder to penetrate and flexible

Negatives of Foil:

• Not as effective shield as braid
• More easily penetrated

Negatives of Braid:

• Limited coverage
• More expensive than foil
• Adds size to diameter of the wire

Do you ever use both Foil and Braid together? Yes

In “noisy” environments, it is common to use a combination shield—foil layer followed by a braided layer. In multiconductor applications, it is not uncommon to shield the individual pairs with foil and then shield to complete wire with a braided shield. This provides “crosstalk” protection.

As we’re beginning to see, so much goes into just the cabling of a connector and we haven’t even started in on the connection portion of the interconnect. Interested in connecting with an interconnect expert to see how ATL could benefit you and your project? Connect with us here.

Cable 101: Insulation and How it Helps

Cable 101: Insulation and How it Helps

Whether designing a disposable medical device, mass-producing a consumer charging cable or developing a wire harness for a piece of capital equipment, careful detail must be paid to connect the different components. This coming-together is most typically accomplished using some version of wire. Unbeknownst to the majority of the general public, this much design and engineering that goes into each of these types of wire. At the core of a wire are conductors aiding the movement of the electrical charge, the question is—how do we prevent the loss of the free-flowing electricity? Like a home keeping warm air in and cool air out in the winter, this is where wire insulation enters the picture.

Before we discuss what the “Insulation” is, let establish the very basic anatomy of a wire. Within a “simple” wire you have, moving from inside to outside;

  1. Conductor
  2. Insulation
  3. Shield
  4. Jacket

What is “Insulation”?

Insulation provides resistivity to the wire, separating the conductors both electrically and physically. The insulation minimizes free flowing electric charges from the conductor segments of the wire. When choosing an insulation considering the environment it will be used in is crucial. Physical considerations can be things like temperature rating, flexibility, the life of the application, flammability and more.

What is the insulation made of?

Guarding against interference as well as keeping the signal as strong as possible, insulation always consists of non-metallic, non-conductive material to resist the flow of electricity. Insulators come in multiple forms; solids, liquids, and gases. For this discussion, we are only going to consider three types of solid insulators, those being: Plastics, Teflon, Rubber and Paper.

Plastics

Plastic insulators range from various polyvinylchloride (PVC) to polyurethane and polyethylene—to name only a few of the more common. Pricing ranges from inexpensive PVCs to expensive implantable polyurethanes. Plastics provide use in diverse applications and exposures. Plastics have a vast range of rigidity and thickness.

Fluoropolymers

Fluoropolymers are excellent insulators for high-temperature applications, they also have superior mechanical strength at high temperatures. The unique material that is Teflon provides unsurpassed electrical properties, such as, high dielectric strength, low dielectric loss and low dielectric constant.

Rubber

Chosen for its long life, flexibility and performance under high temperatures, rubber is another common insulation type. Common rubbers include ethylene propylene, silicone and neoprene.

Paper

Originally used for its pure cellulose, for decades you could find paper in telephone cables—it’s true, kids, our telephones were once tethered to a wall by wires and cords and didn’t send pictures. Paper as an insulator has several drawing backs and has widely been replaced by plastics, rubbers and Teflon.

Now that you’ve crammed your head with knowledge about conductors and insulation and your dreams will be filled with wire, we can’t stop now. The next installment of Electric Wire 101 will be the exciting world of shielding. I know you can hardly contain your excitement—neither can we—so check back soon, or subscribe to our blog, for the long and short of shielding.

Have more questions about how ATL can connect with you on your connectivity needs? Or maybe you’re interested in using ATL’s expertise to get the right wiring and interconnect solution for your application. To find out how ATL can make your life easier, your connection more stable and much more, please contact us.

Cable 101: What is the Conductor?

Cable 101: What is the Conductor?

Whether designing a disposable medical device, mass-producing a consumer charging cable or developing a wire harness for a piece of capital equipment, careful detail must be paid to connect the different components. This coming-together is most typically accomplished using some version of wire. Unbeknownst to the majority of the general public, this much design and engineering that goes into each of these types of wire. At the core of a wire is the conductor, the question is, do you need one, two, 8, or even more conductors in your wire to make your product function?

Before we discuss what the “Conductor” is, let establish the very basic anatomy of a wire. Within a “simple” wire you have, moving from inside to outside;

  1. Conductor
  2. Insulation
  3. SHIELD
  4. Jacket

What is a “Conductor”?

Whether in a powering a small device or the powerlines providing electricity to an entire city, a conductor is the material that allows the free flow of electric current. In the case of the electrical circuit system, “conductor” specifically refers to the piece that transports the electrical current from the source to its load.

What is a conductor made of?

When an electrical charge is applied, metals provide the best conductive properties. This is the reason why metals are the conductor of choice in electric wires. Although we are all used to seeing copper as the most used conductor, the best metallic conductor is actually silver. But because of outrageous sticker price, copper is the most often used. Other metals—such as aluminum, gold, steel and brass—are also conductors, but they’re not considered to be as effective as copper and silver and using these metals may present other complications.

How do I decide on the size of the conductor wire?

Base conductor wires range from a stand or wire that is smaller than a human hair to 0000. American wire gauge* (AWG) is a standardized system for wire gauging that spells out the diameters of round, solid, nonferrous, electrically conductive wire. So, finding a conductor wire for your product depends on how big or small you want it to be, coupled with the product or device power requirements.

How many conductors do I need in my wire?

We wish we could tell you, but answering this would be like looking into a crystal ball and instantaneously making ATL a unicorn, but we don’t know your business—and we don’t have a crystal ball, unfortunately. It really all depends on what you need to device or product to do.

A common wire most of us are aware of is the wires running through our homes. This wire has three conductors: Hot, Neutral and Ground. Wires being produced today range from one conductor to literally hundreds of conductors.

As an example, let’s discuss the anatomy of a USB 3.0 Cable. The construction of this cable includes the following conductors:

  • 2 power conductors that range from 20 – 28 AWG
  • 1 set of unshielded twisted pair that range from 28-34 AWG
  • 2 sets of shielded twisted pairs that range from 26-34 AWG
  • 1 drain wire

A total of nine conductors are needed to produce a USB cable (we would commonly describe this cable as 8 conductors and a drain wire, even though the drain wire is technically a conductor as well). Any device may need less or it may need significantly more—it is all down to what you need the connector to do.

We have only merely scratched the surface of the components of wire. This is the first in a series of four that breaks down the components of wire and what we, at ATL, need to build you the best connector for your application.

 

* W&M Wire Gauge, US Steel Wire Gauge and Music Wire Gauge are different systems