In the design and manufacture of electronic devices, reliable electrical connection between components is as important as the circuitry itself. In applications where solder joints are not feasible, either due to temperature, space or flexibility, conductive adhesives present themselves as an efficient, safe and versatile technical alternative.

However, not all conductive adhesives work the same way or serve the same purpose. In this article we look at the two main families available on the market: isotropic adhesives (ICA) and anisotropic adhesives (ACA). We will look at their differences, advantages and limitations, and help you choose the most suitable option for your industry and application.

What are conductive adhesives?

Conductive adhesives are materials that, in addition to joining two surfaces, allow the passage of electric current between them. They are composed of a polymeric matrix (usually epoxy or acrylic) and conductive particles, such as silver, gold or nickel, dispersed inside.

They are used in applications where traditional welding is not possible or desirable, either due to thermal sensitivity, miniaturization, flexibility or assembly requirements.

Isotropic vs. anisotropic adhesives: what is the difference?

Isotropic conductive adhesives (ICA)

Isotropic adhesives conduct electricity in all directions: vertically and horizontally. This makes them ideal for applications where an overall electrical bond between two surfaces is required, such as:

• Pad bonding on PCBs

• Flexible Flat Cable Fixing (FFC/FPC)

• Repair of damaged runways

• Electromagnetic shielding

They are easy to apply, compatible with different substrates (flexible, ceramic, plastic) and offer good mechanical resistance.

Typical applications: consumer electronics, industrial sensors, touch screens, wearables, LEDs.

Anisotropic conductive adhesives (ACA)

Anisotropic adhesives, on the other hand, only allow the passage of current in the vertical direction (z-axis), between two aligned contact points. Their formulation includes larger conductive particles, which are only activated under pressure and alignment during curing.

This allows multiple tracks to be joined in parallel without the risk of lateral short circuits. It is the ideal solution for high density and small size connections .

Typical applications: microconnectors, LCDs, cameras, flexible displays, medical devices, defense.

We previously discussed a specific solution: the anisotropic adhesive IQ-BOND 5976-ACE. IQ-BOND 5976-ACE from Roartisspecially formulated for high-reliability applications in sectors such as automotive, optics or medical electronics.

Recommendations by sector

Automotive

For control modules, sensors and displays, where vibrations are constant and space is limited, ICA adhesives are a good choice for their versatility and mechanical strength. In critical high-density applications, such as cameras or displays, ACAs with controlled curing are recommended.

Defense and aerospace

The focus here is on long-term reliability and resistance under extreme conditions. ACAs are preferred for high-precision connections, and ICAs for structural fasteners that also require electrical conduction.

Consumer electronics and wearables

Wristbands, headphones, flexible LEDs and smart clothing require adhesives that can work with flexible substrates. Low-temperature curable ICAs are ideal, allowing delicate materials to be bonded without damaging them.

Medical sector

For biosensors, smart patches and wearable devices, ACAs offer secure interconnection without lateral interference. In low-cost sensors and disposable applications, flexible and fast-curing ICAs are used.

What to consider when choosing?

Before selecting a conductive adhesive, consider these factors:

• Does the application require multiple nearby tracks? → Better ACA

• Does it need to be applied without pressure and simply? → Better ICA

• Is the substrate flexible or heat sensitive? → Search for low temperature curing ICAs.

• Is this a permanent or temporary application? → ICAs are easier to reprocess.

• What level of electrical resistance is required? → See data sheet and perform preliminary tests

Our solutions

At Cyclops Synergies we represent leading brands in conductive adhesives and have a technical portfolio specialized in both ICAs and ACAs. We do not offer generic products: we evaluate each application together with our customers to recommend the most suitable solution according to the environment, electrical requirements and assembly process.

We work with industrial, automotive, defense, consumer and medical sectors, and offer full technical support in the selection, testing and application of each product.

If you have doubts about which adhesive to use in your electronic design, please contact us. We will be happy to help you find the best option for your case.