Electrically Conductive Adhesives: Advantages and Disadvantages

This page explores the advantages and disadvantages of electrically conductive adhesives (ECAs), providing a comprehensive overview.

Introduction

Traditionally, lead-free solders have been used to mount integrated circuits (ICs), LEDs, and other electronic components onto substrates, especially in rigid printed circuit boards (PCBs). However, this technique isn’t well-suited for flexible substrates. ECAs offer a valuable alternative. ECAs are used in a wide range of applications, including:

• Consumer electronics
• Automotive electronics
• EMI shielding
• Displays
• RFID tags
• Wearable electronics
• In-mould electronics
• Printed electronics

What are Electrically Conductive Adhesives?

ECAs provide high strength and are safe to use. There are two main types of ECAs:

• Isotropic Conductive Adhesives (ICAs): Conduct electricity equally in all directions.
• Anisotropic Conductive Adhesives (ACAs): Conduct electricity in only one direction.

ACAs are further categorized into:

• Anisotropic Conductive Paste (ACP)
• Anisotropic Conductive Film (ACF)

ICAs require a smaller amount of adhesive between the metal pad and connection, as electricity is passed in all directions. ACAs, on the other hand, conduct electric charges in one direction only, ensuring electrical connectivity across the joint without causing short circuits.

Benefits/Advantages of Electrically Conductive Adhesives (ECAs)

The following are the benefits of using electrically conductive adhesives:

• Environmentally Friendly: ECAs have a lower environmental impact because they don’t use heavy or toxic metals.
• Fine Pitch Connections: ECAs are suited for connecting components with very fine pitches, allowing for the assembly of more components in a smaller area of the circuit.
• Mechanically Soft: The polymer filler provides mechanical softness, which is beneficial for certain applications.
• Low-Temperature Processing: ECAs require lower processing temperatures compared to soldering, making them ideal for temperature-sensitive components.
• Improved Fatigue Resistance: ECAs demonstrate better fatigue resistance compared to traditional solder joints, leading to longer-lasting connections.

Drawbacks/Disadvantages of Electrically Conductive Adhesives (ECAs)

The following are the drawbacks of using electrically conductive adhesives:

• Longer Curing Time: While ECAs require lower curing temperatures, they often take longer to cure than traditional soldering methods.
• Cost: The silver often used in ECAs is expensive, potentially making it less feasible for large-scale applications.
• Equipment Investment: ECAs require different equipment than lead-free soldering techniques, which can increase the initial investment cost for a company.
• Placement Precision: ECAs require more precise component placement compared to solders, which can tolerate slight misplacements.
• Higher Resistance: ECAs typically offer higher electrical and thermal resistance compared to solders.