Whether you’re a manufacturer, engineer or hobbyist, choosing the right electronics adhesive can make all the difference in your project. From bonding components to protecting sensitive circuits, adhesives play a crucial role. In this guide, we’ll walk you through the options available to help you solve challenges, meet engineering goals, and confidently bring your project to completion.
Mechanical Properties of Adhesives
Working Time
Working time refers to how long you can handle or position a product before it becomes too thick to spread. The working time helps users plan and prepare the batch size of adhesive to mix, so they avoid wasting material.
Thermal Conductivity
This property measures a material’s ability to conduct heat. Metals, for example, are excellent heat conductors, while insulators like Styrofoam or oven mitts conduct very little. Thermal conductivity is expressed in W/(m·K) and represents how quickly heat can move through a material. Higher thermal conductivity values mean the material conducts heat better.
Shear Strength
Shear strength refers to the total pressure a bonded lap sample can withstand before failure (bond pulls apart). To measure this, a test known as a lap shear (measured in N/mm2) is commonly used. Figure 1 illustrates the basic premise of a lap shear test.
Although lap shear testing does not directly replicate real-world conditions, it provides a valuable comparative measure of how different adhesives perform against one another.
Tensile Strength
Tensile strength is the resistance of a material to being pulled apart, measured in N/mm2 or PSI. The total force a material can withstand (before breaking) follows an inverse square relationship to its cross-sectional area. For example, a 2-inch square bar of material can support four times the tensile load of a 1-inch square bar material. Figure 2 below illustrates the basic setup for a tensile test.
Compressive Strength
Compressive strength is the measured property of a material that indicates its ability to resist crushing, measured in N/mm2 or PSI. This property is critical in applications such as semiconductor underfills, potting compounds for shock absorption, and bonding of vehicle body panels (automotive, drones, etc.), where adhesives must withstand significant compressive forces or possible collisions.
Glass Transition Temperature (Tg)
Tg is the temperature at which a material changes from a hard, rigid state to a softer, more flexible, rubber-like state. It should be noted that the Tg is not the upper temperature limit which is often quite higher than the Tg. Mechanical properties like those mentioned above will all reduce above the Tg but that is different than the material undergoing failure. High Tg materials like our 9310 are meant to ensure material rigidity at high temperatures whereas low Tg materials are more ideal for applications involving thermal cycling.
Coefficient of Thermal Expansion (CTE)
Materials expand when heated and contract when cooled. The CTE is simply a measure of how much they do so. When bonding materials, designers should try and best match up CTE value of the adhesive with the substrates to avoid stress along the bond line. CTE is reported in ppm/ °C and varies with respect to the Tg.
Types of Adhesives for Electronics
Electrically Conductive Adhesives (ECAs)
An electrically conductive adhesive (ECA) is an epoxy-based adhesive filled with conductive particles such as silver. Once cured, these fillers form conductive pathways that allow electricity to flow through the adhesive. If you’d like to explore ECAs in more detail, this article is a great place to start.
Silver is great for applications where a high level of conductivity is necessary, like high-frequency shielding. Below are specific applications that use ECAs.
Applications
- Cold Soldering
- EMI Gaskets
- Trace fabrication and repair
To see the entire catalog of our ECAs and how they compare, click here.
Thermally Conductive Adhesives (TCA)
Electronics produce heat, and a lot of it. Computing components like CPUs and GPUs can often reach temperatures upwards of 70 °C under load. Even high-powered LEDs can reach temperatures hot enough to destroy themselves. Designers put a lot of work into keeping devices cool so they can operate reliably, safely, and as intended.
A TCA enables the bonding of components such as heatsinks or LEDs while simultaneously facilitating efficient heat transfer. The NorthWestern University Formula Racing team applied our 8349TFM in their battery pack design to reliably monitor cell temperatures. This precaution helps prevent the pack from exceeding 60 °C, a threshold beyond which serious damage or even catastrophic failure could occur.
Applications
- Bonding heat sinks
- Power semiconductor devices
- Flip chip BGA heat spreaders
- Battery modules and battery packs
- LED lighting
- Automotive lighting
- Appliances
To view our entire catalog our TCAs, click here.
Bonding Adhesives
This is a category most of us are already familiar with. Sometimes referred to as structural adhesives, their function is simple: to hold things together. In an assembly, they may be used to fasten electrical components to structural parts, make repairs, bond parts of a housing together, etc.
Compared to mechanical fasteners like screws and clips, bonding adhesives have a few key advantages:
- They are lightweight
- They are easy to use and implement in a design
Bonding adhesives eliminate the challenge of working with screw-hole tolerances and heatset inserts, especially in plastic parts, where these dimensions will often change after the printed or injection molded part has cooled. They may also be used in conjunction with mechanical fasteners to enhance the strength of the structure entirely.
Applications
- Automotive body panels
- Bonding to vertical surfaces
- Battery assembly
- Aircraft structural adhesives
- Surface mount technology (SMT)
- Die attach
- Sealing
- Potting
- Gap filling
- Bonding windows
ECAs, TCAs, and bonding adhesives from MG Chemicals are all available in both 1 and 2-part systems.
To view our entire catalog of bonding adhesives, click here.
UV-Curable Adhesives
Think of UV-curable adhesives as the scalpel of the adhesive world—precise, fast, and indispensable. These 1-part adhesives cure when exposed to UV light, with products like our UVLED82 capable of encapsulating up to 5 mm in thickness. Their biggest advantage is speed: while a heat-cured epoxy might take 30 minutes or more, a UV adhesive cures in seconds, enabling extremely high throughput for manufacturers. Because no heat is required, they’re especially well-suited for sensitive electronics that could be damaged by thermal curing.
With its low viscosity and single-component format, UVLED82 is easy to dispense manually or with automated pneumatic equipment. UV exposure can also be precisely controlled, allowing selective curing in specific areas of a PCB. For added reliability, UVLED82 includes a secondary moisture-cure mechanism, ensuring complete curing even in shadowed areas of a board.
Applications
- Edge bonding chips
- Read/write heads on disk drives
- Camera modules
- Fibre optic connectors, couplers and isolators
- Bonding photovoltaic cells
- PCB encapsulation
- Glob top
Conclusion
With so many types of adhesives available, choosing the right one for your application can be challenging. That’s where we come in. MG is your trusted partner in electronics, dedicated to delivering high-quality chemical products and expert service. Through resources like our knowledgebase and detailed TDS documents, we provide the solutions our customers need for their specific design requirements.
Need more help finding the right adhesive for your application? Don’t hesitate to reach out to [email protected].
