thermal pad placement

Advantages of Thermal Interface Pads Vs. Thermal Paste

Thermal Interface Materials (TMIs) are a critical aspect in the design of electronic components, making the difference between a working product and a faulty product. The purpose of Thermal Interface Pads is to provide a preferential heat transfer path between heat-generating components like integrated circuit chips (CPUs) and heat spreaders such as a heat sink.

Why are these needed? If you take a close look at the surface of a CPU or a heat sink, the surface will never be entirely even or level. There will be minuscule bumps, spaces and gaps allowing air to pass between the heat sink and components. Since air is not a good conductor of heat, these gaps would allow heat to build up and collect, potentially causing damage to sensitive components. 

Thermal interface materials with high thermal conductivity are used to fill those gaps to improve heat conductivity between the CPU and heat sink, preventing damage from overheating and extending product life. 

What are thermal interface materials?

Thermal interface materials transfer heat from one surface to another. Ultimately, the goal is to dissipate heat generated from an electrical or mechanical component and into a heat sink, which is usually made of aluminum, copper or even ceramic. The heat sink is made up of deep ridges, allowing gaps of air to help channel heat away from sensitive components. 

Some thermal interface materials solve a common problem in machinery and electrical components. All too frequently, these components have rough, uneven and wavy surfaces, making it difficult to establish surface contact to establish  thermal conductivity to get it to flow away from the component. 

That’s when thermal interface materials serve as gap fillers. It’s specially cut and fitted to create a tight-fitting connection between the two elements, filling the air pockets with thermally conductive material and allowing the heat to flow from the component and into the heat sink. 

There are a number of heat management materials and solutions, but the two most common are thermal interface units and thermal paste.

How to apply thermal interface materials

Applying thermal interface pads

Many thermal pads are silicone-based but acyclic gap pads can provide a cost-effective alternative that works just as well when supplies and costs are a consideration. To install a thermal pad, simply peel the adhesive backing and apply. If these are die-cut to size in advance, assembly is faster with a higher degree of accuracy. 

Applying thermal paste

Apply a thin line of thermal paste on the component, allowing the weight of the heat sink to spread the paste as you join the materials. Thermal paste is made of thermally conductive materials, such as metallic elements, ceramic or silicone.

Advantages of Thermal Interface Pads Vs. Thermal Paste

Thermal pads are less messy than thermal paste 

Applying thermal paste can be a messy process. Thermal pad installation is simply peel and stick and its ready to be moved and handled. 

Effectively fills larger or irregularly sized gaps

Thermal Pads can come in various thicknesses making it easier to hard to fit gaps, whereas thermal paste must be applied in a uniform thin layer, requiring skill and precision to apply evenly and in just the correct amount. You need to apply enough paste to effectively conduct heat. However, applying too much product to fill larger gaps can backfire because the overage can provide insulation to the application, hindering the heat transfer it was designed to provide. 

Easier Installation

Thermal Pads can be custom die-cut to the exact specification of the component for a perfect fit, every time. Simply remove the liner from the tacky surface and apply. 

Better conformity to irregular surfaces 

Thermal Pads conform precisely to uneven and irregular surfaces to eliminate gaps. The silicone layer of the thermal pad becomes softer and more pliable in higher temperatures; by applying light pressure, you can achieve an even snugger fit.

Faster Assembly

Certain thermal pastes require curing time, which can delay assembly and take up space that could be used for production. Others, however, are ready to perform upon installation. Still, the advantage is thermal interface pads allow the component to be moved and handled immediately after assembly. 

Important Aspects to Consider When Choosing A Thermal Interface Material

When developing electrical components, the design and engineering teams should work closely together to determine key design and functionality factors:

  • The amount of electricity that would be generated from the components
  • Identify any gaps early in the design phase to prevent design changes down the road

Doing this could save a lot of time and money when it comes to prototyping and testing.

Application mistakes with Thermal Interface Materials – and how to avoid them 

When using thermal interface materials, steer clear of these common application errors.

  • Combining thermal pads and thermal pastes, in most instances, will reduce the thermal conductivity needed to effectively reach the heat sink. For larger and hard to fit gaps, thermal pads are your best bet. 
  • Stacking thermal pads can be detrimental to the material’s performance. One thermal pad with the correct thickness and thermal conductivity rating is all that is required to solve even the most stringent application issues.
  • Reusing thermal pads can diminish performance. If you ever remove a heat sink, the Thermal Pad will need to be replaced to properly conform to the surface. Be sure to remove any debris that may have entered the component as well.
  • Irregularities in sizing can make performance less effective. Using a pad that is too small may leave critical areas exposed, while a pad that is too large can cause poor seating or overlap that traps air. Custom die-cut pads ensure precise coverage for consistent heat transfer.
  • Failing to clean component surfaces before applying the thermal interface material can trap debris or oils that interfere with thermal conductivity. Always clean surfaces with isopropyl alcohol and a lint-free cloth before application.
  • Applying too much or too little pressure on the thermal pad can reduce its effectiveness. Some materials require a specific compression range to reach optimal performance. Follow manufacturer guidelines for compression force, especially in applications with torque-controlled fasteners.

Find your custom thermal solution with SRP 

Since 1951, SRP has been building customer relationships through precision converting solutions. We offer:

  • Custom die-cut thermal interface pads
  • Material sampling and prototyping
  • Scalable manufacturing and on-time delivery from our Illinois facility
  • Expertise to match the best materials to your application

Whether you’re developing a new product or optimizing an existing design, SRP is your partner in thermal management.

Ready for a quote? Show us your design and we’ll have a fast, accurate quote within one business day. Fill out the online form or call 847-593-5630.