Thermal Pad Advantages and Disadvantages

 

Thermal Gap Pads are available in thicknesses from 0.25 mm to 5.3 mm (0.01″ – 0.21″). Whether interfacing a small heat sink to a single chip or an entire module to metal plate, our compressible Thermal Gap Pads are the ideal solution.

 

Pre-cured thermal pads are used in TIM applications with gaps of 0.25 to 5.0 mm between component and heat sink. They are usually supplied in sheet form or in roll form as die-cut pieces and applied either manually or with automation. Fully cured from the factory, thermal pads have less shelf life concerns and devices can be assembled and packaged immediately. Most pre-cured pads are soft and gel-like to minimize compression forces on the electronics and available in a broad range of both thicknesses and thermal conductivity.


 

 

Thermal pads are typically cut from sheets based on customer requirements.  Depending on the thermal interface material manufacturer, standard sheet sizes are typically less than 24” x 24”.  Many material converters (companies like Modus™ who convert sheets to pads) use a die cutting process to manufacture thermal pads to customer specific requirements.  While there are a variety of ways to cut thermal pads, the die cutting or stamping method can consistently produce excellent quality parts, meeting the toughest tolerance specifications, especially on thinner materials. 

 

A die is required to manufacture thermal pads using this cutting method. What’s nice is, the die can be used to make tens of thousands of parts, or even hundreds of thousands of parts in some cases before it needs to be replaced.

 

 

Probably the biggest advantage to using thermal pads are their portability.  Die cut thermal pads can be shipped anywhere in the world and used in multiple locations on the factory floor without having to program robots or train technicians. Pads are cut in advanced and used on demand.

 

The pads also continue to be portable after being mounted in place. It is fully possible to mount pads; e.g., on a heat sink day one; and then ship these to an assembly plant to mount on the PCB two days later.

 

Another major advantage to using die cut thermal pads is the wide variety of materials available to overcome thermal management challenges. Today’s thermal management consumer can literally pick from hundreds, if not thousands, of material variations from sources all over the world. A word of caution, be sure to research material quality and supplier claims before picking a material! Many of the top thermal suppliers make test reports available to potential customers to help back up their claims.

 

 

Probably the biggest disadvantage to using thermal pads is they could be more expensive than the thermal filler option. As previously discussed, thermal pads are cut from sheets. Depending on the pad and sheet size, you can typically expect a maximum sheet utilization of 90%. Of course, there are exceptions where “Mr. Super Die Cut Operator” will get a 95% yield, but don’t count on it! 

 

Depending on the type of cutting operation, the form factor of the parts, and the flexibility of the sheet forming process, this can vary a lot more towards more efficient sheet utilization. With the rectangular parts usually used in the telecommunications industry, in addition to “Mr. Super Die Cut Operator”, you could actually see yield rates in the 95 – 100% range! 

 

Full disclosure – depending on the shape of the part, yields of 80% are also very common. This means the customer is paying for not only the pads cut from the sheet, but also the 20% of the sheet being discarded.  For lower volumes, the sheet yield may not be much of a consideration, but those with higher volumes should at least consider a dispensing option.