Thermaphase overcomes all of the problems of mica/grease, of polymeric thermal pads, and PCM materials without introducing new problems.  Thermaphase, in addition to it's  very low thermal resistance at low closure force, is dry to the touch  and flexible at room temperature. At elevated temperature the material changes to a thixotropic state and flows under low pressure into the surface irregularities of both electronic component and heat sink to provide a very low thermal resistance interface. Thermaphase compounds have unique characteristics that are unavailable in any other material; such as differential phase change characteristic, reversible adhesive bond. These and other unique features of ORCUS materials are presented in the following pages. Please call us early in your design process.

Thermaphase is available in several forms:

1. Precoated onto both sides of electrically insulating polyimide film (Kapton). This is used in applications requiring electrical insulation between component and heat sink.

2. Precoated onto both sides of electrically conductive aluminum foil. This is called Thermafoil.  This is used where electrical insulation is not required between component and heat sink.  It is similar to Free Standing Film (see 3 below) but has a higher thermal resistance then FSF (Free Standing Film)

3. Free Standing Film material(FSF) has no substrate. Used in same applications as Thermafoil but has a lower thermal resistance.

4. Hot-melt compound is suitable for automatic hot-melt application equipment.

5. Thermal Applicator Rods ("Thermaps") that can be used in automatic equipment to create thermal pads.

You will find technical information on these products by going to the menu tab "Data Sheets".

Thermaphase compound is available in three phase change temperatures (52°C , 71°C and 98°C)
Thermaphase compound is also available in several special formulations, with different thermal characteristics. 

ORCUS produces the widest range of Phase Change materials on the market.  

Your answers to the following questions will help you select the best material for your application.

Do you need Electrical Insulation between your component and heat sink?

If YES then you need Thermaphase on Kapton.

Dielectric Strength of 1 mil Kapton = 3900V

Dielectric Strength of 2 mil Kapton = 7800V

Dielectric Strength of 3 mil Kapton = 11000V

If NO insulation required, then you can use either Thermafoil or FSF material.  

Does you component generate a very hot, very localized source of heat? 

If YES, then you may want to use Thermafoil because the foil can serve as a heat spreader. 

If NO, then FSF material is your best choice because it has the lowest thermal resistance. 

Is your electronic component and heat sink smooth or rough?

Sheet metal surface roughness may be about 125 micro inches.  Metal tabs on semiconductors may have a surface finish of about 8-10 micro inches.
Typical heat sink surfaces are frequently about 40 micro inches.   A 1 mil coating on each side of a substrate or our standard 5 mil thick FSF materials will provide plenty of thermal compound to fill voids in this range.  In almost all applications, a coating thickness of 1 mil  is quite sufficient to fill in the surface roughness of components and heat sinks.

Are your electronic component and heat sink flat, or do they have hills and valleys?

Typically heat sinks have a flatness somewhere around 0.001" per square inch.  But some items are flatter than that.  The gaps between two "mating" surfaces of Power Modules, for example, may be much larger than this.  When trying to mate a circuit board with an aluminum chassis, the gaps may be quite considerable. If you have  surface gaps of several mils, you may need a thicker coating on one or both sides of the substrate.We can make materials with coatings on one or both sides up to 6 mils thick.This is sufficient to fill in quite large gaps because the Thermaphase material where the two surface mountains meet will be forced into the gap valleys.Therefore a 6 mil coating can fill gaps wider than 6 mils. On special orders we can make our FSF (Free Standing Film) materials up to 0.125" thick. For additional technical assistance on this, contact ORCUS inc. 

How do I determine if I should use 52°C, 71°C or 98°C phase change material?

You can operate any Thermaphase materials up to 200°C continuously. Any of these materials can operate continuously in the molten state.  In most applications it is best to use 52°C material because it has the lowest thermal resistance at lowest closure force.  The 71°C material is naturally slightly sticky at room temperature for easy attachment to heat sinks.  It requires a higher closure force to obtain low thermal resistance.  The reasons for using 98°C material instead of 52°C  or 71°C material are:

1) Use 98°C material if you have a problem with outgassing such as in a space environment, or with Laser Diodes where you want to be sure that no window clouding can occur.  

2) Use 98°C material if you want to reflow the Thermaphase compound using external heat and then operate your component at under 80°C.  In this situation, your component will remain firmly adhered to the heat sink during operation, even without fasteners.

Do I need adhesive and if so, what type?

For reasons of limited shelf-life and ease of handling, you are better off without any adhesive.

Most of our Thermaphase compounds are not adhesive at room temperature. An exception to this is our Thermaphase 71°C Tacky2.  This material is slightly adhesive on both sides at Room Temperature. It can be applied  by removing the release liner from side (removes easily) and pressing it firmly against the heat sink or component surface. Tacky 2, when reflowed above its reflow temperature and under low closure force flows into the pores of the heat sink and component surfaces.  When Tacky 2 resolidifies, the heat sink and component are adhered to each other. This material is thermoplastic. Reheating above the phase change temperature will allow easy removal of the component.

Our other compounds are completely dry-to-the-touch at room temperature. They are not adhesive at room temperature. But they are thermoplastic adhesives. When melted under low pressure between two rigid surfaces, the thermal material flows into all surface imperfections. When the thermal material cools and becomes solid again, the two rigid surfaces are firmly adhered together (about 25psi). Since Thermaphase is thermoplastic, you can remelt it and easily separate the two rigid surfaces.  It can melt and solidify an unlimited number of times. For a more detailed discussion of the thermoplastic characteristics see the menu item "Reversible Adhesive Bond".  A material such as Epoxy, on the other hand is thermosetting and once it solidifies, it won't remelt. Thermaphase FSF-52 can be premelted onto a heat sink by peeling the protective liner off one side of the interface material. When placed on a preheated heat sink it melts. When resolidified the FSF interface pad is firmly adhered to the heat sink. The upper protective layer remains on the interface for shipment and/or until the electronic component is installed.  

For more detailed information on adhesives that can be applied to Thermaphase materials, see the menu item
"Adhesive Characteristics."

Kapton® is a registered trademark of Dupont Nemours
Patents and Patents Pending.  Thermaphase is a registered trademark of ORCUS inc.