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Guide to Ceramic Heat Sinks

MPCHS (micro porous ceramic heat sinks) provide very large surface area to contact air and have excellent heat radiation and heat convection properties. The surface area of ceramic heat sinks is 30% greater than traditional metal heat sinks As a result of this, MPCHS have more surface area to contact air (convection medium), and thus dissipate more heat compared to metal heat sinks. In addition to this they also offer a number of other key benefits:

Electrically Insulating: They are non-conductive, eliminating the need for insulating sheets and prevent electrical shortages.

No EMI effect: MPCHS process no antennae effect, meaning they do not produce EMI.

Lightweight and Compact: They are generally 30% lighter than aluminium, and are generally thinner profile compared to metal heat sinks. As a result of this they are suitable for smaller, lighter-weight electronic devices and for narrow enclosures.

High Durability: Ceramic heat sinks have anti-oxidation properties and are corrosion resistant, making then suitable for harsh environments.

The drawback of using ceramic heat sinks is that they have lower thermal conductivity and thermal capacity compared to metal heat sinks. This means that for high power applications of 5W and above, MPCHS are not as efficient as metal heat sinks due to their lower heat conductivity. Instead, the ceramic heat sinks are more suited to low power applications below 5W, where heat dissipation is a higher priority compared to heat conductivity.

Unlike traditional metal heat sinks, our MPCHS are used to assist with heat circulation rather than absorbing heat. They are best used together with either a fan or thin metal conductive block and are a lower cost option compared to traditional heat sinks. Typical applications include LED lighting, power modules, automotive engineering and frequency converters.

As well as the standard MPC Series, we also offer our FCH ceramic heat sinks that offer greater surface areas compared to the MPC series. For further product information, pricing or samples please contact one of our global sales offices. Small quantities of the MPC series is available to purchase through our distributors Farnell and Digi-Key.

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Boron Nitride Thermal Pads

Thermal interface materials (TIMs) must reduce interfacial thermal resistance whilst withstanding stresses such as vibration and humidity. Traditional TIMs cannot meet this requirement. Thermal paste for example performs well with micron-level surface matching and precise clamping, but is prone to contamination and increases the difficulty of automated assembly. Ordinary silicone thermal pads sometimes lack the thermal conductivity required for high TDP modules.

AMEC Thermasol’s WG-BN boron nitride thermal pads meet this requirement. They offer relatively high thermal conductivity while maintaining robustness and repeatability. The boron nitride filler forms a conductive network within a flexible substrate, which transfers heat through phonon and percolation contacts. The resulting interface product reduces temperature differences across gap widths without sacrificing dielectric isolation.

Boron nitride thermal pads typically consist of a polymeric matrix loaded with hexagonal boron nitride (h-BN). The polymer provides elasticity and the h-BN platelets create continuous or semi-continuous thermal pathways. Additives such as adhesion layers or EMI foils can be laminated to the base material for enhanced handling.

One key advantage of boron nitride thermal pads is they are more effective in heat transfer compared to traditional thermal pads. Their dielectric properties are usually superior to metal filled pads and their galvanic neutrality mitigates corrosion risk. Whilst silicone and silicone free thermal pads are more cost effective and more conformable, they lose thermal headroom where larger gaps persist. Below are some application examples highlighting the advantages of boron nitride thermal pads compared to traditional thermal pads:

High power processors and GPUs
Server blades, compute accelerators and high-end GPUs generate concentrated heat flux. BN thermal pads provide a compromise between the high performance of thermal paste and the practicality of thermal pads. This is especially important for when electrical insulation is needed or gap heights fluctuate.

Automotive electronics and power modules
Robustness is mandatory for in traction inverters, DC-DC converters and onboard chargers. The WG-BN series offer low compression set and high dielectric strength. This maintains thermal pathways during vibration and thermal cycling, thus reducing field failures.

Telecom and 5G infrastructure hardware
Remote radio units and baseband modules operate in harsh environments and require predictable thermal behaviour. Boron nitride thermal pads maintain thermal continuity across larger tolerance stacks where traditional thermal pastes would either squeeze out or fail to bridge.

The WG-BN material is ROHS and REACH compliant and is halogen free. In addition to this it meets RBA (Responsible Business Alliance) and ISO/TS 16949 standards. For samples or pricing on the WG-NS range please contact one of our global sales offices.

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Product Guide – Thermal Tape

Our double sided thermal conductive adhesive tape is dual function material that acts as both a TIM (thermal interface material) and a mechanical fastener. The thermal tape is made by coating both sides of an acrylic carrier with a high performance thermally conductive adhesive. The result is a low cost TIM with an exceptional bonding strength in a thin format.

Thermal tape is considerably easier to apply to applications compared to thermal paste or grease and provides greater bonding strength compared to paste or grease. In addition to this, thermal tape has a longer lifespan compared to thermal paste and grease. Another advantage to thermal tape is that it can flatten and fill uneven surfaces.

This product series can be supplied in sheet or roll format as well as custom sizes, and are silicone and halogen free as well as ROHS and REACH compliant. Select lines have UL 94-V-0 flammability rating. The FCT Series is available with fibreglass reinforcement that provides the material with additional strength and better handling properties.

In addition to the FCT Series we can also offer our TH-10NF material. This is an extremely high performance adhesive with thermal conductivity of 2.5W/mk. The high thermal conductivity makes the TH-10NF series an ideal lower cost replacement for thermal pads.

Thermal adhesive tape is generally used for attaching heat sinks to electronic devices. Typical applications include LEDs, LCDs, Smart TVs and mounting heat spreaders onto PCBs.

For pricing or samples of our thermal conductive tapes please contact the relevant sales office.

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Thermal Conductive Glue – TCG Series

We have recently expanded our range of thermal interface materials and can now offer thermal glue. The TCG200 Series is a single compound material primarily made of silicone resin. It offers good stability and long term high temperature resistance.

The thermal conductive glue also provides high bonding performance and is suited for use with automated dispensing equipment. This makes it an ideal solution for high volume applications. Another advantage of the high bonding level is that it eliminates the need to use screws or washers, thus reducing weight and size of the application.

Particularly suited for micro electronics and for coupling PCB board level components with a heat sink, the thermal glue provides a thin bond line and excellent thermal path.

Our TCG200 Series is ROHS and REACH SVHC compliant and halogen free. In addition to this it can meet RBA (Responsible Business Alliance) and ISO/TS 16949 requirements. Material is available to purchase in either 120ml or 300ml tube sizes.

If this material is of further interest then please see our datasheet for further information, or contact our sales team for pricing and/or samples.

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Thermal Pads – WG Series

AMEC Thermasol have increased their range of silicone thermal pads and can now offer the WG-S Series which can offer thermal conductivity of up to 12.0W/mk.

Thermal conductive pads are a TIM that is used to improve the heat transfer between a heat source and a heat sink. Often heat sources and heat sinks have surface imperfections that produce air gaps that reduce heat transfer performance. Thermal pads help remove these air gaps and replaces them with a thermal conductive material.

The WG-S Series is engineered to be soft so that they can conform to uneven surfaces and fill the microscopic air voids. One key advantage of thermal pads is their ease of use. They are easy to cut and shape to size using scissors. For mass production purposes we can offer custom shapes and sizes with low tooling costs and short lead times.

For sensitive electronic applications we can offer our WG-NS silicone free thermal pads. Unlike traditional silicone thermal pads they do not leak organic oil. Thermal conductivity available up to 8.0W/mk.

Material properties of the entire WG Series such as Shore hardness, tensile strength and elongation can be fully customised. In addition to this the thermal pads can be fitted with backing material or adhesive one/both sides.

Our WG-S and WG-NS thermal conductive pads are halogen free, ROHS and REACH compliant, and can also meet ISO 16949 and RBA (Responsible Business Alliance) standards.

If any of these part numbers are of interest then please do not hesitate to contact our sales team. Small quantities and samples are held in stock in our UK office for rapid test and prototyping requirements.

 

 

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Soldering To Heat Pipes Via Ultrasonic Bonding

Heat pipes are used to transfer heat from concentrated heat sources such as light emitting diodes (LEDs) and high computing speed CPUs. These active thermal management devices are enclosures/tubes that have porous wick materials lining the walls that provide condensation surfaces and small connected pores that via capillary force, transfer condensed fluids that were originally vaporized at heat source.

When the vapour is transported via convection to the cooler surface to condense, the fluid is then channelled back to the heat source surfaces in a continuous cycle, in effect pumping the heat out of the package without using external power surfaces.

Thermal management is critical in the life and performance of such electronic components that they all employ a variety of thermal interface materials (TIMs). With increased power and speed, the polymer-based TIMs being used today are limiting and metal bonding with solders is growing in application.

Conventional Sn-Ag soldering temperatures can overheat the thermal fluids in heat pipes. Indium (In) solders are expensive and do not bond as well as active solders.

Responding to this need, engineers at S-Bond Technologies have announced its latest alloy, S-Bond 140 as an effective TIM for bonding CPUs or LEDS to heat pipes.  The Bi-Sn-Ag-Ti alloy can wet and join to all metals including aluminium, and to most ceramics and glasses.
S-Bond 140 is lead free, does not require plating and flux thus keeping electronic and LED packages clean.

Normally when soldering heat pipes over 200°C, the working fluid in the heat pipe goes to vapor and the resultant pressure distends/distorts the thin copper/aluminium inner walls. However, by using S-Bond 140, it enhances the cooling from the heat pipe to the connecting device without plating and flux. It also provides a high strength and high thermal conductivity bond, thus preventing distortion to the heat pipe.

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Thermal Pad with 45.0W/mk Thermal Conductivity

AMEC Thermasol have recently extended their product range and can now offer thermal pads with thermal conductivity up to 45.0W/mk.

The WGCF Series is a carbon fibre silicone material that is renowned for its distinct characteristics. The thermal pads offer high compressibility, softness and elasticity, making them ideal for low pressure applications.

Featuring natural tackiness for easy application and rework, the thermal gap pads can also be supplied with adhesive backing one or both sides for permanent fixing. Available in various thickness from 0.3mm to 20mm, the WGCF series can be supplied in custom shapes upon customer request.

The carbon fibre thermal pads are ROHS and REACH compliant as well as halogen free. In addition to this they are manufactured to ISO 9001 and ISO 14001 standards, and can also meet ISO 16949 and RBA (Responsible Business Alliance) standards.

Further product data can be found on our website. For pricing or sample requests please contact our sales team.

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Pulsating Heat Pipe

AMEC Thermasol have increased their range of heat pipes and can now offer a flat pulsating heat pipe. Heat pipes are used to transfer large amounts of heat quickly without requiring a power source. This is done by utilizing the phenomenon of thermal energy being absorbed when a liquid changes into a gas, and then being released when a gas changes into a liquid state.

In a pulsating heat pipe (PHP), when heat is applied, fluid partially evaporates in nucleation areas inside a serpent shape. Small masses of liquid are converted to much lighter vapour, exerting positive pressure on neighbouring fluid when expanding. The contraction of vapour into heavier liquid in the condenser end applies such to neighbouring fluid. These frequent imbalances in pressure sustains the liquid/vapour flow, thus removing the need for mechanical drivers.

The significant advantage that PHPs have over traditional heat pipes is their anti-gravity properties. They can operate in earth, micro and hyper gravity in any direction, whereas heat pipes can only work efficiently in vertical orientation with the heat source located below the condenser end.

PHPs also have an advantage over copper vapour chambers in that they are more lightweight and have lower thermal resistance. Pulsating heat pipes also offer thermal conductivity of up to 20000W/mk compared to 10000W/mk of copper vapour chambers. PHPs can also be bended and customised without it having any effect on the heat pipe performance. This product also meets REACH and ROHS requirements.

For further information on this series please refer to our product literature. To discuss your application in further detail, please contact our sales team.

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New Round Copper Heat Pipes

AMEC Thermasol have extended their range of heat pipes and can now offer round copper heat pipes. Heat pipes are devices that are used to transfer heat from one point to another, typically from a heat source to a heat sink.

The heat source causes the working fluid of the heat pipe to evaporate, creating a vapour that travels to the cooler end of the pipe where it condenses back into liquid. This process of evaporation and condensation allows the heat to be efficiently transferred along the length of the pipe.

Overall the copper heat pipes work by utilizing the phase change of the working fluid to transfer heat from one location to another, providing a highly reliable method of heat transfer. The CHP series can generally provide dissipated heat of between 20-200 watts and power density up to 25W/cm2.

Under the right conditions, heat pipes dramatically improve heat sink performance. Due to the very high thermal conductive nature of heat pipes, they offer 10-100 times better thermal conductivity compared to solid metal heat sinks.

Round heat pipes are better for transferring heat between widely spaced points compared to flat heat pipes due to their easy bendability. They are particularly suited for when you do not want the heat pipe to come into direct contact with the components, or you need a specific 3D path for heat transfer.

Typical operating temperature of the CHP series is between 0-250C. They have a typical lifespan of at least 20 years and can go through thousands of freeze-thaw cycles without damage.

One common cause of heat pipe failure is due to poor manufacturing quality. The QC process of the copper heat pipes eliminates this risk by helium testing every single heat pipe for leakage and Qmax performance. In addition to this an optional nickel plating finish prevents damage to the heat pipes caused by corrosive substances and poor handling.

Please refer to our website for further product information. If this product range is of further interest, then please do not hesitate to contact our sales team.

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Guide to Thermal Grease

AMEC Thermasol’s thermal grease (sometimes called thermal paste) is a thermal conductive material used to connect a heat source to a thermal device. It improves a systems overall thermal conductive effectiveness and helps transfer heat away from heat generating components.

Thermal grease is typically made from a mixture of thermally conductive fillers such as aluminium oxide and mixed with carrier fluid such as silicone oil. The materials are chosen to maximise thermal conductivity whilst also minimizing electric conductivity, thus avoiding component failure.

When applied between two surfaces, the paste fills any microscopic gaps and improves contact area between the two surfaces. Without the use of thermal grease, a heat source in contact with a thermal accessory would develop air pockets between the two devices, thus reducing thermal conductive effectiveness.

Thermal grease can be a popular choice for engineers as it is very easy to shape the material to their requirements, making it an ideal solution for filling irregular gaps. This gives it a significant advantage over thermal pads. In addition to this the thermal grease provides better surface contact compared to thermal pads or putty.

However, thermal grease can be very messy to work with and is difficult to remove if spilled on electronic devices. Thus it is not suited for mass volume applications compared to other TIMs. Therefore it is best to use this material for applications designed for short term use and require frequent maintenance or rework. In this instance thermal grease can be a more economical option compared to thermal pads or putty.

Our thermal paste can be supplied in a variety of tub sizes and are REACH and ROHS compliant as well as halogen free. Silicone free material is also available and SDS documents can be supplied upon request. For further product information please refer to our product datasheets.