Gallium Nitride (GaN) for blue LEDs?

Do you know how Gallium Nitride (GaN) plays a big role in blue LED lightings?

Gallium Nitrid (GaN) is not only used for blue LED, but, as SiC, it is widely used for next generation wide band gap semiconductor devices.

Unlike Si or SiC, it cannot be created as a wafer.

Instead it is epitaxial grown, as a thin film, on a Si or Sapphire substrate.

Therefore, if you want to evaluate the thermal conductivity of GaN, you must evaluate as thin film.

Engineers are researching high purity GaN crystals these days also.

But it could be created in a small amount only.

Thermal Microscope (TM) could evaluate GaN in either forms.

We cannot share the actual results from our clients in details, but as we measured GaN, the values were very similar to the literature values.

TM could evaluate the samples with high spatial resolutions.

It could also evaluate the thin film samples as well.

If you are interested, please take a look at Thermal Microscope (TM).

eigyo@bethel.co.jp

SEM and Sputtering Service

Bethel is offering services with SEM and sputtering.

SEM:

We have a Keyence SEM.

The price is 15,000JPY for 2 photographs for single sample.

+5,000JPY per extra photos.

Sputtering: Molybdenum(Mo)

The price if 15,000JPY for one batch.

7,500JPY/batch for more than 2 batches.

The standard thickness of Mo will be 100 to 299nm.

For thickness 300 to 599nm, the price will be x1.3 the price of standard.

For tickness 600 to 1000nm, the price will be x1.5 the price of standard.

If you want to know the details, please feel free to ask me.

eigyo@bethel.co.jp

Junichi

Aluminum Nitride (AlN) for heat sink?

Did you know Aluminum Nitride is well used for "heat sink?"

Aluminum Nitride(AlN) is a good insulator but high in thermal conductivity.
It is very popular for using as "heat sink."

It is also used for PCB boards as well from the same reason.

For high heating energy sources, such as power electric devices or LEDs, AlN plays a big role.

Do you know how Aluminum Nitride is made?

AlN is made by sintering.
The thermal characteristic of AlN is differed by how they were sintered.

These days, the sintering technology for AlN has been drastically advanced.
The thermal conductivity of AlN has been improved very much.

It is very significant to control the process of sintering, however, it is a critical issue for the manufacturer to monitor the distribution of thermal conductivity within the product.

But ordinal methods could NOT evaluate the distribution of AlN in details.

Thermal Microscope (TM3) has a spatial resolution of 3um and able to evaluate the distribution of thermal conductivity of the samples in 2D.

The following is the result of AlN which was measured with TM3.

Aluminum Nitride (AlN): 282 W/mK

We also noticed that the thermal conductivity varies within the sample.
It had a range of 219 to 318 W/mK

For details, please take a look at
Journal of the Ceramic Society of Japan 116[12] 1260-1264 2008

We do testing service for AlN using Thermal Microsope (TM3).
If you are interested, please feel free to contact us.

eigyo@bethel.co.jp

Junichi

New website!

The new website for Thermowave Analyzer is opened!

Please visit the website at
http://thermalresistance.jp/

Thank you.

junichi

Silicon Carbide(SiC) for what? Many applications!

Silicon Carbide(SiC) has become a popular keywords in semiconductor industries.

Few years back, we received inquiries from our clients to measure thermal conductivity of SiC.
Back then, they were under the research and development.
But now, they have been mass produced.

We were astonished by the speed of R&D on SiC.

The thermal property of SiC is not good as diamonds, but higher than normal metals.
i.e. about 100 to 350 [W/mK]

The applications of SiC are written in wikipedia.
1 Abrasive and cutting tool
2 Structural material
3 Automobile parts
4 Electric systems
5 Electronic circuit elements
6 Astronomy
7 Thin filament pyrometry
8 Heating elements
9 Nuclear fuel elements
10 Jewelry
11 Steel production
12 Catalyst support
13 Carborundum printmaking
14 Graphene production

Today, I would like to share the results of 6H-SiC which were measured with Thermowave Analyzer (TA) with you.

Thermal conductivity is about 350 [W/mK]

Thermal conductivity is calculated from thermal diffusivity, density, and heat capacity.
The values for density and heat capacity were found in literature.

We also measured different crystalline of 4H-SiC and 6H-SiC.
The results on these SiC were higher than 350 [W/mK].
We don't know why the results were higher but reason must be due to how SiCs were produced.

Anyway, if you want to evaluate your SiC, please feel free to contact us.

eigyo@bethel.co.jp

The methods to diffuse the heat - part2

In part I, I talked about how to increase the thermal conductivity by putting some fillers inside your samples.

These days, people are more concern with "thermal resistance of boundaries."

The biggest issue might be the "undulation" of boundaries.
This undulation is the "air gap" between the boundaries and will cause thermal resistance.

Keeping this in your mind,

1. To decrease the thermal resistance, we must
2. Decrease the air gap and dissipate the heat.
3. To decrease the air gap, we should use heat dissipation sheet which is "flexible" and "adhesive."

As you noticed, if you want to measure the thermal diffusivity of this sample, you should not press down the sample too much. Since the sample is "flexible", the pressing might cause the deformation of the sample. (Of course, you might want to measure the thermal diffusivity of your sample as it is pressed)

If you use Thermowave Analyzer(TA), you do NOT need to press down the sample.
It can measure without any physical contact to your samples.

One another thing which I want to mention is that the structure of the sample I described above is multi-layer. You cannot find any literature data on multi-layer materials. Therefore, you might want to measure the actual thermal diffusivity on your own.

If you would like to do the testing service, please feel free to contact us.

eigyo@bethel.co.jp

Junichi

Would you like to have a diamond? for industry?

Diamonds.
Would you like to have a diamond Big one?

Yes, we do!

But sorry, the diamonds we are dealing with are not the jewelry.
They are made for industrial use.

Engineers and researchers bring their single cryrstal and multi-crystal diamonds to our lab.

We heard that Silicon Carbide (SiC) are now ready for mass production.
But diamonds are also ready to use for industry as well.

As you all know, diamonds are the hardest material on earth, and they have the highest thermal conductivity on earth as well.
The thermal conductivity is higher than graphite sheet, HOPG and SiC.
It is about 600 -2,000[W/mK]

If the diamonds are used for electrical vehicles(EV) and other semiconductor markets, the efficiency will increase drastically.
Some says the efficiency will increased by several time to more than ten times!
And our lives will be better with diamonds!

Today, we would like to share our results on diamonds.

An industrial diamond sample was measured with our Thermowave Analyzer (TA).
The thermal conductivity was about 1,200 W/mK

We also have the results on single crystal and multi-crystal diamonds as well.
They are higher than the above value.
(It is confidential so that we can not share with you orz)

The researchers and engineers are working so hard to improve the quality of diamonds, and we are very pleased with them.
And we are happy to help them to create a better diamonds with our system.


If you would like to learn more about Thermowave Analyzer (TA), please check our website or email us.

eigyo@bethel.co.jp

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The methods to diffuse the heat - part1

The heat dissipation of a device is one of key issue for electrical components.

I would like to share the methods to diffuse the heat from your devices.

Method 1:
Mix the polymer with "fillers" and the raise the thermal conductivity of your samples.
You can raise the thermal conductivity of polymer as high as ceramics.
The fillers could be fiber or particles.

Method 2:
Place your heat source (where heated the most) on or by materials with higher thermal conductivity, such as graphite sheets or diamonds.

These methods are not introduced in textbooks, and you need to actually measure the thermal conductivity of your sample.

Our Thermowave Analyzer is the right tool to measure the thermal conductivity of thermal resistance.

If you need an assistance. Please email us.

eigyo@bethel.co.jp

What do we do with graphite sheet?

Considering the heat dissipation and thermal resistance of electrical devices is critical issues for engineers.
The newspaper and magazine articles regarding to heat dissipation for electrical devices are very common these days.

Therefore, it is very easy to imagine the race for developing a better heat dissipation material is getting severe.

Although there are many materials with high thermal conductivity, graphite sheet is one of the most popular heat dissipation material in industry.

A graphite sheet is thin, flexible, easy to deform and especially has high thermal conductivity in "in-plane" orientation.
It has thermal conductivity of 5 times as large as silver.

It looks like a gray or black sheet of paper.
You can make ORIGAMI with it!

As you can imagine, graphite sheet is made mostly out of graphite.
Please imagine large sheets of crystals are piling up.
This is the reason why graphite sheet has such a HIGH thermal conductivity for in-plane orientation and LOW for out-of-plane orientation.

In industries, graphite sheets are well used for decreasing the heat concentration for laptop pc and fix the temperature ununiformity for LCD.

With Thermowave Analyzer alone,we could measure both orientation with one single sample.

For example, the difference in thermal conductivities for graphite sheet in different orientations are distinctively different,

In-plane: about 1,000 W/mK
Out-of-plane: about 5W/mK

Amazing!
The values are different by 2 digits!

In-plane thermal conductivity is as high as diamonds.
In another hand, out-of-plane thermal conductivity is as low as ceramics.

notice:
Thermal conductivities are calculated from thermal diffusivity measured by TA and heat capacity and density from literature.

If you are interested in testing service or just want to know about TA, please feel free to contact us.

eigyo@bethel.co.jp

Thermowave Analyzer for polymer sheets

The number of "Ecological" home electrical appliance, such as LED lighting, is increasing.


Analyzing the thermal resistance and heat control of the devices is one of the biggest issue for engineers.

To help the engineers, Thermowave Analyzer(TA) enables to measure the thermal diffusivity of heat dissipation materials which are used for the devices.

The features are:
1. Enable to measure any shapes i.e. solids and sheets.
2. Very wide dynamic range. It enables to measure from polymer to diamonds.
3. TA enable to measure in both orientation, in-plane and out-of-plane.

Above features are very unique for TA and never done by other systems before.

If you are interested, please feel free to contact us.

eigyo@bethel.co.jp
http://www.bethel.co.jp/eng/TA.html

Interested in sample values of polyimide and alumina?

Measured Values （Thermal Diffusivity）

[Measured / Literature]

Polyimide　　　　　　　　　　1.35×10-7　/　1.74×10-7 (m2/s)
Stabilized Zirconia　　　　1.13×10-6　/　1.20×10-6 (m2/s)
Alumina 　　　　　　　　　　 1.21×10-5　 /　 1.19×10-5 (m2/s)
Germanium 　　　　　　　　3.67×10-5　/　3.46×10-5 (m2/s)
Silicon　　　　　　　　　　　　8.85×10-5　/ 　 8.80×10-5 (m2/s)
Cupper 　　　　　　　　　　　1.14×10-4　/ 1.17×10-4 (m2/s)
Silver 　　　　　　　　　　　　1.73×10-4　 / 1.74×10-4 (m2/s)

Thermal conductivity could be calculated from thermal diffusivity measured with our system Thermowave Analyzer and heat capacity and density from literature values.

Thermal diffusivity or conductivity could be used to analyze the thermal resistance of materials and devices. It plays an important role for thermal designing.

Thermal Spread Inspection

We would like to introduce Thermal Spread Inspection system, TSI-1.
It is a non-contact inspection system.

The features are

1. Don't need any coating on its surface
2. Visualize the defects of the samples as temperature difference.

We would like to share the testing results on this blog in the future.

Please keep up with us.

Thermal Microscope

Do you have any problems measuring thermophysical properties of thin films?

Well, then, Thermal Microscope(TM) is your answer!

TM enables you to measure the thermal effusivity of thin films with several hundredth of nano meter thickness.
TM also enables you to measure the thermal effusivity of micro region as well.
Measured values could be used to analyze and design thermal resistance of your materials and devices.
We would like to share our research and product information on FB.

If you are interested, feel free to email us.
eigyo@bethel.co.jp