What is the thermal conductivity of the dielectric in your aluminum pcbs?
Hi Jay,
Welcome to the Seeed Fusion forums, great to have you here.
I’ve just double checked with the engineers and they have informed me that the thermal conductivity of the dielectric for aluminium boards produced using the standard service is 1.0W/m*K.
Hope that helps,
Yes. That is the specification I was looking for. If I want to specify a thermal conductivity of 1.6W/mK or better, do I need to use the more expensive Advanced PCB option to order my boards? Thank you.
Yes, Advanced PCB is the way to go. Just make sure you specify the requirement in the files or even specify the exact material you want.
Hy,
Can you tell me the possible thicknesses of the dielectric on metall boards?
Hiya Stallinger,
The dielectric for aluminum boards ordered via the standard service is 0.1mm thick. The thickness of the aluminum substrate varies with the selected overall board thickness.
For the Advanced service you can specify thinner and thicker thicknesses as required and the engineers will try to match it as best as possible.
To understand the heat transfer properties of thermal interface materials (TIMs) we need to understand the meaning of thermal conduction, convection and resistance. The following is a sneak peak from Clemens Lasance’s Thermal Interface Material Basics for Electronic Engineers. Clemens recently presented this information in relation to the role of the PCB in Thermal LED Applications at the MCPCB Design and Fabrication webinar.
Conduction
The notion of thermal conduction is not very old. Biot (1804) and Fourier (1822) were the first to quantitatively study the heat flow through a piece of solid material. Fourier observed that the heat flow q was proportional to the temperature difference ΔT over the test piece, proportional to the cross sectional area A of the bar, and inversely proportional to the length or thickness ℓ., known as Fourier’s law:
The proportionality constant k is called the thermal conductivity in W/mK. It is a material property and a measure for the ability of a material to conduct heat. The range for engineering materials is from air (0.03W/mK), via plastics (0.2 W/mK), glass (1 W/mK), aluminum PCB board (200 W/mK) to copper board (400 W/mK). Typical TIM values cover the range 0.4-4 W/mK.
Convection
The heat generated in an electronic device is usually transported by conduction to a heat sink or an area where the heat is transferred to a fluid which is called convection. The fluid can be a gas such as air, or a ‘real’ fluid such as water. As a result, the convection heat is proportional to the area A and the temperature difference between the wall and the main stream flow.
This equation is commonly known as “Newton’s Cooling Law”; however, it should be realized that it is neither a law nor was it derived by Newton. In this equation, the proportionality coefficient h is called the heat transfer coefficient in W/m2 K. As a rule-of-thumb, take for natural convection h=10 W/m2 K and for fan-driven forced convection h=50 W/m2 K.
Resistance
The last term to discuss shortly is the thermal resistance. In a DC electrical circuit, Ohm’s law describes the relations between the voltages and the currents. It states that a voltage difference over a resistor causes an electrical current, which is proportional to the voltage difference: ΔV = I * R.
In steady state heat transfer, a temperature difference causes a heat flow which is proportional to the temperature difference as is seen in equations (1,2). Both equations can be written in the form ΔT = q * Rth, with Rth the thermal resistance (also commonly noted as R when there is no chance for misreading it as an electrical resistance). This is analogous to Ohm’s law. In both the electrical and the thermal case we observe that a driving force exists (either voltage difference or temperature difference), which causes a flow (of current, or of heat) over a resistor.
The thermal resistance per unit area is equal to the ratio between thickness t and thermal conductivity k and is often used to allow for a direct comparison of the heat transfer performance of commercially available TIMs.
About Clemens Lasance
Clemens is a former Principal Scientist Emeritus with Philips Research, the Netherlands, with a 30 year + focus on thermal management of electronic systems. He is now a consultant for Somelikeit Cool, contact info: [email protected]
About Saturn Electronics Corporation
Aluminum PCB Manufacturer Saturn is a top 30 domestic bare printed circuit board fabricator managing the nuances between prototype and production while providing advanced technologies such as thermal management for LED PCBs.
The warmth exchange coefficient is characterized as the temperature distinction between the opposite sides of the surface in 1m (K, ℃),
in 1 second (1S), through the warmth exchange zone of 1 square meter, the unit is W/m ° (W/(m · K), where K can be supplanted by ° C).
Warm conductivity is just for the presence of warmth move as warmth exchange when there are different structures,
for example, radiation, convection and mass exchange and different types of warmth exchange when the composite warmth exchange relationship,
the property is generally alluded to as evident warmth Coefficient, express warm conductivity or warm transmissivity of material.
What’s more, the warm conductivity is for the homogeneous material, the real circumstance, there are likewise permeable,
multi-layer, multi-structure, anisotropic material, the warm conductivity of this material is really an exhaustive execution of warm conductivity ,
Otherwise called the normal warm conductivity.