We are prominent manufacturers of Heat Dissipation Compounds for various applications. We have designed more than 13 products as per specific applications demands.
Key Features
- Excellent heat flow
- Never cure, no hardening
- Heavy-duty long-term resistance to thermal degradation
- Exhibiting virtually no bleed, no creep or migration even at high temperatures
- Excellent oxidation resistance
- Free from V.O.C. & O.D.C.
- Safe to human skin, can be applied by hand
- Prevents corrosion & rust formation
- Excellent thermal conductivity over wide temperature range
- Extremely stable between variable very high to low temperature cycles
- Compatible with all metals, nonmetals, rubber and plastic
- Excellent long-term adherence to metal surface
- Extends life of equipment’s
One of the important functions of packages is to dissipate the heat generated by the semiconductor devices they house.
Heat Generation
Heat generation affects safety, reliability, and performance.
Heat is generated when a current flows through a resistor in an electric circuit.
A semiconductor device may be regarded as a type of resistor that generates heat in proportion to the ON resistance (internal resistance when a current flows through the device) as current flows through.
Heat can adversely affect the semiconductor device itself as well as the electronic system that uses that device. In particular, it may seriously impair safety, performance, and reliability.
Excessive heat caused by a poor heat dissipation design may result in emitting smoke or catching fire, as well as degrade the performance of the device such as slowing its operating speed, and in the worst case, damaging the device or rendering it inoperable. Even if the worst case can be avoided, reliability is adversely affected through device malfunctions and a shorter system life.
To avoid these adverse effects, thermal design is essential for semiconductor packages.
Heat is released in three ways: conduction, convection and radiation.
Heat is transferred in three ways: conduction, convection, and radiation. the image below shows how heat flows from the source (i.e. the chip) to the final destination, the atmosphere, in the context of an actual operating environment that includes printed wiring board (PWB) and an atmosphere.
Heat Transfer & Thermodynamics
Relevance of Heat Transfer
Heat transfer is indeed a relevant subject. We will devote much time to acquire an understanding of heat transfer effects and to develop the skills needed to predict heat transfer rates. What is the value of this knowledge, and to what kinds of problems may it be applied?
Heat transfer is commonly encountered in engineering systems and other aspects of life, and one does not need to go very far to see some application areas of heat transfer. Many ordinary household appliances are designed, in whole or in part, by using the principles of heat transfer. Some examples include the heating or air-conditioning system, the refrigerator, freezer, the water heater, the iron and even the computer, the TV, and the VCR. Of course, energy-efficient homes are designed on the basis of minimizing the heat loss in winter and heat gain in summer. Heat transfer plays a major role in the design of many other devices, such as car radiators, solar collectors, various components of power plants, and even spacecraft. The thickness of insulation in the walls and roof of the houses, on hot water or steam pipes, or on water heaters is again determined on the basis of heat transfer analysis with economic consideration.
On a smaller scale, there are many heat transfer problems related to the development of solar energy conversion systems for space heating as well as for electric power production. Heat transfer processes also affect the performance of propulsion systems, such as internal combustion, gas turbine and rocket engines. Heat transfer problems arise in the design of conventional space and water heating systems, in the design of incinerators and cryogenic storage equipment, in the cooling of electronic equipment, in the design of refrigeration and air-conditioning systems, and in many manufacturing processes.
Heat and Temperature
Heat and temperature are different concepts in engineering &technology, although related. Heat is the total energy of molecular motion in a substance, while temperature is a measure of its average molecular energy.
Heat depends on the speed of the particles, their number, size and type. Temperature does not depend on the size, number or type.
For example, the temperature of a small glass of hot water will be higher than the temperature of an ocean, but the ocean has more heat because it has more water – more particles – and therefore more total thermal energy.
There are also differences in the types of study of the processes that need to be developed. Beginning with the sciences involved:
The transfer of energy – heat – always goes from the higher temperature medium (with a higher measurement) to the lower temperature and stops when the two media have the same temperature and reach therefore a state of thermal equilibrium.
Thermodynamics is the science that deals with the amount of heat transfer from one initial equilibrium state to another, and makes no reference or indication to the duration of the process.
A thermodynamic analysis simply tells us how much heat must be transferred to make a change from a specific state of equilibrium to another, to satisfy the principle of conservation of energy.
Although it establishes the necessary basic parameters and a framework for action, in practice it is not enough.
It tells us how much heat to dissipate to cool our beer to get the temperature we want, but does not give us any guidance on the time to do so and, of course, in our production process problem, we cannot establish any solution.
Heat transfer
What we are really interested in is the rate of heat transfer. The determination of the heat transfer rates to or from a system and, therefore, the heating or cooling times and temperature variation is the subject of the science of heat transfer.
Heat transfer helps us resolve the issues raised at the beginning of this text and plays a decisive role in the design of virtually all the equipment and devices that surround us: our computers and televisions must consider heat transfer rates so they cool and do not overheat, affecting their operation; appliances such as cookers, dryers and fridges have to ensure the heating and cooling properties for which they will be sold.
In the industrial sector, equipment such as heat exchangers, boilers, furnaces, condensers, batteries, heaters, fridges and solar panels are mainly designed on the basis of heat transfer analysis.
More sophisticated equipment such as cars and planes require these studies to prevent engines or cabins from overheating.
Heat transfer processes not only increase, decrease or maintain the temperatures of the affected bodies; they can also produce phase changes, such as melting ice or boiling water.
In engineering, heat transfer processes are often designed to take advantage of these phenomena.
Most of the heat produced by friction with the atmosphere is used to melt the heat shield and not to increase the temperature of the capsule.
The transfer of heat is therefore the process by which energy is exchanged in the form of heat between different bodies, or between different parts of the same body at different temperatures. This heat can be transferred in three ways: by conduction, convection or radiation. Although these three transfer methods take place many times simultaneously, usually one of the mechanisms predominates over the other two.
Steady and Unsteady Conditions of Heat Transfer:
Heat exchange between two systems may take place under steady (stable) thermal conditions or under unsteady (unstable) thermal conditions. Steady state implies that temperature at each point of the system remains constant in the course of time, and it is a function only of space co-ordinates.
Steady state results in a constant rate of heat exchange (heat influx equals heat efflux), and there is no change in the internal energy of the system during such a process.
Under unsteady thermal conditions, temperature of the system changes continuously with time. Temperature is obviously a function of space and time co-ordinates.
Unsteady state results in heat transfer rate which changes with time. Further, a change in temperature indicates a change of internal energy of the system. Energy storage is thus a part and parcel of unsteady heat flow.
A special kind of unsteady process is the transient state wherein the system is subjected to cyclic variations in the temperature of its environment. The temperature at a particular point of the system returns periodically to the same value; the rate of heat flow and energy storage also undergo periodic variations. Examples are- Heating or cooling of the water of an I.C. engine; heating or cooling of the walls of a building during the 24-hours cycle of the day.
Further, the heat transfer in a system may be in one, two or more directions. In a one dimensional heat flow, there is a single predominant direction in which temperature differential exists and obviously the heat flow takes place; heat flow in the other two directions can be safely neglected. When the temperature is a function of two co-ordinates, heat flow is two- dimensional. A three-dimensional heat flow stipulates that temperature is a function of three co-ordinates, and consequently heat flow occurs in all three directions.
Significance of Heat Transfer:
Design of cooling systems for electric motors, generators and transformers in electrical engineering so that the heat generated during the flow of current through the windings of these machines can be effectively dissipated. This is to avoid the conditions which will cause overheating and damage the equipment.
The various engineering problems involving heat transfer can be categorised into two groups:
- Heat flow situations where maximum heat transfer is desirable with minimum possible heat exchange area. Gas turbine blades, walls of I.C. engines and combustion chambers, outer surface of a space vehicle all depend for their durability on rapid removal of heat from their surfaces. The design of heat exchangers is considered to be optimum under specified temperature conditions when maximum heat transfer occurs with minimum surface area.
- Heat flow situations where heat transfer is undesirable and its flow is to be prevented. The walls of centrally heated buildings and the steam pipes in a steam power plant are properly insulated to restrict heat losses.
With few exceptions, engineering problems involve more than one of the three modes of heat transfer and this aspect results into a complicated heat exchange pattern.