Professional High Power Cooling Solution Service Provider And Manufacturers

Bonded fin technology

When higher ratios are required for high power applications, bonded fin heat sinks (thermal epoxy or brazing) with higher finned aspect ratios are usually used to overcome the finned ratio limitations in extrusion processes (usually 19:1). Bonded fin heat sinks usually involve the use of thermal epoxy to bond the coils of aluminum to aluminum extruded pieces or plates. It is usually necessary to cut a groove into the plate, and then the connect the aluminum coil to the base.

Friction welding technology

Our friction stir-welding (FSW) modular heat sink offers a different approach, with a thermal efficiency 8% more than that of the bonded fin heat sink, and with more options, such as custom features that reduce assembly costs. Combining the extrusion process with the friction stir welding technology, we can achieve a large heat sink ratio of more than 40:1. The combination of FSW and extruder provides maximum flexibility in terms of fin geometry and fin ratia, while also reducing fin size and simplifying the production of large heat sink (30 inches width).The friction stir welding process is also used in liquid cold plate to seal them effectively while adding more features to the cold plate at a lower cost.

Advantages of friction stir welding technology compared with fusion welding technology include:

• Increased welding strength

• Homogeneous material, no filler metal or insulator in the material

• Enhanced impermeability -- completely nonporous, sealed joints

• The joint is flush with the surface

• Reduced thermal deformation -- there is only a small amount of thermal stress in the material, and therefore, a flat surface

• Higher repeatability -- production variables are few and easy to control, which also results in close tolerances

A new method of joining metal surfaces

Friction stir welding is a solid-state bonding method that has been used in aluminum welding since the 1990s. It joins the homogeneous metal surfaces by the mechanical action of the rotating tool and produces a high strength, non-porous, homogeneous joint that does not degrade over time. Under the influence of pressure and heat, a new homogenous structure can be obtained without filling materials or insulators.

Instead of using thermal epoxy to manually join the aluminum coil to the aluminum base,  custom aluminum profiles replace the coil aspect of the bonded fin heat sink .They are welded together by friction stirring without the need for a separate base plate.

The process begins with the extrusion section, which includes the base and heat sink fin, which is held together by clamping and stamping. The heat sinks are permanently joined by FSW. Since the extrusion section can be any extrudable contour and size, there are fewer limits in the design. For example, these segments could be 10 inches high. This method not only produces widths up to 20 in. large heat sinks, but also very suitable for mass production, making these types of heat sinks competitive products in the market.

While the extruded heat sinks ratio is up to 19:1, many companies in the power industry require a larger ratios heat sink . At the same time, the LED lighting industry is looking for extrusions larger than the typical maximum extrusion width of 20 inches. Friction stir welding heat sink solves these two problems.

Comparison of friction stir welding module heat sink and bonded fin heat sink

The test results of FSW welding modular heat sink and bonded fin heat sink show that FSW technology has some improvement in cooling.The dimensions of the heat sink and the aspect ratio of the heat sink fin are designed to be suitable for extrusion and an extruded heat sink was used as the benchmark.The experiments were carried out in wind tunnels with a variety of airflow.The power resistor is used as a heat source.Thermal resistance, pressure drop and temperature distributions were obtained and compared.The result is an 8% improvement in thermal performance over the epoxy bonded fin heat sink while maintaining the equivalent pressure drop.

An 8% increase in thermal efficiency offers power electronics designers two options.The first is the ability to increase the power generated by electronic devices without increasing the size of the heat sink.The second is to reduce the size of the FSW heat sink by 8% and still provide the same thermal management. Both options help reduce the cost of the heat sink.

The increase in thermal efficiency gives the power electronics designer two options. The first is the ability to increase the amount of power the electronics generate without increasing the size of the heat sink. The second is to decrease the size of the FSW heat sink by 8% and still provide the same thermal management. Either option helps reduce the cost of the large heat sink.

In many cases, the technology to manufacture a new product is even more advanced than the product itself. In the case of aluminum extruders, knowing of the material alone is often not enough for engineers and designers to take full advantage of the versatility of aluminum. It is also important to understand innovative processes (such as friction stir welding) and the development of alloys and extrusion processes to properly choose the most effective material or product solution.

Expand the technology of friction stir welding to develop solutions in the field of thermal managementFriction stir welding technology is not new. It has been used by different industries for years.It is not well known because it is a proprietary licensed process and uses automation equipment that is not normally available in traditional welding workshops. This innovation is driven by the expansion of friction stir welding technology to develop solutions in the field of thermal management to produce large heat sinks with low price and high performance, which offers exciting answers to a big challenge for the power electronics industry.

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