Comparison of laser welding and extrusion for heat sinks
Conventional manufacturing processes such as extrusion are based on a functioning die and the corresponding application of pressure. When designing the heat sinks, one quickly reaches the limits due to too narrow fin spacing in relation to the length to base thickness. Heavy profiles are also only possible to a limited extent, as large presses are required for weights of >30kg per linear meter and above.
To meet customer-specific requirements for the design and size of heat sinks, the laser welding manufacturing process was developed. This new technology is suitable for aluminum and copper alloys. Different aluminum alloys are combined according to individual requirements.
In an air heat sink, the fins can be used in a high thermal conductivity alloy and the bottom plates in a physically stronger alloy EN AW 6060. This guarantees excellent heat transfer with through-welded transitions.
Comparison extrusion and laser welding
| Laser welding | Extrusion | |||
|---|---|---|---|---|
| Materials | Laser welding | Aluminum EN AW 10500 Base and ribs |
Extrusion | Aluminum EN AW 6060 Base and ribs |
| Size | Laser welding | 450 x 400 x 100 mm (w x l x h) | Extrusion | 450 x 400 x 100 mm (w x l x h) (heat sink width with friction stir welding) |
| Rib spacing | Laser welding | 5.5 mm | Extrusion | 7 mm |
| Rib thickness | Laser welding | 1.5 mm | Extrusion | 1.5 mm |
| Number of ribs | Laser welding | 80 | Extrusion | 62 |
| Maximum surface temperature | Laser welding | 90 °C | Extrusion | 102 °C |
| Rth | Laser welding | 16.6 C/kW | Extrusion | 20.4 C/kW |
| Pressure flow rate | Laser welding | 825 m3/h | Extrusion | 874 m3/h |
| Pressure drop | Laser welding | 265 mbar | Extrusion | 185 mbar |
| Power loss line | Laser welding | Power loss 3 kW at 40 °C ambient temperature | Extrusion | 3kW at 40 °C ambient temperature |
Performance advantage in laser welding
The performance advantage of the laser-welded heat sink results in a reduction of the RTH value of about 15% and a hotspot temperature reduction of about 12 degrees. Here in the application example, the technology was used for a converter in the field of railroad technology.
In the future, demand for specific thermal management systems for batteries and motors will grow in many industries. These include applications such as battery coolers, OBC's (On Borad Charger), Electric Motor Housing, inverters or CCU's (Connectivity Control Unit). Laser welding is the optimal technology to meet these high cooling requirements.
v.l. Temperature distribution on IGBT / Forced ventilation 825 m3/h
.Trendsetting thermal management
Laser welding has revolutionized the design of heat sinks. The new process incorporates the design of the heat sink into the product development process right at the start. This means that the design of the cooling structure is optimally tailored to the application and maximum efficiency in heat transfer is achieved. In addition to its great flexibility, this pioneering technology also offers efficient heat transfer and savings in materials, production time and product costs.
.
