LED aluminum plate design options

led by the general thermal design and simulation of fluid dynamics software to do basic design.

The resistance to fluid flow: As the fluid viscosity and solid boundaries, making the fluid flow process of resistance, this resistance is called the flow resistance along the way can be divided into two kinds of resistance and local resistance.

Resistance along the way: in the same region along the border, the fluid along the entire process Friction resistance.

Local resistance: rapid changes in the border areas, such as a sudden increase or sudden narrowing cross-section, elbow and other local areas, is the state of the fluid flow generated by dramatic changes in flow resistance.

LED is usually used natural cooling heat sink, heat sink design is divided into three steps 1: According to the relevant design constraints at the contour map. 2: According to the radiator on the radiator design criteria related to tooth thickness, tooth shape, tooth spacing, substrate thickness optimization. 3: for checking the calculation.

Heat sink design

Natural cooling radiator design

Taking into account the temperature boundary layer thick natural cooling, if the spacing is too small teeth, two teeth easily cross the thermal boundary layer, affecting the tooth surface convection, so under normal circumstances, the proposed natural cooling radiator tooth spacing greater than 12mm, If the tooth height is less than Radiator 10mm, tooth spacing can be ≥ 1.2 times the tooth to determine the heat sink teeth spacing. Natural cooling radiator surface heat transfer is weak, the tooth surface to increase heat wave will not have much effect on the natural convection effect, it is recommended that heat gear tooth surface kapa pattern. Natural convection radiator black surface treatment commonly used to increase the heat radiation surface coefficient, enhanced radiation heat transfer. Due to natural convection longer time to reach thermal equilibrium, so the natural convection heat sink substrate and the tooth thickness should be sufficient to counter the impact of transient heat load, we recommend more than 5mm or more.

LED circuit design in order to better solve the heat problem, LED, and some high-power IC circuit board need to use aluminum.

From the circuit board pcb aluminum layer (copper layer), thermal insulation and metal composition of grass-roots level. Circuit layer requires a large current carrying capacity, which should be used thick copper foil, thickness 35μm "280μm; thermal insulation layer is the core technology of the PCB where the aluminum plate, which is usually filled by a special ceramic special polymer composition, thermal resistance, viscoelastic properties, excellent resistance to thermal aging, with the ability to withstand mechanical and thermal stress. IMS-H01, IMS-H02 and the LED-0601 and other high-performance aluminum plate PCB thermal insulation is the use of such technology, it has very good thermal conductivity and high strength electrical insulation; primary metal is aluminum plate support components, requires a high thermal conductivity, usually aluminum, copper can also be used (where copper can provide better thermal conductivity), suitable for drilling, punching and cutting other conventional machining. Process requirements are: gold, HAL, osp antioxidant, immersion gold, lead-free ROHS process and so on.

Substrate: aluminum plate Features: thin insulation, thermal resistance is small; non-magnetic; heat well; mechanical strength high product standard thickness: 0.8,1.0,1.2,1.5,2.0,2.5,3.0 mm copper foil thickness: 1.8um35um70um105um140um Features : High heat dissipation, electromagnetic shielding, high mechanical strength, excellent processability. Usage: LED special power hybrid IC (HIC).

Aluminum plate and the device is carrying the LED heat conduction, heat mainly by size, concentration of high thermal conductivity, thermal conductivity can choose the plate, such as the United States plates Beggs; slow thermal or thermal materials can be made general. Large price difference, Beggs plate to produce the finished product takes about 4,000 yuan square meter, general domestic material on 1,000 yuan square meters. LED Voltage is not generally very high, select 1mil thickness of the insulating layer can withstand greater than 2000V.

Thermal reference design:

Why should the thermal design?

The impact of high temperature on the electronic products: insulation degradation; component damage; the thermal aging; low-melting weld cracking, solder off.

The impact of temperature on the components: In general, temperature resistance decreased; temperature will reduce the life of the capacitor; temperature will transformers, chokes down the performance of insulating materials, general transformer, choke to allow temperature lower than 95C; temperature solder alloy will result in changes in the structure-IMC thickening, brittle solder joints, mechanical strength; transistor junction temperature rise will increase the current magnification rapidly, leading to the collector current increase, and the junction temperature increased further, eventually leading to component failure.

The purpose of thermal design

Control of all electronic components within the product temperature to work in the environmental conditions in which the standards and norms do not exceed the maximum temperature. The calculation of the maximum allowable temperature shall be based on stress analysis of components and the reliability of the product.(more information please visit www.greendyled.com)