Challenges of PCB Heat Sinks

In both processes, pressing down the board with the heatsink was a challenge. . The surface distribution of thermal adhesives without air pockets between the two components was an unsolved problem, especially due to the low flow of thermal adhesives. Sufficient compression was achieved by pressing with so-called pressure pins. distribution, but this method is only applicable to a certain extent. The result is often that, especially on thin and large-area ceramic substrates, punctual and excessive force action causes the ceramic plate to fracture.

Solutions for PCB Heatsinks

After applying adhesive strips to the heatsink and attaching the circuit boards, the unassembled components are directed into a miniature vacuum chamber. Due to the small size of the vacuum box (15 X 12 X 7 cm3), evacuation and subsequent ventilation are only It takes one second. When evacuating, all air, including between the track of the sticky bead or between the heat sink and the board, is completely removed. When venting, the rapid increase in air pressure means that the board is evenly Press. Gap size is defined by adding larger solids to the adhesive. These are evenly distributed in the thermal paste and determine the gap size across the board area. Finally, the gap distance is defined based on the size of the solids .

However, not all dosing systems are suitable for this application. The ideal piston dispenser is designed for large particles and can handle highly filled abrasive binders even when used for extended periods of time.

The main problem developers face is and still dissipates heat loss from the chip. However, the way to connect the heat sink to the heat source is very different. How are they different?

Microelectronic circuits are becoming more and more complex and provide more and more computing power. The resulting power losses and how to effectively install heat sinks for the most efficient heat dissipation remain major challenges for developers. Although increasing The electronic components consume less power, this problem is still a major problem.
The question is the best way to mount the heatsink so that it can be disconnected if necessary connection, and at the same time can provide the best cooling effect. (Functionality). Many methods of attaching heat sinks to electronic components have been developed to dissipate the heat generated by data processing chips during operation.

Use the circuit board as a heat sink

As the heat dissipation per unit area of a PCB increases with the miniaturization of electronic components, thermal management becomes increasingly important. How components heat up depends on the "bottom" and "top" resistors and the heat dissipation from the copper on the board. Next Article The article explains how to optimize thermal management here.

In short, a printed circuit board is a laminate made of copper-clad plastic sheets pressed with the help of synthetic resin and fiberglass. With the exception of copper, the materials involved have poor thermal conductivity. Nonetheless, most Components without a printed circuit board have no chance of thermal survival, as they do not have the surface area necessary for the PCB to dissipate heat: only through heat transfer into the printed circuit board, and the heat spread there (or through an attached heat sink) can be Release heat to the environment at low temperatures.

With standard material FR4, it is recommended to The maximum temperature under value load is about. 135 degrees Celsius. Bending and delamination can occur at higher temperatures, thereby losing functionality. Table 1 shows the thermal conductivity of materials in a printed circuit board.

Thermal power loss of components

How much a component heats in a component depends on its thermal power loss, which is the "bottom" thermal resistance between the component and the circuit board, which is the "optimal" resistance between the top of the component and the air, especially from the copper on the circuit board resistance to heat. Depending on the component type, bottom or top resistance (and therefore temperature rise) can be reduced by using suitable cooling hardware (underfill or heat sink).

However, hot spots (and therefore target areas for cooling air and radiation) can also be amplified by using appropriate copper in the layout; thus reducing the temperature and also reducing thermal stress in the board caused by temperature differences. Suitable for Small components such as LEDs, this is the only cooling method (possibly combined with thermal vias).