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Shenzhen Tianweisheng Electronic Co., Ltd.
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Technicial Articles
Thermal management is a growing issue. According to BPA Consulting, the thermally conductive pathways created using metal in the board (MiB) enable compact, multidimensional management of heat transfer/dissipation as a cost-effective alternative to convective methods involving fans and heatsinks.
BPA Consulting has identified a variety of approaches, which include pathways in the "Z" axis (normal to the emitter), "XY" (in-plane), or both. The design choice of which way to get the heat out typically depends on:
- The thermal density;
- Number of emitters;
- Size of the substrate;
- Shortest path to ambient heatsink; and
- Thermal resistance to ambient heatsink.
These approaches can be modeled using methods ranging from Finite element analysis to ohmic equivalent circuits. The probability of multiple solutions to a given design problem creates new opportunities for innovation in materials, methods, and stackups.
Multiple Thermal Pathways: A Key Characteristic of MiB
Thermal Management Challenge
The objective is to channel the heat away from the emitter, usually a highpower semiconductor or LED. "High" is a relative term, defined by the dissipation of the device, ambient operating conditions, other sources of heat in the assembly, etc., but in modern microelectronic packaging usually means anything much more than about 1 watt.
How are designers dealing with this issue?
A typical stackup for a simple MiB LED board looks something like this:
where the metal base is usually screwed or glued onto a dissipator housing, or serves as a convective heatsink.
Where interconnection densities require more than just a single wiring layer, or other components/functions have unique requirements such as EMI shielding, digital switching, or low loss dielectrics, the problem can get more complicated.
