Some of us are also sharing professional experience. 
Designing for heat dispersion is a huge issue in battery-operated devices, and even more so in networked devices. it doesnât mean itâs hot enough for you to feel a difference when you touch the device.
By the way, have you had a chance to read any of the threads in the forum on using PIR motion sensors outdoors? Thatâs an entirely separate issue, but itâs something you should probably be aware of.
Anyway, by all means, write the manufacturer of the specific device youâre considering and ask them if itâs OK to weatherproof it with silicone or anything else.
And for those interested in technical details:
with shrinking form factor and increasing functionality and performance, portable battery power equipment is demanding more power than ever before with a limited board space, making thermal management One of the most critical design challenges today.
Unfortunately, sometimes system design engineers fall into the trap of assuming that the IC components they use in their equipment designs are also âplug and play.â It is easy to assume that if you just âconnect the dotsâ in the same way that is shown in the application diagram from the ICâs data sheet, you wonât have to do any additional analysis or validation of your design. But while the guidelines and suggestions provided in modern IC data sheets might simplify system design, they donât entirely eliminate the work that needs to be done by the product design engineer.
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Designing the power system for battery-operated equipment consists of two major sections. First, we have to choose the right type of battery technology and pack design. Second, we have to develop the electronic circuitry to charge that battery pack and convert the batteryâs unregulated ârawâ voltage into the regulated output rails needed to operate the actual system electronics. Last month, we talked about the importance of choosing the right type of battery technology as the first step. Once we do this, then the âreal workâ begins.
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A very common oversight is the lack of thermal analysis. In particular, for very low-power battery-operated equipment, itâs easy to think that the power levels are not high enough to worry about thermal management. However, remember that the power density of these handheld systems can actually be quite high.
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Table 1 shows us that even devices with low absolute power consumption need to be carefully designed, keeping thermal management in mind.
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Remember, we are cramming that low power consumption into a very tiny space. For higher power devices such as ultrabooks, notebooks and computers, heat dissipation is quite noticeable. The device actually feels warm to the touch.
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For lower power devices, with only milliwatts of internal dissipation, the end-user may not feel the unit case getting hot. However, if the dissipation in the low-power circuitry is localized to a small âhot spotâ inside the unit, there may be concerns associated with device reliability or usability. This is especially true if the semiconductor components are being operated closer to (or above) the recommended thermal limits.
When you seal it, you inevitably raise the internal temperature of the device. But beyond that, I can pretty much guarantee you that the engineering process for designing that device looked at how heat would dissipate through that specific case. Weatherproofing materials can change the thermal patterns, creating the hot spots mentioned in the article. Thatâs the main reason that that kind of process almost always voids the warranty on the device.
But again, the best thing is probably to talk to the manufacturer of the specific device youâre intending to modify. Theyâll know best what impact, if any, you can expect. 