Heat sink modding... thermal mass vs surface area?

[eccerr0r]

Well, my Gateway monitor seems to eat caps. So I was thinking there was some systemic issue going on here and what I'm thinking: the heatsink is blocking convection flow and thus roasts capacitors by radiation!

Now what I wonder. This piece of aluminum heatsink is obviously blocking convective flow. I could add a fan but there are some other issues involved here. How about...drilling holes into the aluminum?

The holes would add surface area and allow air to convectively flow through the heatsink which could reduce temperatures. However this would of course reduce the thermal mass of the heatsink which might cause other issues.

Some mechanical engineering/fluid dynamics at work here... hmm! But a design defect here methinks.

(And I'm out of 1000uF 25V low esr caps... sigh.)

[sam_sam_sam]

Re: Heat sink modding... thermal mass vs surface area?

I can not see how add a small cooling fan is going to all of that unless you just do not have the room to put a fan on the heat sink that a hole another story

I have a boost converter that has a fairly good size heat sink and a very small cooling fan I found this to be a little odd that a designer would go this route because there is enough room to put a bigger cooling fan on it or another small cooling fan on the other end of the heat sink

[eccerr0r]

Re: Heat sink modding... thermal mass vs surface area?

There is no room for a cooling fan really, at least without making the monitor fatter than it already is...

[eccerr0r]

Re: Heat sink modding... thermal mass vs surface area?

A picture of the crappy heatsink...

There is a metal shield on both sides of the PCB with almost no gap.

The dual diode MBR10100CT points straight downward. Seems the capacitors are basically radiated upon...

[sam_sam_sam]

Re: Heat sink modding... thermal mass vs surface area?

A picture of the crappy heatsink...

There is a metal shield on both sides of the PCB with almost no gap.

The dual diode MBR10100CT points straight downward. Seems the capacitors are basically radiated upon...

How tall is the heat sink is at least 40mm because you can get 40 mm fans there seems to be a space on the back of the heat sink in one corner I do not know if you can find a 30 mm fan or not but I would try it if the heat sink is extremely hot running it might help in the long run

[eccerr0r]

Re: Heat sink modding... thermal mass vs surface area?

around 25mm; maybe 30 mm or so with the board standoffs... the metal case just barely has space to fit standoffs and the board.

[sam_sam_sam]

Re: Heat sink modding... thermal mass vs surface area?

around 25mm; maybe 30 mm or so with the board standoffs... the metal case just barely has space to fit standoffs and the board.

I hate manufacturers that do this crap I really do not think that they care if and how long something will last just get it out the door and it is not my problem anymore

What about putting the fan in such a way that it blow on the heat sink ( and be mount on the case or on the heat sink where I have the text on the picture that you posted ) of the device just a thought I did this once and surprisingly enough it turned out better than I expected it to in fact it look like it was made that way but it took a lot of planing and a lot of patience to pull this off ( I have seen both extreme hot having enough cooling and to much cooling when not need and in both cases really are you kidding me )

It might not matter to much if you can put it where it can not be seen easily it is just a thought

I just bought a ZD-987 soldering iron/gun combination that I know is going to have a heating issue that I am going to have addresses because how this unit is setup and because of the amount of heat that is generated the switching power supply heat sink enclosure and it has two of them and you have the vacuum suction pump heat as well and this unit has the same very small cooling fan only on one side of it really are you kidding me you as a manufacturer of a device would do this crap

I would be running them at the same time and for hours at a time failure is just around the corner

[eccerr0r]

Re: Heat sink modding... thermal mass vs surface area?

Blowing on the heatsink is one thing but the main problem is that the airflow is blocked by the heatsink itself... Can put a fan underneath but after it blows, the hot air has nowhere to go...

... hence if I drilled holes or cut slots into the heatsink, at least air will go through the heatsink and that's beside the advantage of having more surface area... though again loss of thermal mass/conductivity due to the holes...

[sam_sam_sam]

Re: Heat sink modding... thermal mass vs surface area?

though again loss of thermal mass/conductivity due to the holes...

I really do not think that this would be a big issue I could be completely wrong

I would think that if you drilled very small holes through the heat sink where the fan is mounted I really do not think that you would loss that much thermal mass but you might gain a cooler heat sink in the long run

[eccerr0r]

Re: Heat sink modding... thermal mass vs surface area?

but the idea is larger holes to let more air through instead of blocking... tough choice ...
In any case it would be best to have... no fan. Monitors usually don't have fans...

[stj]

Re: Heat sink modding... thermal mass vs surface area?

can you get a long thin cap and mount it under the board?

[eccerr0r]

Re: Heat sink modding... thermal mass vs surface area?

BTW the photo has a missing cap there that was removed... and there's another removed one right next to it just to the right and bottom above the heatsink. The two caps are both 470uF 25V and connected in parallel. I had a 1000uF there bent (see the picture in the other thread) to allow heat to escape, but as seen it died anyway.

So, need 1000uF (and there's less than 4mm clearance on the bottom side and almost 0 to the top)...