|
Title: more expencive thermal idea for you hardware developers? Post by: AJRGale on November 20, 2014, 03:38:54 AM i have to ask, after seeing thishttp://tem-products.com/index.php/powpeg.html (http://tem-products.com/index.php/powpeg.html) on eevblogs.
Do you developers know about these "PowerPeg Thermal Connectors" ? i want to know if they do any better then vias under the QFN chips? so it'll make the cost per chip $1.50c more, but it should hold the sink to the chips, and be a direct thermal connection to them too. Its just a thought though.. Title: Re: more expencive thermal idea for you hardware developers? Post by: TheRealSteve on November 20, 2014, 11:44:46 AM I saw them about last month, and I had a couple of concerns with their use as well as cost.
Right now they're only available for a single board thickness - while the most common, this does mean you limit yourself to that option short of making indents or shaving the peg, which you may have to resort to anyway as board thicknesses aren't nearly as uniform as one would hope. The thermal cycles that the pegs themselves go through also cause expansion and contraction (for a miner this should be a minimum, hopefully it mines 24/7) and they don't have data on how that affects the surrounding board and/or any use of solder at this time. It's not cheap. Yes, the part itself is about $1.50, now add in the set-up to put these into place. Either you'll have to make the hole big enough that a PTH placement machine could theoretically do it (once it's programmer in, and then deal with the gap, vibration, etc.), or you'll have to make it press-fit and either go to a different machine that you otherwise might not have needed to use at all, or have a human do it. Heat transfer is undoubtedly better (if using an appropriate size) than through an array of filled vias, and it's certainly worth exploring, but at some point you might as well just drill a larger hole under the chip and drop in a slab of coated aluminum and have a more fitting solution for the exact chip than the prefab pegs can deliver. Title: Re: more expencive thermal idea for you hardware developers? Post by: AJRGale on November 20, 2014, 02:09:03 PM I saw them about last month, and I had a couple of concerns with their use as well as cost. Right now they're only available for a single board thickness - while the most common, this does mean you limit yourself to that option short of making indents or shaving the peg, which you may have to resort to anyway as board thicknesses aren't nearly as uniform as one would hope. The thermal cycles that the pegs themselves go through also cause expansion and contraction (for a miner this should be a minimum, hopefully it mines 24/7) and they don't have data on how that affects the surrounding board and/or any use of solder at this time. It's not cheap. Yes, the part itself is about $1.50, now add in the set-up to put these into place. Either you'll have to make the hole big enough that a PTH placement machine could theoretically do it (once it's programmer in, and then deal with the gap, vibration, etc.), or you'll have to make it press-fit and either go to a different machine that you otherwise might not have needed to use at all, or have a human do it. Heat transfer is undoubtedly better (if using an appropriate size) than through an array of filled vias, and it's certainly worth exploring, but at some point you might as well just drill a larger hole under the chip and drop in a slab of coated aluminum and have a more fitting solution for the exact chip than the prefab pegs can deliver. hmm, good points there, i like the idea that you can use the to mount a heatsink directly to them, but as you said, thermal stresses, and mechanical stresses come into play. I had thought about drilling out the vias on some miners and filling them with a copper plug, but i have no idea if they have any tracks running between the vias. or even plugging the vias with single strand copper wires to help draw the heat out (flush cut to the board). Still though i see what people think if the idea |