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Forum Index : Microcontroller and PC projects : Maximite processor heatsink
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BobD Guru  Joined: 07/12/2011 Location: AustraliaPosts: 935 |
I can't find the thread but some time back some of the Maximites were having trouble with the processor thought to be overheating. There was a search on for heatsinks. Jaycar have one that may be a possible. See it here . It may be a bit big at 21x21x6.2mm but it does stick on which was one major requirement. |
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boss Senior Member  Joined: 19/08/2011 Location: CanadaPosts: 268 |
Hi Bob, http://www.ebay.ca/itm/5-Pcs-10x13x11mm-Heatsink-Heat-Diffus e-Aluminium-Cooling-Fin-/310466974749?pt=LH_DefaultDomain_0& hash=item484946141d These fit for me and they are for good price. JB Weld for gluing on chip work perfectly. |
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donmck Guru Joined: 09/06/2011 Location: AustraliaPosts: 1313 |
Boss, I took the liberty of making the URL linkable, and also made it link to the Australian site: http://www.ebay.com.au/itm/5-Pcs-10x13x11mm-Heatsink-Heat-Di ffuse-Aluminium-Cooling-Fin-/380503631886?pt=AU_B_I_Electric al_Test_Equipment&hash=item5897c8a80e JB Weld is available in Australia, but apparently only in QLD: http://jbweldit.com.au/index.php?main_page=product_info&cPat h=1&products_id=1 The heatsink price is good, just wondering if the glue can be found on local shelves, or if anyone had tried an alternative. EDIT: Just found it at Jaycar. not cheap however: http://www.jaycar.com.au/productView.asp?ID=NA1518 Don... https://www.dontronics.com |
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djuqa Guru Joined: 23/11/2011 Location: AustraliaPosts: 447 |
People still use Jaycar?? I surely don't because they refuse to accept the need for online businesses to accept PayPal. Plastibond is an acceptable alternative to JBweld. I have serviced computers where the Manufacturer used/specified to use it. VK4MU MicroController Units |
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| boss Senior Member Joined: 19/08/2011 Location: CanadaPosts: 268 |
Hi, Jaycar price is as twice high as price in US. Try look local Wallmart store if you have one in AU. They keep it in the automotive department. Another possible source can be some car store. Tested and it works for years. Regards boss |
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| donmck Guru Joined: 09/06/2011 Location: AustraliaPosts: 1313 |
Thanks Boss, unfortunately there are many products in Australia that are double the US and other countries prices. The general public are now waking up to this because of the internet. I would consider that the members of this forum will already know, as they are internet savvy. As David suggested, their are alternatives. We don't have Wallmart. I just looked at some of the JB Weld products on ebay, and in some cases, they want $30 for postage. So many things are scams these days. Don... https://www.dontronics.com |
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| boss Senior Member Joined: 19/08/2011 Location: CanadaPosts: 268 |
Hi Don, the same situation is in CANADA. Almost everything is overpriced and it is a "crap" compare to same goods in the US. The car made in CANADA and purchased in CANADAis 20-30% expensive and have less features than the same car made in CANADA and purchase in USA. Fortunately I'm living 40km from US border and once in week we are traveling to US for shopping. That's life boss |
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| donmck Guru Joined: 09/06/2011 Location: AustraliaPosts: 1313 |
Example: Chevy Volt US Price $31,645 Chevy Volt AU Price $62,000 (Estimated last time I looked.) Why would anyone want to try this new technology at these prices? Don... https://www.dontronics.com |
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| paceman Guru Joined: 07/10/2011 Location: AustraliaPosts: 1329 |
The JB Weld is no doubt strong but what we're looking for is thermal transfer. Probably the best there is for this is "Silver Thermal cooling Heatsink Compound". Not cheap at $5.20 for a 1.5g syringe (Rockby - Stock No. 34274 Rockby) but you only use a tiny amount. Greg |
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| djuqa Guru Joined: 23/11/2011 Location: AustraliaPosts: 447 |
Thermal compound is not good as an adhesive. The epoxy adhesives mentioned have more than enough thermal transfer to suffice. VK4MU MicroController Units |
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| BobD Guru Joined: 07/12/2011 Location: AustraliaPosts: 935 |
The Jaycar heatsink has its own adhesive thermal transfer tape. This is the Jaycar description. Heatsink Pin Grid Array with Adheasive Thermal Transfer Tape
This heatsink makes a perfect partner to Star LED modules. It doesn't get quicker or easier than this! Just peel the backing from the pre-mounted thermal transfer tape, press the Star LED (or whatever device) to the heatsink and SHAZAM!! It's ready to go! Don't be fooled by the compact size. The "pin grid array" design provides excellent thermal resistance and heat dissipation. HH-8580 Size: 21x21x6.2mm Thermal Resistance: 5.9 deg C/W |
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| jdh2550 Regular Member  Joined: 16/07/2012 Location: United StatesPosts: 62 |
I was told that JBWeld actually has pretty poor thermal transfer characteristics (we thought it would be good). The best practice that was suggested was epoxy adhesive around the perimeter and thermal paste in the middle. BTW, if there's a US product that you want I'd be happy to buy it and send it to you... (not sure about the Chevy Volt though!) |
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| boss Senior Member Joined: 19/08/2011 Location: CanadaPosts: 268 |
Good morning, the problem is how to fix heatsink on the top of the chip. Thermal compound is a paste and not strong enough. There are some kind of epoxid based materials for electronic on ebay but in large quantity (and price). JB Weld is not designed primary for electronic circuit but it works and one set last you for years. I'm not JB owner or dealer.  Probably any kind of strong enough and chemicaly neutral adhesive will be OK. Just look at local shops.
Regards boss |
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| jdh2550 Regular Member Joined: 16/07/2012 Location: United StatesPosts: 62 |
I agree that thermal paste isn't glue, and my answer was based on using a thin bead of epoxy around the perimeter to fix the heatsink on top of the chip while having thermal paste in the middle for it's superior thermal characteristics. We were told by an "adhesives expert" that JB Weld has poor thermal conductivity. In fact I think he indicated it would act as insulator rather than conductor. So, glue & paste seems to be the best of both worlds - good strong bond thanks to the epoxy & good heat transfer because of the thermal compound. |
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bigmik Guru Joined: 20/06/2011 Location: AustraliaPosts: 2914 |
Hi All, Wouldn't it be better to use something designed for the job that can be removed easilly enough if needed. Like this Thermal Adhesive Tape ?? Even factoring in postage its not too bad you would have enough there to do about 64 PIC32 chips for $7. Regards, Mick Mick's uMite Stuff can be found >>> HERE (Kindly hosted by Dontronics) <<< |
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| paceman Guru Joined: 07/10/2011 Location: AustraliaPosts: 1329 |
That may or may not be the case, depending on the individual chip and presumably the program and other hardware it's running. It still surprises me that some forum members have a heat problem at all because in my MM (Altronics, second batch) the chip only ever gets just warm to the touch running MMBasic V4 and any program I use. The lid of course is removed when I've "tested" the temperature and that no doubt makes a difference. Also the current draw (about 140mA) doesn't seem to change much with different programs, (measured on the 9v supply), which maybe is because the PIC32 and MMBasic interpreter by itself is the biggest load, running a program or not - not sure about this point though. Since the outer case temperature doesn't seem to change much from ambient (on mine at least), putting a heatsink on it is unlikely to improve things for most people. If we assume the video jitter some members see is caused by chip temperature, I'd wonder whether there's been a marginal batch get through quality control - is it possible to ID different batches/manufacture dates from the chip markings? Something the affected members could try, would be to remove the top cover and see if the jitter problem persists. If it goes away maybe simply drilling a few holes in the case (sides and/or top?) might do the job. Greg |
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| shoebuckle Senior Member Joined: 21/01/2012 Location: AustraliaPosts: 189 |
Jitter occurs with mine with the case open. Cooling the Pic with a freezer can stops it, but it soon returns. I suspect that I have a marginal Pic. My best option will be to try a heat sink. Cheers, Hugh |
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| paceman Guru Joined: 07/10/2011 Location: AustraliaPosts: 1329 |
Hi Hugh, The datasheet for the PIC32 family (all 250+ pages of it) has the markings info on page 215 and says: Legend: XX...X Customer-specific information Y Year code (last digit of calendar year) YY Year code (last 2 digits of calendar year) WW Week code (week of January 1 is week ‘01’) NNN Alphanumeric traceability code The X's are the chip type designation e.g. PIC32MX695F512...etc and are on the first two lines on the chip. The rest, i.e. Y's, W's and N's are all contiguous on the bottom line e.g.: 0901157 where 09 is the year, 01 the week number (starting 1st Jan) and 157 the "traceability" code - presumably batch number. What is the bottom line on yours? If you and the other members reporting heat problems report your bottom line maybe we can see a common denominator. Or if others that don't have a problem have the same designation we can probably rule a bad batch out - but individual chips could still be a problem e.g from board manufacturing (soldering?). Greg |
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| isochronic Guru Joined: 21/01/2012 Location: AustraliaPosts: 689 |
If the pic32 is still only at forty degrees or so, a heatsink is not going to have much effect, especially when summer hits. 
One known cause (in general) of temperature affecting timings etc is when a r-c oscillator is used, the temperature causes resistance change and thus frequency and timing. The output video synch timers (timer3 ?) might use the optional r-c option ? There is manufacturing variation in the chip r-c oscillators as they are not meant to be precise, and usually the spec is a range. |
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