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Solving the thermal problems of HD2 or other snapdragon powered devices

OP motoi_bogdan

15th March 2011, 11:00 PM   |  #11  
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When i will get back from my holiday i will try your thing on my hd2 as it does all the freaky parts even when doing nothing.

today i noticed 7vibrations and got scared, got artemis as a backup, using now, but after a week will try re-solder and give back feedback.

still-after few years of silence in doing electronics- i got my hermes back to life-white screen due to faulty front pcb keyboard, had tp2 and exchanged for hd2-want to see it fully working for the price i paid for it.

regards
16th March 2011, 12:10 AM   |  #12  
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Very cool thread...reminds me of days of palm pda when people were more technically
Inclined. Will have to try this out as well.
16th March 2011, 10:52 AM   |  #13  
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Just one silly question.

I mended pcb on hermes using heating torch(butane powered)

do you use the same sort of thing or special ones?
16th March 2011, 03:57 PM   |  #14  
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first of all heating up the qualcom chip is recomanded as a last resort option. however if you reheat it, pressing the chip to the board is VERRY dangerous, as it could permanently damage the BGA connection.

Here's some sort of guide on doing this. You will need a screwdriver, some 4-5 mica foil pads (you can get them from any electronic component store (get them for either TO3 or TO220 casing and cut them to the size of the cpu inside hd2) some good thermal grease (arctic silver or something for pc cpu's) an aluminum sheet for you to cut a piece of it.
* i don't recommend silicon thermal pads, use only mica crystal pads
* you can substitute the aluminum plate with aluminum/copper foil - the first is the one used for food wrapping)
* i don't recommend using anything beside a smd rework station (either hot air or infrared) to heat up the board. Although a heat gun can develop high temperatures, the air debit is to high (dangerous, you can blow up other components) and you will lack precise temperature control needed for this job.


1. Disassemble the phone following HTC's official videos. Completely remove the motherboard from the phone's casing.
2. Once you have the motherboard de-attached remove all metallic shields on both sides. Normally these prevent EM interferences from the outside to get in and mess with electric signals over the PCB. We can use them as part of the "cooling" system later.
3. OPTIONAL - efficiency yet to be determined/great risk involved - use either a special oven (not microwave !! it WILL kill the phone!) or a smd rework station to pre-heat the mainboard. Temperature must be set at around 95-110 degrees. Board must be heated from both sides, or at least one at a time, beginning with the one opposing the cpu side. Let it preheat at least 10 minutes.
3a. after preheating, use an aluminum foil to cover the rest of the components, anything other then the cpu itself then get to the actual heating, switching first to 250 degrees and directing the air stream on the cpu itself (using a larger nozzle for the tip of the heating gun). After 2-3 minutes of 250 degrees, swich to 340-360 degrees and heat the chip for another 5minutes. Move the heating gun around the surface of the chip and try to heat it evenly. If you have the guts and you are crazy enough use a knife with a larger blade and put the tip of the blade in the hot air stream in front of the cpu. Let it heat for a while, and also, continue heating the cpu. When the blade tip is hot enough press the chip with it , starting from the center and following each side. Apply even force on each press and try to have the blade as parallel with the chip possible. Don't press too hard, if you haven't kill the chip yet, that will kill it.
3b. let the board to cool down on it's own and during cooling try not to move it or do anything to it.

4. place a little amount of thermal grease on top of the cpu then place 1-2 mica foil pads (depending on thickness) over the cpu. Gently press the mica foil with one finger over the cpu. Now place more thermal grease over that mica foil and try to place the metalic shield over that area. If successfully done, the metallic shield should be in contact with the mica foil and the grease. Place back all shields on the main board.
5. On the phone's casing, measure the back of the display and try to cut an aluminum sheet of exactly the same size. If the sheet you can find is too thick - polish it and place it in a solution of either caustic soda or ferric chloride. This will get it thinner, but you have to supervise the process as if you leave it for long, the sheet could get completely dissolved. Check the sheet on short intervals (1min) to see the progress. Always use gloves and eye protection as both substances are dangerous (never mix them, use only one of them, the one you can get or already have). Once done, you will have a thin aluminum sheet that's flexible and about 1mm thick.
6. notice there are some ribbons connecting the display to the motherboard or other exposed metallic contacts. Before placing the aluminum sheet over the display's back, place some insulating tape over those metallic contacts to prevent any shortcircuit forming between them and the aluminum sheet. Next place the aluminum sheet over the display's back. Be careful not to damage any connector or ribbon in the process.
7. place more thermal grease on the cpu's metallic shield and check to see if the motherboard gets in good thermal contact with the aluminum sheet you just placed over the display's back. If there is still some space between them, use another mica foil and place thermal grease on both sides of it.
8. reassemble the phone, and make some tests to see if you get some improvements.

One more thing, this little project of our is in a "more to be seen/tested" state. As of now... only one device was fixed by this method - mine, it could have been simple luck. I don't know yet. more then a week later (strange weather also, + 20 degrees outside then last time i wrote the original post) the phone still works ok. Now running 1.3Ghz overclocked with NAND Android


@ januszgorlewski i remember the first time the phone was vibrating 7 times and i didn't know about this problem, i though it was an WM6.5 Energy Rom feature .
Last edited by motoi_bogdan; 16th March 2011 at 04:53 PM.
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22nd March 2011, 06:14 PM   |  #15  
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yep.. more than 2 weeks have passed and after i completed all possible tests the phone still works ok.
About 22-25 roms flashed (wp7, wm6.5, android, ubuntu) phone was used either normally or heated with a hair dryer. At about 30 degrees ambient room temperature, i run some 720p testing and manage to run sample videos until battery died out, then rerun the videos while charging (charging induces more heat also).
In all those 2 weeks i had only 2 restarts, both in wp7 (can't remember what rom version did that) and both occurring when i was setting up the phone after the phone update. Phone was cold however. I didn't manage to produce more restarts either when the phone heated up or i tried running intensive apps on it. Guess it was software related.
So.. i guess it's over with this problem.
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23rd March 2011, 04:51 AM   |  #16  
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This thread is awesome. I've opened my HD2 a few times in the past week to replace the LCD. Between the first time and opening it last night the LCM (LCD and touchscreen module) was slightly loose from the chassis so the screen was protruding a little and the front AP buttons were sunken. This was the case for a period of about a week, during which I noticed the phone would get very, very hot towards the bottom on the posterior surface, beneath the battery cover (around the area of the main board). Last night I properly assembled the whole device and it's now completely flush. The overheating doesn't seem to be occurring now.

I wasn't experiencing any restarts or lockups during the time it was overheating.

When I can get hold of the materials I'm definitely trying your heatsink. Thanks for sharing this.
23rd March 2011, 10:39 AM   |  #17  
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Exclamation Packaging Reliability - 7 vibration lock-ups
Thanks facdemol for your investigation and sharing.

I have been typing a lengthy description of what happend to me and then my browser hang - annoying so now only the short version
My long awaited factory fresh HD2 that failed exactly as described within 2 month at winter season. I was lucky get the original SPL back after storing it on the balcony at minus 5 and flashing from SD. Please mind, that for me the issue was heavily accelerated with the HD2 plugged in.

Yesterday I got mine back from warranty repair with the main board swapped. Since I am now anxious about this to happen again I asked about similar experience from others which has been denied. After reading this I recommend starting a petition, as this is obviously an wrong thermal design. I work as an packaging engineer and can access this as x-ray, ultrasound microscope (water bath only) and infrared imaging. Even though I dont have the time start this petition I would offer to help putting some serious reliability research behind.
So you could donate malicious hardware for inspection, as mine is still in warranty.

Few years back I had a good RMA experience with my Canon camera that died in warm humidity. After some research in the net I found the policy that all models will be replaced for exactly this failure -no matter when it occurs, as it was a design error (wrong material for CCD attach at this case).

So please people with thermally instable snapdragon devices STAND UP and ask HTC for seriously handling these mistakes. They should replace even after the warranty expiration if they only admit, it was their design flaw...

I for myself will probably try to stress my repiared HD2 in order to have this failure again and then I can opt for exchanging the device. Buth then, what device to buy? For the dual cores this might be even worse. Suppliers do not have long enough life cycles for their products to really do good redesign.

Keep it up
24th March 2011, 03:58 PM   |  #18  
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I had 7 vibrations while on the plane, just switched on, play solitaire 5min, then reset-7vibrations, took battery out, start it up, same 7vibrations, about five times same cycle.

Then i thought, ok I am done now-it's a brick, as PC's have BIOS which can tell you by beeping what the hell the problem is. In this case, no idea... Then i found this thread.

@ facdemol I might try only a heatsink - reheating cpu not needed, right? but i will wait for insurance exchange of my phone...
25th March 2011, 11:20 PM   |  #19  
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sir first of all i want to thank u for this excellent post . . . . Cn u tell some other easy material than mica foil pads which may b available .. I hav same prob with my hd2 with expired warranty .
26th March 2011, 12:17 PM   |  #20  
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the mica crystal pads should be available at any electronic components store. If you can't find any, you could try to substitute them with any other similar purpose material. Use only thermal pads used in electronics for semiconductor (transistors mostly) thermal dissipation. However from what i know or can test, the mica ones are superior to other designs or materials.
Also, good quality thermal paste is a MUST. Cheap one tend to dry out or loose effectiveness over time.

@ profahmad - yes, the back of the lcd unit is metallic. Normally it was not intended to provide heat dissipation, neither is in direct contact with the heat making components, but it takes some of the heat and spreads it over it's surface. What i did is to forcefully use this piece of metal along with the materials i used for the "heat sync" in order to facilitate better thermal dissipation. The HD2 is build on the "edge" as you can see, even if the display unit is removed or improperly mounted, the small effect in cooling the board it once had is enough now to provoke some of the thermal issues.

@januszgorlewski reheating is very risky without solid previous experience. Simply reheating the cpu didn't solve the problem for me, it only ameliorated it a bit. The new heat sync did the trick so i suspect you can skip reheating with not much of a loss in effectiveness. However i should have experienced with more devices in order to know for sure the effects of each stage of my experiment.

@sqeeza yes, a petition could be filed out. However, there are 20-30 topics in this area about hd2 freezing or restarting but most people don't know there is a thermal problem related with these events. If we advertise the problem and it's cause to these people they could run some simple test to determine if their phones are also suffering from this problem.

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