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Old 03-05-2016, 11:03 AM   #16
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Default Re: Xbox 360 Xenon Motherboard Capacitor Replacements?

Originally Posted by momaka View Post
As for reflowing and reballing, we used to do that with a proper rework station. But if you all have is a heatgun, you can still do a proper reflow. Just do NOT bake the board in the oven, as that *will* destroy all of the electrolytic capacitors. I've seen this mistake way too many times.

I wouldn't say that Mad_Professor's way of doing is wrong, but I do have some things to add to that process.

First and foremost, you *will* need proper flux for lead-free solder. Regular rosin may not do so well (in fact, it may burn of and harden way before the lead-free solder melts, which may actually cause an even worse chance of successful reflow). Kingo RMA-218 is a cheap Chinese generic that works fairly well. But I think Kester had some better fluxes available.

As for the reflow process itself:

1) Clean around the chip you will be reflowing with 90+% IPA (isopropyl alcohol).

2) Make a heat shield for any nearby capacitors. I've seen way too many people not do that and pop the caps on their board. Aluminum foil works fine for that. Don't completely cover the caps, though - we are not trying to cook a Turkey here . Just cover them on the side that they are likely to get hit by hot air from the heat gun.

3) Place the board on some kind of a metal stand so that you have access to both the top side and the bottom. I usually do this by clamping metal rods to a table and have the metal rods sticking past the edge of the table. Then I place the board there, so I can have access to both the top and the bottom of the board. This way, I don't have to flip the board when it is hot, which greatly reduces stress on the various BGA components on the board. The chip you are trying to reflow/remove/rebal should always be on the top side.

3a) (Optional, but very highly recommended) If you have a type-K temperature thermometer, put the thermocouple probe near the chip you will be reflowing. Don't put it on the ship itself or under its BGA, as that may actually cause the chip to move out of place once it is hot. As for type-K thermometers, the Lutron TM-902C can be found for about $5 on eBay, and I highly recommend it.

4) Assuming you have a high-power dual temperature heat gun, turn ON the heat gun to the low setting (which should be around 500 Watts, give or take 150) and heat the board from the bottom side, focusing mostly in the area under the BGA chip you are trying to reflow.

5) When the temperature readout of the type-K thermometer reaches 150C-160C (if you don't have a thermometer, it will probably take 3-5 minutes to get up to that temperature), stop heating and gently apply flux around the edges of the chip. The hot air coming from between the board and the chip will actually suck the flux right into the BGA, so no need to worry how to put the flux under the chip. Also, do NOT drown the chip in flux. Too much flux can actually cause the solder balls to move around and short out to each other.

6) Switch the heat gun to the high setting (should be around 1000 Watts) and continue heating the chip from the bottom of the board.

7) When the temperature reaches around 180C (again, if you don't have a thermometer, this could take another 2-3 minutes), stop the heatgun and carefully move it to the top side of the board. Begin heating the top side of the board on the high setting again.

8) When the temperature reaches around 220-230C and stays in that range for 10 seconds (again, if you don't have a thermometer, this could take another 2-3 minutes), turn OFF the heat gun.

9) Let the board cool down for about 10-20 minutes (this will depend on how hot/cold it is where you are working).

10) Remove protective heat shield around caps and test the board. (Don't forget to add thermal compound to the CPU and GPU, of course. )
Firstly thanks for your quick reply yes i do have liquid no clean flux also a type-K thermometer i have artic siver five or Arctic Silver Ceramique Thermal Compound i can use (used these for a laptop reflow basically i did the same as you have wrote in this thread) and the laptop is still going strong after 1 year typing on it now infact. So just to make it clear formyself do i reflow both chips whilst i have the chance? And yes i have already made a tin foil shield with holes cut out for both chips, this xbox has the proper x clamps on still so i will replace these also on a forum ive read you can add a thin piece of aliminium sheet under the heat sinks too add more pressure on the chips whats your thoughts? and heres a link to the secondary codes etc thanks again for te help/advice.
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