Intel 5400 Northbridge profile

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Intel 5400 Northbridge profile

Postby ruckusman » Thu Jul 06, 2017 10:16 am

Hi Guys,

my first post here, though not my first FC-BGA reflow. I've had success with both main board mounted graphics and discrete graphics previously.

Anyway I've decided to reflow the Intel 5400 Northbridge chip on a 2008 Mac Pro logic board as a last step prior to basically parting the system out.

It will boot very occasionally, however initialising the graphics is the intermittent part of both the boot process and spontaneous reboots. CPU's reseated and thermal paste re-applied to both CPU's and northbridge chip as well as minimum memory config have all been part of my diagnostic process. I basically have nothing to lose at this point.
That said I do want to maximise my chances of success in the rework as much as a troubleshooting exercise and personal satisfaction perspectives.

So I've found a very informative document published by Intel on smt board assembly which has some excellent sample reflow/rework profiles on pages 12 & 24.

https://www.intel.com/content/www/us/en ... guide.html
same document as a PDF here
https://www.intel.com/content/dam/www/p ... -guide.pdf

I am unable to locate the Intel BGA/OLGA Assembly Development Guide referenced in the https://www.intel.com/content/dam/doc/d ... elines.pdf

The reason I am posting is because the smt board assembly guide above has removed all references to PB based solder in the 2016 revision.

Now this board dates from 2007/2008 prior to PB free RoHS soldering initiatives and I know this will obviously affect the rework maximum temperature.
There are no RoHS marking on the top side of the board.
I am yet to remove it from the case to do the reflow so there may be a marking on the underside.

Now assuming that it's not PB free, which may be incorrect, do you feel it's safe to work in the upper temperature range for the preheat and heat soak for SnPb solder, prior to going to the point of liquid for lead - checking the chip for movement, if it is still rigid, then continuing to ramp up the rework temperature for SAC305.

Given that the 225 degree peak reflow temperature for PB solder is close to the 220 degree liquid temperature for SAC305 I shouldn't be deviating from either profile too radically.

I have a good temperature controlled, variable airflow rework station and temperature probe so I won't be guessing at the temperatures at the board at least.

happy to hear your thoughts

thanks

Glenn
ruckusman
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Intel 5400 Northbridge profile

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Re: Intel 5400 Northbridge profile

Postby Deus » Thu Jul 20, 2017 9:13 am

It's most likely ROHS compliant as this was obligatory, in EU at least, from 1 july 2006.

Shouldn't it be, then you can idd check for movement if you want to stay on the safer side but as you said yourself 225 should be ok too.

On this:
ruckusman wrote:I have a good temperature controlled, variable airflow rework station and temperature probe so I won't be guessing at the temperatures at the board at least.

You mean that W.E.R. 852D (isn't it W.E.P. 852D)? You want to reflow or reball it with that?
Not saying it's bad, but not that much power. Luckily it's not a very large bga but it does have a heat spreader on it.
Hope you have a preheater?
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