# Hand soldering PS4 APU

#### metiz

Joined Oct 27, 2014
62
Would it be possible to resolder all the PS4's APU solder points by hand, without the use of solder balls? I doesn't matter if it takes a long time. When applying solder on a small solder pad, it tends to ball up on its own if you apply more solder than necessary.

#### SLK001

Joined Nov 29, 2011
1,548
If you're good enough, then yes, it can be done by hand. I don't know how many balls that an APU has, but you're probably looking at north of 300 separate pads. I use to do this by hand for chips with an 8 by 8 matrix of pads before I knew any better. I would bump the pads, then sight along the top of the solder plane for pads that were over or under and redo those.

But now, I would buy the balls (less than $3.00 for 10k of one size) and at least a generic ball stencil (maybe$10 for a generic set) and reball the chip properly. Remember that it only takes one unconnected line for your efforts to fail.

Also, remember to BAKE OUT the moisture prior to removing the part from the board. Eight hours at 125°C should be enough. Then reball and replace within 48 hours.

#### metiz

Joined Oct 27, 2014
62

I've watched a bunch of video's on the reballing proces. The PS4's motherboard is usually placed over a reflow station, presumably to heat up the board. Is that necessary, and if so, can I give the board, or at least the vicinity of the APU, a preheat using a hot air soldering rework station? I asume the preheat is to prevent any thermal stresses from building. If I heat up the area around the processor, and the rest of the board to a lesser extent, should that prevent any problems?

#### SLK001

Joined Nov 29, 2011
1,548
Mask off the area around the APU with aluminum foil and Kapton tape and use the hot air rework station as you normally would. Reball/bump with Pb/Sn solder, then place the part back in place.

#### metiz

Joined Oct 27, 2014
62
Alright thanks. One more: In some video's, but not all, I see the repair man put 1 or 2 strings of metal underneath the APU, like here

He does this for both the removal and replacement of the chip. What's the purpose of this?

#### SLK001

Joined Nov 29, 2011
1,548
I don't think that they are underneath the APU. I believe that they are just "edges" for the chip to touch so that they don't move during reflow.

It also looks like there are multiple ball sizes on the chip. How the guy in the video placed them is not known, since he "skips" that part of the process. I hope that you have the datasheet for the device, so you will know what size of solder glump to add to what pad.

#### metiz

Joined Oct 27, 2014
62
Hmm hadn't thought about that, pretty clever. I've seen several video's where the actual reballing process was included. The solder balls are the same size for all the pads, I believe either .6 or .8mm. Regardless, I think I'm going to go for the time consuming method of reballing by hand, since I would also need a stencil for the APU to correctly place them. I did order some of that Kapton tape. If there is some hight difference in the solder pads, wouldn't heating them up to melting with the reflow even them out again?

*edit* here's a pic of the business end of the apu. More than 1000 pads
http://www.taifa-gameschip.com/phot...apu_ps4_repair_parts_cuh_1109a_cxd90026ag.jpg

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#### SLK001

Joined Nov 29, 2011
1,548
I still say you're not going to have much luck doing 1000 pads by hand. Here is a $2 reballing stencil from eBay: Spend another$3 for 0.55mm balls and you're in business.

#### metiz

Joined Oct 27, 2014
62
That does seem like the better option.I thought those things were prohibitively expensive. To the ebay!

#### metiz

Joined Oct 27, 2014
62
Alright, bought all the necessary kit, including solder balls. Should be in by late next week. I'll give an update later. Any more advice you can instill me?

#### SLK001

Joined Nov 29, 2011
1,548
The stencil is placed, taped in place, then the balls are "poured in" to fill all holes. Then the whole thing, stencil and all is reflowed (hot air, oven, etc). Once the solder has flowed, remove the stencil and clean the chip (and the stencil) to remove the flux. Use heat to help remove the stencil from the device, as the flux will be very sticky.

Be sure to BAKE OUT the whole board before you try to remove the device from the board.