Introduction: How to Fix a YLOD PS3... With an Oven.
More by the author:
About: I am a sophomore in Computer Engineering at Purdue University in Lafayette, IN. Over the past few years a have fixed just about anything you can think of for friends, family, and whoever can find me. My area i…
To start, I'll first just admit that I have always been an XBOX 360 fan boy. I have done my fair share of ridiculing the PS3, and even deterred people from buying one. But that was all before Gran Turismo 5, which literally had me convinced at first sight that a PS3 was something that I had to own. So, I bought one. A broken one. A YLOD one. Now, some might think that was a stupid choice, with good reason.
However, because I was an XBOX fan, I was very familiar with the Red Rings of Death, or RROD for short. And because I am an aspiring engineer and experienced tinkerer, I had gotten very familiar (and very good) at fixing consoles with this problem, thanks to the many helpful tutorials posted on sites like xbox-experts.com. Once I discovered that the YLOD is basically the same problem as the RROD, I made the choice to buy a broken PS3 and fix it. This tutorial explains how I did it, using tips, tricks, and methods I have used to fix XBOX's in the past.
BE AWARE THAT PERFORMING THE METHOD WILL VOID VOID VOID YOUR WARRANTY (which is probably expired anyway if you are fixing a launch console). I will also say right now that I AM NOT RESPONSIBLE for any damage you may do to your PS3 or your oven (I'm talking about a conventional kitchen oven BTW, not a microwave!) by following this guide, and I do not guarantee a fixed console. But I will say that if you follow this guide, your chances are good.
However, because I was an XBOX fan, I was very familiar with the Red Rings of Death, or RROD for short. And because I am an aspiring engineer and experienced tinkerer, I had gotten very familiar (and very good) at fixing consoles with this problem, thanks to the many helpful tutorials posted on sites like xbox-experts.com. Once I discovered that the YLOD is basically the same problem as the RROD, I made the choice to buy a broken PS3 and fix it. This tutorial explains how I did it, using tips, tricks, and methods I have used to fix XBOX's in the past.
BE AWARE THAT PERFORMING THE METHOD WILL VOID VOID VOID YOUR WARRANTY (which is probably expired anyway if you are fixing a launch console). I will also say right now that I AM NOT RESPONSIBLE for any damage you may do to your PS3 or your oven (I'm talking about a conventional kitchen oven BTW, not a microwave!) by following this guide, and I do not guarantee a fixed console. But I will say that if you follow this guide, your chances are good.
Step 1: Background & Theory
So what causes the YLOD? There are several prevailing theories, including a faulty power supply, corrupted hard drive, or virus circulating through the PSN (which is probably 100% false). But, while I'm not saying that these AREN'T the cause of your particular case of YLOD, I will say that most likely, the cause of your issue are the solder balls underneath the RSX (basically the GPU, or Graphics Processing Unit) and Cell BE (basically the CPU, or Central Processing Unit) chips. These can be seen in the picture on this page. This style of fastening the chips to the board is know as BGA, or Ball Grid Array. What you really need to know though, is that under the chips their are hundreds of tiny balls of solder, which pass information from the chip to the motherboard. These balls are constantly submitted to intense heat due to the chip above them, which is being cooled by a huge heat-sink and fan.
This would all be hunky dory, except for the lead free solder which composes the chips. The European Union, a political and economic union of 27 countries, banned the importation of electronics containing lead in 2006, which has caused most electronics manufactures to switch to lead free solder in their products, even those sold in the U.S. (thanks to Entropy512 for the information). Unfortunately lead free solder has two (theorized) weaknesses. The first is that with repeated, high temperature (higher than what Sony engineers intended) exposure caused by 8 hour Call of Duty marathons or similar, followed by rapid cooling of the console once turned off, the balls begin to lose their elasticity, and eventually crack. This causes an open circuit, and when you try and power the PS3 up again, you are greeted with the YLOD. The other theory is that over time, due to the aforementioned high temperatures, the balls begin to grow "tin whiskers" which cause a short with another ball nearby, once again causing the YLOD. Which actual cause it really is doesn't matter, because the method I outline here will fix both.
This magical method is known as an oven re-flow. In a nutshell, the oven is used to heat the PS3 motherboard up to a temperature high enough to melt the solder balls underneath the RSX and Cell BE chips. When the board cools, the balls are reformed with the help of flux, which gives them back their elasticity. Don't worry, the oven will not get hot enough to "liquefy" the solder and cause it to pool into one giant glob, but only enough to cause it to "goo up" and reform each individual ball.
After the re flow, high quality thermal paste can be used to increase the PS3's cooling efficiency and lessen the chance of the YLOD reoccurring. More info on and clarification will be given on this later.
Now, the last thing is to "critique" other methods of fixing the YLOD. The main one that you may have heard of is the heat-gun method, which works, but has several downfalls, the first of which in my mind is the price. A heat-gun costs like 50 bucks at your local hardware store. The oven method is almost free - all you need are some basic supplies, which are less than 20 bucks. The other big downfall is that the heat-gun warps the motherboard because it heats one area while other areas stay cool. This means that when you put the warped board back in the case and bolt it all in, it puts stress on the new solder balls, which is never good and will help to cause failure in the future. The oven method avoids this by EVENLY heating all areas of the board, keeping flex very minimal. The other "trick" I have heard of is using a blow dryer to heat up the innards of the console. While this also works, it does not re-flow, but instead will un-flex the motherboard over its whole area (similar to the low temp. oven bake detailed later in the instructable), which causes a temporary re-alignment of the cracked solder balls. However, after a few cycles of hard gaming, the board will warp back to the way it was, and the console will fail once again. The best way to fix BGA related failure is to use a professional re-flow station and griddle, but these cost big bucks, and would be pointless to buy for a one time fix.
Alright, lets do it.
This would all be hunky dory, except for the lead free solder which composes the chips. The European Union, a political and economic union of 27 countries, banned the importation of electronics containing lead in 2006, which has caused most electronics manufactures to switch to lead free solder in their products, even those sold in the U.S. (thanks to Entropy512 for the information). Unfortunately lead free solder has two (theorized) weaknesses. The first is that with repeated, high temperature (higher than what Sony engineers intended) exposure caused by 8 hour Call of Duty marathons or similar, followed by rapid cooling of the console once turned off, the balls begin to lose their elasticity, and eventually crack. This causes an open circuit, and when you try and power the PS3 up again, you are greeted with the YLOD. The other theory is that over time, due to the aforementioned high temperatures, the balls begin to grow "tin whiskers" which cause a short with another ball nearby, once again causing the YLOD. Which actual cause it really is doesn't matter, because the method I outline here will fix both.
This magical method is known as an oven re-flow. In a nutshell, the oven is used to heat the PS3 motherboard up to a temperature high enough to melt the solder balls underneath the RSX and Cell BE chips. When the board cools, the balls are reformed with the help of flux, which gives them back their elasticity. Don't worry, the oven will not get hot enough to "liquefy" the solder and cause it to pool into one giant glob, but only enough to cause it to "goo up" and reform each individual ball.
After the re flow, high quality thermal paste can be used to increase the PS3's cooling efficiency and lessen the chance of the YLOD reoccurring. More info on and clarification will be given on this later.
Now, the last thing is to "critique" other methods of fixing the YLOD. The main one that you may have heard of is the heat-gun method, which works, but has several downfalls, the first of which in my mind is the price. A heat-gun costs like 50 bucks at your local hardware store. The oven method is almost free - all you need are some basic supplies, which are less than 20 bucks. The other big downfall is that the heat-gun warps the motherboard because it heats one area while other areas stay cool. This means that when you put the warped board back in the case and bolt it all in, it puts stress on the new solder balls, which is never good and will help to cause failure in the future. The oven method avoids this by EVENLY heating all areas of the board, keeping flex very minimal. The other "trick" I have heard of is using a blow dryer to heat up the innards of the console. While this also works, it does not re-flow, but instead will un-flex the motherboard over its whole area (similar to the low temp. oven bake detailed later in the instructable), which causes a temporary re-alignment of the cracked solder balls. However, after a few cycles of hard gaming, the board will warp back to the way it was, and the console will fail once again. The best way to fix BGA related failure is to use a professional re-flow station and griddle, but these cost big bucks, and would be pointless to buy for a one time fix.
Alright, lets do it.
Step 2: Supplies & Disassembly
Alright, so the following is what you will need:
- Four M4 X 30mm hex bolts
- Eight matching M4 hex nuts
- Two M5 X 30mm hex bolts
- Four matching M5 hex nuts
- One pack of Blu Tack, Sticky Tack, or similar (can be found at Walmart)
- Rubbing Alcohol
- No clean flux (get on ebay and search "flux RROD YLOD" and you should find the stuff. It comes in a small bottle with a pipet)
- Goo Gone Extreme, Goof Off, or similar
- Q-tips and Paper Towels (or Napkins)
- Aluminum Foil
- Arctic Silver 5 Thermal Compound (can be found at Radio Shack) OR if you're on a budget, you can get the cheaper ceramic based compound. It should still be an improvement over the stock paste, but AS5 will be better if you can spring for it.
-Oven thermometer (these are like $3 at Walmart, please please please use one if you want to eliminate all chances of melting components)
-A box fan or equivalent
As for disassembly of the PS3, I wont provide instructions because their are many good tutorials out there. My personal favorite is this chain of videos, which is actually a heat-gun tutorial. The guy does a great job of showing not only how to disassemble, but reassemble, the PS3.
http://www.youtube.com/watch?v=4_Ic1_TY-GU&feature=related
http://www.youtube.com/watch?v=Vr1zyAGwnuU&feature=related
http://www.youtube.com/watch?v=VHgCa3XEPic&feature=related
- Four M4 X 30mm hex bolts
- Eight matching M4 hex nuts
- Two M5 X 30mm hex bolts
- Four matching M5 hex nuts
- One pack of Blu Tack, Sticky Tack, or similar (can be found at Walmart)
- Rubbing Alcohol
- No clean flux (get on ebay and search "flux RROD YLOD" and you should find the stuff. It comes in a small bottle with a pipet)
- Goo Gone Extreme, Goof Off, or similar
- Q-tips and Paper Towels (or Napkins)
- Aluminum Foil
- Arctic Silver 5 Thermal Compound (can be found at Radio Shack) OR if you're on a budget, you can get the cheaper ceramic based compound. It should still be an improvement over the stock paste, but AS5 will be better if you can spring for it.
-Oven thermometer (these are like $3 at Walmart, please please please use one if you want to eliminate all chances of melting components)
-A box fan or equivalent
As for disassembly of the PS3, I wont provide instructions because their are many good tutorials out there. My personal favorite is this chain of videos, which is actually a heat-gun tutorial. The guy does a great job of showing not only how to disassemble, but reassemble, the PS3.
http://www.youtube.com/watch?v=4_Ic1_TY-GU&feature=related
http://www.youtube.com/watch?v=Vr1zyAGwnuU&feature=related
http://www.youtube.com/watch?v=VHgCa3XEPic&feature=related
Step 3: Board Preperation
So once you've stripped the PS3 all the way down to the board, there's a few things you need to do. Firstly, the old and probably dried up thermal paste on the RSX and Cell BE chips needs to be cleaned off. This paste transfers the heat from the chips to the heat sink, and if your PlayStation's paste looked like mine did, it's obvious it wasn't doing its job. To clean it, drip a little bit of Goo Gone onto the chip you're cleaning and let it sit for about 30 seconds. This will dissolve the old compound. Then wipe it away with a paper towel, and repeat. To get the edges of the chip, soak a Q-tip with Goo Gone and wipe them off. When it's clean, wipe it down with rubbing alcohol. There are pictures on this page of me doing this, if you want to see the technique. Also clean the metal pads on the heat-sink using this same method.
After the chips are clean, all the thermal pads on the board should be removed. Be careful - some may be stuck to the metal plate that covers the top of the motherboard - make sure they either stay on it, or you pull them off and put them with their siblings that you took off the motherboard. Also, if you're fixing a backwards compatible 60GB model, be VERY CAREFUL when removing the thermal pad from the PS2 chip. It seems to be very gooey and easy to tear - I included a picture of mine after I got it off - you can see what I mean. Also remove the silver strip on top of a small BGA chip (it can be seen in my pictures) and the spongy metal looking thing on top of one of the ports on the back of the board.
After the chips are clean, all the thermal pads on the board should be removed. Be careful - some may be stuck to the metal plate that covers the top of the motherboard - make sure they either stay on it, or you pull them off and put them with their siblings that you took off the motherboard. Also, if you're fixing a backwards compatible 60GB model, be VERY CAREFUL when removing the thermal pad from the PS2 chip. It seems to be very gooey and easy to tear - I included a picture of mine after I got it off - you can see what I mean. Also remove the silver strip on top of a small BGA chip (it can be seen in my pictures) and the spongy metal looking thing on top of one of the ports on the back of the board.
Step 4: Low Temperature Oven Bake
Alright, so the purpose of this step is twofold. First, it helps to gently unflex the mainboard, and second, it serves to evaporate moisture that has trapped itself in the board over time, which is critical to get rid of in order to perform a good re-flow. However, the motherboard can't just be tossed on a pizza tray and then into the oven. This is where the bolts come in. They will be used to create a simple stand for the board, so no parts of it will be directly touching the tray.
First, put a nut about 10mm down on a bolt you are going to use. The smaller M4 bolts go around the outside of the board, and the M5's go in two of the big holes in the middle (see pictures). Then, place it in a hole on the board. Now, take another nut and screw it down until the top of the nut is flush with the top to the bolt. Then tighten the nut underneath the board until it "pinches" the board tightly. No need to crank down on these - finger tightening is good enough. Do this for all the bolts. Make sure when you do the M5's that the nut on top of the board does not come into contact with any chips or other small components.
Then, set the board on an even surface like a counter-top. You want to look straight on at the board and make sure it is level. If it sags or curves in the middle, adjust the middle bolts so that it does not.
Once this is done, it's time to cook. Preheat the oven to 150 degrees Fahrenheit. If your oven will not go this low, you can go as high as 170 without insulation, but any higher and you risk damaging the board. If you simply cannot get your oven to do this you can skip this step, but it is very beneficial to do it if possible.
Alright, when the oven is ready put the board on a pizza tray and pop it in the oven for 8 HOURS. That's right, 8 hours. This ensures a completely dry and straight board, and is totally worth the wait. If possible start the bake early - then you will have time to re-flow later in the same day.
Once the wait is over, take the mainboard out of the oven and let it cool completely. Now it's time to insulate.
First, put a nut about 10mm down on a bolt you are going to use. The smaller M4 bolts go around the outside of the board, and the M5's go in two of the big holes in the middle (see pictures). Then, place it in a hole on the board. Now, take another nut and screw it down until the top of the nut is flush with the top to the bolt. Then tighten the nut underneath the board until it "pinches" the board tightly. No need to crank down on these - finger tightening is good enough. Do this for all the bolts. Make sure when you do the M5's that the nut on top of the board does not come into contact with any chips or other small components.
Then, set the board on an even surface like a counter-top. You want to look straight on at the board and make sure it is level. If it sags or curves in the middle, adjust the middle bolts so that it does not.
Once this is done, it's time to cook. Preheat the oven to 150 degrees Fahrenheit. If your oven will not go this low, you can go as high as 170 without insulation, but any higher and you risk damaging the board. If you simply cannot get your oven to do this you can skip this step, but it is very beneficial to do it if possible.
Alright, when the oven is ready put the board on a pizza tray and pop it in the oven for 8 HOURS. That's right, 8 hours. This ensures a completely dry and straight board, and is totally worth the wait. If possible start the bake early - then you will have time to re-flow later in the same day.
Once the wait is over, take the mainboard out of the oven and let it cool completely. Now it's time to insulate.
Step 5: Insulation and Fluxing
Really the only things on the board that need to be insulated are the capacitors, which are very susceptible to heat. The ports, which I insulated during my reflow, are much hardier than I expected (I left one uncovered) and do not need to be insulated. So, if you see extra insulation in my pictures, it's just ports, which can be ignored.
I have also read about people cooking the board without ANY insulation. Honestly this worries me, and I don't think I could bring myself to do this. However, I did decide to go with "light" insulation compared to typical XBOX 360 insulation because of these reports, and it seemed to work well.
This is where the sticky tack comes in. This stuff has excellent heat resistivity, and is mold-able, which is handy. Just take it and surround all capacitors on the board. Try to keep it off of big chips and mold it as compactly as you can while still leaving about .25 of an inch of thickness around the capacitors. Once this is done cover all the globs in foil, SHINY SIDE OUT. This will help to reflect the heat.
EDIT 8/24/11 - thanks to graphicsgod, I have become aware of some possible melting hazards on the board. I highly recommend insulating the component cable jack, along with the small cylindrical piezospeaker (can be seen in the first picture) in the same way you insulated the caps.
This completes the insulation, and leaves one final step before re-flowing - fluxing. The flux re-conditions the solder balls and gives them back their flexibility and strength. You need a very specific type - No Clean. This stuff does not need to be cleaned off the board like other types of flux (which eat into the solder pads to help the solder "stick") and is very liquidy. The type of choice is Kester 951, which can be had on eBay in small bottles. Just search "flux YLOD" and you'll find it. To use it, you basically take the pipet and squirt flux under the chips you wish to reflow. Now, in reality every part of the board will be reflowed, but we only need to flux the parts that have become fatigued and failed, causing the YLOD. I have outlined these specific chips in red in two of the pictures.
Here's a video which shows how to flux a 360 - the method will work for the PS3. And you don't need to be shy with this stuff - make sure you have gotten it under the chips.
http://www.youtube.com/watch?v=h2R_NqF5wAc
Once done, we're finally ready to re-flow.
I have also read about people cooking the board without ANY insulation. Honestly this worries me, and I don't think I could bring myself to do this. However, I did decide to go with "light" insulation compared to typical XBOX 360 insulation because of these reports, and it seemed to work well.
This is where the sticky tack comes in. This stuff has excellent heat resistivity, and is mold-able, which is handy. Just take it and surround all capacitors on the board. Try to keep it off of big chips and mold it as compactly as you can while still leaving about .25 of an inch of thickness around the capacitors. Once this is done cover all the globs in foil, SHINY SIDE OUT. This will help to reflect the heat.
EDIT 8/24/11 - thanks to graphicsgod, I have become aware of some possible melting hazards on the board. I highly recommend insulating the component cable jack, along with the small cylindrical piezospeaker (can be seen in the first picture) in the same way you insulated the caps.
This completes the insulation, and leaves one final step before re-flowing - fluxing. The flux re-conditions the solder balls and gives them back their flexibility and strength. You need a very specific type - No Clean. This stuff does not need to be cleaned off the board like other types of flux (which eat into the solder pads to help the solder "stick") and is very liquidy. The type of choice is Kester 951, which can be had on eBay in small bottles. Just search "flux YLOD" and you'll find it. To use it, you basically take the pipet and squirt flux under the chips you wish to reflow. Now, in reality every part of the board will be reflowed, but we only need to flux the parts that have become fatigued and failed, causing the YLOD. I have outlined these specific chips in red in two of the pictures.
Here's a video which shows how to flux a 360 - the method will work for the PS3. And you don't need to be shy with this stuff - make sure you have gotten it under the chips.
http://www.youtube.com/watch?v=h2R_NqF5wAc
Once done, we're finally ready to re-flow.
Step 6: Reflowing
EDIT 8/24/11 - I have revised this step to use a much more efficient reflow technique. Trust me, it's better and safer.
SHORT THEORY:
After reading a few articles on the reflow ovens used in industry, I realized that the method I was using was clunky and far from ideal.
In a perfect situation, a reflow should minimize time spent above the solder melting point, while still reaching a temperature somewhat above this melting point. The shorter the time, the less brittle the solder. Reaching the correct temperature ensures the solder "sticks" correctly. Also, the board must be the same temperature across its area so it does not warp.
When you plot these criteria against time, you get what's called a reflow profile. I have created one for the average home oven, which I've uploaded. Please ignore the "Soak" step - it is unnecessary due to the slowness of the oven.
So here's a quick run through of the profile: the board goes in the oven cold, and is kept in while the oven approaches the reflow temperature. This ensures the board is the same temperature everywhere (because the oven heats up slowly, giving the heat enough time to penetrate and soak all areas). As the reflow temperature is reached and surpassed, the solder melts. Once the correct temperature above the solder melting point is reached, the door is opened and a fan is used to gently draw hot air away from the face of the oven, which shortens the time the solder is liquid by speeding its cool-down.
An oven thermometer is used to 1) ensure accurate temperature readings, allowing for shorter times spent with the solder liquid, and most importantly 2) to make sure the oven does not reach a temperature that is much hotter than what it reports (some can go over by 20F or more).
THE ACTUAL STEPS:
Well, the time has finally come. Place the PS3 board on a counter top like you did when you prepped it for the low temp bake and check to make sure it is level. Then, put it on a pizza tray.
Put the motherboard in on the middle rack, towards the front of your oven. Place the thermometer you hopefully purchased in the oven, where you can see it through the door. Turn the temperature up to 500 degrees Fahrenheit. Relax. The oven will not reach this temperature. Take a seat on the floor and watch the thermometer. Once the needle rolls to approximately 460F, turn off the oven an throw open the door. The thermometer will rise a few degrees before it falls. Do not panic.
Take a box fan, osculating fan (set to not osculate), or similar, put it on its lowest setting, and place it OUTSIDE THE EDGE OF THE OVEN DOOR TO THE LEFT OR RIGHT, NOT DIRECTLY IN FRONT, WITH THE FAN BLOWING AIR AWAY FROM, I REPEAT, AWAY FROM THE OVEN, AND NOT NOT NOT INTO IT. The idea here is the pull hot air from the face of the oven, without creating any significant disturbance to the motherboard within. This will speed up the cool down, as explained in the theory. Once the board is close to room temp, feel free to remove it.
Congratulations! You've re-flowed your PS3.
SHORT THEORY:
After reading a few articles on the reflow ovens used in industry, I realized that the method I was using was clunky and far from ideal.
In a perfect situation, a reflow should minimize time spent above the solder melting point, while still reaching a temperature somewhat above this melting point. The shorter the time, the less brittle the solder. Reaching the correct temperature ensures the solder "sticks" correctly. Also, the board must be the same temperature across its area so it does not warp.
When you plot these criteria against time, you get what's called a reflow profile. I have created one for the average home oven, which I've uploaded. Please ignore the "Soak" step - it is unnecessary due to the slowness of the oven.
So here's a quick run through of the profile: the board goes in the oven cold, and is kept in while the oven approaches the reflow temperature. This ensures the board is the same temperature everywhere (because the oven heats up slowly, giving the heat enough time to penetrate and soak all areas). As the reflow temperature is reached and surpassed, the solder melts. Once the correct temperature above the solder melting point is reached, the door is opened and a fan is used to gently draw hot air away from the face of the oven, which shortens the time the solder is liquid by speeding its cool-down.
An oven thermometer is used to 1) ensure accurate temperature readings, allowing for shorter times spent with the solder liquid, and most importantly 2) to make sure the oven does not reach a temperature that is much hotter than what it reports (some can go over by 20F or more).
THE ACTUAL STEPS:
Well, the time has finally come. Place the PS3 board on a counter top like you did when you prepped it for the low temp bake and check to make sure it is level. Then, put it on a pizza tray.
Put the motherboard in on the middle rack, towards the front of your oven. Place the thermometer you hopefully purchased in the oven, where you can see it through the door. Turn the temperature up to 500 degrees Fahrenheit. Relax. The oven will not reach this temperature. Take a seat on the floor and watch the thermometer. Once the needle rolls to approximately 460F, turn off the oven an throw open the door. The thermometer will rise a few degrees before it falls. Do not panic.
Take a box fan, osculating fan (set to not osculate), or similar, put it on its lowest setting, and place it OUTSIDE THE EDGE OF THE OVEN DOOR TO THE LEFT OR RIGHT, NOT DIRECTLY IN FRONT, WITH THE FAN BLOWING AIR AWAY FROM, I REPEAT, AWAY FROM THE OVEN, AND NOT NOT NOT INTO IT. The idea here is the pull hot air from the face of the oven, without creating any significant disturbance to the motherboard within. This will speed up the cool down, as explained in the theory. Once the board is close to room temp, feel free to remove it.
Congratulations! You've re-flowed your PS3.
Step 7: Board Preparation and Re-assembly
You're on the home stretch now. To get the board ready for reassembly, you first need to remove the sticky tack and foil. It shouldn't leave too much residue on the board - if it does, just be patient and get as much off as you can. Nothing bad will happen if you leave a little on the board - it is an excellent electrical insulator.
Next, put some new thermal compound on the RSX and Cell BE chips. I recommend Arctic Silver 5 - it is much better than the stock compound. Just be careful - it has microscopic pieces of silver in it, and will CONDUCT ELECTRICITY. So keep it on the chips. To apply it, I usually put a glob on a chip, and then take a credit card or something similar and spread it out. You don't want very much - a paper thin layer will suffice. The pics I provided show about what your's should look like.
Next, put all the thermal pads you took off back on the board. Don't forget any! If you do, you could nuke an important component and kill your PS3.
The last thing I want to mention is a trick I found in a YouTube video. The little bendy clamps that hold the heat-sink to the chips (there should be two) can be bent slightly more to increase the pressure they "pull" with, which should increase the thermal efficiency of the PS3. They are really hard to bend, but a little extra bend goes a long way, so don't overdo it. I included a picture showing me bending the clamps.
Use the video's I linked to earlier to reassemble. And now, the moment of truth.
Next, put some new thermal compound on the RSX and Cell BE chips. I recommend Arctic Silver 5 - it is much better than the stock compound. Just be careful - it has microscopic pieces of silver in it, and will CONDUCT ELECTRICITY. So keep it on the chips. To apply it, I usually put a glob on a chip, and then take a credit card or something similar and spread it out. You don't want very much - a paper thin layer will suffice. The pics I provided show about what your's should look like.
Next, put all the thermal pads you took off back on the board. Don't forget any! If you do, you could nuke an important component and kill your PS3.
The last thing I want to mention is a trick I found in a YouTube video. The little bendy clamps that hold the heat-sink to the chips (there should be two) can be bent slightly more to increase the pressure they "pull" with, which should increase the thermal efficiency of the PS3. They are really hard to bend, but a little extra bend goes a long way, so don't overdo it. I included a picture showing me bending the clamps.
Use the video's I linked to earlier to reassemble. And now, the moment of truth.
Step 8: The Green Light
Hopefully you will see what I saw when I turned on my PS3. If not, perhaps your YLOD is caused by a power supply issue or something, which I will not go into here. If you still believe it's the solder balls, you could try sending it to a professional reflower or get if re-balled, but this will unfortunately cost you. But if you saw a beautiful green light like I did - congrats, you have fixed your PS3. Now try to keep it in an open area where it can breath cool air, and have fun :)