south bridge heat spreader wires

[samuel-a]

Geo

Since the subject brought up and you supplied a link, i though i'd share what i know (or think i know :mrgreen: ).
Though it might seem that way, i did not ment to be petty and i apologize if offened you.

I think it all comes down to terminology, as long as we all understand each other. Nither us or a scientist who write patents are bulletproof when it comes to writing/pronouncing mistakes.

On a side note, I do agree that the package material does somewhat act as a heat spreader, very much like all other materials on earth that absorbe and emit energy. Some are better heat conductors then other, like metals and graphite/diamond. Plastics and most organic compounds (solids) are bad conductors of heat, so it's hard for me to imagine the sole or main purpose of the packing material will be to spread heat (thereby naming it a "heat spreader").
As far as i know, the professional literature relates to the Epoxy+Resin as "Package Material" or "Mold Material" and the entire composition of these materials are considered proprietary information.


p.s. - here's the picture of the graphite sheet. it used insted of theraml grease.

 

[Geo]

no apology needed. since i started reading about these things, thats the description that stuck in my mind and ive referred to them that way ever since.i have no other term to describe them other than "that black flat piece on top of the green flat piece" :lol: after members read this topic, they will know whats meant when they are referred to as a "heat spreader".

 

[zenophryk]

So I'm wondering, once the top black piece is seperated from the bottom green piece, it looks and sounds like the only materials in the top black piece is the silicon wafer, the bonding wires, and the resin encapsulation. There's no Iron, or copper or anything else right? So if I were to incinerate a bunch of the black tops and crush that up there should be no magnetic material right? So couldn't I just throw it in some AC solution and disolve the bonding wires? is the ash going to cause much of a problem with AC? I know it would with AR.

-Z

 

[patnor1011]

So I'm wondering, once the top black piece is seperated from the bottom green piece, it looks and sounds like the only materials in the top black piece is the silicon wafer, the bonding wires, and the resin encapsulation. There's no Iron, or copper or anything else right?

That is correct.

So if I were to incinerate a bunch of the black tops and crush that up there should be no magnetic material right?

Again correct, however some of them do have round piece of magnetic metal on top but this can be separated easily after incineration.

So couldn't I just throw it in some AC solution and disolve the bonding wires? is the ash going to cause much of a problem with AC? I know it would with AR.
-Z

By AC you mean HCl/Clorox? I would say that you will save on acid spent - I mean amount of acid used if you carefully wash them with water prior dissolution in AC. Also your AC will be nice yellow and easier to be filtered if you remove burnt powdered resin.

 

[Geo]

the ash needs to be removed as much as possible because it is like a sponge and will soak up some of your solution. be sure to rinse any remaining ash well after dissolving the gold.

 

[rotorpowa]

Hi Geo, First let me say well done. I have had a go at doing these and found it very hard to seperate the gold from the crushed black top. I useed a small gas torch to get them off, first tried a bigger one but ended up with a cap that was close going bang. Everyone keep in mind that these wires are so thin and to get all the gold the black top has to be crushed very fine any uncrushed bits bigger than the thickness of the wire can contain bits of gold. I used a blue bowl to seperate and found that even then some of the gold wire wanted to ride out with the crushed material. I crushed about 30 of them and must say it looked really good in the bowl. I am going to do some more today I will take some pics

 

[Geo]

great,good going. yes it does have to be powdered very fine.the best trick to it i could figure out is to crush first and then remove the silicon chips.its easier to powder the ash after the chips are out. the chips are like glass and are very hard to crush into a powder.i used a mortar and pestle but maybe a small tumbler or ball mill would work better on large quantities.

 

[rotorpowa]

Yeah, I was thinking the same and will be working on a small ball mill soon. I also used a mortar and pestle and spent over 1 hour crushing, then wet screened it and ran it in the blue bowl. I must give credit to your panning this stuff is super fine and I spent around 2 hours with the blue bowl and had alot to trouble tring not to take out the gold aswell as the ash. I think the surface area of the wire vs the SG of the gold was causing it to pull out some of the gold and I will have to re run to see how much I missed.

 

[Geo]

after i crushed to powder,i put all the material in a pot and the pot in a catch pan. add a few drops of dish soap and fill with water. then i ran water into the pot until the water ran clear. i checked the catch pan and didnt find one wire.the picture of the small pile was done this way. i repeated this wash on that material twice.

 

[TheVogfather]

this isn't a heat spreader it just looks like one. when they build the chip layers as it gets closer to the die less outer material is needed to hold the leads in place. so really its several layers that are smaller then the main part of the chip which resembles a heat spreader.

 

[steyr223]

Geo Buddy how are the grandkids

After you are done crushing all the top parts
Dont the gold wires get crushed to?

How come all the pics are always of the whole wire
(There not even bent) :lol:

Till i actually see a pay streak as you call it ,i will never know

I will look.for the wires in my smaller bga packages

Excellent post by the way it adds the perfect info to patnors process

Thanks steyr223. Rob

 

[joubjonn]

When I do the black tops I usually get little curled wires. I don't crush the chips after incineration, just use my hands to break them up then run through a sieve then sort out the ash. I find HCl/Cl will work but it's time consuming especially if your acid/water mixture is a few inches tall and all the gold wires are under another inch of cons. AR is the way to go with these. I don't know if it's totally necessary to crush. I think lasersteve has mentioned before that as long as the chips are broken and the wire exposed the AR will get to it. I don't know how you could totally prove this to be true. It would be difficult to test.

 

[Geo]

Hello Rob. the boys are doing great and growing like weeds, thank you for asking. I was very careful to preserve the wires for the close ups. If you take a close look at the following pictures, they are all wrinkled where the ash crushed. I bought a 4" porcelain mortar and pestle to do small batches but still use a food blender for larger batches. Some of those VGA chips have a sizable copper heat spreader incorporated into the resin body. I dont recommend processing those in a blender for obvious reasons.

 

[Geo]

When I do the black tops I usually get little curled wires. I don't crush the chips after incineration, just use my hands to break them up then run through a sieve then sort out the ash. I find HCl/Cl will work but it's time consuming especially if your acid/water mixture is a few inches tall and all the gold wires are under another inch of cons. AR is the way to go with these. I don't know if it's totally necessary to crush. I think lasersteve has mentioned before that as long as the chips are broken and the wire exposed the AR will get to it. I don't know how you could totally prove this to be true. It would be difficult to test.

I believe that is for the ceramic body chips and not the plastic body chips. I recommend that ALL the plastic be incinerated and crushed or milled. Any sizable piece of resin plastic can hold bonding wires trapped. The object is to convert all the carbon to carbon dioxide or as close as you can get so all the wires will be released. Any encased wires will not dissolve.

 

[necromancer]

Geo, this is a fantastic post. Thank You So Much

i dont know how i missed this

 

[joubjonn]

It was a really old thread 2009 maybe? He was using a paper shredder on plastic IC's but I can't remember if it was the black tops or just plastic IC's. But you're probably right. I'm sure you would get a better yield crushing it all up. And I think Steve was doing that so he didn't have to incinerate which I'm sure throws another variable into the mix. Having incinerated it probably would be better to crush everything where you could get away with just shredding and not crushing for the AR to get into the crevices and dissolve the wires.

 

[eesakiwi]

To get those chips off, I just bend the board away from the chip.
Like I put the board over my knee directly under tge chip and bend it away from the chip.
Normally I hear the 'crack' as the solder breaks, then I turn the board by 90 deg and do it again.

Once the chips lifted at least one corner off the board, I slip a kitchen knife under the lifted edge.
The kitchen knifes with the bone handle work best, they are the same thickness right thru.

Then I straighten the board that lifts more of the chip off, then I lever the knife and the chip pops off.

 

[Geo]

To get those chips off, I just bend the board away from the chip.
Like I put the board over my knee directly under tge chip and bend it away from the chip.
Normally I hear the 'crack' as the solder breaks, then I turn the board by 90 deg and do it again.

Once the chips lifted at least one corner off the board, I slip a kitchen knife under the lifted edge.
The kitchen knifes with the bone handle work best, they are the same thickness right thru.

Then I straighten the board that lifts more of the chip off, then I lever the knife and the chip pops off.

Many people that scrap these things do the same thing. The only problem with it is it rips the gold plated traces from the green base. If you heat one until the epoxy comes loose, you will see a pattern of gold plated traces under the black epoxy. Other than that, rip them things off.

 

[solar_plasma]

I scrape the leftover solder balls from the PCB and save them together with the green basis for a later tin/lead/silver/gold adventure.

 

[johnny309]

I scrape the leftover solder balls from the PCB and save them together with the green basis for a later tin/lead/silver/gold adventure.

Good luck....come with numbers....how it sound tin/lead alloy 70/30.....tin/copper/silver alloy....90/7/3......gold from soldered pad ...1 square millimeter...
First of all...I will go for the Sn....giving the most present element...but....in a form of hydroxides....
i'll be tempted to do this just because I don't want metals to go wasted....and only if I got in hand over 500 lbs....
P.S.: I did that ....on a small quantity.....and it was a mess....half a kilo of solder....and 15 liters of various solutions....and in the end.....after 2 days of work...the only conclusion was ...that I need to reconsider metal bonding and complex alloys .