Amount of Keyboards required for a DIY Silver Heatsink for a Nexus 4

[moriel5]

Hi, I am planning on making a 15x15x0.5mm silver heatsink for my Nexus 4 (see here for the inspiration) , and I was wondering how many keyboards do I need for this much silver?

 

By the way, aside from an incomplete Dell Dimension 4700 case transfer (I am still trying to find a compatible copper/aluminum heatsink), this is my first real hardware mod.

[kelvinhall05]

WTF why keyboards?

[moriel5]

Since I don't have the budget to get anything better, the keyboards are already non-functional (that is why I get them for free), and I have a friend who can help me extract the silver from them.

 

I have already taken out 6 sheets containing silver from 3 keyboards (each keyboard contains 3 sheets, two of which contain silver), and I am getting another non-functional keyboard from my workplace tomorrow (I had forgotten to take it today), so that is another 2 sheets on their way.

 

My boss doesn't need them (we have several keyboards for our KVM setup in the repair lab, the room I work in most, and new keyboards are cheap enough for our customers (no mechanicals, just standards)), so I take them for my pet projects.

[SquintyG33Rs]

i don't think it's silver... ?? like literally a silver sheet in the keyboard already? that sound like it's just iron. the rare metals in electronic are in very small quantities and need a few chemical baths to be extracted and then melted into ingots you can processes.

[moriel5]

Nay, it is silver.

However, it is just as you had said, the quantity is very small, and it takes quite some effort to extract it.

[mariushm]

It's highly unlikely that it's silver in the keyboards. They're probably just tinned, so that the copper won't oxidize.

 

You can buy proper heat spreader components, like this one for example : https://www.digikey.com/product-detail/en/american-technical-ceramics/QB0402A20WCATD/1284-1338-1-ND/5209931

It's exactly 0.51mm in thickness , but it's also only 1mm by 0.5 mm in size ( QB0402A20  .. 0402 means 0.04" by 0.02" and A20 means 0.020" thickness, 0.51mm). Even just two of these in the center of the chip, or 5 (one in each corner of the chip and one in the center) in some thermal paste to keep them from moving around inside the case after closing it, would be enough.

 

Alternatively, see PH3 series from t-Global Technology : https://www.digikey.com/short/q71cr9

 

It's 0.21mm thick, but you could stack 2 or 3 on top of each other (of course not as efficient as a single sheet but still better than nothing). 

Basically, they're made out of a 0.1mm sheet of copper, 0.05mm of adhesive (to stick it to the chip) and 0.05mm of polyester to electrically insulate heatsink from the case metal while still transferring heat)

A 2$ rectangle ~ 75mm x 25mm x 0.21mm will be enough for you.  Though you'd pay for shipping maybe 5-6$ ... don't know how much it's these days.

 

OR ... get a heatsink like this one which is 1.05 mm thick and made of tinned copper (copper with a fine layer of tin on top) and HAMMER it until it's 0.5mm thick... then cut a 15x15 square or whatever size you want. Copper cuts easily.

 

later edit : you'll get more silver out of silver plated wires .. for example a 13$ spool of wire  will be plated with 40 micro-inch thick silver, which will result in about 0.303 lbs ( 137 grams) of silver in 1000 feet (305 meters) ... so the 13$ spool of wire that has 30 meters of wire on it will have around 13 grams of silver on it.  But, separating it from the copper will be a bitch.

 

One cubic millimeter of silver has about 0.01 grams of silver , so if my math is right then 15x15x1mm would be 225 cubic mm of silver, so you'd need 225x0.01 = 2.25 grams of silver to make a 1 mm thick heatsink.

 

[moriel5]

From what I had read, the plastic pages do contain slivers of silver (and the keyboard I shall be recieving soon is an old high quality HP keyboard, so there may be more there).

 

Thank you very much, however I want to get silver specifically (this is for my daily driver, and the only one that can function as a phone (hardware not damaged), and is new enough to use (with a custom rom, of course)).

 

About shipping, I do not live in the US, so shipping (unless it is from China, and even then, not always), is an issue (I don't currently have the budget for anything beyond ~12-13$ per month, beyond real-life requirements, and I have already used this month's allowance on an Intel Wireless AC 7260 through eBay (the RTL8211AE on my laptop has been driving me crazy ever since I had bought my laptop, to the point that I had left the laptop completely off for half a year (back when I had still used Windows, thankfully the situation is better on Linux (it is usable, but barely, and kernel updates can always throw it off)).

[mariushm]

2 minutes ago, moriel5 said:

Thank you very much, however I want to get silver specifically (this is for my daily driver, and the only one that can function as a phone (hardware not damaged), and is new enough to use (with a custom rom, of course)).

Re-read my comment, I edited it.

You can extract a reasonable amount of silver from silver plated wire, see the link I gave you.  13$ will get you around 10-15 grams of silver if my math is right, which should be more than enough for your needs.

It may be cheaper just to go to some jeweler (or some pawn shop) and pay a few dollars for 2-3 grams of silver and maybe even ask him to shape it for you in a 15x15 mold of some sort.

Silver trades at 0.56$ per gram today, so 2-3 grams may cost you 5$ and give the jeweler guy some entertainment.

[moriel5]

Hmm... the silver wire idea is intriguing, if only I could get ahold of some, however I have no jeweler (nor pawn shop) around my place (though I do know of a pawn shop about a few hours away via hitchhike, but I have work and family (not yet a father, nor a husband, but I do need to take my sister from kindergarten, among other things) I could turn to, so I can't really take that route (my friend can also help me with molding the silver, he has the necessary tools for that as well, being a dentist that makes the fillings himself).

 

I'll think about somehow getting ahold of some wire, but until then, I don't have much choice (or much time) other than attempting to extract silver from keyboards.

 

So if we theoretically say that the keyboards contain silver, how many sheets do you think I'll need?

[mariushm]

No idea.

According to this document ( https://www.smta.org/chapters/files/UMW_Viasystems_Surface_Finishes.pdf page 9 ) , immersion silver plating results in 8-15 microinches thick plating (which is 4-5 times thinner plating compared to wires above).

In theory, you can estimate the width of the traces on the sheet and then calculate their length and then multiply by let's say 10 microinches thickness (0.0002450 mm) and you know 1 cubic mm gives you 0.01 grams of silver

So you'll need 10000 x 1 mm x 1mm x 10 microInch to get  1mm x 1mm x 2.45 mm  or 2.45 cubic mm or 0.0245 grams of silver if my math is right.

Traces on a keyboard would be 10 mils (10 thousands of an inch wide, 0.254 mm) or less so you'll need 4 traces to get the 1mm width and therefore you'll basically need 250 meters of traces to get 0.025 grams of silver?

 

It's 3:30 am here, just doing some rough math, probably am wrong...

 

 

[moriel5]

Thanks a lot, I'll try doing the math and will later post the results here.

By the, you just said that it's 3:30AM at your time, could you possibly be living in the same country as me (my current time is ~3:26AM)? Edit: I had just seen your location under your name, so we are in different countries, sorry about that.

 

Update: I am probably simply be miscalculating here, but it would seem to me that 1-2 sheets would be more than enough?

 

Since the traces seem to be ~0.03mm thick in my case, it would seem that I only need around 1-2 sheets to amass ~2-3 grams of "silver" (this is a rough estimation based upon your calculation, modified to work with a ~14.5mm long section where there are 4 traces side-by-side, and comparing it to the rest of the sheet).

Edited October 17, 2017 by moriel5
Fixing a mistake.